An Evaluation of Occlusal Relationship and Primate Space in Deciduous Dentition in Kancheepuram District, Tamil Nadu, India.

AIM: The objective of the study was to evaluate the occlusal characteristics of primary dentition in 3-5-year-old children in Kancheepuram district.
MATERIALS AND METHODS: A cross-sectional survey was carried out on children aged 3-5 year old in the Kancheepuram district. A total of 603 children were examined. Occlusal relationship was assessed separately on both right and left side and was classified as a flush terminal plane, mesial step, or distal step. Similarly, occlusal relationship of primary canine was examined and classified as Class I, II, or III. Primate space was measured in both the arches using digital Vernier caliper.
RESULTS: Pearson Chi-square test was used. Statistical significance was noted on both right and left side primary molar occlusion as well as in the canine occlusion across the three age groups. Primate spaces in both arches have been found to be significant across the three age groups. Mann-Whitney test between gender and occlusal relationship was found to be not significant.
CONCLUSION: Flush terminal plane is the most common primary molar occlusion found in the present study which is statistically significant. Most of the children had primate space present in upper and lower teeth which is statistically significant.

INTRODUCTION

The occlusal relationship of primary dentition determines the occlusion of future permanent dentition.[1] During infancy dental arches are small with crowding of tooth germs. With increase in growth of the jaws, tooth germs get enough space and subsequently erupt. Some of the general characteristics of a deciduous dentition are arches being half round in shape, almost having no curve of Spee, shallow intercuspal digitation, and little or no crowding. According to Baume's study,[2] primary dentition can be divided into spaced and nonspaced dentition. Spaced dentition means there is a good amount of spaces between the teeth. This space can be used to accommodate larger size permanent teeth. Space found in primary dentition is of two types - physiological and primate space. Physiological space is present between the primary teeth. Primate space is present between lateral incisor and canine in upper and canine and deciduous first molar in the lower. These spaces are also called anthropoid space or simian space. With eruption of primary second molar, future eruption of permanent teeth is determined.[3]

The occlusion of primary molar can be divided into three relationships - flush terminal plane, distal step, and mesial step. The distal surface of upper and lower primary second molar in centric occlusion is in a straight line is called as flush terminal plane. The distal surface of lower primary second molar is ahead or mesial to distal surface of upper primary second molar in centric occlusion is called as mesial step. The distal surface of lower primary second molar is behind or distal to upper primary second molar in centric occlusion is called as distal step. Identifying the primary molar relationship is very vital as it reflects the future permanent molar relationship and possible malocclusion. The flush terminal plane can lead to end on the relationship of permanent molars or can lead to Class I permanent molar occlusion with forward growth of mandible. The mesial step can lead to Class I permanent molar relationship and with forward growth of mandible can lead to Class III molar relationship. The distal step can lead to Class II permanent molar relationship and with forward growth of mandible can lead to end on occlusion of permanent molars.

Aim

The aim of the study was to find occlusal characteristics of primary dentition in 3–5-year-old children in Kancheepuram district.

MATERIALS AND METHODS

The study was a cross-sectional survey carried out on children aged 3–5-year-old children of Kancheepuram district. A total of 603 children were examined. The sample was selected using stratified random sampling technique. The age of each child was obtained from school records which the parents had submitted earlier.

Children selected in the study had fulfilled the following criteria:

No missing teeth

No grossly decayed teeth

No permanent teeth

No developmental anomalies

No stainless steel crown in the posterior tooth

No tooth with proximal restorations.

Examination was done by a single examiner using mouth mirror, and the child was asked to bite in centric occlusion. Occlusal relationship both on right and left side was assessed separately and was classified as flush terminal plane, mesial step, or distal step.

The occlusal relationship of primary canine[45] was noted as Class I cusp tip of maxillary canine tooth is in same vertical plane as distal surface of mandibular primary canine. Class II cusp tip of maxillary primary canine is mesial to distal surface of mandibular primary canine or Class III - cusp tip of maxillary canine is distal to distal surface of primary mandibular canine. Primate space was measured between primary lateral incisor and canine in the upper and primary canine and deciduous first molar on the lower on both the arches using a digital caliper. The values were rounded off to nearest whole number.

RESULTS

The results were tabulated and analyzed using Statistical Package for the Social Sciences (SPSS version 16) for Windows. The groups were compared using Pearson's Chi-square test. Table 1 summarizes the distribution of children among ages of 3, 4, and 5 years. Distribution of various occlusal relationships is given in Table 2. Among 3-year-old children, 72.64% and 76.12% had flush terminal relationship both on right and left side, 18.9% and 16.4% had distal step on right and left side, and 8.4% and 7.4% had mesial step on right and left side, respectively. Among 4 years old, 88.06% and 89.05% had flush terminal plane relationship both on right and left side, 5.47% and 1.49% had distal step relationship both on right and left side, and 6.47% and 9.4% had distal step on both right and left side, respectively. Among 5 year old, 91.04% and 88.56% had flush terminal plane on both right and left side, 5.97% had distal step on both right and left side, and 2.99%and 5.47% had mesial step on both right and left side, respectively. Age-wise distribution of various molar relationships was found to be significant at both right and left side. On both sides, molar occlusion has been found to be significant with respect to three age groups. Right side occlusion was found to be very significant when compared to left side. Occlusion on both right and left side across gender is tabulated in Table 3. Flush terminal plane, distal step, and mesial step were compared between both male and female. The result indicates statistical insignificance.

Table 1

Distribution of children across three age groups

Table 2

Distribution of occlusion on both right and left side across three age groups

Table 3

Distribution of occlusion on both right and left side across gender

Primary canine relationship among various age groups is tabulated in Table 4. In age group of 3, Class I was most found canine relationship on both right (70.64%) and left side (77.11%). This is followed by Class II (20.89% on right and 17.91% on left) and Class III canine relationship (8.45% on right and 4.97% on left). In age group of 4, Class I was most found canine relationship on both right (84.57%) and left side (87.06%). This is followed by Class II (7.9% on right and 6.96% on left) and Class III canine relationship (7.4% on right and 5.9% on left). In age group of 5, Class I was mostly found canine relationship on both right (90.54%) and left side (89.05%). This is followed by Class II (6.46% on both right and left side) and Class III canine relationship (2.99% on right and 4.47% on left). Both right and left side primary canine occlusions have been found to be very significant with respect to three age groups.

Table 4

Distribution of canine relationship on right and left side

Table 5 summarizes the distribution of primate space of both upper and lower among the three age groups. In age group of 3 in maxillary teeth, 35.3% had 1 mm, 27.8% had 2 mm, and 24.8% had 0 mm of primate space. In mandibular teeth of same age group, 32.3% had 1 mm, 32.3% had 0 mm, and 24.8% had 2 mm of primate space. In age group of 4 in maxillary teeth, 43.28% had 1 mm, 28.86% had 2 mm, and 24.88% had 0 mm of primate space in maxillary teeth. In mandibular teeth, 42.78% had 1 mm of primate space, 28.35% had 2 mm of primate space, and 25.37 had 0 mm of primate space. In age group of 5 in maxillary teeth, 37.31% had 2 mm, 31.84% had 1 mm, and 20.9% had 0 mm of primate space. In mandibular teeth of same age group, 33.83% had 1 mm, 32.83% had 2 mm, and 24.87% had 0 mm of primate space. Primate spaces of both upper and lower teeth have been found to be significant across three age groups.

Table 5

Distribution of primate space across three age groups

DISCUSSION

The primary molar relationship can predict future permanent molar occlusion and probable potential malocclusion. Some of the features seen in primary dentition such as anterior deep bite get corrected with eruption of molars[6] and also with downward and forward growth of mandible. Flush terminal plane gets corrected to Class I molar occlusion with the utilization of primate space if present. This is called as early mesial shift. In case of absence of primate space, the permanent first molar utilizes Leeway space to come to Class I molar occlusion. This is called as late mesial shift. Thus, primary molar occlusion and primate Space are an essential indicator for future permanent occlusion and potential malocclusion that can arise. In the present study which was conducted on children of Kancheepuram district, Tamil Nadu state, the sample demonstrated a higher percentage of flush terminal plane relationship. The result is in concurrence with other similar studies.[5789101112131415] However, some of other studies have also shown increased mesial step prevalence.[116171819] Flush terminal plane relationship has been found to decrease at the age of 5 years,[20] but this was not observed in the present study. Bhat et al.[21] have found increase in mesial step prevalence with advancing age but was not found in the present study. The present study did not find difference in primary molar occlusal pattern between the sexes. The primary molar occlusal relationships are seemed to be distributed equally between the sexes. The difference could be probably found during preadolescent growth period, for which a longitudinal study might be needed. The most common canine relationship found as Class I followed by Class II and Class III in all age groups. These results are similar to other studies.[518]

Primate spaces have been found to be greater in other population.[141920] Primate space is found to be less in children of Udaipur.[13] Most of the studies having recorded primate space as presence or absence and measurement has not been done. In the present study, primate space has been recorded both in upper and lower from 0 to 4 mm. It has been observed that primate space is present both in upper and lower dentition in the present population. It is observed that large percentage of children has 1–2 mm of primate space in both the arches and less than 3.5% of sample had 4 mm of primate space. Variance in primate space may be related to ethnic and environmental factors. The study is essential because they reflect the need of future orthodontic needs of the population. Lack of space in deciduous dentition could be due to disproportion concerning jaw and tooth size. Spaced dentition in primary tooth indicates decreased tendency of crowding in permanent dentition. Bishara et al.[1] had found in evaluating the changes from primary to permanent dentition that cases which had shown flush terminal plane turned 56% to Class I occlusion and 44% to Class II occlusion. In distal step cases, treatment should be started early as there is less chance of self-correction. Mesial step in primary dentition leads to Class I permanent molar relationship.[1] Occurrence of Class III molar relationship in mesial step depends on the magnitude of the mesial step. Thus, primary molar occlusion should be observed for early orthodontic intervention if necessary.

CONCLUSION

Flush terminal plane is the most common primary molar occlusion found in the present study which is statistically significant. Most of the children had primate space present in upper and lower teeth which is also statistically significant. Differences in primary molar occlusion between the sexes have not been observed. The study provides an insightful approach to occlusal morphology of 3–5-year-old children. A further longitudinal study is also being carried out to ascertain the changes from deciduous dentition to permanent dentition.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.