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10.5005/jp-journals-10021-1144 RESEARCH ARTICLE Prerna Raje Batham et al Curve of Spee and Its Relationship with Dentoskeletal Morphology 1 Prerna Raje Batham, 2Pradeep Tandon, 3Vijay Prakash Sharma, 4Alka Singh ABSTRACT Objective: The influence of craniofacial morphology on the variation of the depth of curve of Spee includes multiple factors. This plays an important role in the leveling 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. Materials and methods: 120 diagnostic casts and lateral head cephalograms of selected subjects on the basis of depths of curve of Spee as measured on the mandibular casts were selected. The subjects were divided into three Groups (Group-I- 0-2 mm, Group -II >2-4 mm and Group-III >4 mm of curve of Spee), and further into subgroups according to sex. Cephalometric and study cast variables were measured and subjected to statistical analysis with curve of Spee as the dependent variable and others as independent variables. Results: SNB, APDI, OM, Md5 - MP (mm), OJ and mandibular arch length were negatively correlated and ANB, Md6 to MP, ODI, overbite and overjet were positively correlated with depth of curve of Spee in both males and females. Conclusion: The curve of Spee is related to various dentoskeletal variables. Thus, the determination of this relationship is useful to assess the feasibility of leveling the curve of Spee by orthodontic treatment. Keywords: Curve of Spee, Dentoskeletal morphology. How to cite this article: Batham PR, Tandon P, Sharma VP, Singh A. Curve of Spee and Its Relationship with Dentoskeletal Morphology. J Ind Orthod Soc 2013;47(3):128-134. INTRODUCTION A profile view of human skull reveals an upward, concave curve in the mandibular teeth extending from molars to incisors and corresponding downward, convex curve in the maxillary arch. These peculiarities of the geometric arrangement of the teeth were first described by Ferdinand Graf Von Spee1 in 1890, using 120 skulls with abraded teeth to define a line of occlusion, to lie on a cylinder which is tangent to the anterior border of the condyle, the occlusal surfaces of second molar and incisal edges of the mandibular incisors and has since been referred to as ‘The curve of Spee’. It has been suggested that the curve of Spee has a biomechanical function during food processing by increasing the crush shear ratio between the posterior teeth and the efficiency of the occlusal forces during mastication.2,3 Andrews LF4 considered flat to slight curve of Spee to be one of the six characteristics of normal occlusion. He also 1 Lecturer, 2Professor and Head, 3Professor and Ex-Head, 4Assistant Professor 1 Department of Orthodontics and Dentofacial Orthopedics, Sri Auribindo Institute of Medical Sciences, Indore, Madhya Pradesh, India 2-4 Department of Orthodontics and Dentofacial Orthopedics, Faculty of Dental Sciences, CSM Medical University (Erstwhile KGMC), Lucknow Uttar Pradesh, India Corresponding Author: Prerna Raje Batham, I-43, RSS Nagar, LIG Colony, Indore, Madhya Pradesh, India, e-mail: [email protected] Received on: 11/4/12 Accepted after Revision: 25/8/12 128 stated that, there was a natural tendency for the curve to deepen with time because the lower jaw sometimes grows faster and continues for longer period than that of the upper jaw. This causes the lower anterior teeth, which are confined by the upper anterior teeth and lips, to be forced backward and upward, resulting in deeper overbite and deeper curve of Spee. So, the treatment objective should be to achieve a flat curve as an over treatment. Recently, the morphologic arrangement of the teeth in the sagittal plane has been related to the deep overbite, lower incisor proclination and lower arch circumference.5-7 Although, 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 leveling of the curve which is an everyday occurrence in orthodontic practices and are required for stable results. MATERIALS AND METHODS The present study was conducted on pretreatment study cast and lateral head cephalogram of 120 selected subjects on the basis of varying depths of curve of Spee as measured on the mandibular study cast5 with the age range of 18 to 25 years (mean age-21.5 years). Distribution of sample is showen in Table 1. Subjects had a full complement of teeth with all teeth in occlusion up to second molar. No previous orthodontic treatment was received by any of the subjects. Mild crowding cases were accepted but gross crowding cases were excluded. JIOS Curve of Spee and Its Relationship with Dentoskeletal Morphology No anterior or lateral cross bite was present. No cast restoration or cuspal coverage was present. High quality orthodontic impressions for diagnostic casts were taken by alginate impression material in the rim lock impression trays. The lateral cephalograms of the selected subjects were taken using the standard technique employed in the Department of Orthodontics and Dentofacial Orthopedics, CSM Medical University (Erstwhile KGMC). The lateral cephalograms were traced on acetate tracing sheets 50 micron in thickness using a sharp 4H pencil on a view box using transilluminated light in a dark room. MEASUREMENT OF CURVE OF SPEE ON STUDY CAST The depth of curve of Spee was measured as the perpendicular distance between the deepest buccal cusp tips and a scale that was laid on the top of the mandibular dental cast, touching the incisal edges of the central incisors and the distal cusp tips of the most posterior teeth in the lower arch (Fig. 1). The depth of curve of Spee was measured with divider placed between the deepest cusp tip and the scale. The measurements was made on the right and left side of the mandibular cast and the mean value of these two measurements was used as the depth of curve of Spee.5 The cephalometric and study cast measurements used in the study are described in Figures 2 to 7. The six skeletal parameters, nine dentoalveolar parameters and three study cast parameters were measured. Measurement of Reliability Reliability of measurements was tested by doing double determinations of 20 cephalograms and 20 study casts randomly selected at 15 days interval from the collected sample by the same operator and comparison was drawn between first and second determinations by paired ‘t’ test, whereas testing for method errors was done by using Dahlberg’s formula. No significant differences in initial and repeat readings of parameters were found. Hence, good reliability can be laid on the observations made (Table 2). RESULTS The data so obtained was subjected to the statistical analysis using statistical package program STATA version 9.2. Descriptive statistics, including the mean and standard Fig. 1: Measurement of curve of Spee Fig. 3: Skeletal vertical parameters Fig. 2: Skeletal horizontal parameters Fig. 4: Dentoalveolar horizontal parameters The Journal of Indian Orthodontic Society, July-September 2013;47(3):128-134 129 Prerna Raje Batham et al Fig. 5: Dentoalveolar vertical parameters Fig. 7: Measurement of mandibular arch length (mm) Table 1: Distribution of sample Fig. 6: Measurement of overbite (a) and overjet (b) deviation values were calculated for all the parameters in each Group. Student t-test was used to determine the significant differences between the mean and standard deviations of various parameters in the three Groups but among the same Group I (flat = 0-2 mm) (n = 40) Group II (normal = 2-4 mm) (n = 40) Group III (deep > 4 mm) (n = 40) Ia—20 males Ib—20 females IIa—20 males IIb—20 females IIIa—20 males IIIb—20 females sex. Pearson’s correlation analysis was used to determine correlation coefficients between the depths of the curve of Spee and other variables used in the study. Furthermore a multiple linear regression analysis was performed to determine the relationship between the curve of Spee as the dependent variable and other parameters as the independent variables. Descriptive statistics, including the mean and SD values, were determined for each Spee Group and are shown in Tables 3 and 4 for both males and females. The correlation (Table 6) shows SNB, APDI, OM, Md5— MP (mm), OJ and mandibular arch length were negatively Table 2: Intraobserver comparison of mean ± SD of values of parameters S. no. Parameters Mean ± SD values of initial readings Mean ± SD values of repeat readings t-value p-value Skeletal horizontal 1. SNB (degree) 2. ANB (degree) 3. APDI (degree) 80.40 ± 1.86 2.84 ± 1.32 85.40 ± 2.84 80.30 ± 1.89 2.86 ± 1.73 85.03 ± 4.28 2.39 4.61 5.75 0.95 0.35 0.18 Skeletal vertical 4. ODI (degree) 76.05 ± 5.99 76.24 ± 6.59 2.23 0.18 Dentoalveolar horizontal 5. Md6 to MP (degree) 6. Md7 to MP (degree) 7. OM (mm) 83.20 ± 5.98 94.45 ± 5.39 44.40 ± 3.32 83.74 ± 3.17 94.20 ± 4.91 44.20 ± 4.09 0.82 0.15 1.58 0.41 0.87 0.12 Dentoalveolar vertical 8. Md5 to MP (mm) 9. Md6 to MP (mm) 10. OJ (mm) 34.45 ± 2.24 33.95 ± 2.37 41.45 ± 4.03 34.35 ± 4.95 33.87 ± 3.15 41.35 ± 3.37 1.49 1.23 2.64 0.14 0.23 0.16 Study cast 11. Overbite (mm) 12. Overjet (mm) 13. Md. arch length (mm) 3.48 ± 1.44 2.50 ± 0.83 39.50 ± 2.03 3.57 ± 1.32 2.72 ± 1.47 39.32 ± 2.89 3.68 3.70 4.39 0.22 0.34 0.27 p-value: >0.05: nonsignificant; <0.05: just significant; <0.01: moderately significant; <0.001: highly significant 130 JIOS Curve of Spee and Its Relationship with Dentoskeletal Morphology Table 3: Comparison of mean and standard deviation values for Groups Ia, IIa and IIIa (males) S. no. Parameters Group Ia flat Mean ± SD Group IIa normal Mean ± SD Group IIIa deep Mean ± SD Ia vs IIa p-value Ia vs IIIa IIa vs IIIa Skeletal horizontal 1. SNB 2. ANB 3. APDI 82.75 ± 3.58 2.60 ± 1.27 85.85 ± 3.53 79.85 ± 2.43 3.80 ± 1.24 83.15 ± 2.39 78.10 ± 3.57 5.55 ± 1.57 77.95 ± 4.94 <0.01** <0.01** <0.01** <0.001*** <0.001*** <0.001*** 0.07 <0.001*** <0.001*** Skeletal vertical 4. ODI 77.35 ± 5.87 81.30 ± 4.62 83.90 ± 8.93 <0.05* <0.01** 0.25 Dentoalveolar horizontal 5. Md6 to MP 6. Md7 to MP 7. OM (mm) 82.70 ± 6.02 92.60 ± 7.42 47.05 ± 3.92 84.95 ± 5.27 95.05 ± 6.17 46.80 ± 3.33 85.85 ± 6.27 95.20 ± 3.96 43.05 ± 3.78 0.51 0.18 0.82 <0.05* <0.05* <0.01** 0.94 0.92 <0.01** Dentoalveolar vertical 8. Md5 to MP 9. Md6 to MP 10. OJ (mm) 39.20 ± 2.35 37.75 ± 2.38 47.05 ± 4.96 38.00 ± 3.09 37.00 ± 3.36 42.60 ± 4.38 36.95 ± 2.99 36.15 ± 2.74 42.55 ± 5.14 0.17 0.42 <0.01** <0.05* 0.18 <0.05* 0.28 0.38 0.97 Study cast 11. 12. 13. 2.88 ± 1.37 2.20 ± 0.77 40.50 ± 2.09 3.73 ± 1.19 3.25 ± 0.82 38.30 ± 2.20 6.78 ± 2.67 6.65 ± 4.47 37.40 ± 1.76 <0.05* <0.001*** <0.01** <0.001*** <0.001*** <0.001*** <0.001*** <0.01** 0.16 Overbite Overjet Md. arch length p-value : >0.05: nonsignificant; *<0.05: just significant; **<0.01: moderately significant; ***<0.001: highly significant Table 4: Comparison of mean and standard deviation for Groups Ib, IIb and IIIb (females) S. no. Parameters Skeletal horizontal 1. SNB 2. ANB 3. APDI Skeletal vertical 4. ODI Dentoalveolar horizontal 5. Md6 to MP 6. Md7 to MP 7. OM (mm) Dentoalveolar vertical 8. Md5 to MP 9. Md6 to MP 10. OJ (mm) Study cast 11. Overbite 12. Overjet 13. Md. arch length Group Ib flat (0-2 mm) Mean ± SD Group IIb normal (2-4 mm) Mean ± SD Group IIIb deep (<4 mm) Mean ± SD p-value Ib vs IIb Ib vs IIIb IIb vs IIIb 80.45 ± 1.76 2.80 ± 1.32 85.40 ± 2.84 80.40 ± 2.78 3.20 ± 1.32 84.65 ± 3.97 78.25 ± 3.61 5.05 ± 1.73 77.53 ± 5.28 0.57 0.34 0.49 <0.05* <0.001*** <0.001*** <0.05* <0.001*** <0.001*** 76.05 ± 5.99 77.20 ± 5.75 80.50 ± 6.59 0.53 <0.05* 0.10 83.20 ± 5.98 94.20 ± 4.91 44.40 ± 3.32 84.80 ± 6.27 94.45 ± 5.39 42.70 ± 4.09 86.55 ± 5.17 94.90 ± 5.32 42.25 ± 5.09 0.06 0.79 0.11 <0.05* 0.87 0.12 0.34 0.67 0.76 34.45 ± 2.24 33.95 ± 2.37 41.45 ± 4.03 34.25 ± 2.55 33.80 ± 2.09 39.55 ± 4.27 33.10 ± 3.35 32.90 ± 2.51 38.70 ± 2.32 0.79 0.83 0.16 0.14 0.23 <0.05* 0.23 0.18 0.44 3.48 ± 1.44 2.50 ± 0.83 39.50 ± 2.03 3.90 ± 1.05 2.80 ± 8.6 38.30 ± 1.41 6.28 ± 2.48 5.38 ± 3.57 36.35 ± 2.89 0.26 0.26 <0.05* <0.001*** <0.001*** <0.001*** <0.001*** <0.001*** <0.001*** p-value : >0.05: nonsignificant; *<0.05: just significant; **<0.01: moderately significant; ***<0.001: highly significant correlated and ANB, Md6 to MP, ODI, overbite and overjet were positively correlated with depth of curve of Spee in both males and females. Multiple regression analysis was performed to see the linear dependence of various studied parameters on curve of Spee. Corresponding -coefficient and their 95% confidence interval (CI) are described in Table 5. Regression analysis shows that there was highly significant correlation between curve of Spee and ANB, overbite, mandibular archlength (<0.001***), where as for OJ (mm) it was moderately significant (<0.01**) and for Md5 to MP (mm) and Md6 to MP (degree) was just significant (<0.05*). These parameters explained 66% of the total variation of the curve of Spee. Table 5: Multiple regression analysis Parameters -coefficient (95% CI) ANB Overbite Mandibular archlength OJ (mm) Md5-MP (mm) Md6-MP (degree) Constant 0.250 (0.17, 0.33) <0.001*** 0.189 (0.12, 0.26) <0.001*** –0.119 (–0.18, –0.06) <0.001*** –0.044 (–0.07, –0.01) <0.01** 0.66 –0.043 (–0.10, 0.00) <0.05* 0.041 ( 0.01, 0.11) <0.05* 10.547 (6.16, 14.94) 0.000 p-value R2 change DISCUSSION The assessment of relationship of curve of Spee with the dentoskeletal morphology is essential to understand the The Journal of Indian Orthodontic Society, July-September 2013;47(3):128-134 131 Prerna Raje Batham et al Table 6: Correlation of depth of curve of Spee with different parameters used in the study in male and female samples S.no. Parameters Males ‘R’ Skeletal horizontal 1. 2. 3. Skeletal vertical 4. Dentoalveolar horizontal 5. 6. 7. Dentoalveolar vertical 8. 9. 10. Study cast 11. 12. 13. SNB ANB APDI ODI – 0.54 0.66 – 0.69 0.35 Females ‘p’ <0.001*** <0.001*** <0.001*** <0.01** ‘R’ – 0.30 0.55 – 0.59 ‘p’ <0.05* <0.001*** <0.001*** 0.31 <0.05* Md6 to MP Md7 to MP OM (mm) 0.34 0.09 – 0.46 <0.05* 0.08 <0.001*** 0.33 0.06 – 0.20 <0.05* 0.67 0.12 Md5 to MP Md6 to MP OJ (mm) – 0.32 – 0.23 – 0.40 <0.05* 0.08 <0.05* – 0.21 – 0.17 – 0.34 0.09 0.19 <0.01** Overbite Overjet Mandibular arch length 0.76 0.71 – 0.56 <0.001*** <0.001*** <0.001*** 0.61 0.51 – 0.54 <0.001*** <0.001*** <0.001*** p-value : NS: nonsignificant; *<0.05: just significant; **<0.01: moderately significant; ***<0.001: highly significant influence of multiple factors that leads to variation in the depth of the curve. It has been suggested that the mandibular sagittal and vertical position relative to the cranium is related to the curve of Spee, which is present in various forms in mammals (Farella et al).8 In humans, an increased curve of Spee is often seen in brachycephalic facial patterns (Wylie9 and Bjork)10 and associated with short mandibular bodies (Salem OH et al).11 Although, leveling of the curve of Spee is an everyday occurrence in orthodontic practices, little research has been done to examine the relationship of the curve of Spee and the multiple factors causing variation in its depth, which may be useful to assess the feasibility of leveling the curve of Spee by orthodontic treatment. The measurement of curve of Spee was done and the average of the distance on right and left side was taken as the depth of curve of Spee (Nanda SK,12 Dale J,13 and Baydas et al).5 This method of assessment of curve of Spee was easy to perform and lacked any magnificational and projectional errors. Other authors like Baldridge6 used the perpendicular distances on both sides, Sondhi et al14 used the sum of the perpendiculars, Bishara et al15 used the average of the sum of the perpendicular distances to each cusp tip and Braun et al7 and Braun and Schmidt16 used the sum of the maximum depth on both sides. The age group was in the range of 18 to 25 years to omit any effect of growth on the curve of Spee since, the depth remained relatively constant during adulthood as compared to the flat curve in decidous dentition and maximum deepening during adolescent dentition (Marshall et al).17 This was also supported by Farella et al8 who said that homogenous dental wear could be the reason for maintenance of curve of Spee in adulthood. 132 The parameters used were 10 cephalometric and 3 study cast, of which cephalometric parameters were further divided into skeletal and dentoalveolar. Since the curve of Spee was significantly influenced by sagittal and vertical craniofacial morphology as suggested by Farella et al,8 the cephalometric parameters were further divided into four skeletal horizontal, two skeletal vertical, five dentoalveolar horizontal and four dentoalveolar vertical parameters. The findings suggested that the depth curve of Spee was influenced by the position of the mandible with respect to the anterior cranial base, i.e. SNB. The negative correlation value suggested that more the mandible was positioned anteriorly (large SNB angle) the depth of curve of Spee was less, and as the SNB angle decreased from Groups I to III, depth also increased in both males and females. This was supported by studies done by Farella et al8 and Cheon et al.18 It was found that the subjects with higher maxillomandibular discrepancies tend to have deeper curve of Spee. The value of ANB showed positive correlation with the depth of curve of Spee, i.e. was less in subjects with small value of ANB angle (suggesting Class I skeletal pattern) and as the value of ANB angle increased the depth of curve of Spee also increased (the Class-II skeletal pattern) also supported by Cheon et al18 and Orthlieb JD19 who suggested that the depth of curve of Spee was lesser in those with Class III malocclusions than in Class II malocclusions. The curve of Spee was influenced by the skeletal pattern of the subjects as suggested by the values of APDI, that is smaller the APDI value in relation to the normal mean greater was the probability of distocclusion thus suggesting Class II skeletal pattern and deep curve of Spee. This finding was similar to a study conducted by Cheon et al.18 JIOS Curve of Spee and Its Relationship with Dentoskeletal Morphology Overbite depth indicator was given by Kim,20 suggesting that lower the ODI value greater the chance of there being openbite or tendency toward an openbite. The overbite and tendency toward deepbite were found to increase as the ODI value increased. In the present study the findings suggested that as the depth of curve of Spee increases from Groups I to II the tendency for deep bite in the subjects also increases, this correlates with the increase value of overbite in Group III as compared to Group I. Similar findings were also reported by Trauten et al,21 who reported negative curve of Spee in openbite cases and deep curve of Spee in deep bite cases. The positive correlation value for both males and females suggested that the value of ODI increases with increase in the depth of curve of Spee. The higher value of ODI among Group-III signifies deep bite and tendency toward deep bite in deep curve of Spee Groups for both males and females Cheon et al.18 Md6 to MP and Md7 to MP angles were considered to asses the possible relation between the axial inclination of the mandibular molars and the depth of curve of Spee. The mean values were found to be increased with increase in curve of Spee depth suggesting that the mesial inclination of the molars were increasing as the depth of the curve of Spee was increased and the difference was found to be statistically significant. Similar findings were also reported by Shannon and Nanda22 and Lie F,23 who suggested that deepening of curve of Spee can occur as the axial inclination of the teeth increases. Osborn24 also showed similar findings and related forward tilting of molars to the inclination of masseter muscle thus increasing crush- shear ratio, also supported by Hemley25 and Thompson and Strang.26 OM (mm) was the distance measured from the most posterior point of the dentition on the occlusal plane (point ‘M’) to the point of intersection (point ‘O’) of a line perpendicular from the superior most point on the condyle (Farella et al).8 It is the linear distance signifying the horizontal positioning of the dentition with respect to the condyle. The value of OM (mm) was found to be decreasing from Groups I to III suggesting that the samples in which the dentition was more posteriorly positioned with respect to the condyle, i.e. smaller the value of ‘OM’ greater the depth of curve of Spee. The finding of present study supported the hypothesis by Farella et al8 that the position of dentition in the mandibular arch in relation to the condyle influences the shape of the curve of Spee. The difference of the mean value for Md5 to MP (mm) was just significant (<0.05) for Groups I vs III in male samples. Rest all the Groups showed nonsignificant correlations. This was due to greater infraposition of the mandibular second premolar with relation to mandibular plane in Group III as compared to other Groups leading to deep curve of Spee. In the present study the deepest point of the curve of Spee was found to be the cusp tip of second premolar region in maximum number of samples. Koyama27 and Lie F23 also supported this finding and suggested that the deepest point of the curve is the cusp tip of mandibular second premolar. Shannon and Nanda,22 reported in their study that there is lack of correlation between the depth of curve of Spee and perpendicular distance of mandibular plane to the molar cusp tip same was found in this study. OJ signifies the vertical positioning of the lower dentition with respect to the condyle. It was measured as the perpendicular distance between the superior most point on the condylar head (point ‘J’) and the point of intersection of this perpendicular to the occlusal plane (point ‘O’). In this study the mean value for OJ (mm) was found to be decreasing from Groups I to III, this finding suggested that the dentition had moved upward with respect to the condyle in deep curve of Spee Groups for both males and females. The finding signifies that as the vertical distance between the lower dentition and the condyle had decreased as the depth of curve of Spee was increased. The finding of the study was supported by the findings of Farella et al.8 The mean value for overbite and overjet was found to be increased from Groups I to III in both males and females. This suggested that when the anterior teeth have no vertical stop, their continued eruption leads to deepening of anterior aspect of the curve. This was supported by findings of Shannon and Nanda.22 The positive correlation coefficient value also proved as the overbite increases depth of curve of Spee also increases. These findings were supported by studies done by Alqubandi28 and Lie F.23 These finding showed that the overbite measurements in the deep Spee Group were significantly larger than in the moderate and flat Spee Groups. The most pronounced differences for overbite were found between the flat and deep Spee Groups as supported by studies of Kuitert,29 Baydas et al5 and Cheon et al.18 The statistically significant beta-correlation coefficients between the depth of curve of Spee and overbite (0.189) confirmed this result. These finding were supported by Trauten et al21 and Orthlieb,19 they showed that there is negative curve of Spee in open bite cases and as the curve of Spee deepens the overbite also deepens. The value for mandibular arch length was found to be decreased from Groups I to III in both males and Females. The possible explanation for these finding could be that as the curve of Spee is deepening from Groups I to III the mandibular incisors are becoming more uprighted and thus the perpendicular distance from the midpoint between the incisal edges and a line passing through the distobuccal cusp tips was becoming shorter, thus decreasing the mandibular arch length. These findings were supported by De Praeter et al,30 who said that more pronounce curve could be considered as compensation for lack of arch circumference. In similar findings Braun et al7 and Al Qubandi,28 said that deep curve of Spee is associated with smaller mandibular arch length and there is increase in the arch length as the curve of Spee is leveled. The purpose of this cross-sectional study was to find out the correlation between the dentoskeletal morphology and the depth of curve of Spee. This study has unmasked the dentoskeletal morphologic features associated with the flat, The Journal of Indian Orthodontic Society, July-September 2013;47(3):128-134 133 Prerna Raje Batham et al moderate and deep curve of Spee. Subjects with deep curve of Spee had shown to have sagittal discrepancies, posteriorly and superiorly positioned dentition in the mandible suggesting Class II pattern. Dentally these subjects showed deep overbites, elevated anterior teeth, depressed premolars and mesially inclined molars. CONCLUSION Following conclusions were drawn on the basis of the findings of this study: 1. The depth of curve of Spee was greatly influenced by sagittal maxillomandibular discrepancies. The values for parameters SNB, ANB and APDI suggested that the mandible was located more posteriorly in deep curve of Spee Group. 2. The variation in the depth of curve of Spee significantly influences the overbite, overjet and the inclination of mandibular first molar. 3. The height of mandibular second premolar, position of mandibular dentition with respect to the condyle and mandibular arch length showed significant decrease with increase in the depth of curve of Spee. 4. The correlation coefficients obtained from the study suggested that the depth of curve of Spee was positively correlated with ANB, ODI, Md6 to MP (degree), overbite and overjet that is, as the value of above mentioned parameters increases as the depth of curve of Spee increases and negatively correlated with SNB, APDI, Md5 to MP (mm) and mandibular arch length that is, with decrease in the depth of curve of Spee, the value of above mentioned parameters decreases. 5. The multiple regression analysis showed that the curve of Spee was significantly influenced by ANB, overbite, mandibular arch length, vertical positioning of dentition with respect to condyle (OJ), Md5 to MP (mm) and Md6 to MP (degree). 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