Prevalence and characteristics of non-syndromic hypodontia among Turkish orthodontic patient population

Prevalence and patterns of tooth agenesis among patients aged 12-22 years: A retrospective study

Objective

This study aimed to establish the prevalence and patterns of nonsyndromic tooth agenesis in patients referred to a tertiary health care facility.

Methods

The intraoral records and panoramic radiographs of 9,874 patients aged 12–22 years were evaluated. The study group included 716 patients (371 male, 345 female) with non-syndromic agenesis of at least one tooth (except the third molars). The study data were assessed using descriptive statistics, chi-square test, and Mann–Whitney U test, while patterns were evaluated using a tooth agenesis code (TAC) tool.

Results

A total of 1,627 congenitally missing teeth, were found in patients with non-syndromic tooth agenesis, with an average of 2.27 missing teeth per patient. The prevalence of tooth agenesis was 7.25%, and the most commonly missing teeth were the left mandibular second premolars (10.17%). The age group comparison revealed no significant difference in the median number of missing teeth per patient according to the cutoff values for ages between 12 and 22 years. When the missing teeth were examined separately according to quadrants, 114 different tooth agenesis patterns (upper right quadrant = 28, upper left quadrant = 27, lower left quadrant = 31, and lower right quadrant = 28) were identified, and 81 of these patterns appeared only once.

Conclusions

This study highlights the benefits of applying the TAC tool in a large sample population. The application of the TAC tool in such studies will enable the development of template treatment plans by determining homogenous patterns of tooth agenesis in certain populations.

Prevalence of Class I, II and III skeletal relationships and its association with dental anomalies in an ethnic Chinese orthodontic population

Objectives:

To investigate the prevalence of skeletal Classes I, II and III in a Chinese orthodontic population, and determine its association with the prevalence of dental anomalies.

Methods:

This retrospective cross-sectional study was conducted on 2508 ethnic Chinese orthodontic patients aged 14 to 25 years who attended the Department of Orthodontics at the National Dental Centre Singapore. Radiographs, photographs and clinical records of the study sample were examined for the prevalence of dental anomalies in the permanent dentition, excluding third molars. The anteroposterior skeletal relationship was determined based on the A point–Nasion–B point angle measured from the lateral cephalogram, whereby Class I: A point–Nasion–B point = 3.6° ± 2.5° (1 standard deviation) that is 1.1° to 6.1°; Class II: A point–Nasion–B point greater than 6.1°; Class III: A point–Nasion–B point less than 1.1°. Logistic regression was used to determine the association between the anteroposterior skeletal relationship and the occurrence of various dental anomalies.

Results:

The prevalence of the anteroposterior skeletal relationship was: 49.5% Class I; 23.1% Class II; and 27.4% Class III. Class III patients had significantly lower odds of impacted teeth compared to Class I patients (odds ratio 0.608, 95% confidence interval 0.463–0.798; P=0.00009). There was no significant difference in the occurrence of the anomalies among the various anteroposterior skeletal types.

Conclusions:

The occurrence of impacted teeth was lower in Class III than Class I, while no significant differences were noted for hyperdontia, hypodontia, peg-shaped upper lateral incisors, transposition and double teeth. The occurrence of all investigated dental anomalies had no significant difference between Class II and Class I.

Prevalence of Hypodontia in a Sample of Spanish Dental Patients

Objectives

The aim of this retrospective study was to evaluate the prevalence of hypodontia in a sample of dental patients, aged between seven and eleven years at University Alfonso X in Madrid (Spain).

Materials and Methods

The number of hypodontia cases and the most affected teeth were evaluated in 2500 panoramic radiographs in a random sample of dental patients consisting of 1235 females and 1265 males. We divided them according to age, number of hypodontia present in each patient (multiple or single), each side, each quadrant either in the upper jaw or in the mandible. The chi-square test (P <0.05) was used to compare the differences in agenesis among males and females.

Results

The sample of 2500 patients who were studied consisted of 1235 women, out of which 41 presented hypodontia (3.31%) and 1265 men, out of which 46 had at least a dental absence (3.63%). There was no significant difference in the proportion of hypodontia between men and women (p> 0.05).

Conclusion

The percentage of total agenesis of 2500 patients studied was 3.48%.