Scholarly article on topic 'Sexual dimorphism, pattern of third molar and mandibular second premolar agenesis in Indian paediatric orthodontic patients'

Sexual dimorphism, pattern of third molar and mandibular second premolar agenesis in Indian paediatric orthodontic patients Academic research paper on "Clinical medicine"

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{"Tooth agenesis" / "Third molar" / "Mandibular second premolar" / "Paediatric orthodontic patients" / "Pattern of agenesis" / "Missing third molar"}

Abstract of research paper on Clinical medicine, author of scientific article — Apurva Mishra, Ramesh K. Pandey

Abstract Objective To determine and compare the prevalence and pattern of agenesis of third molar and mandibular second premolar in paediatric orthodontic patients of age group 9–15 for sexual dimorphism. Methods The digital orthopantograph was obtained from the archive record of patients of age group 9–15year. Radiographs of 301 patients were evaluated after taking exclusion criteria into account and were assessed for the presence/absence of third molars and mandibular second premolar. Tooth development evaluation followed the method of Demirjian et al., based on eight stages of tooth formation. The agenesis of third molar in maxilla and mandible between age groups and gender was compared using Chi-squared test. Results The rate of agenesis of third molars was observed 36.8% in the present study. Twenty-four (24.3%) percentage of the study population showed agenesis of all the four third molars. The agenesis of third molars was found to be higher among males than females (p >0.05). Prevalence of agenesis of mandibular second premolar was 4.7–5%. Conclusions Agenesis of third molars was more commonly seen in the maxilla, having male predilection. Maxillary right third molar was the most commonly missing tooth irrespective of gender.

Academic research paper on topic "Sexual dimorphism, pattern of third molar and mandibular second premolar agenesis in Indian paediatric orthodontic patients"

No. of Pages 5

The Saudi Dental Journal (2017) xxx, xxx-xxx

King Saud University The Saudi Dental Journal

www.ksu.edu.sa www.sciencedirect.com

ORIGINAL ARTICLE

Sexual dimorphism, pattern of third molar and mandibular second premolar agenesis in Indian paediatric orthodontic patients

Apurva Mishra *, Ramesh K. Pandey

Department of Paediatric and Preventive Dentistry, Faculty of Dental Sciences, King George Medical University, Lucknow, India Received 29 January 2016; revised 27 October 2016; accepted 22 January 2017

KEYWORDS

Tooth agenesis; Third molar;

Mandibular second premolar;

Paediatric orthodontic patients;

Pattern of agenesis; Missing third molar

Abstract Objective: To determine and compare the prevalence and pattern of agenesis of third molar and mandibular second premolar in paediatric orthodontic patients of age group 9-15 for sexual dimorphism.

Methods: The digital orthopantograph was obtained from the archive record of patients of age group 9-15 year. Radiographs of 301 patients were evaluated after taking exclusion criteria into account and were assessed for the presence/absence of third molars and mandibular second premolar. Tooth development evaluation followed the method of Demirjian et al., based on eight stages of tooth formation. The agenesis of third molar in maxilla and mandible between age groups and gender was compared using Chi-squared test.

Results: The rate of agenesis of third molars was observed 36.8% in the present study. Twenty-four (24.3%) percentage of the study population showed agenesis of all the four third molars. The agenesis of third molars was found to be higher among males than females (p > 0.05). Prevalence of agenesis of mandibular second premolar was 4.7-5%.

Conclusions: Agenesis of third molars was more commonly seen in the maxilla, having male predilection. Maxillary right third molar was the most commonly missing tooth irrespective of gender.

© 2017 Production and hosting by Elsevier B.V. on behalf of King Saud University. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Corresponding author at: Department of Paediatric and Preventive Dentistry, Faculty of Dental Sciences, King George Medical University, Lucknow 226003, U.P., India.

E-mail address: apurvamishra7@gamil.com (A. Mishra). Peer review under responsibility of King Saud University.

Production and hosting by Elsevier

1. Introduction 23

Evolving with the evolution, the modern human stomatog- 24

nathic system has undergone many considerable changes. 25

The variation in the number of permanent teeth has drawn 26

the attention of researchers repeatedly, resulting in abundance 27

of literature establishing two generations of pedigrees for miss- 28

ing teeth, prevalence of agenesis in Mendelian population and 29

demographic variation (Garn et al., 1963). According to Bolk's 30

http://dx.doi.org/10.1016/j.sdentj.2017.01.004

1013-9052 © 2017 Production and hosting by Elsevier B.V. on behalf of King Saud University.

This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

31 theory of terminal reduction, due to the phylogenetic evolution

32 of mankind, the reduction in the distal element of a tooth

33 group occurs more frequently than mesially placed teeth (De

34 Beer, 1953), thus establishing an axiom, that most common

35 missing teeth would be third molar, second premolar and lat-

36 eral incisor. Another reasoning suggested by Butler's field the-

37 ory related to mammalian teeth, states that the most mesial

38 situated tooth is the most stable in each morphological class

39 laying down a blueprint for human dental genetics and tooth

40 polymorphism (Butler, 1939). Third molar being last tooth

41 to calcify and erupt shows a large amount of variation with

42 a prevalence of 20-30% for agenesis of at least one third molar

43 (Lavelle et al., 1970). Therefore irrespective of the influence of

44 genetic drift and consanguinity on population, the polymor-

45 phism in the number of third molar still holds ground for study

46 and comparison of human population with evolution. Butler in

47 his classic study on horse fossil dentition advocated that reduc-

48 tion in number of teeth in a morphological class is associated

49 with reduction in size of teeth for that class (Butler, 1939). This

50 could be due to varying expression of genes responsible for

51 teeth formation and their eruption and similarly might affect

52 the formation and eruption of other tooth.

53 Overview of literature reveals abundance of data regarding

54 prevalence of agenesis in adult orthodontic patients (Celikoglu

55 et al., 2010; Upadhyaya et al., (2012); Saravakumar and

56 George, 2015). However, there is still lack of data when

57 orthodontic patients of age 9-15 years are concerned. The pre-

58 sent study was aimed to determine the prevalence of agenesis

59 of maxillary and mandibular third molar for each quadrant

60 separately along with agenesis of mandibular second premolar,

61 in paediatric orthodontic patients.

62 2. Material & methods

63 The study design was approved by the institutional ethical com-

64 mittee (Reference no. ECM II-B/P19). The digital orthopan-

65 tograph radiograph (OPG) was obtained from the archive

66 records of patients in age group 9-15 years, who attended the out-

67 patient door in the department of paediatric and preventive den-

68 tistry in the time period of December 2014 to April 2015 for

69 orthodontic treatment needs. The rationale behind the use of

70 OPG was that it allowed quick evaluation of both the maxilla

71 and mandible in a single radiographic film and also assessment

72 of the status of unerupted teeth in all four quadrants at the same

73 time. The exclusion criteria were child suffering from any systemic

74 disease, oligodontia, malnourished/underweight children and

75 patients with syndromes. Radiographs of 301 patients were eval-

76 uated after taking exclusion criteria into account. Tooth develop-

77 ment evaluation followed the method of Demirjian et al. (1973),

78 based on eight stages of tooth formation. The minimum age

79 was set at 9 years for the present study as calcification of third

80 molar starts from 7 to 10 years and crown calcification completes

81 at 12-16 years of age (Massler et al., 1941). The presence of calci-

82 fication of third molar was determined radiographically for all

83 four quadrants so as for the mandibular second premolar.

84 3. Results

85 Total 301 digital OPG was examined for the presence/absence of third

86 molar in all the quadrants and so as mandibular second premolar by

87 two different observers. The inter observer reliability was (kappa)

A. Mishra, R.K. Pandey

0.82. The demographic profile showed, out of the total patients' 88

records examined 86.7% were of age more than 10 years and 51.5% 89

were males. The presence/absence of third molar in maxilla and mand- 90

ible between age groups and gender was compared by using Chi- 91

square test. The p-value < 0.05 was considered significant. All the ana- 92

lyses were carried out using SPSS 16.0 version (Chicago, Inc., USA). 93

The prevalence of the absence of third molar was found to be high- 94

est for maxillary right third molar (28.6%) while least for mandibular 95

left third molar (21.6%) (Table 1). Comparing the study parameter 96

with age, the absence of right and left third molar in maxilla and 97

mandible was observed to be higher among the patients of <10 years 98

than >10 and the differences were statistically significant (p = 0.0001) 99

(Table 2). Sexual dimorphism with agenesis of third molar showed a 100

marked increase in agenesis of third molars in males as compared to 101

females; however, the difference was not statically significant (Table 3). 102

Comparing the prevalence of bilateral absence of third molars with 103

gender, the higher number of prevalence for the agenesis was found 104

for females as compared to males (Table 4). The order of agenesis 105

for the third molar was observed to be any three third molars missing 106

(5.3%) followed by one third molar missing (7.3%), followed by two 107

third molars (13.3%) missing and all four third molars missing 108

(24.3%) (Table 5). 109

4. Discussion 110

In the present study agenesis of third molars was more preva- 111

lent in males as compared to females which was in agreement 112

with the study conducted by Kaur et al. (2012), Upadhyaya 113

et al. (2012) but was in contrary to the findings of Sandhu 114

and Kaur (2005) and Sujon et al. (2016) as they observed age- 115

nesis to be more prevalent in females. However, the difference 116

was not statistically significant, and this finding of the present 117

study is in concurrence with the studies conducted by Endo 118

et al. (2006), Chung et al. (2008), Celikoglu and Kamak, 119

(2012). Alam et al. (2014) reported that third molar agenesis 120

was not influenced by sex. 121

Celikoglu et al. (2011) concluded that agenesis of all four 122

third molars simultaneously was the most prevalent form of 123

third molar agenesis which was in agreement with the present 124

study (24.3%). The rate of agenesis of third molar in the pre- 125

sent study was 36.8%, which was found to be higher than the 126

findings of Nanda and Chawla (1959) (25.8%) and Kruger 127

et al. (2011) (15.2%) but is in agreement with the findings of 128

Sujon et al. (2016) (38.4%). 129

Agenesis of third molars was more commonly seen in the 130

maxilla than mandible. The finding was in agreement with 131

those of Sandhu and Kaur (2005), Rahardjo (2006), Jacob 132

et al. (2012) and Sujon et al. (2016) but was in contrast to 133

the findings of Nanda (1954), Keene (1965) and Kermani 134

et al. (2002). It is evident that in due course of evolution the 135

size of skull has shrunken from that of ape to modern human 136

being and so has the size of jaws. In an animal study, Yamada 137

and Kimmel (1991) observed that diet and masticatory func- 138

tion had a direct relationship with craniofacial growth, affect- 139

ing the mandible, which could be responsible for the presence/ 140

agenesis of third molar. Thus, it can be postulated that with 141

the advance in evolution, there is reduction in the size of max- 142

illa when compared with mandible. 143

Intra arch comparison revealed maxillary right third molar 144

to be most commonly missing tooth irrespective of gender 145

which is in agreement with the findings of Sujon et al. 146

(2016), John et al. (2012) followed by maxillary left third 147

molar. 148

SDENTJ256 31 March 2017

Pattern and prevalence of third molar and mandibular second premolar agenesis 3

Table 1 Distribution of study parameters of the patients.

Study parameters Present Absent Agenesis percentage

No. % No. %

Maxillary right third molar 174 57.8 127 42.2 28.6

Mandibular right third molar 193 64.1 108 35.9 24.3

Maxillary left third molar 188 62.5 113 37.5 25.4

Mandibular left third molar 205 68.1 96 31.9 21.6

Mandibular right second premolar 286 95.0 15 5.0 5.0

Mandibular left second premolar 287 95.3 14 4.7 4.7

Table 2 Comparison of study parameters according to age.

Study parameters Age in years p-Value1

<10 >10

Present Absent Present Absent

No. % No. % No. % No. %

10 25.0 30 75.0 164 62.8 97 37.2 0.0001*

13 32.5 27 67.5 180 69.0 81 31.0 0.0001* 10 25.0 30 75.0 178 68.2 83 31.8 0.0001*

14 35.0 26 65.0 191 73.2 70 26.8 0.0001* 39 97.5 1 2.5 247 94.6 14 5.4 0.43 39 97.5 1 2.5 248 95.0 13 5.0 0.48

* Statistically significant.

Maxillary right third molar Mandibular right third molar Maxillary left third molar Mandibular left third molar Mandibular right second premolar Mandibular left second premolar

Table 3 Comparison of study parameters according to gender.

Study parameters Gender p-Value1

Male Female

Present Absent Present Absent

No. % No. % No. % No. %

Maxillary right third molar 89 57.4 66 42.6 85 58.2 61 41.8 0.88

Mandibular right third molar 99 63.9 56 36.1 94 64.4 52 35.6 0.92

Maxillary left third molar 97 62.6 58 37.4 91 62.3 55 37.7 0.96

Mandibular left third molar 106 68.4 49 31.6 99 67.8 47 32.2 0.91

Mandibular right second premolar 151 97.4 4 2.6 135 92.5 11 7.5 0.04

Mandibular left second premolar 151 97.4 4 2.6 136 93.2 10 6.8 0.07

149 In the present study the order of agenesis for the third

150 molar was observed to be any three third molars missing fol-

151 lowed by one third molar missing, followed by two third

152 molars missing and all four third molars missing. However,

153 as per observations made by Nanda (1954), Hattab et al.

154 (1995), Kruger et al. (2001) and Celikoglu et al. (2010) the

155 order of frequency for missing third molars is single third

156 molar missing, followed by two third molars missing and three

157 third molars.

158 Overview of literature reveals that from second to third

159 molar, mandibular second premolar shows great variation in

160 differentiation and calcification. The prevalence for agenesis

161 of mandibular second premolar accounts for 2.4-4.3%

162 (Bergstrom, 1977; Locht, 1980). Ravn (1971) concluded that

163 agenesis of second premolar could be confirmed at the age of

164 8-9 years, as premolars rarely calcify after 9 years. In the pre-

165 sent study agenesis of mandibular right second premolar was

found to be 5% whereas that of mandibular left second premo- 166

lar was 4.7%. High prevalence in the present study for the 167

mandibular second premolar could be because of small sample 168

size, conferring the limitation of the present study. Higher 169

prevalence was observed in children of age more than 10 years, 170

which can be explained by the fact that 86.7% per cent of the 171 study population constituted children older than 10 years of 172

age. A marked increase in agenesis of mandibular second pre- 173

molar was observed in female population when compared to 174

male which is in concurrence with previous studies. 175

Svinhufvud et al. (1988) have explained the selectivity of tooth 176

agenesis in terms of an anatomic rather than an evolutionary 177

model. According to them, permanent tooth agenesis occurs 178

most frequently in the area of the mandibular second premo- 179

lar. This corresponds to the distal end of the primary dental 180

lamina, and because of its susceptibility to agenesis, this area 181 is called as "fragile" site. Interestingly, however, this site of 182

No. of Pages 5

A. Mishra, R.K. Pandey

Table 4 Comparison of bilateral agenesis of third molars according to gender.

Study parameters Gender

Male Female

Present Absent Present Absent

No. % No. % No. % No. %

Maxilla Mandible All four third molars 54 46 40 34.8 29.7 25.8 101 109 115 65.2 70.3 74.2 48 43 33 32.9 29.5 22.6 98 103 113 67.1 70.5 77.4

Table 5 Distribution of study subjects according to genesis of

third molars.

Number Percentage

All third molars absent 73 24.3

Any three absent 16 5.3

Any two absent 40 13.3

Any one absent 22 7.3

All 4 third molars present 150 49.8

183 mandibular agenesis appears to be specific for permanent den-

184 tition; the loss of second primary molars is rare.

185 Grahnen (1956) has suggested that tooth agenesis is typi-

186 cally transmitted as an autosomal dominant trait with incom-

187 plete penetrance and variable expressivity. Phylogenetic

188 changes in the dentition correlate with functional adaptation.

189 Lavelle et al. (1970) observed that Homo sapiens have devel-

190 oped a tendency towards a shortened maxilla-mandibular

191 skeleton compared to their ancestors. The number of teeth

192 diminishes in parallel with these changes in the jaw skeleton.

193 It has been suggested that one incisor, one canine, one premo-

194 lar, and two molars per quadrant are likely to be the dental

195 profile of future man. Genetic and molecular genetic causes

196 of agenesis have begun to identify genes important in tooth

197 agenesis. The transcription factor genes MSX1 and PAX9 were

198 the first genes identified for non-syndromic tooth agenesis.

199 Although both genes affect third molars, a significantly higher

200 frequency of agenesis associated with mutations in MSX1 than

201 in PAX9 has been found for second premolars (Vastardis,

202 2000).

203 Many studies have been conducted across the world esti-

204 mating the prevalence of third molar and second premolar age-

205 nesis. It is evident the prevalence of tooth agenesis cannot be

206 brought under same umbrella for different ethnic groups

207 because of heterogeneity in gene expression responsible for

208 tooth formation and influence of local and environmental fac-

209 tors. More research should be conducted in direction of map-

210 ping inherited conditions for tooth agenesis, to actually assess

211 the penetrance of tooth agenesis in a population.

212 5. Conclusion

213 Within the limitation of the present study, it can be concluded

214 that arch size is continuously narrowing as a part of evolution

215 leading to agenesis of third molar, hence rendering it vestigial.

216 Researchers should aim to establish a familial tree for tooth

agenesis and genetic linkage for better visualization of futuris- 217

tic trends in agenesis and narrowing of dental arch. 218

Conflict of interest 219

The author has no conflict of interest to declare. 220

6. Uncited reference 221

Mok and Ho (1996). 222

References 223

Alam, M.K., Hamza, M.A., Khafiz, M.A., Rahman, S.A., Shaari, R., 224

Hassan, A., 2014. Multivariate analysis of factors affecting 225

presence and/or agenesis of third molar tooth. PLoS ONE 9 (6), 226

e101157 . 227

Bergstrom, K., 1977. An orthopantomographic study of hypodontia, 228

supernumeraries and other anomalies in school children between 229

the ages of 8-9 years. Swedish Dental J. 1, 145-157. 230

Butler, P.M., 1939. Studies of the Mammalian Dentition. Differenti- 231

ation of the Post-canine Dentition. In: Proc. Zool. Soc. Lond., B, 232

vol. 109, pp. 1-36 . 233

Celikoglu, M., Kamak, H., 2012. Patterns of third-molar agenesis in 234

an orthodontic patient population with different skeletal maloc- 235

clusions. Angle Orthod. 82, 165-169. 236

Celikoglu, M., Kazanci, F., Miloglu, O., Oztek, O., Kamak, H., 237

Ceylan, I., 2010. Frequency and characteristics of tooth agenesis 238

among an orthodontic patient population. Med. Oral Patol. Oral 239

Cir. Bucal. 15, e797-801. 240

Celikoglu, M., Bayram, M., Nur, M., 2011. Patterns of third-molar 241

agenesis and associated dental anomalies in an orthodontic 242

population. Am. J. Orthod. Dentofac. Orthop. 140, 8 56-8 60 . 243

Chung, C.J., Han, J.H., Kim, K.H., 2008. The pattern and prevalence 244

of hypodontia in Koreans. Oral Dis. 14, 620-625. 245

De Beer, G.R., 1953. Embryos and Ancestors. Clarendon Press, 246

Oxford, pp. 58-59 . 247

Demirjian, A., Goldstein, H., Tanner, J.M., 1973. A new system of 248

dental age assessment. Hum. Biol. 42, 211-227. 249

Endo, T., Ozoe, R., Kubota, M., Akiyama, M., Shimooka, S., 2006. A 250

survey of hypodontia in Japanese orthodontic patients. Am. J. 251

Orthod. Dentofacial Orthop. 129, 29-35 . 252

Garn, Stanley M., Lewis, Arthur B., Vicinus, Joan H., 1963. Third 253

molar polymorphism and its significance to dental genetics. J. Dent. 254

Res. 6, 1344-13 64 . 255

Grahnen, H., 1956. Hypodontia in the permanent dentition: a clinical 256

and genetical investigation. Odont. Revy. 7, 1-100. 257

Hattab, F.N., Rawashdeh, M.A., Fahmy, M.S., 1995. Impaction 258

status of third molars in Jordanian students. Oral Surg. Oral Med. 259

Oral Pathol. Oral Radiol. Endod. 79, 24-29. 260

SDENTJ 256 31 March 2017

Pattern and prevalence of third molar and mandibular second premolar agenesis 5

261 John, J., Nambiar, P., Mani, S.A., Mohamed, N.H., Ahmad, N.F.,

262 Murad, N.A., 2012. Third molar agenesis among children and

263 youths from three major races of Malaysians. J. Dent Sci. 7, 211264 217.

265 Kaur, B., Sheikh, S., Pallagatti, S., 2012. Radiographic assessment of

266 agenesis of third molars and para-radicular third molar radiolu-

267 cencies in population of age group 18-25 years old - a radiographic

268 survey. Arch. Oral Res. 8, 13-18.

269 Keene, H.J., 1965. The relationship between the third molars agenesis

270 and morphological variability of the molar teeth. Angle Orthod. 35,

271 289-298.

272 Kermani, H.T., Kapur, R., Sciote, J., 2002. Tooth agenesis and

273 craniofacial morphology in an orthodontic population. Am. J.

274 Orthod. Dentofacial Orthop. 122, 39-47.

275 Kruger, E., Thomson, W.M., Konthasinghe, P., 2001. Third molar

276 outcomes from age 18 to 26: findings from a population-based New

277 Zealand longitudinal study. Oral Surg. Oral Med. Oral Pathol.

278 Oral Radiol. Endod. 95, 150-155.

279 Lavelle, C.L., Ashton, E.H., Flinn, R.M., 1970. Cusp pattern, tooth

280 size and third molar agenesis in the human mandibular dentition.

281 Arch. Oral Biol. 15, 227-237.

282 Locht, S., 1980. Panoramic radiographic examination of 704 Danish

283 children aged 9-10 years. Commun. Dent. Oral Epidemiol. 8, 375284 378.

285 Massler, M., Schour, I., Poncher, H.G., 1941. Development pattern of

286 the child as reflected in the calcification pattern of the teeth. Am. J.

287 Dis Child. 62, 33-67.

288 Mok, Y.Y., Ho, K.K., 1996. Congenitally absent third molars in 12289 16 years old Singaporean-Chinese patients: a retrospective radio-290 graphic study. Ann. Acad. Med. Singapore 25, 828-830.

Nanda, R.S., 1954. Agenesis of third molar in man. Am. J. Orthod. 291

Dentofacial Orthop. 40, 698-706. 292

Nanda, R.S., Chawla, T.N., 1959. Status of third molar teeth. J. A. 293

Ind. Dent. Assoc. 31, 19-29. 294

Rahardjo, P., 2006. Prevalence of hypodontia in Chinese orthodontic 295

population. Dent. J. (Maj. Ked. Gigi) 39, 147-150. 296

Ravn, J.J., 1971. Aplasia, supernumerary teeth and fused teeth in the 297

primary dentition: an epidemiologic study. Scand. J. Dent Res. 79, 298

1-6. 299

Sandhu, S., Kaur, T., 2005. Radiographic evaluation of the status of 300

third molars in the Asian Indian students. J. Oral Maxillofac. Surg. 301

63, 640-645. 302

Saravakumar, George, Sosa, 2015. Agenesis of third molars and its 303

aetiology in Tamil Nadu population. Indian J. Dental Adv. 7 (3), 304

165. 305

Sujon, M.K., Alam, M.K., Rahman, S.A., 2016. Prevalence of third 306

molar agenesis: associated dental anomalies in non-syndromic 5923 307

patients. PLoS ONE 11 (8), e0 1 62070 . 308

Svinhufvud, E., Myllarniemi, S., Norio, R., 1988. Dominant inheri- 309

tance of tooth malpositions and their association to hypodontia. 310

Clin. Genet. 34, 373-381. 311

Upadhyaya, C., Adhikari, B.R., Kafle, D., Humagain, M., 2012. 312

Agenesis of third molars in orthodontic patIents attending Dhu- 313

likhel Hospital. Orthodontic J. Nepal. 2, 32-35. 314

Vastardis, Heleni, 2000. The genetics of human tooth agenesis: new 315

discoveries for understanding dental anomalies. Am. J. Orthod. 316

Dentofac. Orthop. 117, 650-656. 317

Yamada, K., Kimmel, D.B., 1991. The effect of dietary consistency on 318

bone mass and turnover in the growing rat mandible. Arch. Oral 319

Biol. 36, 129-138. 320