Introduction: The influence of craniofacial morphology on the curve of Spee has been investigated, these studies ignore the simultaneous contribution of multiple factors to the individual

variation of the curve. These individual variations play important role in the levelling of the curve which is an everyday occurrence in orthodontic practices and are required for stable results.

Objective: The influence of craniofacial morphology on the variation of the curve of spee includes multiple factors. This plays an important role in the levelling of the curve which is required for retention of achieved results. The study evaluates relationship between the varying depths of curve of spee and dentoskeletal features in malocclusions.

Material and Method: Pre treatment lateral cephalographs and dental casts of 30 orthodontic patients collected and divided into three groups according to different malocclusion. Cephalometric and study cast variables will be measured and subjected to statistical analysis with curve of spee as dependent factor and others as independent variables. Four linear and four angular cephalometric measurements will be done. Four study cast parameters will be measured.  Analysis will be performed to determine correlation coefficients between the depth of curve of spee and other variables.

Results: lateral cephalograms and study casts were obtained from 30 patients which includes 10 skeletal class I, 10 skeletal Class II and 10 skeletal class III patients. Multiple regression analysis was performed to see the linear dependence of various studied parameters on curve ofSpee. Corresponding beta -coefficient and their 95% confidence interval (CI) are described. Regression analysis shows that there was no significant correlation between curve of Spee and various parameters. These parameters explained 73% of the total variation of the curve of Spee.

Conclusion: Following conclusions were drawn on the basis of the findings of this study: The depth of curve of Spee was greatly influenced by sagittal maxillomandibular discrepancies. The variation in the depth of curve of Spee significantly influences the overbite, overjet and the inclination of mandibular first molar. SNA, OM, MD5MP, MD6MP, and OJ were negatively correlated and ANB, APDI, ODI, MD6MP, MD7MP, overbite and overjet were positively correlated with depth of curve of Spee for CLASS I SKELETAL. APDI, MD7MP, MD6MP, and OJ were negatively correlated and SNA, ANB, ODI, MD6MP, OM, overbite and overjet were positively correlated with depth of curve of Spee for CLASS II SKELETAL. SNA, ANB, APDI, ODI, OM, MD5MP, MD6MP, OJ and overjet were negatively correlated and MD6MP, MD7MP, and overbite were positively correlated with depth of curve of Spee for CLASS III SKELETAL. The multiple regression analysis showed that the curve of Spee was significantly influenced ODI, overjet and overbite in CLASS I skeletal, overjet and overbite in CLASS II skeletal and only overbite in CLASS III skeletal.

Keywords: craniofacial morphology, Curve of Spee, lateral cephalograms.

1. No author listed. The gliding path of the mandible along the skull. Ferdinand Graf Spee (1855-1937), Prosector at the Anatomy Institute of Krel. J Am DentAssoc 1980; 100: 670-5.
2. Osborn JW. Relationship between the mandibular condyle and the occlusal plane during hominid evolution: some of its effects on jaw mechanics. Am J Phys Anthropol 1987; 73: 193-207.
3. Tweed CH. Clinical orthodontics. St Louis: CV Mosby, 1966.
4. Braun S, Hnat WP, Johnson BE. The curve of Spee revisited. Am J Orthod Dentofacial Orthop 1996; 110: 206–210.
5. Germane N, Staggers JA, Rubenstein L, Revere JT. Arch length considerations due to the curve of Spee: a mathematical model. Am J Orthod Dentofacial Orthop 1992; 102: 251–255.
6. Orthlieb JD, Slaviceck R. Geometrische interpretation der Spee kurve. Z Stomatologie 1985; 82: 1–18.
7. Ghezzi F, Drago E, De Thomatis P, Zallio F. Profondita`della curva di Spee in rapporto a FMA, FH, ANB e classe dentale. Mondo Ortodontico 1991; 1: 73–76.
8. Orthlieb JD. The curve of Spee: understanding the sagittal organization of mandibular teeth. Cranio 1997; 15: 333–340.
9. Andrews LF. The six keys to normal occlusion. Am J Orthod. 1972;62:296–309.
10. Veli I, Ozturk MA, Uysal T. Curve of spee and its relationship to vertical eruption of teeth among different malocclusion groups. Am J Orthod Dentofacial Orthop 2015; 147(3):305-12.
11. Dhiman S. Curve of Spee - from orthodontic perspective. Indian J Dent 2015; 6(4):199-202.
12. Naeije M, Van Loon LAJ. Craniomandibulaire functie en dysfunctie. Houten: Bohn Stafleu Van Loghum; 1998.
13. Baydas B, Yavuz I, Atasarl N, Ceylan T, Dagsuyu I. Investigationof the changes in the positions of upper and lower incisors, overjet, overbite and irregularity index in subjects with different depths of curve of Spee. Angle Orthod 2004;74:349-55.
14. Farella M, Michelotti A, van Eijden TMG, Martina R. The curve of Spee and craniofacial morphology: A multiple regression analysis European J Oral Sciences 2002;110:277-81.
15. Wylie WL. Overbite and vertical facial dimensions in terms of muscle balance. Angle orthod 1944;14:13-27.
16. Bjork A. Variability and age changes in overjet and overbite. Am J Orthod 1953;39:779-801.
17. Salem OH, Al-Sehaibany F, Preston CB. Aspects of mandibular morphology, with specific reference to the antegonial notch and the curve of Spee. J Clin Pediar Dent 2003;27:261-65.
18. Nanda Surinder K. The developmental basis of occlusion and malocclusion. Chicago Quintessence Publishing Company 1983;244-58.
19. Dale Jack G. Guidance of occlusion: Serial extraction. Chapter 5, ln: Graber TM and Swain BF (Eds), Orthodontics current principles and techniques, St Louis, The CV Mosby Company 1985;pp 303.
20. Marshall SD, Caspersen M, Hardinger RR. Franciscus RG, Aquilino SA, Southard TE. Development of the curve of Spee. Am J Orthod Dentofacial Orthop 2008;134:344-52.
21. Cheon S, Park Y, Paik K, Ahn S, Hayashi K, Yi W, Lee S. Relationship between the curve of Spee and dentofacial morphology evaluated with a 3-dimensional reconstruction method in Korean adults. Am J Orthod Dentofacial Orthop 2008;133:640:e7-14
22. Orthlieb JD. The curve of Spee: Understanding the sagittal organization of mandibular teeth. Cranio 1997;15:333-40.
23. Kim YH. Overbite depth indicator with particular reference to anterior openbite. Am J Orthod 1974;65:586-611.
24. Shannon KR, Nanda R. Changes in the curve of Spee with treatment and at years post-treatment. Am J Orthod Dentofacial Orthop 2004;125:589-96.
25. Lie F, Kuitert R, Zenter A. Post-treatment development of the curve of Spee. Eu J Orthod 2006;28:262-68.
26. Koyama TA. Comparative analysis of the curve of Spee (lateral aspect) before and after orthodontic treatment with particular reference to overbite patients. J Nihon Univ Sch Dent 1979;21:25-34.

Dr Chandrashekhargouda Patil MDS

Plot No-44, “Basava Sadan”, Girish Nagar. Bagalkot Road, Near Micro-Wave Station. Vijaypur-586109, Karnataka