Evaluation of the frequency of third molar agenesis according to different age groups.

PURPOSE: Third molars (M3s) are the most common congenitally missing teeth. The aim of this study was to compare the frequency of M3 agenesis in two different age groups. METHODS: This study examined the panoramic radiographic images of 1036 patients. Two groups, each consisting of 518 patients, were arranged based on age ranges. The patients aged 12 to 19 years were in the first group and those 20 years and older were in the second group. The frequency of M3 agenesis was examined in both age groups. The distribution of M3 agenesis by sex and jaw was also recorded, along with the number of M3s affected by agenesis. Chi-square tests were used to examine the relationships between categorical variables. RESULTS: M3 agenesis was observed in 29.3% and 20.5% in the first and second groups, respectively; the difference was statistically significant (P < .01). It was more common in female (27.3%) than in male patients (21.4%), and in the maxilla (11.2%) than in the mandible (5.8%), and the differences were statistically significant (P < .05). It was mostly observed forthemaxilla right M3 (18) (30.9%) and in the single quadrant of the jaws (9.7%). CONCLUSIONS: The frequency of M3 agenesis was more common in patients aged 12 to 19 years than in those aged 20 years and older. Additionally, M3 agenesis was more common in females and in the maxilla.

The relationship of masseter muscle thickness with face morphology and parafunctional habits: an ultrasound study.

OBJECTIVE: The aim of this study was to determine the normal range of masseter muscle thickness by ultrasonographic measurement in individuals over 15 years of age, and to evaluate its relationship with age, gender, facial morphology, body mass index and parafunctional habits. METHODS: The study was conducted on 115 volunteers whose lateral cephalometric radiography was performed within the indication in Gazi University Faculty of Dentistry, Department of Dentomaxillofacial Radiology. The participants in the study were asked questions about their parafunctional habits, age, height and weight. Individuals were grouped as hypodivergent (n = 28), normdivergent (n = 55), or hyperdivergent (n = 32) according to vertical face morphology by making measurements on lateral cephalometric films. Right and left masseter muscle thicknesses of individuals were measured by ultrasonography while at rest and in contraction. RESULTS: The mean value of masseter muscle thickness was found to be 13.57 ± 2.57 mm. The rest and contracted muscle thicknesses were significantly higher in males than in females for the right and left masseter muscles (p < 0.05). When the masseter muscle was at rest and contracted, its thickness was higher in individuals with hypodivergent facial morphology, than in the other groups. No statistically significant difference was found in terms of masseter muscle thickness between individuals having parafunctional habits and those who did not have parafunctional habits (p > 0.05). CONCLUSION: Although masseter muscle thickness varied according to vertical facial morphology, this was not the case for parafunctional habits.

Evaluation of the compatibility of C2, C3, and C4 fractal dimension values with hand-wrist and cervical vertebra maturation methods in determining skeletal maturation.

OBJECTIVES: To examine the correlation between the fractal dimension (FD) values of cervical vertebrae (C2, C3, and C4) and hand-wrist maturation (HWM) and cervical vertebra maturation (CVM) methods. In addition, the correlation between the pubertal growth spurt (PGS) and FD values was examined. METHODS: The lateral cephalometric and hand-wrist radiographs of 120 subjects (61 females and 59 males) aged 8-18 years with a mean age of 13 years, were evaluated retrospectively. The CVM stages were determined in accordance with Hassel-Farman's modification of Lamparski criteria. The HWM stages were determined in accordance with Björk and Grave-Brown criteria. Both HWM and CVM stages were divided into two according to PGS. Fractal analysis of cervical vertebrae was performed according to the White-Rudolph method. The relationships between HWM stages, CVM stages and other variables were evaluated by Spearman's rank-order correlation coefficient. The relationships between FD values, chronological age, and divided stages were evaluated by the Pearson correlation coefficient. The Mann-Whitney U test was used to compare the FD values of two divided stages. RESULTS: There were positive and statistically significant positive correlations between chronological age and both HWM and CVM stages. There was a positive and statistically significant correlation between CVM and HWM stages. In females and total, there were negative and statistically significant correlations between C4 FD values and divided HWM stages, and the differences between C4 FD values of divided HWM stages were also statistically significant. In total, there was a negative and statistically significant correlation between C4 FD values and divided CVM stages, and the difference between C4 FD values of divided CVM stages was also statistically significant. CONCLUSION: The negative correlations found between C4 FD values and divided HWM and CVM stages suggest the fractal analysis of cervical vertebrae, especially of C4, may be used as an objective tool for evaluating the PGS.