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 examine the effects of three different parameters-pH value, type of archwire, and length of immersion-on release of metal ions from orthodontic appliances. Materials and Methods: Simulated fixed orthodontic appliances that corresponded to one-half of the maxillary arch were immersed in artificial saliva of different pH values (6.75 Ϯ 0.15 and 3.5 Ϯ 0.15) during a 28-day period. Three types of archwires were used: stainless steel (SS), nickeltitanium (NiTi), and thermo NiTi. The quantity of metal ions was determined with the use of a high-resolution mass spectrophotometer (HR-ICP/MS). Results: The release of six different metal ions was observed: titanium (Ti), chromium (Cr), nickel (Ni), iron (Fe), copper (Cu), and zinc (Zn). Repeated measures statistical analysis of variance (ANOVA) was used. Results showed that (1) the appliances released measurable quantities of all ions examined; (2) the change in pH had a very strong effect (up to 100-fold) on the release of ions; and (3) the release of ions was dependent on wire composition, but it was not proportional to the content of metal in the wire. The largest number of ions was released during the first week of appliance immersion. Conclusion: Levels of released ions are sufficient to cause delayed allergic reactions. This must be taken into account when type of archwire is selected, especially in patients with hypersensitivity or compromised oral hygiene. (Angle Orthod. 2009;79:102-110.)

An aesthetically pleasing and balanced face is one of the objectives of orthodontic treatment. An understanding of the soft tissues and their normal ranges enables a treatment plan to be formulated to normalize the facial traits for a given individual. The aim of this study was to evaluate the variables defining the soft tissue facial profile of a Croatian (Caucasian) sample, by means of angular measurements typically used for aesthetic treatment goals. Additionally, gender differences were tested. The soft tissue facial profiles of 110 dental students (52 males and 58 females) between 23 and 28 years of age at the University of Zagreb, Croatia, with a dental Class I occlusal relationship and harmonious soft tissue profile were studied by means of standardized photographs taken in the natural head position (NHP). To compare males and females, a Student's t-test was used. The reliability of the method was analysed using Dahlberg's formula. There were distinct gender differences. All angles were larger in females: nasofrontal (G-N-Nd, females = 139.11 degrees; males 136.38 degrees; P = 0.030), nasolabial (Cm-Sn-Ls, females = 109.39 degrees; males = 105.42 degrees; P = 0.018), mentolabial (Li-Sm-Pg, females = 134.5 degrees; males = 129.26 degrees; P = 0.019), and nasal tip angle (N-Prn-Cm, female = 84.12 degrees; male = 79.85; P = 0.001). The greatest variability was found for mentolabial angle. The findings demonstrate a distinct profile trait for female Croatian patients compared with male subjects.

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.