Indian Journal of Dental Research

: 2011  |  Volume : 22  |  Issue : 1  |  Page : 179-

Comparative evaluation of the curve of Spee in two age groups and its relation to posterior teeth disclusion

Mandakini Mohan1, Marriette D'Souza1, Giridhar Kamath1, Abhishek Parolia2,  
1 Department of Prosthodontics, Manipal College of Dental Sciences, Mangalore, Karnataka, India
2 Department of Conservative Dentistry and Endodontics, Manipal College of Dental Sciences, Mangalore, Karnataka, India

Correspondence Address:
Mandakini Mohan
Department of Prosthodontics, Manipal College of Dental Sciences, Mangalore, Karnataka


Objectives: This study aims to compare the curve of Spee in human permanent healthy dentitions in two age groups to the disclusion in the premolar and molar region during protrusion. Materials and Methods: Sixty subjects were chosen and equally divided into two age groups of 18-25 years and 35-44 years. The left side of the mandibular dental casts was photographed using a digital camera to measure the curve of Spee. The canine cusp, mesiobuccal cusp of the first molar and the distal cusp of the second molar were marked and joined to form an arc. Using AUTOCAD software, the radius for this arc was obtained. A protrusive interocclusal record was made using rigid bite registration material to measure the amount of posterior disclusion during edge to edge protrusion. A dial gauge with an accuracy of 1/100 of a millimeter was used to measure the distance between the cusp tip indentations at the region of the buccal cusp of the mandibular 2nd premolar and distobuccal cusp of mandibular 1st molar. The results obtained were statistically analyzed. Results: The radius of curve of Spee increased nonsignificantly with age. The mean disclusion values measured in premolar and molar region showed a nonsignificant decrease with age. Conclusion: As age advances, there is a flattening of the curve of Spee and a concurrent reduction in the disclusion values during protrusion.

How to cite this article:
Mohan M, D'Souza M, Kamath G, Parolia A. Comparative evaluation of the curve of Spee in two age groups and its relation to posterior teeth disclusion.Indian J Dent Res 2011;22:179-179

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Mohan M, D'Souza M, Kamath G, Parolia A. Comparative evaluation of the curve of Spee in two age groups and its relation to posterior teeth disclusion. Indian J Dent Res [serial online] 2011 [cited 2020 Sep 25 ];22:179-179
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The curve of Spee was first described by F. Graf Von Spee in 1890 as a line of occlusion that lies on a cylinder tangent to the anterior border of the condyle, the occlusal surface of the second molar, andthe incisal edges of the mandibular incisors. [1] Clinically, the curve of Spee is defined as the anatomic curve established by occlusal alignment of the teeth, as projected on to the median plane, beginning with the cusp tip of the mandibular canine, and following the buccal cusp tips of the premolar and molar teeth. Given proper anterior teeth guidance, it permits total posterior disclusion on mandibular protrusion. The concept of disclusion was first introduced by D'Amico in 1961 and is said to be effective in eliminating harmful forces during eccentric movements. This disclusion has been studied to be dependent on the anterior, condylar guidance and the cusp shape factor. [2] The curve of Spee may get altered physiologically with age or pathologically in situations resulting from rotation, tipping, extrusion of teeth. Restoration of the dentition to such an altered occlusal plane can introduce posterior protrusive interferences, which have been shown to cause abnormal activity in mandibular elevator muscles. [3] This can be avoided by reconstructing the curve of Spee to allow harmony to exist between the anterior and condylar guidance so as to allow posterior disclusion on mandibular protrusion. With this background, the present study was aimed to compare the curve of Spee in the mandible of human permanent healthy dentitions in two age groups and to relate this to the disclusion in the premolar and molar region during edge to edge protrusion quantitatively.

 Materials and Methods

Sixty healthy human subjects were selected for this study and grouped according to age as Group A and Group B. Group A subjects belonged to the age group of 18-25 years and Group B subjects belonged to the age group of 35-44 years. A specially designed Performa [Table 1] was filled out for each subject and they were selected according to the following criteria given by Ferrario et al.[4]

Absence of moderate or severe clinical mandibular disorders [no temperomandibular joint (TMJ) sounds, tenderness of TMJ and masticatory muscles on palpation, painful limitations of mandibular movements)].Complete permanent dentition including 2nd molar (minimum of 28 teeth) with bilateral Angle's class I permanent molar and canine relationship with a horizontal and vertical overlap ranging from 2-4 millimeter.Absence of extensive restorations, cast restorations or cuspal coverage.No previous or current orthodontic treatment.Absence of anterior or lateral cross bite.Absence of pathological periodontal conditions.{Table 1}

Following selection, the curve of Spee and posterior disclusion were measured in the subjects of both the groups.

Measurement of the curve of Spee

The subject was seated on the dental chair in a relaxed and upright position. A sterilized perforated stock metal tray of appropriate size was selected to make an irreversible hydrocolloid impression of the mandibular arch. The irreversible hydrocolloid impression material (Imprint DPI, Mumbai, India) was uniformly loaded on to the selected impression tray. The loaded tray was carried to the mouth and centered over the teeth. Uniform pressure was applied to obtain an accurate impression. After the material was set, the impression was removed with a sudden jerk from the mouth and inspected. The impression was washed under running water, disinfected and poured using type III dental stone (KalabhaiKarson Private Ltd., Mumbai, India) to obtain a cast. The left hand side of the mandibular dental casts was photographed by means of a digital camera (8800 VR Nikon). The cast was oriented such that the lens of the camera was parallel to the buccal surfaces of the posterior teeth and the line joining the distal cusps of the 2nd molar with the cusp of the canine was parallel to the horizontal axis of the camera display. The camera to cast distance was kept as 15 cm and the magnification was 1:1 for all photographs. The photographs were then transferred to a computer and on each photograph, three points, namely, the cusp tip of the canine, the mesiobuccal cusp tip of the first molar and the distal cusp of the second molar, were marked. These points were joined to form an arc [Figure 1] and the radius of this arc was obtained in millimeter using AUTOCAD (Version: 2006) software. These values were recorded and analyzed.{Figure 1}

Measurement of the posterior disclusion during protrusion

A rigid bite registration material (Futar D, Kettenbach, Eschenburg, Germany) was used to make a protrusive interocclusal record. Subject was seated upright and instructed to bring the upper and lower anterior teeth in edge to edge position while visualizing the position in a face mirror. This was repeated several times until the subject was satisfactorily closing into the required position. The bite registration material was then dispensed using an automix gun (HareusKulzar) with disposable plastic tips. The material was injected onto the occlusal surfaces of the left mandibular teeth starting from the posteriormost tooth to the canine anteriorly [Figure 2]. The subject was then instructed to close the jaw slowly into the practiced edge to edge incisor position and hold this position until the material sets [Figure 3]. Once the bite registration was rigidly set, the subject was instructed to open the mouth and the material released carefully to avoid distortion. The bite was inspected to ensure proper indentations of the cusp tips and the excess material was trimmed using a sharp blade. A dial gauge (Schnelltester) with an accuracy of 1/100 of a millimeter was used to measure the distance between the cusp tip indentations at two locations on the protrusive record [Figure 4]. The first location selected was at the region of the buccal cusp tip of the mandibular second premolar. The second location was selected at the region of the distobuccal cusp of mandibular first molar. For regions showing perforation or extremely thin section of the bite registration material, a value of 0 (mm) was recorded. These values were statistically analyzed using Mann Whitney U and Spearman's tests by applying SPSS 13 software. A P value of <0.05 was considered to be significant.{Figure 2}{Figure 3}{Figure 4}


The mean value of the curve of Spee was 18.51 mm in group A and 26.53 mm in group B. This showed a statistically significant difference (P value 0.015) in the curve of Spee between group A and B [Table 2]. In relation to disclusion, there was no statistically significant difference (P value 0.110) between group A (mean value 1.71 mm) and B (mean value 1.04 mm) in premolar region [Table 3], while in molar region both group A (mean value 1.61 mm) and group B (1.03 mm) showed a statistically significant difference (P value 0.038) [Table 4]. Spearman correlation coefficient showed a negative nonsignificant correlation between the curve of Spee and the posterior disclusion for both group A and B [Table 5] and [Table 6].{Table 2}{Table 3}{Table 4}{Table 5}{Table 6}


There are various factors that interplay to influence the human dentition and its occlusion at different stages. Despite the various attempts made at defining these factors, controversies still exist regarding is true nature. These controversies stem from the fact that it is difficult, if not impossible, to prove beyond fact that one concept is better than another. This study was undertaken to shed some light on one such vital aspect of the occlusal scheme in human dentitions, namely, the curve of Spee. This curve is said to permit total posterior disclusion on mandibular protrusion when proper anterior tooth guidance is present. Thomas [5] stated that when each cusp is waxed using the cusp fossa waxing technique, a cusp to cusp relation during lateral movement has 1 mm posterior disclusion. This is similar to Reynold's statement that the optimum clearance of posterior teeth is 1.0 mm in edge to edge anterior closures. [6] The present study evaluated the changes taking place in the curve of Spee in healthy human dentitions in two age groups and related it to the posterior disclusion values during protrusion.

The two age groups selected for this study were:

18-25 years: This describes the age wherein all the permanent teeth (except the third molars) have erupted into the oral cavity and have been functioning for a few years.35-44 years: This age group is the standard monitoring group for health conditions of adults. The full effect of dental caries, the level of severe periodontal involvement, and the general effects of care provided can be monitored using data for this age group.

All the subjects selected had an Angle's class I molar relationship with an acceptable range of overbite and overjet between 2 and 4 mm. The overjet and overbite values determine the anterior guidance [7] and these were controlled in both the age groups in this study to avoid their influence on the disclusion values. There is little consensus in literature regarding the measurement of the curve of Spee. The method employed in this study is similar to that used by Xu et al.[8] wherein the curve was measured on standardized digitalized images of the left side of the mandibular casts using an advanced computer software AUTOCAD (version: 2006). The results from the present study show that the radius of the curve of Spee increases significantly, thus becoming flatter with age. This concurs with the findings of Sengupta et al.[9] who stated that with age there is an increased wear of the teeth with a resultant reversing of the curve of Spee. This is also in agreement the with indings of Brown [10] Knott [11] Bjork [12] and De Kock [13] reported that there is a natural tendency for the depth of the curve of Spee to decrease with age. The interocclusal material used for making the protrusive record was a highly rigid addition polysilicone which has been found to be most consistent for recording interocclusal relations by various studies. [14],[15] The mean disclusion values measured in the premolar region for both the groups showed a nonsignificant decrease while the disclusion values in the molar region showed a significant decrease with age. These findings are similar to the findings of Hobo and Takayama [16] who investigated molar disclusion during eccentric movements of adults with good occlusion and devoid of temperomandibular abnormalities. The reduced disclusion values in the present study could be attributed to the change in the topography of the condyle and glenoid fossa with age which affects the condylar guidance that is determined by the distal slope of the articular eminence. [17],[18] The steeper the eminence, the more the condyle is forced to move inferiorly as it shifts anteriorly. This results in greater vertical movement of the condyle, mandible and mandibular teeth. Consequently, a flatter guidance will permit a more horizontal component of movement. [19] The curve of Spee defines the plane of occlusion as the chord of its arc. [20] Thus, the plane of occlusion is said to be the position of the curve of Spee with relation to the condylar path. The closer the plane of occlusion comes to being parallel with the condylar path, the lower the cuspal height and the lesser the separation. [21]


This study indicates that as the age advances, there is a significant change in the curve of Spee and decrease in posterior disclusion during mandibular protrusion. Hence, as patients grow older, clinicians should be aware that the occlusal adjustments with age have gradually altered the curve of Spee of youth toward a more favorable individual occlusal curvature. Thus, if the curve of Spee is not maintained in these dentitions during full mouth rehabilitation, it may lead to interferences along the mandibular movements which will jeopardize the health of the masticatory system.


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