Anatomy of apical third/ dental implant courses by Indian dental academy

Anatomy of the apical third INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com

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Achievement of a perfect seal at the apex using an inert filling material is the ultimate goal for every endodontist. The crux of endodontics revolves around the efficient and effective manipulation and obturation of the apical third of the root canal. The importance of a thorough cleaning and hermetic filling of the apical part of the canal for successful healing of the periapex was highlighted analogically as early as 1939 itself, by Kronfeld.

Appreciable knowledge of the morphology of this ‘small zone’ and its variance, ability

to interpret it correctly in

radiograph, and to ‘feel’ it through tactile sensation during instrumentation are essential for an effective rendering of the treatment of root canals. www.indiandentalacademy.com

CONTENTS  Anatomy and Histology  Eruption, Root Length and Apical Closure  Morphology of Apical 1/3rd  Anatomical variation and pathology in Apex  Length determination at apex  Instrumentation  Preparation of Apical Zone  Irrigation and Apex  Obturation and Apex  Repair at Apex  Periapical Surgery and Apex  Recent Advances

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HISTORY  1929 – Stallard stated that the final root end completion occurs by down growth of the epithelial root sheath after eruption and occlusal contact with opposing teeth.  1980 - Ten Cate proposed that development of apical foramina on number of invaginations of root sheath.  Frank 1966, Steiner (1968) Heithersay (1970) Ham (1972 Holland et al (1973) – CaOH emerged as material of choice for apexification.  1955, 1956, 1960 – Green studied the correlation of apical foramen to the actual www.indiandentalacademy.com apex.

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 1925 - Hess, 1960 – Kramer, Studied lateral accessory canals and apical delta’s in detail.  1958 – Kuttler detailed the cemento dentinal junction.  1968 – Seltzer et al studied the deleterious effects of overzealous

instrumentation

beyond

the

apical

foramina.  1950 – Grossman suggested filling right to the apex.  1951, 1958 – Kuttler suggested filling till CDJ.  1976 - Altonen and Matilla concluded that insufficient apical sealing as significant factor for failure of www.indiandentalacademy.com

periapical surgeries.

Anatomy of Apical Canal According to Kuttler, the narrowest diameter of the canal is definitely not at the site of exiting of the canal from the tooth but usually occurs within the dentin, just prior to the initial layers of cementum.

He referred to this position as the minor diameter of the canal, although others call it the apical constriction. The diameter of the canal at the site of exiting from the tooth (major diameter) was found to be approximately twice as wide as minor diameter. This means that the longitudinal view of the canal as a tapering funnel to the tip of the root is incorrect.

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Because the adjacent walls of cementum are slightly convex or hyperbolic or funnel shaped when viewed in long section, the configuration of the area between the minor and major diameters resembles that of a morning glory of a flower.

Histological Development of Root Structures During tooth development, the inner and outer dental epithelium fuse to form the cervical loop, which invaginates into the underlying connective tissue. The epithelial root sheath consists of inner and outer epithelial cells.

The inner epithelial cells form a

filamentous layer which is associated with the basal lamina. www.indiandentalacademy.com

After making contact with the basal lamina of the inner epithelial cells, the odontoblasts fully differentiate and then produce dentin. Following dentin deposition, the odontoblastic processes withdraw from the epithelium and the outer layer of root dentin.

The root sheath determines the number, size and shape of the roots (Ten Cate, 1965) and the future cementoenamel junction.

It then becomes known as

Hertwig’s epithelial root sheath. The invaginated portion remains as a continuous layer until the dentin of the root is formed.

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After dentin,

deposition Hertwig’s

disintegrates

in

of

root

sheath

a

coronal

direction following the ingrowth of the connective tissue of the dental sac.

When the root

sheath begins to disintegrate, cells of the connective tissue differentiate into cementoblasts, and cementum is deposited on the dentin. www.indiandentalacademy.com

According to Orban (1928), the root apex remains in its

place

during

eruption,the

tooth

and

surrounding

supporting structures move occlusally, with continual root formation. There is little bone formation opposite the root apex, whereas large quantities of bone formed in the bifurcation regions of the erupting teeth. After eruption and occlusal contact with an opposing tooth, further down-growth of the root sheath provides the matrix for final root end completion (Orband and Mueller, 1929).

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Eruption and Root Apex Eruption represents the process of movement of the teeth from their functional position in the dental arch.

A

unified concept has not yet emerged. Previous theories have included the roles of collagenase in the dental follicle (Cahill, 1970, Woessner and Cahill, 1974) and increased pulpal pressure (Van Hassel and McMinn, 1972).

A predominant theory holds that the motility of the periodontal fibroblasts actively generates the eruptive force.

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Root Length and Apical Closure

The root length and apical closure are completed for the permanent teeth according to the following schedule,

varying

somewhat

according

to

sex

differences.

It is obvious that mature root length is obtained for all the permanent teeth, with the exception of the second and third molars, by 12 years of age. www.indiandentalacademy.com

Ages of Tooth Eruption and Calcification of Root Apices (in years) Centr Later Cus First Secon Firs Seco al al pid Prem d t nd olar Premo Mol Mola Incis Incis or lar ar r or Erupt 6-8 ion

7-9

1012

9-11

11-12

5-7 12-13

Calci 10-12 11ficati 12 on

1314

12-14 13-14

10- 15-16 11

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Clinical Correlations in Endodontic Therapy Successful repair of inflamed dental pulps in teeth with incomplete apical root closure is enhanced compared to that teeth with

completed

root

formation,

possibly

because

of

the

unrestricted metabolism in the former group (Ouostarinen et al, 1966). Thus pulp capping or pulpotomy procedures have a better chance for successful resolution in teeth with open apexes.

Once root end has been completed, complete endodontic therapy has a better prognosis than pulp capping or pulpotomy procedures. www.indiandentalacademy.com

APICAL PULP TISSUE  The apical pulp tissue differs structurally from the coronal pulp tissue.

The coronal pulp tissue consists mainly of

cellular connective tissue and fewer collagen fibres. The apical pulp tissue is more fibrous and contain fewer cells.  This fibrous structure appears to act as a barrier against the apical progression of pulp inflammation. However, in partial or total pulpitis complete inhibition of inflammation of periapical tissue doeswww.indiandentalacademy.com not usually occur.

Clinical correlation in Endodontic therapy A vital pulp extirpation involves severance of pulp tissues somewhere in the apical region of main canal.  Actually plane of severance of the pulp tissue from the periodontal ligament is not under complete control of operator. The separation can occur anywhere in the root canal or even beyond the apical foramen, somewhere in periodontal ligament.  When the latter type of pulp severance occur, the www.indiandentalacademy.com

ensuing hemorrhagewww.indiandentalacademy.com causes painful pericementitis.

Blood & nerve supply – apical pulp The fibrous structure of the apical pulp tissue supports the blood vessel and nerves which enter the pulp. The pulp of tooth is supplied by a no. of blood vessels which originate in the medullary space of the bone surrounding root apex. The blood vessel course between the bone trabeculae and through periodontal ligament before entering apical foramina as arteries or arterioles. The blood vessel ramify in the apical pulp tissue. www.indiandentalacademy.com

 These vessel are surrounded by large medullated nerves which also branch after it enter the pulp.  The intimate relationship of blood and nerve supplies of the pulp and periodontal ligament provides a background for the inter relationship of pulp and periodontal disease.

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Apical Dentin  In the apical region, the odontoblasts of the pulp are absent or flattened or cuboidal in shape. The dentin that is produced is not as tubular as coronal dentin but, is more amorphous and irregular. This type of dentin is sclerotic dentin. The amount of sclerotic dentin increases with age (Azaz et al 1977, Johansen 1971).

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SEM and TEM studies have shown that the translucency of the apical dentin apparently results from diminution in width of the tubules.  The dentin becomes optically transparent being uniform enough to avoid scatter of transmitted light.

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 The sclerotic apical dentin is considered less permeable than the coronal dentin.

This reduced permeability is significant because the sclerosed dentinal tubules are less readily penetrated by microbes and other irritants.

 Towards the apex of teeth, the dentinal tubules appear to blend with cementum canaliculi.

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The apical foramina tend to become obliterated both by the deposition of 20 dentin within root canal and by the deposition of cementum outside the root canal.

 Continuous dentin and cementum deposition throughout life gradually tends to reduce the width of apical foramina, but complete closure does not occur as long as vital pulp tissue remains. www.indiandentalacademy.com

Apical Cementum Cementum formation begins in the more apical region of the tooth, spreading toward the crown.

Cellular cementum containing cementocytes, is usually found around apical and furcation regions of the tooth.

Sharpey’s fibres - 20µm, are embedded in both surface and deeper layer of tissue.

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When heavy stress is placed on tooth, thickened amount of cementum is elaborated, increasing the area of periodontal attachment and strengthening the supporting mechanism this increased deposition of cementum is in response to function and is known as hypercementosis (hypertrophy).

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“A

histological

examination

of

a

root

canal

demonstrate that we are dealing not with a canal but rather with a root canal system complete with torturous turns, apical foramina, at times with accessory canals. This ‘real’ picture is far different from image evoked by word-’root canal”.  This root canal system whose shape has been altered by age, operative procedure, decay and trauma is unique for each tooth and is different from tooth to tooth. A standardized root canal is non existent. www.indiandentalacademy.com

- Lukes & Bolatin

Morphology of the Apical third Root canal system :

•Apical part of root canal •apical foramen •Accessory & Lateral canal

Apical part of root canal • Morphologically – this is the most complex region; therapeutically-a challenging zone,prognostically – an important part; unfortunately radiographically – the most obscure & unclear area. However an endodontic treatment is almost always gauged by the way the root canal filling appears in apical 1/3 in the post filling X-ray.

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A detailed knowledge of apical part of root canal system is essential as it is common area for procedural error (e.g.

Ripping, zipping, ledging, false canal formation, instrument breakage etc) during instrumentation.

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Advancement in knowledge of the apical 1/3 has also led to changes in procedural concepts. Currently, ‘effective cleaning’ and irrigating technique without under / over enlargement are favoured.

• The clinically significant features of apical part of root canal system are:Accessory canals : Principal or main canal in a root may communicate with surrounding Periodontium at any level of root through “accessory or lateral canals” before exiting from tooth at or near anatomic apex of root. www.indiandentalacademy.com

A lateral canal is a canal that is located at approximately right angles to main root canal.

An

accessory canals is one that branches off from the main root canal, usually somewhere in apical region of two root.

According to Green, the incidence of accessory foramina ranged from 10% in

maxillary

mandibular

central cuspids

incisor to

47%

and in

mandibular 2nd premolar with other teeth having incidences within this range. www.indiandentalacademy.com

Lateral canals

by gross methods of

detection – vulcanite corrosion specimen of root canals, have indicated that there is an incidence of 16.9% of such canals in all teeth (Hess 1928).

However

Seltzer’s

histological

examination

indicate that incidence is much greater.

According to Hess et al (1983), an accessory canal foramina will have a mean diameter of 6 to 60 µm. www.indiandentalacademy.com

In anterior teeth, accessory and lateral canals were observed in an incidence of 34%. In a no. of teeth a Y shaped branching – dichotomy of the root canal near the apex of the tooth were evident (histological section). No relationship between presence of accessory canals or foramina and age of the patient was apparent. In molars, a multitude of accessory canals are present, especially, within the cementum “web” fusing the roots.

The canals were filled with capillaries, pulp cells, ground substance and fibers , confluent with pulp tissue. www.indiandentalacademy.com

In many teeth, however, the width of the accessory of lateral canal is exceedingly small, permitting only the presence of small capillaries and their supporting stroma.

Usually, these small canals cannot be observed in radiography when interference occurs with the nutrition of the pulp through involvement of these foramina

by

periodontal disease, small region of necrosis or infarction occurs within pulp causing pulp tissue breakdown, fatty degeneration and mineralization of pulp tissue. www.indiandentalacademy.com

Frequently, the canals in the distal roots of lower molars and palatal roots of upper molars, fan out towards the apex in a ‘canoe – shaped’ arrangement.

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Implications

of lateral and accessory canals in

endodontic therapy.  The presence of multiple accessory and lateral canals is the rule, not the exception, as can be discerned from the detailed studies of Green (1955, 1960,1986) & Ainamo and Loe (1986).  The no. of accessory canals in the root does not appear to be significant factor in success or failure of endodontic therapy in teeth with vital pulps. If they were, most endodontic therapy would fail. It would be difficult, if not impossible, by our current techniques to instrument and cleanse the accessory canals, even with thorough reaming and filling. www.indiandentalacademy.com

 In teeth with totally inflamed or necrotic pulps, granulation

tissue is found in the accessory canals prior to endodontic therapy.  The significance of the involved tissue remaining in accessory foramina as a factor in failure or repair after endodontic therapy has not yet been definitely, determined.  Following endodontics treatment, the pulp tissue in the instrumented branches may become inflammed but usually retains its viability with passage of time, continuous deposition of dentin or cementum tends to narrow the lumen of these canals.

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Interestingly, although the incidence of occurrence of lateral and accessory canal in human teeth is high and canals are believed to have potential to harbor irritant and perpetuate pathological problem, the percentage of failures due to unfilled lateral canals is small in clinical practice.

It has been pointed out that this is probably because of biological hard (cementum & dentin) closure of lateral canal foramina subsequent to elimination of chronic inflammation of the pulp or irritants from main root canal. www.indiandentalacademy.com

Reason biologically :2 changes happen as tooth become functional.

1. It is made to bear the biting stress which may move the tooth is mesial direction.

2.

Occlusal load may disturb the curtain like HERS at apical end.

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•

Epithelium of HERS is required for initiation of dentinogenesis in any given point of root.

•

Its absence causes development of accessory / lateral canal. The root sheath should disintegrate before dentin elaboration, to form a lateral canal.

•

In addition, accessory or lateral canals may results from lack of dentin elaboration around blood vessel which is present in periradicular connective tissue.

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The preparation should extend to narrowest part of root canal – apical constriction, the progress of root canal treatment is then clearly at its best (Beer and Boumenn 1994) The apical foramen is the circumference at end of root canal where pulp tissue is continuous with apical periodontal tissue.

The apical constriction lies within root canal just coronal to apical foramen & corresponds to dentino cemental junction, which is where the dentin of root canal meets cellular cementum (Simon 1993). www.indiandentalacademy.com

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1931- Grove recommended the DCJ as ideal end point for root canal preparation.

The philosophy of correct end point for root canal instrumentation is derived from extensive histological study by Kuttler (1955) who calculated average distance b/w centre of apical foramen and apical constriction in people younger than 25 yrs to be 0.52 mm and 0.66 mm is those older than 55 years. www.indiandentalacademy.com

Detecting location of apical foramen : X-ray cannot be belittled here, determination can be made on radiograph and may be supported by tactile feedback and electronic aids. Blood or exudate on paper points are also clues working length.

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Shape :- This is the most naturally constricted point of main root canal. Endodontic literature describes over all- shape of apical foramen appropriately as ‘funnel – shaped’.

Significance : Apical constriction is of adv. during endo therapy as it can act as a natural ‘stop’ during filling procedure.

Maintaining the original position and shape of the apical constriction are two main objectives of root canal preparation procedure . www.indiandentalacademy.com

Foll. steps taken to maintain the original position & shape of the constriction: a. Working length of root canal should be measured correctly. b. Canal

patency

should

be

maintained

through

recapitulation c. Proper and adequate irrigation of apical 1/3. Irrigate well flush out the debris and dentin shavings, preventing accumulation of ‘dentin mud’ www.indiandentalacademy.com

Following endodontic treatment, a root canal filling to a



foramen that is not situated directly at the root apex would appear short of the apex in a radiograph.

Most of apical foramina are not present directly at the apex



of tooth, an apparently well filled root canal that appears flush with the apex in a radiograph is actually overfilled.

Repair of periapical tissue is then impeded because of the



presence of foreign body- the root filling material. www.indiandentalacademy.com

Radiographic assessment of apical 1/3 : following appearance of apical 1/3 indicate deviation in internal anatomy.

Thin ‘pinched’ apex : over enlargement of the canal may lead to perforation.

Bulbous apex : due to hypercementosis. In these cases apical foramen / connection may be significantly shorter than radiographic apex. www.indiandentalacademy.com

Resorbed apex : Advanced inflammation at periapex cause resorption of cementum, dentin and widening of apical foramen.

Blunder buss : X-ray of newly erupted tooth would normally show an incompletely formed root having a wide root canal and open apex. Standard root instrumentation and obturation techniques not favorable as morphologically the wall of blunder buss canals are thin and fragile particularly near apical 1/3.

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CHANGES IN APICAL 1/3RD According to Buchanan ‘calcification is a degenerative process near site of injury, around pulp chamber and progress apically. Therefore, there is always a path in any calcified canal that is not obstructed.

The cognizance of the fact that deposition of calcific material is more in the cervical part of the canal compared to its apical part is of great clinical importance.

• Just enlarging of the orifice and cervical 1/3 of canal would enable easier passage of even a relatively bigger instrument directly to apex. The fact is, it is the cervical third of canal which is generally narrower or more calcified. www.indiandentalacademy.com

The rule of the thumb of ‘3 yrs’ may be considered to be true only for the completion of overall ‘length of root’ and time schedule of 3 yrs need not be applied for completion or maturation of the apex of root.

Thomas et al stated that

apices may not mature until 5 years after eruption.

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Remodeling / deposition of cementum occuring at apex is an ageing process. This probably occurs to compensate for altered enamel, or due to physiological mesial migration of teeth or as response to occlusal process.

As a sequel to deposition, there is an increase in overall distance from the root apex to apical constriction of root canal. (increase occurs b/w apex and foramen and foramen to constriction).

This is of clinical significance as working length of tooth is relatively shorter from the radiographic apex for an aged tooth than its for a young adult. The diameter of the apical foramen www.indiandentalacademy.com

As age advances, the anatomical length of the root may increase due to deposition of cementum, however the working length decreases due to the deposition of 20 dentin at the level of the apical constriction.

• Sclerosed dentin, narrowing obliteration of accessory canals, and stronger apical dentin matrix due to thicker apical cementum may be considered the reason for endodotic therapy to be relatively more successful in older teeth.

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Cemento dentin junction Acc. to Kuttler (1958) the root canal is divided into a long conical dentinal portion and a short funnel shaped cemental portion.

The cemental portion is usually in the form of an inverted cone with its narrowest diameter at or near the Cementodentinal junction and it base at the apical foramen.

Occasionally the cementum abuts directly on the dentin at the apex, at times, the cementum extends into the root canal, lining the dentin an an irregular manner.

The extent of cementum deposition on each wall of the root canal varies, one wall is usually covered with a greater quantity of cementum www.indiandentalacademy.com than the other wall.

No definite morphologic pattern of the CDJ is found consistently. The thickness of cementum around the apical foramen is inconsistent & varies greatly.

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Guides to the position of apical foramen Factors such as root curvature, areas of occlusal stress,

amount

of

cementum

deposition,

and

tooth

morphology determine the position of the apical foramen to the root. The film does not indicate if the exit occurs on the buccal or the lingual surface.

However if it appears that the pulp canal space abruptly halts at a point near the apex, it is usually indicative that the canal does exit short of the radiographic apex on either the buccal or lingual agent. www.indiandentalacademy.com

Anatomical variations and pathology in root apex Apical Delta The apical delta is Y-shaped branching of the root canal near the apex of the tooth. Such apical deltas were found to be frequent by Seltzer et al 1966 and Hess et al 1983.

It is difficult to instrument and obturate both the branches. If it is not visible in radiograph, it may be left untreated. The pulp tissue in the branches may become inflamed, but continuous deposition of dentin or cementum, tends to narrow the lumen of these canals.

Recent thermoplasticized root canal filling – like obtura and thermafill obturate these variation more successfully. www.indiandentalacademy.com

Denticles (Pulp stones) Pulp stones form around foci of mineralizing pulps tissues components such as collagen and nerve fibres, blood vessels ground substance, inflammatory and necrotic cells.

Pulp stones in apical 1/3 of roots are present in approximately 15% of the teeth and more than one stone is usually found (Seltzer et al, 1966).

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Clinical correlation in Endodontic therapy

The denticles that are found within pulp tissue in apical third of the root may account for some difficulties in root canal instrumentation. During reaming and filing of the root canal, they may become detached and impacted into apical foramen, rendering further instrumentation difficult.

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Apical calcification In case of chronic inflammation, ageing etc. the calcification of the root canal occurs. In some root canals the apical 1/3 are calcified, complete obturation of such cases would be difficult.

Effort should be made to negotiate the

canal with help of EDTA and thin files.

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ISTHMUS  An isthmus is defined as a narrow strip of land connecting two larger land areas or a narrow anatomic part or passage connecting two larger structures or cavities.  Green in 1973 described the isthmus as a corridor between the two roots.  The ishmus connection can be observed between two root canal systems that occur within one root www.indiandentalacademy.com

ISTHMUS FORMATION  The actual formation of the isthmus is from the embryonic origin is through the epithelial root sheaths.  In teeth with single roots, the inner cells of the root sheaths next to the dental pulp differentiate in to odontoblasts and start secreting dentin matrix.  As the matrix is laid down and begins mineralizing ,the epithelial root sheath cells secrete a thin layer of cementum on this newly formed dentine. www.indiandentalacademy.com

ISTHMUS CLASSIFICATION  Type I –Two or three canals with no notable communications.  Type II – Two canals that possessed a definite connection between two main canals.  Type III – Three canals that possessed a definite connection between three main canals.  Type IV – when canals extend into isthmus area.  Type V – True connection or corridor throughout the section. www.indiandentalacademy.com

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Incidence of Isthmus  The incidence of isthmus is highest in the apical 3-5 mm levels.  In teeth that have two canals , the 4 mm sections contain an isthmus 100 % of the time  In the mesial root of the mandibular first molar , the incidence of two canals increases as the cut levels goes up.The highest incidence of isthmus at 4 to 6 mm. www.indiandentalacademy.com

Clinical significance  Conventional mechanical cleaning and shaping methods can not physically debride this vitally important area.  The only way to clean such anatomic variations is through the use of chemical irrigants such as full strength sodium hypochlorite. www.indiandentalacademy.com

 This area which can lead to failures of conventional orthograde endodontic treatment must also be considered in failures of traditional endodontic surgery.  The tissue that can be left over after traditional surgical procedures with a micro head handpiece and micro burs can be a nidus for recurrent infections. www.indiandentalacademy.com

 Mechanical cleaning ultrasonics and their associated tips have aided in thorough debridement of the apical root canal system

 The recognition and management of the canal isthmus is the one factor that may improve the success rate of surgical endodontics in posterior teeth. www.indiandentalacademy.com

Open Apex Endodontic management of the pulpless, permanent teeth with wide open blunder buss apex offers dentists a most difficult condition to treat.

Problem of open apex - the open apex occurs when trauma or caries cause pulpal exposure prior to the completion of root development.

An open apex refer to absence of sufficient root development to provide a conical taper to the canal - “Blunderbuss� canal.

Since it is necessary to seal the apex to gain endodontic success, it is physically impossible to achieve this objective www.indiandentalacademy.com through ordinary procedure in open apex cases.

Before introduction of apical closure techniques, the usual approach to this problem was surgical.

The preferable solution,however, is to allow the apex its complete development.

Treatment of open apex with vital pulp - A pulpotomy procedure is indicated in the tooth with an open apex to allow completion of apical closure, as long as apical pulp remains vital.

This is referred to as

apexogenesis (physiological) when the apical pulp can be retained in vital condition, the root end and canal usually will and shape.

assume a relatively normal size www.indiandentalacademy.com

Apexification procedure – treatment of open apex with non-vital pulp.

Apexification

is

a

method

to

induce

development of the root apex of an immature, pulpless

tooth

by

formation

of

osteocementum or other bone –like tissue.

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The most widely accepted technique involve cleaning and filling the canal with a temporary paste to stimulate the formation of calcified tissue at the apex.  An alternate approach on which a material is placed into the apical 2–4 mm of blunder buss canal to act as a barrier agent into which guttapercha is condensed is becoming accepted as treatment of choice.

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Many materials have been reported to successfully stimulate apexification. The use of Ca(OH)2 for apexification in pulpless tooth was first reported by Kaiser in 1964. The technique was popularized by Frank. The Ca(OH)2 has been mixed with

CMCP, metacreysl

acetate, cresannol, physiologic saline, ringer soln, distilled water. Tricalcium phosphate, collagen Ca phosphate, osteogenic protein-1, bone growth factor, MTA. www.indiandentalacademy.com

 But the most important factors is achieving apexification seems to be thorough debridment of root canal (to remove all necrotic pulp tissue) and sealing of the tooth (to prevent ingress of bacteria and substrate)

Ca(OH)2 technique Commercial paste (e.g. Calasept, pulpdent, calyxyl) may be used to fill the canals. www.indiandentalacademy.com

The usual time required to achieve apexification is 6-24 months (average 1yr + 7 months) Patient is recalled at 3 months intervals for monitoring of the tooth. After clinical verification of apexification made by failure of small instrument to penetrate through apex, canal is obturated with GP in usual manner.

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Histology of apexification with Ca(OH)2 The calcified material that forms over apical foramen has been identified as osteoid (bone) or cementoid (cementum like) material. The formation of osteodentin also has been reported. Histologic studies consistently report absence of HERS normal root formation usually does not occur after apexification. Instead there appears to be a differentiation of adjacent connective tissue cells into specialized cells, there is also deposition of calcified tissue adjacent to filling material. The closure of apex has minute communication with periapical tissues. For this reason apexification must always be followed by www.indiandentalacademy.com filling of canal with permanent root canal filling.

Apical root resorption Apical periodontitis resorption.

with

apical

root

Practically all teeth exhibiting apical periodontitis exhibit root resorption. The resorption can be minor & practically -invisible radiographically or can be so extensive that a significant amount of root tip is lost.

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•The cemental layer is a physical barrier that separates the root canal system from surrounding periodontal attachment. It appears that the intense & progressive inflammation confined at the apex overcome the resistance of the cemental layer to resorption. • Radiographically it is diagnosed by radiolucencies at root tip and adjacent bone.

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Length determination Determination of working length is obtaining the hermetic seal,as wrong lead to enlarged foramen resulting in 1. Periapical irritation 2. Possible weeping of the canal 3. Lose of control during obturation short of foramen with resultant accumulation of dentinal mud.

an essential step in estimation could either

or lead to preparation ledge formation and

The clinician should try to determine the foramen constriction by “Tactile sense”. He should be able to “feel” the foramen and then confirm by any recent electronic method.

Common Methods include : Radiographic, Tactile,www.indiandentalacademy.com paper point evaluation, electronic aids.

Electronic apex locator are also important adjuncts to length determination. At this time they are not accurate enough to replace traditional radiograph but are useful in establishing estimated lengths & finalizing working lengths in cases were apex cannot be visualized.

Based on three different electrical principle

Electrical resistance : Resistance locators are based on fact that electrical resistance between periodontal membrane & oral mucosa is constant. The RAL was first to be developed and utilized a direct current. The early model was often inaccurate in presence of vital pulp, tissue, solution – irrigants, tissue fluids, blood, pus & local anesthetics & when contacting metallic restoration. E.g., Neosono McPlus, Digipex III, Apex www.indiandentalacademy.com finder.

Impedance type : Require calibration & operate on principle the tooth is hollow tube with closed end. There is electrical impedance across the walls of the canal.

At the CDJ there is an abrupt decrease in impedance which is detected by the unit indicating the apical termination. E.g., Endocator

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Frequency dependent : Operate on the principle that there is maximum difference of impedance between electrodes depending on 2 frequency waves employed. The instrument is calibrated by inserting the file into coronal portion of the root canal where difference between 2 frequencies is constant. The max difference in impedance between 2 frequencies is at apical constriction.

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Advantage : Operate in fluid environment.

E.g., Root ZX, Endex.

Disadvantage : Do not reveal the number, curvature, width, other complexities of root canal.

Are not consistent with their performance. Might give false reading.

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Controversy exists as to the length of root canal be prepared & subsequently obturated. Theoretically, the canal should be prepared to CDJ, however translating this histological entity into a clinical reality is not possible. In addition, the CDJ is variable within apical portion of the canal. For this reason most clinicians calculate the corrected working length empirically, others view radiographic apex as the only consistent reproducible point.

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A rational approach to establishing corrected working length can be obtained from review of the apical anatomy & correlating this information with presence or absence of pathosis.

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Burch & Hales noted that foramen deviated from apex - 92.4% of the time & average distance was 0.57mm.

Chapman in studying anterior human teeth noted the apical constriction lies between 0.5mm to 1mm 92% of the time. The average foramen diameter was 0.297mm for max 0.260mm for mandibular teeth. www.indiandentalacademy.com

teeth &

Dummy et al found average apex to constriction distance was 0.89 and 95% of constriction were between 0.5 to 1mm from apex.

It has been demonstrated that when periradicular lesion is present root resorption that is not radiographically visible is likely. This will affect the clinicians ability to establish a seat a stop for maintaining the obturating material.

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When

the

periapical

tissue

exhibits

normal

structures, the corrected working length should be established 1mm from radiographic apex. This will account for apex to foramen difference.

When bone resorption is evident the corrected working length is established 1.5mm short of apex and when bone & apex exhibit resorption the length should be 2mm from apex (or POE).

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Weins modification www.indiandentalacademy.com

One constant in length determination is the fact that preparation & obturation to radiographic apex is beyond the apical constriction. Prognosis studies indicate that success rates are higher when obturating materials are confined to root canal space.

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Biological rationale for working length The most clinically relevant working length landmark is the constriction - the narrowest point of canal & therefore the narrowest diameter of the blood supply. Beyond the constriction, the canal Widens & develops a broad vascular supply.

Therefore from biological perspective, the constriction is the most rational point at which to end canal preparation, since the existence of functional blood supply controls the inflammatory process. Intra radicular termination of the clearing process leaves a canal contact interface equal in www.indiandentalacademy.com area to the inflammatory process (1:1).

Termination beyond the constriction provides a greater area of blood supply than of irritant interface.

Extra radicular termination of working length can theoretically provide a hemisphere of vascular support to the inflammatory process. This gives a numerically superior advantage to inflammatory process.

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The surrounding vital tissue have more capacity to destroy irritants and restore the area to a biologically functional state cleaning & shaping to apical constriction allows the inflammatory healing mechanism to complete.

Optimal length From a procedural perspective it is advantageous – to treat till the constriction that can be felt by the experienced. After coronal shaping, the experienced hand can detect an abrupt increase in resistance followed by rapid decline as instrument tip passes beyond constriction. This preparation shape helps to optimize the apical seal when the canal is subsequently filled. www.indiandentalacademy.com

The radiographic apex is where the root apex appears to join PDL. The vast majority of endodontists prefer filling the canal to DCJ so as not to impinge on periapical tissue, permitting, hopefully physiologic closure of root canal by cementum.

Filling the canal so it appear flush with radiographic apex produce esthetically pleasing radiographs, however in reality, the filling is probably slightly overextended, especially in roots curved in bucco-lingual direction.

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The most desirable vertical extent of root canal filling is a homogenously dense filling extending 0.5 – 1mm short of radiographic apex.

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Instruments & Instrumentation Improperly prepared access cavity would presupposedly affect the preparation of the apical zone. Impingement of the endo instrument coronally would result in either ripping of the foramen or formation of a ledge.

Ninety percent of the canals are curved (Christie & Peikoff 1980); and precurving of the files is a must in all such cases.

Files are not to be given 1/4 turn bites into dentin or pulled forcibly with lateral pressure along the canal walls when preparing the apical end of the canal.

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Rotation of instruments has been found (Weine et al. 1975) to violate the basic principle as it forms an ‘hour-glass’ outline rather than a smooth taper near the apex.

Flexible files are preferred over stiffer varieties since they may change the course of the canal, form a ledge or or transport the foramen by ripping.

D-type files (produced from rhombus blanks) are more flexible than regular K-type files (produced from square blanks) (Anderson et al. 1985).

The new K-type file –triangular in cross section – is more flexible than H-file (Roane et al. 1985). www.indiandentalacademy.com

Successful treatment in dependent on diagnosis, treatment planning

skills,

knowledge

of

radicular

anatomy

&

application of cleaning & shaping procedure. Careful pretreatment evaluation is essential prior to RCT to assess possible complicatory factors.

In 1974, Schilder outlined the principles of cleaning & shaping, • Cleaning is removal of all contents of root canal system before & during shaping, infected material, antigenic material, organic substrates, microflora, bacterial by product Food, caries, tissue remnants, pulpstone, collagen, contaminated canal filling material & dentinal debris. www.indiandentalacademy.com

Apical shape.

The ideal apical shape is to leave natural apical foramen alone, clean it so that it is patent & obturate it 3 dimensionally. The last few mm of canal that approach apical foreman are critical in that the shape developed there must be tapering tunnel form that allow distortion of obturation materials by compacting into the asymmetric perimeter of foramen. www.indiandentalacademy.com

Serial shaping techniques Schilder stressed on 5 mechanical objective for successful cleaning & shaping.

Mechanical objective a) develop a continuously tapering conical form in the root canal preparation. b) make the canal narrower apically with the narrowest cross sectional diameter at its terminus. c) Make the preparation in multiple planes d) Never transport the foramen e) Keep the apical foramen as small as is practical.

The mechanical objective are in harmony with natural root www.indiandentalacademy.com canal anatomy.

An additional objective is adequate preparation of the apical region.

Preparation of Apical Zone An apical control zone establishes an apical constriction by forming rapid canal taper at a clinician defined location.

This is near location of natural constriction but is mechanically defined relative to canal exit itself.

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This procedural nuance eliminates extensive searching for the natural constriction. Preparing to natural constriction is difficult

because

of

great

variability

in

location

of

constriction. Properly done, a control zone dependably & easily establishes a round & clear apical foramen for obturation.

Apical foramen patency Confirming apical foraminal patency is the last step for any cleaning & shaping. It is a feature of control zone and is important to provide a complete severance of the pulp from PDL. Endodontic files lack sufficient sharpness the cut fibrous Connective tissue unless tissue is engaged between cutting edges & canalwww.indiandentalacademy.com wall .

To assure that a severance occur near the PDL, the clinician must complete the patency opening with the first file that fits tightly in the foraminal passage.

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The master apical file - largest file to bind slightly at corrected working length following straight line access. It is determined by placing successively larger files to corrected working lengths until a file binds.

This process defines the size of the canal in the apical 1/3 of root prior to cleaning & shaping. Pulpal severance is accomplished by extending the file just through apical foramen and with a very light pressure rotating it one revolution to cause the cutting edges to engage trap, & severe the remaining tissue. www.indiandentalacademy.com

Canal preparation is considered complete with the production of a tapered preparation with placing smooth walls.

But even more critical is the creation of an apical matrix constriction.

The apical matrix has 2 purposes - To help confine instruments materials & chemicals to canal space - To create (or retain) barrier against which guttapercha can be condensed.

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After cleaning & shaping procedures the apical configuration should be assessed. This is accomplished with master apical file & smaller files.

Apical stop – A barrier prevents the master apical file & smaller files from being placed beyond the corrected working length.

Apical seat – A barrier prevents the master apical file from being extended beyond the corrected working length but smaller files pass through the apical foramen & beyond the corrected working length.

Open Apex – The master apical file will pass through apical foramen, it resembles an open cylinder. www.indiandentalacademy.com

Apical clearing It is performed in cases where there is an apical stop. This procedure enlarges and opens the canal in apical region at the correct working length. It consist of 2 parts 1. Final apical enlargement, 2. Dry reaming.

Final apical enlargement – This step is done after canal preparation is complete & has met criteria for adequate cleaning & shaping. Instead of final recapitulation, instrument 2 to 4 size larger than MAF are carefully reamed in clockwise manner at working length in wet canal. Therefore final apical size in a smaller canal would be a 35 # 40. www.indiandentalacademy.com

When used in a rotational fashion, the instrument become centered and remove dentin uniformly from the canal walls producing round prep. Since apical enlargement is only performed after establishing a coronal taper, transportation of canal is eliminated.

Final apical enlargement is not done in canals greater than size 40. if MAF size is already greater than 40 and there is an apical stop, dry reaming is done with MAF only.

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Dry reaming is done after final apical enlargement & irrigation and drying with paper points. The last size file used for final apical enlargement (or MAF of larger than size 40) is then spun carefully in a clockwise manner to length. This is the final apical file (FAF), it removes dentin chips that pack apically during drying.

Clinical description - The access cavity is aligned to provide straight unimpeded entry into canal orifice. The chamber & canal are irrigated with NaOCl. The orifice of each canal is identified with an endodontic explorer.

Then No. 15 Flex-R files is marked with rubber stop to identify approx. length of canal as it appears in pretreatment radiograph. www.indiandentalacademy.com

Roane et al. (1985) introduced a new balanced force concept using the latest K-type file triangular in cross cut, for the preparation of apical zone in deeply curved canals.

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Change in path of canal result from exertion of unbalanced forces (Miserendno 1994). The objective is minimum alteration of canal course.

Significantly less dentin debris is pushed out through apical foramen than with step back technique (McKendry 1990).

Then the MAF is determined by placing successively larger files to corrected working length until a file binds slightly.

This process defines size of the canal in apical 1/3 of root prior to cleaning & shaping. www.indiandentalacademy.com

Step back technique Flared preparation provides a cleaner environment, better receptacle for the obturating material, and a stronger apical dentin matrix (Weine 1982). Chances of apical ripping and shifting in foramen are less with step-back technique (Christie & Peikoff 1980).

Because there is very little canal enlargement and removal of dentin near the apex, danger of perforation is reduced. Here the apical portion is instrumented first, then coronal portion is shaped.

Frequent recapitulation -sequential reuse & reentry of previous instruments, ensure canal remain patent. www.indiandentalacademy.com

Instrumentation of fine curved canals is difficult because the canal lacks natural taper. The clinician must develop this shape during prep. phase of treatment.

Loss of length is common procedural error.

Two common causes for loosing length are failure to maintain accurate measurements and packing debris into apical portion of canal. Recapitulation with small files & copious irrigation after each successive file size can prevent packing of dentinal debris.. www.indiandentalacademy.com

Then complete the cleaning and shaping by redefining the control zone and establishing apical patency.

The fundamental technique are patency confirmation & serial carving.

Step down technique In this the coronal portion is enlarged first, only then the apical portion of root prepared.

An adv. is coronal

enlargement makes it possible to insert the irrigating canula quite deeply into root canal. www.indiandentalacademy.com

TRANSPORTATION Transportation and ledging occur primarily in curved canals. This error can be prevented by maintaining a small AMF (#20 #35), by coronal flaring, by step back prep

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Blockage of canal system Def : A blockage is an obstruction in a previously patent canal system that prevents access to the apical constriction or apical stop.

To prevent – • Constant flushing and removal of debris by copious irrigation • File, used sequentially and never binding to canal.

• Recapitulation When blocked – a small file with 450 curve at apical 34mm, inserted and rotated circumferentially ‘catch’.

to detect a

After negotiating canal to length, H file used to

remove debris.

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Fractured instrument  If an instrument breaks off in the apical third of a narrow curved canal and the fragment is stuck too tightly to be removed  An attempt is made to by-pass the fragment,to carefully enlarge the canal and to fill it with guttapercha.  Steel instrument fragments that are left in the canal are relatively inert, and no signs of corrosion were detected with SEM.  Silver point fragments corrodes and must be removed. www.indiandentalacademy.com

Altered foramina Ledging (Internal transportation) Def : A ledge is an artificially created irregularity on the surface of root canal wall that prevents placement of instruments to the apex of an otherwise patent canal.

Cause : Insertion of un-curved instruments short of working length with excessive apical pressure. Canal wall is gouged resulting in ledge formation.

Prevent :

Pre-curve apical 3-4 mm. Do not force, rather tease to most apical position.

Sequential and circumferential filing essential www.indiandentalacademy.com

Zipping (Elliptication) -

Transposition or transportation of apical portion of normally

curved canal that has been straightened especially in apical 1/3.

Reason : Failure to pre-curve file, rotation of instruments in curved canals, use of large stiff instruments to bore out curved canal.

Apical foramen tend to be tear drop shaped or elliptical, transported from the curve of canal.

When a file is rotated in curved canal – a biomechanical defect – elbow will form coronally to elliptically shaped apical seat.

This becomes the narrowest portion of the canal.

Obturation terminate at elbow, leaving unfilled zipped canal apical to elbow.

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 Funnel formation:  An apical funnel is the result of improper instrumentation and straightening of the apical portion of the root canal.  To avoid this the apical end of the instrument must be bent even more than the curvature of the canal on the radiograph.

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Prevention : • File over curved in apical 3-4 mm • Do not rotate file • Bulk of cleaning and shaping performed with small, flexible files to enlarge apical seat.

• Anticurvature / reverse filing

Use of thermoplasticized GP, Ca(OH)2 root canal sealer. www.indiandentalacademy.com

Irrigation and Root apex

Canal preparation require the removal of either vital or necrotic pulp tissue. While canal preparation is primary mechanism for removal of canal contents, irrigation is essential regardless of preparation techniques.

Irrigants are important for removal of dentin chips & tissue debris produced during cleaning and shaping. The depth of needle penetration & volume of irrigant delivered are important factors.

Proximity of needle to apex plays a important role in removing debris, therefore the size of canal is an important factor in determining effectiveness. www.indiandentalacademy.com

www.indiandentalacademy.com

Smear Layer Management When blades of any file engage and cut dentin - a smear layer forms on the walls of preparation.

Frequent irrigation in conjunction with clearing and patency files, reduce but do not eliminate the smear layer.

Aqueous 17% EDTA flooded into canal for 1 min. show to eliminate SL. Microbrushes introduced to optimally finish preparation can be used in either rotary or ultrasonic hand piece. www.indiandentalacademy.com

Obturation and Root apex With proper canal preparation, Obturation is one of personal choice.

Radiographic assessment is the most common method for determining the adequacy of root canal obturation.

The radiographic criteria including length, voids & shape.In a properly filled canal GP will be at the prepared length & without voids. The shape will reflect a tapered prep.with apical extent coming to a point.

Obturation is a reflection of the cleaning & shaping procedure.

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Distance from the apical foramen to constriction depends on multitude of factors, Such as increased cemental deposition, radicular resorption. Both process are strongly influenced by age, trauma orthodontic moment, periradicular pathology or periodontal disease.

If a major goal of RCT is to create an environment conductive to regeneration of cementum over the apical foramen, the periodontium that enter the apical foramen in teeth with vital, Yet compromised pulps should not be challenged with extrusion of root canal filling material beyond the end of canal. This concept has been scientifically valid for 65 yr & is supported by numerous retrospective studies. www.indiandentalacademy.com

Overfilling denotes “Total obturation of root canal space with excess material extruding beyond apical foramen�.

Over extension denote extrusion of filling material beyond the apical foramen but with the case that canal has not been adequately filled and the apex has not been sealed.

The major cause of placing the root canal filling material beyond the apical contriction in either overfilling or over extension, when lateral or vertical compaction technique are used,are the follo.: www.indiandentalacademy.com

• Excessive instrumentation (over instrumentation) beyond the apical constriction resulting in the lack of an apical dentin matrix.

• Unanticipated communicating resorptive defects in the canal system.

• Defects incorporated into canal system during cleaning & shaping - zips, perforation etc.

• Excessive compaction forces • Excessive amount of sealer • Use of too small a master cone • Excessive penetration of compacting instrument. www.indiandentalacademy.com

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Contemporary endodontic practices and long term evaluation studies favor (Histologically also) obturation within the confines of the canal system in all cases in an attempt to prevent further challenge to the already compromised and challenged periradicular tissues.

A serious effort to compact the filling material vertically therefore should be made to obtain a dense, homogenous appearing filling in its entire mass. Although tight apical seal is of prime importance for success of endodontics treatment the sealing of accessory canals is no less imp in enhancing www.indiandentalacademy.com

the chance of success.

(Nygard – Ostby, Blaney, Strindberg, Horsted & Nygard). • Stating the space between GP & tissue surface was filled by new connective tissue within a few months.

The Washington study also found no failure among those well obturated cases in which the filling terminated slightly short of the apex whereas 3.85% of the failure were caused by overfilling.

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Ingle (1956) determined 63% of the root canal failures to be due to inadequate filling. The necessity to provide hermetic sealing of the apical foramen as well as filling of the accessory canals has brought forth many dynamic changes in the obturation techniques.

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The current trend in endodontics is towards the provision of an impression – like filling of the root canal and its ramifications with perfect adaptation, and inducing closure of the foramen/foramina by hard tissue formation.

Guttapercha - Hill (1847) - Bowman (1867) It is compatible, thermoplastic, and adaptable (Nguyen 1984).

Negm et al. (1980) have recommended the use of gutta percha coated silver cones as the core material. www.indiandentalacademy.com

Apart from lateral condensation technique and organic solvent-softening methods, a few more techniques have been developed in the recent years, showing promising results, utilising the thermoplastic property of the gutta percha, as the thermoplastic gutta percha was found to flow and adapt close to the canal wall.

Almost all the studies done comparing the sealing abilities of lateral, warm vertical, automated thermatic; condensation and injected thermoplastic gutta percha, have shown their sealing efficiency to be more or less similar (Evans & Simon 1986; Torabinejad et al 1978; Benner et al 1981; Lugassy & Yee 1982)

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Warm guttapercha vertical condensation technique - Schilder (1967).

Comparing

the

sealing

vertical

condensation,

abilities

by

lateral

condensation, and automated thermatic condensation, Wong et al (1981) found that the vertical condensation gave the best replication of the canal system.

This technique - time-consuming. But the material

often

fills

the

accessory

ramifications.

Its use is recommended for most of the clinical cases (Nguyen 1984). www.indiandentalacademy.com

Weine (1982) recommends this technique to be the best when the fitting of a conventional master cone to the apical portion of a canal.

Automated thermatic compaction of guttapercha - John T.McSpadden.

Using a reverse-Hedstroem file-like instrument. Fits into the slow speed contra angle handpiece.

Advantage - Time saving.

Disadvantage - Use is limited to straight and slightly curved canals only. www.indiandentalacademy.com

Injectable thermoplasticized guttapercha delivery system has emerged in the recent years showing promising results. It has been reported by Yee et al (1978) to produce impression – like reproduction of the prepared root canals.

Recently, a warm lateral condensation technique has been introduced by Martin * (1986) using a thermal endodontic condenser system. Though it is claimed to produce good adaptation with dense filling, this device is yet to be studied.

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Fewer stormy postoperative reaction can be expected if canal instrumentation and filing are limited by their narrowest waist of the apical foramen.

Occasionally even though proper techniques has been foll. GP or root canal sealer may be unintentionally pushed beyond the confines of root canal system.

However the GP is a bacteriostatic substance that is generally tolerated by peririradicular tissues. Although sealers may promote an initial inflammatory response, over a short period of time, the macrophage scavenger system eliminate the excessive material from the periradicular tissue. www.indiandentalacademy.com

In either case,the mere placement of filling material outside the canal system is not a major cause for alarm if the canal space is 3 dimensionally obturated because of the rich collateral blood supply & excellent immunological capacity of periradicular tissues.

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Repair of tissue following RCT In teeth with preexisting periapical inflammatory lesion, debridment of inflammed or necrotic tissue within root canal begins process of repair.

Histopathology of repair Granulation tissue Neo Vascularization Fibroblasts + Ground substance + Fibroplasia.

Cementum + Bone apposition (6 months) www.indiandentalacademy.com

Alternate filling techniques of apical 1/3 There are some techniques is which a barrier is created in the apex against which the root canal filling materials can be compacted.

Dentin chip apical filling A method often used to create an apical stop for the purpose of obtaining a biologic seal, support the placement of dentin chips or other artificial barrier (i.e. Ca(OH)2, demineralized dentin, collagen) before canal obturation.

Ironically the packing of chips may occur inadvertently during cleaning & shaping, Especially if a patency file is not used routinely. www.indiandentalacademy.com

The premise that dentin filling will stimulate osteo or cementogenesis is well founded.

Gottileb & Orban, Ketterl reported cementum like closure at the apex around dentin chips.

Baume, Oswald & Friedman described osteodentin closure

Holands, however, found the dentin chips, if infected, are a serious deterrent to healing.

Torneck found that dentin chips may actually irritate & hinder repair. www.indiandentalacademy.com

In addition to possibly creating biologic seal, the packed chips may assist in confining irrigating solution to the canal and preventing overfilling, especially when canal has seen over instrumented.

Favorable periradicular tissue response have been noted with enhanced healing, minimal inflammation & apical cementum deposition.

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Ca(OH)2 apical filling The success of Ca(OH)2 formulation in achieving apical closure has stimulated use

of calcium compounds as

sealers, pastes, filling or apical plugs.

One investigation found that Ca(OH)2 produce a periapical response that overall is indistinguishable from that produced by dentin plugs.

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CaOH2 may be carried into canals by means of small amalgam carrier . messing carrier- with curved tips • small plugger is used to push & pack the material apically • Even with promising data that support the potential use of an artificial barrier in apical portion of the prepared canal the routine clinical use of this technique does not appear to be of standard care

A material with predictable inductive capabilities is necessaryone that seals the canal, negates any bacterial influence, stimulate cementum regeneration across apical foramen www.indiandentalacademy.com

Apical Root Fractures Pulp necrosis occurs in 25% of root fractures.

Endodontic treatment is indicated in coronal segment only, unless periapical pathology is seen at apical segment.

Treatment Option When fracture segment in apposition : If asymptomatic - keep under observation. Adjust occlusion of tooth (splinting). Splinting follow-up - 3.6, 12 months interval.

If symptoms present - treat with non-surgical RCT in both segment, if possible.

If symptom continue - surgically remove segment.

When fracture segment not in apposition : Root tip may have to be surgically removed. www.indiandentalacademy.com

POST ENDODONTIC RESTORATION  The endodontically treated teeth are usually restored with a post, a core and an artificial crown 2 protect them from fracturing.  Encroachment on the apical 1/3rd of the root canal filling could disturb the apical seal during post space preparation  Weine stated that to leave 3 – 5 mm of apical material intact is sufficient to ensure sealing of the apex. www.indiandentalacademy.com

Periapical surgery and root apex Periradicular curettage only eliminate egress of microbes and not the cause. Curettage done alone (without apical resection) will invite recurrence of lesion.

Root – end resection Ablation of the apical portion of the root and attached soft tissue For : • Creation of an apical seal • Removal of pathologic process • Removal of anatomic variations • Removal of operator errors in non surgical treatment A root resection of 3 mm at 0 degree bevel angle (90 0 to long axis of root) removes the majority of anatomic variations. www.indiandentalacademy.com

www.indiandentalacademy.com

Root end preparation Def : Sealing the apical extent of the root canal system through cavity preparation in the resected root end and placement of a restorative filling material.

Types 1) Long axis preparation 2) Preparation perpendicular to the cut root surface (common approach) 3) Vertical slot preparation (matsura) 4) Transverse slot preparation Root end filling materials : ZnOE, Cavit, Diaket, GIC, bone cement, IRM. www.indiandentalacademy.com

Repair following periapical surgery Following surgery blood clot forms at site.

Granulation tissue fills defect.

Bone regeneration (lamina dura).

Callous formation

lamellar structure. 8 - 16 weeks

Regeneration of PDL - 8 weeks - functionally oriented.

Cemental regeneration - 8 weeks - even thickness of cementum. www.indiandentalacademy.com

Recent advances  Co2 and Nd:YAG laser is used for the sealing the apical delta.  Tri-Auto ZX was used to prevent over instrumentation, file breakage and canal transportation with its auto apical reverse system.

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www.indiandentalacademy.com

Conclusion The

morphological

variations

and

the

technical

challenges involved in the treatment of the apical third seems infinite. Fracture of the apical third, resorption, weeping apex, immature foramen are some of the areas which continue to invite fresh views from clinicians and researchers.

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References         

Pathways of pulp - Cohen 7th and 8th edition Endodontic therapy Weine Endodontics - Ingle 4th Endodontics – Harty Endodontology – R Beer baumann DCNA -Microscope in endodontics Endodontics – Jacob Daniel Oral histology - Orbans Oral histology - Ten cate www.indiandentalacademy.com

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