The aims of this investigation were to determine whether stabilization of maximum voluntary bite force (MVBF) occurs between 15 and 18 years of age in subjects with a normal occlusion, and to assess the influence of gender, body mass index (BMI), morphological occlusion, and jaw function measured by the number of occlusal contacts, overjet, overbite, maximal mouth opening, mandibular deflection during opening, sagittal slide between the retruded contact position and the intercuspal position, and number of dental restorations. The sample comprised 60 Caucasian subjects aged 15 (15 males and 15 females) and 18 (14 males and 16 females) years with a neutral occlusion, balanced facial profile, and absence of a previous orthodontic history. Bite force measurements were undertaken using a portable occlusal force gauge on both the left and the right sides of the jaw in the first molar region during maximal clenching. Two independent samples t-tests and multiple regression were used for statistical analysis. MVBFs were age and gender related (P<0.05). Males showed a significant increase in bite force between 15 and 18 years of age (P=0.002), but gender differences were significant only in the 18-year-olds (P=0.003). In subjects with a neutral occlusion, MVBF could best be predicted using multiple regression from age and gender. The regression model accounted for 31.3 percent of the variance in MVBF (P=0.031), with gender contributing 17.9 percent and age 7.9 percent. Morphological occlusion, jaw function, and BMI explained the remaining 5.5 percent of variance. While controlling for all other parameters, the independent contribution of gender to the prediction of MVBF was 16.2 percent, age 6 percent, number of occlusal contacts 3.2 percent, and BMI 1.3 percent.

Objective: To determine the physiologic changes of salivary flow rate, pH, and buffer capacity and the levels of Streptococcus mutans and Lactobacillus spp in patients undergoing fixed orthodontic treatment. Materials and Methods: The study included 23 patients scheduled for fixed orthodontic therapy. All subjects received equal braces, bands, and brackets, bonded with the same material. Stimulated saliva samples were taken before placement of the appliance, and at weeks 6, 12, and 18 during the therapy. Salivary flow rate and salivary pH were measured, and the salivary buffer capacity was determined. Saliva samples were cultivated on selective microbial agar for microorganism detection. Results: A significant (P , .05) increase in stimulated salivary flow rate and salivary pH was found. The salivary levels of S mutans and Lactobacillus spp also inscreased significantly (P , .05), and the major peak was at week 12 of fixed orthodontic therapy. Conclusion: The 6th to 12th week of orthodontic therapy is the period of the most intensive intraoral growth of S mutans and Lactobacillus spp and a time of very intensive salivary functions and physiologic response. (Angle Orthod. 2011;81:901-906.)

Bracket design does not seem to have a strong influence on periodontal clinical parameters and periodontal pathogens in subgingival plaque. The correlation between some periodontal pathogens and clinical periodontal parameters was weak.

The aim of the present study was to determine the dental and occlusal features that could contribute to the aetiology of palatally displaced canines (PDCs). The material consisted of pre-treatment dental casts of 50 patients (36 females and 14 males) with unilateral and bilateral PDCs aged 14-16 years (mean 15.6 +/- 1.6 years). These were compared with a control group of 50 treated subjects (25 males and 25 females) of the same age with normally erupted maxillary canines. The following parameters were measured on the dental casts: the mesiodistal (MD) and buccolingual (BL) width of each maxillary tooth, the maxillary interpremolar and intermolar widths, overjet and overbite, dentoalveolar arch relationship (based on incisor classification), and missing or anomalous teeth. The differences between the PDC group and controls were determined using a Student's t-test. P values less than 0.05 were considered significant. PDCs occurred most frequently in subjects with a Class I occlusion. Sixteen per cent of the PDC subjects had congenital absence or peg-shaped lateral incisors or congenital absence of the second premolar, demonstrating a clear association between palatal impaction of the maxillary canine and anomalous or congenital tooth absence. The overjet was significantly smaller in the PDC female subjects, especially in those with unilateral impaction (P < 0.05). Overbite was significantly greater in PDC male subjects compared with the controls, especially in bilateral impaction cases. There was no statistically significant difference between the groups with regard to the maxillary transverse dimensions, maxillary MD widths, or palatal height for either gender.

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