Does third molar impaction affect age estimation in adolescent and young adults? A radiographic population based study

Few studies consider the effects of impaction, resulting in inaccurate estimation of age using third molar. We aimed to assess the significance of impaction in estimating age using Modified Demirjian's method. 200 orthopantomograms of patients between 16-25 years were collected comprising 171 tests and 212 controls. Chronologic age (CA) and estimated age (EA) were calculated. Independent sample t-test, chi-square test, paired t-test and Kolmogrov-Smirnov test of normality were used. The mean difference between the CA and EA in both the tests and control samples were significant (mean difference test group = 2.6 ± 2.07, control group = 2.0 ± 1.8; p = 0.01). It provided a difference of 0.6 which is equal to 7.2 months. The results of our study indicate that impacted mandibular third molars are susceptible to undergo slower mineralization, leading to erroneous lower age estimation. These results in an Indian population are noteworthy. However further studies are needed.

Clinical Indications to Germectomy in Pediatric Dentistry: A Systematic Review

Germectomy is a procedure often required in patients at developmental age. It is defined as the surgical removal of the third molar at a very specific stage of development. The aim of this study was to systematically analyze the literature in terms of clinical indications for germectomy in patients at developmental age. Literature searches were performed using PubMed, Google Scholar, Cochrane Library and Scopus from 1952 to 30 June 2021. The study protocol was registered after the screening stage (PROSPERO CRD42021262949). The search strategy identified 3829 articles: 167 from PubMed, 2860 from Google Scholar, 799 from Cochrane Library and 3 from Scopus. Finally, eight full-text papers were included into the qualitative analysis. Based on the included studies, clinical indications for germectomy were mainly related to orthodontic causes, infectious and cariogenic causes and prophylaxis. Based on these results, it is not possible to present evidence-based clinical indications for germectomy in patients at developmental age. Clinical trials on this subject focused specifically on patients at developmental age are awaited.

A test to study the influence of impaction on mandibular third molar development and forensic age estimation in a sample of south Indian children and young adults

It has been argued that the impaction of the third molars could result in delayed maturation, which, in turn, could affect age estimations in criminal proceedings. In view of this, the present study was undertaken to determine whether the impaction status could delay the chronological process of third molar mineralization in a sample of south Indian children and young adults. The orthopantomograms (OPGs) of 915 children and young adults of south Indian origin aged between 15 and 22 years were evaluated. Mineralisation stage and impaction status were determined for all lower third molars. Descriptive statistics were performed at stages D to H of Demirjian staging system. The results of independent t-test show that the impaction resulted in statistically significant slower mineralization in impacted lower third molars at stages D to F in both sexes. It was ascertained that the mean ages with the impacted lower third molars at stage G were 0.98-1.38 years higher in males and 0.50-0.80 years higher in females than those with non-impacted lower third molars. For stage H, the mean ages were 0.14-0.21 years higher in males and 0.25-0.44 years higher in females. The probabilities of being 18 years and above is higher for non-impacted lower third molars at stages G and H than those with impacted ones. It is concluded that the impaction could result in delayed maturation in the lower third molars of the studied sample. Further studies are warranted in a more diverse sample.

Evaluation of the effect of impaction on the mineralization of mandibular third molars and forensic age estimation in a sample of south Indian children

Assessment of third molar mineralization is a basic forensic odontological method available for age estimation in children and adolescents. Due to their protracted development into the late adolescence, their development has become the subject of interest and acquired great forensic importance. It is clearly evident in the literature that impaction factor has an influence on the rate of maturation of the third molars. In this regard, the present study was undertaken to test the relationship between impaction and its concomitant effect on the mineralization of the third molar and forensic age estimation. A total of 520 digital orthopantomograms (OPG) of 260 males and 260 females of south Indian origin were assessed retrospectively. Maturation of the third molars (I3M) was assessed using the method of Cameriere et al. (Int J Leg Med 122 (6):493-497, 2008). Impaction status was determined according to the position of lower right and left third molars in relation to the long axis of the second molars. Out of the total sample, 68.1% of lower left third molars and 71.2% of lower right molars were impacted. Statistical measures for I3M were calculated in the males and females for both impacted and non-impacted third molars. It was ascertained that the mean age and I3M values were higher in impacted third molars, indicating the slower rate of maturation than non-impacted ones. The sensitivity and specificity of the test (I3M < 0.08) was 96.2% and 72.4% for non-impacted third molars and 46.2% and 87% for impacted third molars, respectively. Our findings indicate that the cut-off value of I3M < 0.08 resulted in greater number of age misclassifications (false negatives) for impacted molars, highlighting the need for new cut-off value of I3M to meet the legal standards. It was concluded that the mineralization of impacted third molars was slower compared to non-impacted ones in south Indian males and females. Further studies are warranted to validate these findings among a larger and more diverse sample.

Differences in third molar development and angulation in class II subdivision malocclusions

PURPOSE

To assess and compare the developmental stages and angulations of third molars between the class II and class I sides in class II subdivision malocclusions.

METHODS

This retrospective study was performed using panoramic x‑rays of 38 individuals (mean age: 15.5 years; 24 females, 14 males) with class II subdivision malocclusions, which were further divided into type 1 and 2 subgroups according to midline deviation, and a control group of 42 individuals (mean age: 17.0 years; 30 females, 12 males) with normal occlusion. Third molars were categorized using the developmental stages defined by the Demirjian method. Angles between the third molars and horizontal reference lines and also to the second molars were measured.

RESULTS

No difference was found in developmental stages or angulations between the left and right third molars in the control group. In the class II subdivision malocclusion cases, no difference in third molar developmental stages was observed, but the angle between the long axes of the mandibular third and second molars was significantly greater on the class II side. In the type 2 subgroup, developmental stage of the maxillary third molar was more advanced on the class II side. In both subgroups, the angles of the maxillary third molars' long axis to the interorbital plane differed significantly between the two sides.

CONCLUSION

Class II subdivision malocclusion may cause differences in third molar development and angulations between the two sides. Orthodontic treatment should be planned considering the third molars in this malocclusion.

A novel method for measuring tooth angulation in permanent mandibular second molars with delayed tooth eruption

OBJECTIVE

To investigate the effect of angulation of permanent mandibular second molars (MM2) on eruption problems and investigate a new method of measuring MM2 angulation for the diagnosis and evaluation of delayed tooth eruption (DTE) for easy use in dental practice.

DESIGN

Retrospective study.

SETTING

Department of Orthodontics, Necmettin Erbakan University.

PARTICIPANTS

A total of 98 patients aged 9-18 years.

METHODS

Patients with 64 permanent MM2s with delayed eruption problems were included in the study group. The control group consisted of patients with 83 normally erupted teeth. In addition, a sub-group, consisting of 23 patients showing unilaterally delayed eruption of the same teeth, was set as a split-mouth group. All patients with unilateral delayed eruption of second molar teeth were selected from the study group to form the sub-group. Angulations of permanent MM2s were measured on panoramic radiographs with two measurement methods: (1) a new method; and (2) a previously accepted method. The comparison of the study and control groups was performed by Mann-Whitney U-test and the split-mouth group was analysed with the paired t-test. The P value was set at 0.05 for statistical significance.

RESULTS

Measurements of the tooth angulation values of the study group were significantly higher than in the control group for both measurement methods (P < 0.001). In addition, in the split-mouth group, angulation values of delayed eruption side were significantly higher than the erupted side (P < 0.001).

CONCLUSION

Increased angulations of permanent MM2s could be associated with delayed eruption problems of these teeth. This new method could be useful in clinical dentistry to determine the eruption evaluation of lower second molars.

Association between root resorption and tooth development: A quantitative clinical study

INTRODUCTION

The aim of this study was to verify less resorption of incompletely developed roots compared with those that were fully developed during the same orthodontic treatment and to test the value of the amount of external apical root resorption for predicting tooth development.

METHODS

A sample of 524 patients aged 10-15 years was selected following the inclusion criteria. For each subject, pretreatment and posttreatment digital panoramic and lateral radiographs were collected, and tooth development was determined from each radiograph. Through calculations, the amount of root resorption was assessed by a created and scientific approach for large-scale application using radiographs with only 8 measurement indexes for each patient. Other basic information and treatment parameters regarded as possible risk factors were also collected from standardized recordings or radiographs. The root length between the groups or in the single group were compared with t tests and correlation analyses. Linear univariate and multivariate regression analyses were used to test identify predictors for root resorption and to develop a prediction model.

RESULTS

There was a statistically significant difference in the amount of root resorption with tooth development before correction (P <0.001) as well as after correction (P = 0.002). There was a statistically significant correlation (P <0.001) but no difference between pretreatment and posttreatment root length in the immature tooth group because of less root resorption. In the multivariate analyses, tooth development (P <0.001), treatment duration, apex horizontal movements, apex vertical movements, and previous orthodontic treatment were included in the final model as risk factors, and tooth development had the highest beta value.

CONCLUSIONS

There is an association between root resorption and tooth development, and tooth development is an important predictor of root resorption. Patients with immature teeth are at a much lower risk of apical root resorption.

External root resorption of second molars caused by impacted third molars: an observational study in panoramic radiographs

Abstract Objective This research investigate the presence of external root resorption (ERR) in second molars caused by impacted third molars in panoramic radiographs, relating to the position of third molars according to classification of Winter, Pell and Gregory. Material and method A cross-sectional, retrospective study using panoramic radiographs obtained from January 2014 to December 2015. The inclusion criterion was the presence of a second molar adjacent to an impacted third molar. Data were analyzed using descriptive and inferential statistics. Pearson's Chi-Square Test and Fisher's Exact Test (p≤0.05) were performed. Result The sample consisted of 584 panoramic radiographs, 356 (60.95%) of women, and 228 (39.05%) of men, the mean age was 25.31 years. The prevalence of ERR was 12.5%, and the group of 14-24 year olds was the most affected (p = 0.46). The presence of ERR was statistically higher in the mandible (42.1%) with p=0.01. The ERR located in the cervical (57.1%) and medium (58.8%) thirds was proportionally higher in the teeth with B2 (p=0.02) and mesio-angular positions (p=0.26). Conclusion The prevalence of ERR in second molars, caused by impacted third molars, was shown to be similar to results found in the literature, with no gender preference, this affects young patients, occurring frequently in mandible teeth, and presents greater severity in the cervical and middle thirds. The B2 and mesio-angular positions were more prone to ERR.

The influence of impaction to the third molar mineralization in northwestern Chinese population

Age estimation by third molar mineralization has been developed for a period of time. Recent studies showed that impaction status has an influence on the rate of the third molar mineralization in Europids and male Black African populations. In this regard, the present study was conducted to determine whether the impaction status could delay the chronological process of third molar mineralization in northwestern Chinese population too. A total of 3,512 digital orthopantomograms of 1,255 male and 2,257 female northwestern Chinese subjects aged from 11 to 26 years were assessed based on the formation stages described by Demirjian et al. with two modifications. Mineralization stage and impaction status were determined for all third molars. Statistical measures were calculated at stages C-H in the male and female gender for both impacted and non-impacted third molars. It was ascertained that the mean ages with impacted third molars at stages C-H were 0.02-1.42 years higher in males and 0.04-1.52 years higher in females than those with non-impacted third molars, but statistical differences were only found at stages C, D, and E in males and stages D and E in females. The probabilities of being under 14, 16, or 18 years of age with non-impacted third molars were all higher than those with impacted third molars. The results prove that impacted third molars show significant slower mineralization than non-impacted ones at stages D and E in both males and females of northwestern Chinese population. It is recommended to consider the influence of impaction on the rate of third molar mineralization for dental age estimation.