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Curve of spee INDIAN DENTAL ACADEMY Leader in continuing dental education\

HISTORY • F Graf Von Spee, who used skulls with abraded teeth to define aline of occlusion first described the Curve of Spee in 1890.\

DEFINITION • Spee: from a profile view, the molar surface lie on the arch of circle which, continued posteriorly touches the anterior border of condyle.\

• Central axis: Central axis of the cylinder is located some where on the horizontal midorbital plane posterior to the “Cristalacrimalis Posterior”\

CURVE OF SPEE REVISITED • Some of spee hypotheses were tested by Hitchock (1983), he established the circle through contract point on the anterior border of the Condyle and occlusal surface of second and first molar.\

• In most of the sample the incisor tip could not be included along the arch from such a curve.\


Curve of Spee: A. Original Curve of Spee (Von Spee) B. Craniel Curve of Spee C. Flat Curve of Spee\

• In Orthodontics: A flat occlusal plane is more appropriate term to describe the goal of orthodontic treatment.\

CLINICAL DEFINITION OF FLAT CURVE OF SPEE • Hitchcock (1983): The curve of spee is determined by the distal marginal ridges of the most posterior teeth in the arch and incisal edges of the Central Incisors\

• Glossary (1994): Anatomic curve established by the occlusal alignment of the teeth beginning with the Cusp tip of the mandibular Canine and following the buccal cusp tips of the premolar and molar teeth. Similar definitions are given by Ash (1971)\

• There is not agreement on the precise definition and morphology of the curve of spee and also on radius of curve of spee. • • • •

Dawson (1989)  4 inches (101.6 mm) Orthlieb (1997)  80 mm Hitchock (1983)  69.1 mm Spee  65mm – 70mm\





Brauns & Hnat

AJO 1996

Maximum depth of both side

Brauns & Schmit

AJO 1956

The sum of maximum depth of both side

Junger De Practer

AJO 2002

Average of sum of maximum depth of both side

Bulent Baydas

Angle orthodontist 2004

Perpendicular distance of deepest cusp tip and flat plan\





AJO 1989

Average of sum of perpendicular distance to each cusp


AJO 1980

Average of sum of perpendicular distance to each cusp

Abdul Azizkh

AJO 1999

Perpendicular distance of deepest cusp tip and flat plan\





AJO 2003

Perpendicular distance of deepest cusp tip and flat plan


J JPN Orthod Soc

Perpendicular distance of deepest cusp tip and flat plan

Ferdinand Lie

Eu J Ortho 2006

Perpendicular distance of deepest cusp tip and flat plan\


JOURNAL Eu J Ortho 2002\




Ferdinand Lie Masaomi Stanely Braun Abdul Aziz kh Bulent Bayndas

EUR J Ortho 2006 EUR J Ortho 2003 AJO 1996 AJO 1999 Angle 2004

2 to 1 to 1 to 1 to 1 to

Jurgen De Draeter Sondhi

AJO 2002 AJO 1980

2 to 6 2 to 6

Farella M Hui Xu

EUJ J oral 2002 J Prosthet 2004

3 to 7 3 to 7\

7 7 7 7 7

• Brief resume of the intended work: The assessment of the depth of curve of spee is a critical point for the orthodontic diagnostic & treatment protocol and leveling the curve of spee is a routine procedure in orthodontic practice but the influence of craniofacial morphology on the curve of spee has been investigated in very few studied and with conflicting findings.\



The need for the study therefore, is to determine the relationship between the curve of spee and several features of craniofacial morphology.\


A study1 was done to demonstrate more characteristics of normal occlusion continued & identified six characteristics that were present in 120 non-orthodontic models that displayed normal occlusion. The sixth characteristics to normal occlusion relates to curve of spee. research stated that there is a natural tendency for the curve of spee to deepen with time.


Andrews LF: the six Keys to normal occlusion. Am J orthod. 1972;62:296-309\

The study was2 done to evaluate the dept of the curve of spee in relation to FMA, FH, ANB and dental class the test has showed that there are not significant variations of spee’s curve dept in relation with skeletal parameters (FMA and FH) and it has showed significant variations as regards horizontal (ANB)and occlusal (dental class) parameters. The average value of spees curve of skeletal and dental III classes has turned out to be systemically lower than that of other classes.

GhezziF, DragoE, DethomatisP,ZqallioF: Depth of the curve of spee inrelatin to FMA, FH,ANB and dental class. Mondo orthod.1991 JanFeb:16(1):73-6\


A study 3 was done to evaluate the intrinsic morphology of the mandiblular curve of spee. Gender differences were found in both sides. While side differences were found only in the male sample. The right and left male sides showed different Concavities. The right hand side being flatter than the left. Male curves appeared larger than female ones. The left hand side was significantly larger than the right regardless of gender.


Ferrario VF, Sf or ZaC, Miani AJr, Colombo A, Tartaglia: Mathematical definition of the curve of spee in permanent healthy\ dentitions in man. Arch oral Biol.1992 sep-

• A study 4 was done to investigate whether the orthodontic leveling of the curve of spee is a treatment procedure with a stable result on a longterm basis. The following results were noted. Leveling the curve of spee during orthodontic treatment seems to be very stable on along term basis it was correlated with the other variables tested. • De praeterJ, Dermaut L, Martens G, Kuijpers – Jagtman AM: Long- term stability of the Leveling of the curve of spee Am J orthod Detofacial Orthop. 2002 Mar; 121(3):266-271\

• The study 5 was conducted to investigate the relationship between the curve of spee and skeletal facial morphology the result showed the curvature was significantly related to (a) horizontal positon of the condyle with respect to the dentition (b) the sagittal position of the mandible with respect to the anterior cranial base no significant relationship was found between the curve of spee and any of other cephalometric variables. • Farella M, MichelottiA, Van Eijden TMGJ. Martina R: The Curve of spee and Craniofacial morphology: a multiple regression analysis Eur J oral Sci 2002; 110: 277-281.\


The study 6 was done to investigate the relationship between the depth of the curve of spee and positons of upper an lower incisor, overjet, overbite and anterior lower crowding the subjects were divided into three groups with normal spee, flat spee and deep spee and were compared with one another correlation coefficient between the depth of curve of spee and other variables were calculated the result showed that there were no statistically significant.


Baytas B, YavuzI, Atasaral N, Ceylan I DagsuyuIM: Investigation of the changes in the positions of upper and lower incisors, overbite and irregularity index in subjects with different depths of curve of spee. Angle orthod. 2004 Jun; 74 (3):349-55\

MATERIALS & METHOD Patients reporting to out- patient section of Dept.of Orthodontics, Yenpoya Hospital having satisfactory periodontal health will be selected for the study all the subject should be healthy with complete dentition with no history of orthodontic treatment with no severe craniofacial disorders. Such as cleft palate with no absent maxillary and mandibular permanent teeth except for the third molars.\


After the patient selection the routine records are aquired which includes: – – – –

Case history Study models Photographs Lateral cephalometric radiographs\

PHOTOGRAPHS • Standardized photographs will make of the mandibular study models out of the occlusion from the left and right sides with the buccal tooth surfaces aligned in the same plane. The photographs will take in a plane perpendicular to the occlusal plane tangent to the buccal surface of the first molar and canine and centered on the first premolar. A ruler will included in all photographs to determine magnification.\

• The depth of curve of spee will measure as the perpendicular distance between the deepest Cusp tip and flat paln that will Lalid on top of the mandibular dental cast. Touching the incisal edges of the central incisors and the distal cusp tips of the most posterior in the lower arch.\

The three spee group will classified as follows. – – –

Normal spee group the depth of curve spee will >2mm but ≤ 4mm Flat spee group the depth of curve of spee will ≤ 2mm Deep spee group the depth of curve of spee will > 4mm\

• •

The cephalometric radiographs will exposed using standard method. Statistical analysis will be used in the study are ANOVA and student ‘t’ test.\

Thank you Leader in continuing dental education\

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