Cogs soft tissue analysis/ dental implant courses by Indian dental academy

SOFT TISSUE ANALYSIS • BURSTONE

• FACIAL FORM ( describes overall horizontal soft tissue profile )

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G – Sn – Pg ( angle ) • Facial convexity / contour angle.

• Drop a line form Glabella ‘G’ to Subnasale ‘Sn’ and a line Sn to soft tissue pogonion ‘Pg’.

• Mean value : 12 +/- 4* www.indiandentalacademy.com

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• Inference • +ve value =angle is smaller (clockwise) • -ve value=angle is large (counterclockwise) • increased +ve value  convex profile increased-ve value  concave profile (class3 skeletal and dental relationship) www.indiandentalacademy.com

• Disadvantages • The location of deformity cannot be assessed since it is not specific.

• Uses • To analyze the soft tissue profile. www.indiandentalacademy.com

G - Sn • Maxillary prognathism • Drop line perpendicular to horizontal plane from Glabella. Measure the distance from perpendicular line to Sn ( parallel to HP) • Mean value: 6 +/- 3 www.indiandentalacademy.com

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Inference • Describes the amount of maxillary excess/deficiency in anteroposterior dimension

• +ve=maxillary retrusion (anterior) • –ve=maxillary procumbency (posterior) www.indiandentalacademy.com

• Disadvantages

• some individuals have Glabella placed more anteriorly / posteriorly. Therefore correction of placement of glabella and then analyzing is recommended www.indiandentalacademy.com

USES • To determine whether the problem is in maxilla/mandible. • In treatment plan for anterior maxillary advancement setback(+) total alveolar/lefort-1 maxillary horizontal advancement/set back .

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G - Pg • Mandibular prognathism • Drop a perpendicular line to HP from Glabella. Measure the position of the pogonion from this line parallel to HP. • Mean value: 0 +/- 4 www.indiandentalacademy.com

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• Inference • Increased –ve value indicated mandibular deficiency is severe.

• Uses • Indicates mandibular prognathism or retrognathism www.indiandentalacademy.com

• Disadvantages • This measurement should be evaluated in conjunction with other values to distinguish between microgenia ,macrogenia / retognathia ie, if Pg is positioned posteriorly further examination is necessary to determine if the defect is a small hard tissue chin, small mandible, average sized mandible positioned posteriorly thin softtissue chin or a combination of these . www.indiandentalacademy.com

G-Sn / Sn-Me

• Vertical height ratio • (G-Sn / Sn-Me) 1:1

• Drop a perpendicular line to HP from Glabella, to this line drop a perpendicular line from Sn. Transfer the HP through Menton. Measure the distance from G-Sn and Sn – Me ( all perpendicular to HP ) • Mean value: 1 +/- 1

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1:1

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• INFERENCE • The ratio of middle 3rd to lower 3rd facial height measured perpendicular to HP. • Ratio less than 1 = denotes disproportionality and there is large lower 3rd face and vice versa.

• Disadvantages • Further evaluation of lower 3rd of face is needed. www.indiandentalacademy.com

• Uses

• Anterior face proportionality is assessed by taking the ratio of middle 3rd facial height to lower 3rd facial height measured perpendicular to HP.

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Sn – Gn - C • Lower face throat length/angle • Formed by the intersection of lines Sn-Gn & Gn-C. • Mean value:100* +/- 7*

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C

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• INFERENCE • Obtuse lower face neck angle indicates that any procedures that reduce the prominence of chin should not be done (worms & others) • USES • For treatment planning to correct anteroposterior facial dysplasias. www.indiandentalacademy.com

• Class III patients also have short , heavy throats and obtuse lower face throat angles . Should not undergo mandibular setbacks. • Alternate such as maxillary advancement , mandibular subapical, mandibular setback with advancement genioplasty / compromised tooth position may be employed. www.indiandentalacademy.com

( Sn – Gn / C – GN ) • Lower vertical height depth ratio.

• Drop a line from Sn to Gn and C to Gn .

Measure the distance from Sn – Gn and C –Gn .

• Mean value : 1.2 : 1

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Sn 1.2 C 1 www.indiandentalacademy.com

• Ratio of Sn – Gn and C – Gn is a little larger than 1.

• If the ratio is more than 1 = short neck .

• Useful in determining the feasibility of reducing / increasing the chin prominence.

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LIP POSITION AND FORM

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Cm – Sn - Ls • NASOLABIAL ANGLE • Draw a line from Sn to Cm and drop a line from Sn to Ls. Measure the angle formed.

• Mean value : 102* +/- 8* • Important measurement in assessing the anteroposterior maxillary dysplasias. www.indiandentalacademy.com

• Useful in evaluating the position of upper lip.

• ACUTE nasolabial angle => treated by retracting the maxilla / maxillary incisors / both.

• OBTUSE nasolabial angle => suggests the degree of maxillary hypoplasia and indicates for maxillary advancement or orthodontic proclination of maxillary incisors. www.indiandentalacademy.com

Ls To Sn - Pg • Upper lip protrusion.

• It denotes the amount of protrusion of upper lip.

• Draw a line from Sn to soft tissue Pg and the amount of lip Protrusion / Retrusion is measured with perpendicular linear distance from this line to the prominent point of the lip. www.indiandentalacademy.com

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• The abnormal values can be treated by retracting / protracting the incisors , surgically / orthodontically / advancing the maxilla.

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Li to Sn-Pg • Denotes the amount of protrusion of lower lip.

• Drop a line from Sn to Pg and the amount of lip protrusion / retrusion is measured with perpendicular linear distance from this line to the most prominent point of both lips . www.indiandentalacademy.com

• By retracting / protracting the incisors surgically / orthodontically advancing / reducing the chin prominence , possible to achieve desired lower lip .

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Si to Li - Pg • Mento labial sulcus.

• To assess the prominence of the chin.

• Measured from the depth of the sulcus perpendicular to Li – Pg. • Mean value : 4 +/- 2

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•

Deepened mento labial sulcus is due to :

1. Flared lower incisors.

2. Extruded upper incisors impinging on lower lip.

3. Flaccid lip tone and abnormal morphology of the lip itself .

4. Prominence of the chin also contributes to deepened mento labial sulcus. www.indiandentalacademy.com

• TREATMENT • Up righting the lower incisors.

• Intruding the maxillary incisors.

• Cheiloplasty to retract lower lip – helps in reducing the MLS. • Advancement genioplasty  increases the deepening of MLS. • Reduction genioplasty  decreases the excess MLS. www.indiandentalacademy.com

( Sn – Stms / Stmi – Me ) • Vertical Lip Chin Ratio • To assess lower third of face .

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• Mean values : ( 1 : 2 ) www.indiandentalacademy.com

• Lower 3rd of the face ( Sn-Me ) can be divided into three parts : length of the upper lip ( distance from SnStms ) should be approximately 1/3rd the total and distance from Stmi to Me should be 2/3rd.

• 1:2 ratio should be maintained.

• If the ratio becomes less than the normal ( ½ ) -- vertical reduction genioplasty is www.indiandentalacademy.com recommended.

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Stm-U1 Maxillary Incisor Exposure

• Distance from upper lip to maxillary incisor, is the key factor in determining vertical position of maxilla. Also corresponds to the pleasing smile. • Drop a line parallel to HP from Stms and another line from U1 ( incisal edge ) .

Measure the distance between them. www.indiandentalacademy.com

• 2mm of maxillary incisor show below the upper lip when lip at rest is desirable.

• Pts with vertical maxillary excess tend to show a larger amount of upper incisors with the lips in repose.

• Treated orthodontic ally establishing large curve of Spee.

• Long face pts with open bites may have acceptable tooth-lip relations but may need superior repositioning of post.

Portion of maxilla www.indiandentalacademy.com

• Short face : pts with maxillary deficiency tend to show maxillary teeth with lip relaxed and may have incisors at a level superior to upper lip  giving a edentulous look.

• Treatment : orthodontically extruding the incisors and surgically positioning maxilla inferiorly thereby increasing vertical dimension. www.indiandentalacademy.com

Stms-Stmi Interlabial gap • To measure the distance between the upper and lower lip with lips in rest.

• Measure the distance between line drawn from Stms and Stmi parallel to HP. • Patients with vertical maxillary excess have increased interlabial gaps and lip incompetence.

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• Patients with vertical maxillary deficiency often have no interlabial gaps and lip redundancy. • Treatment : raising the level of maxilla to shorten the height will decrease the large interlabial gap and help patient to close the lips without muscle tension.

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Zero Meridian • By dropping a line from the soft tissue (N), the soft tissue surface directly anterior to the hard tissue (N) at right angles to the FH or the constructed HP. • Ideally passes through the soft tissue pogonion ( 0 +/- 2 ) to zero meridian and 8mm posterior to Sn. • Variation indicates Retrusion / Protrusion in mandible and maxilla separately. www.indiandentalacademy.com

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SHORTCOMINGS • Normal values for the COGS analysis are best suited for the white adults population only. • Most patients presenting for orthognathic surgery are young adults , due to the process of facial growth and development , cephalometric norms for children can be expected to differ from those of adults. www.indiandentalacademy.com

• Similarly patients of advanced age may show changes simply due to aging process such as loss of vertical dimension ( attrition of teeth / loss of teeth ) .

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Cephalometric norms for orthognathic surgery in Black American Adults.

Thomas R , Riccardo A , Samuel J

Journal of maxillofacial surgery , 1989 •

Purpose of this study was to develop normal values for COGS analysis in Black American Adults .and compare it with the White adults and among black males and females.

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Post. Cranial base Skeletal angle of facial convexity Maxillary skeletal protrusion Skeletal lower anterior facial height Upper post. Face height Upper ant. Dental height Lower ant. Dental height Mandibular body length Soft tissue thickness in lower lip Lip length www.indiandentalacademy.com

• Were all significantly greater in Black Adults • Less nasal depth and projection , bony chin depth , and smaller nasolabial angle was observed .

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