Treatment Decisions in Class II subdivision Malocclusions: Three Case Reports with Contrasting Strategies.

Class II Subdivision refers to the asymmetric molar relationship that can be commonly accounted to dental and occasionally to the skeletal disharmony. Furthermore, the discrepancy may be present in the maxilla or the mandible. To put it differently, Class II subdivisio) is a heterogeneous group of malocclusions and cannot be considered as a discrete entity to be treated with predefined specific strategies. Treatment goals encompass the usual cook-book approach and entail the orthodontists to think-before-act strategy considering all the parameters that may be affected favorably or deleteriously while executing a specifie plan. Treatment options may vary from non-extraction to 4premolar extractions depending upon the site and severity of the malocclusion. Another consideration would be the indispensable side-effects of the biomechanics involved that may be symmetric or asymmetric, again depending upon the needs of the patient. These not only require thorough diagnosis but clarity in the treatment goals. This article will briefly outline the important considerations while treating Class II subdivision cases with the help of examples of3 patients bearing different etiologies treated with contrasting strategies.

Estimation of nickel and chromium in saliva of patients with fixed orthodontic appliances.

AIM: To examine whether orthodontic treatment induces an increase in salivary nickel and chromium concentration. METHODS: Ten new patients (7 females and 3 males) beginning fixed orthodontic treatment were included in the study. The mean age of the sample was 17.5 years (range 14 to 24 years). Three samples of stimulated saliva were collected from each orthodontic patient, 1 at each of the following times: before insertion of the fixed appliance (which served as a baseline/reference level for salivary nickel and chromium content), 1 week after insertion of the appliance, and 3 weeks after insertion of the appliance. These samples were analyzed for nickel and chromium content using the atomic absorption spectrometer and their values recorded in ng/mL. The Friedman test was used to test the statistical significance of differences in concentrations of each metal before and after insertion of orthodontic appliances. Post-hoc comparisons were performed using the Wilcoxon signed rank test and Mann-Whitney U test. RESULTS: This study showed that there was a statistically significant difference in salivary nickel and chromium concentrations before and 1 week and 3 weeks after insertion of fixed orthodontic appliances. The highest concentrations of nickel and chromium were found after 1 week. The salivary nickel and chromium concentrations tapered off 3 weeks after insertion but were significantly higher than baseline levels. CONCLUSION: The salivary nickel and chromium concentrations significantly increased after insertion of fixed orthodontic appliances as compared to baseline levels, with the maximum concentration seen in the first week after placement of fixed orthodontic appliances.

Biometric study of tooth size in normal, crowded, and spaced permanent dentitions.

INTRODUCTION: At present, there is a void in the orthodontist's armamentarium with regard to the assessment of malocclusion due, in part, to tooth size. A biometric study of tooth size was carried out to examine the extent to which tooth size contributes to dental crowding or spacing. METHODS: A sample of 240 orthodontic study casts was selected from a larger sample. These casts met the selection criteria. The sample was divided into crowded, spaced, and normal dentition groups with 80 casts in each group. The criterion of grouping was based on the tooth size-arch length discrepancy in the arch. Each group comprised 40 maxillary and 40 mandibular casts that were further divided equally by sex. The data were statistically analyzed. RESULTS: Mesiodistal crown dimensions of individual teeth, the sum of the incisors, and the sum of the canines and the premolars were uniformly larger in crowded arches than in normal and spaced dentition groups. Mesiodistal crown dimensions of individual teeth were smaller in the spaced arches compared with normal dental arches, but the difference was significant only in the combined mesiodistal crown dimensions of the mandibular incisors. Correlations of the combined mesiodistal crown dimensions of the incisors with the combined mesiodistal crown dimensions of the canines and the premolars were positive in all 3 groups. CONCLUSIONS: Mesiodistal tooth size is an important factor in the assessment of crowding or spacing and in orthodontic treatment planning.

Evaluation of antimicrobial and physical properties of orthodontic composite resin modified by addition of antimicrobial agents--an in-vitro study.

INTRODUCTION: This study was designed to investigate the antimicrobial and physical properties of orthodontic composite resin modified by the addition of antimicrobial agents. METHODS: Unite bonding adhesive (3M Unitek, Monrovia, Calif), a chemically cured composite resin, modified by the addition of benzalkonium chloride (BAC), chlorhexidine, and triclosan in concentrations of 0.1 wt%, 0.2 wt%, and 0.3 wt%, respectively, was formed into tablets for testing. The tablets of each group and a control group were subjected to the agar plate diffusion test to measure the zone of bacterial inhibition. In addition, they were incubated for 24 hours in tryptic soy broth inoculated with Streptococcus mutans and examined for bacterial growth. A total of 80 extracted premolars were collected and divided into 2 sets of 40 teeth each. Stainless steel Begg brackets were bonded by using control and experimental composites. A universal testing machine was used to determine shear bond strength. The first set of teeth was tested after 24 hours and the second set after 25 days of storage in distilled water. Time-dependent release of antimicrobial agents from the modified composites was monitored spectrophotometrically. RESULTS AND CONCLUSIONS: The findings indicated that (1) addition of BAC to the orthodontic composite resin enhanced its antimicrobial properties, (2) there was no significant difference in the bond strengths of the control and the experimental resin tested after 24 hours and 25 days, and (3) maximum release of BAC from the modified resin was higher than that of chlorhexidine or triclosan, and was much higher than the minimum inhibitory concentration level.