Background The aim of the study was to evaluate the cephalometric and dentoalveolar characteristics of maxillary lateral incisor agenesis patients, and to compare the findings to a matched control group without tooth agenesis, excluding third molars, from the same population. Methods The pre-orthodontic records of 72 non-growing patients, who were treated at the Orthodontic Department, Faculty of Dentistry, Alexandria University, were used to address the aim of this retrospective study. Patients having unilateral or bilateral maxillary lateral incisor agenesis, with no history of previous orthodontic treatment, congenital craniofacial malformations, facial trauma, or surgeries were divided into two test groups based on the pattern of maxillary lateral incisors agenesis (group I: unilateral (UMLIA), group II: bilateral (BMLIA)). A control group (group III (CTRL)) having a complete set of permanent dentition (excluding third molars), and having no dental anomalies was age-matched with the test groups. Measurements were performed on the pre-orthodontic lateral cephalometric radiographs and the pre-orthodontic digital dental casts. The measured variables were compared between the groups using one-way ANOVA and Kruskal Wallis tests according to the normality of the variable. In case of significant results, both tests were followed by multiple pairwise comparisons using Bonferroni adjusted significance level. Significance level was set at P < 0.05. Results BMLIA group showed a smaller SNA angle and maxillary length, a more negative ANB angle and Wits appraisal, and a larger Maxillo-mandibular differential than UMLIA and/or CTRL group. The dental and soft tissue cephalometric measurements did not show any significant differences between the groups. Dentoalveolar cast measurements showed that BMLIA patients presented with significantly smaller maxillary inter-canine width than UMLIA and CTRL patients. Conclusions Cephalometric analysis has shown that subjects with BMLIA have a statistically significant reduced ANB and maxillary length. Tooth eruption may play a role in the development of the maxillary arch.

INTRODUCTION:Using a biocompatible material to control tooth movement and enhance anchorage may be a useful method to help the orthodontist to give better treatment results. OBJECTIVES: To Assess the effect of hyaluronic acid (HA) local injection on orthodontic tooth movement. MATERIALS AND METHODS:The sample size was 15 male New Zealand rabbits. Randomized prospective split mouth trial was conducted on each rabbit. A mesializing force was applied in both sides for 21 days. Group A (control): Saline was injected on day 0. Group B: HA 1% was injected. Tooth movements were measured on 3D models. Histological analysis of alveolar bone modeling was done in the end of this experiment. RESULTS: The quadrant receiving HA showed less amount of tooth movement than that in the control quadrant. Local administration of HA yielded 10% less tooth movement. Histological analysis revealed less resorptive activity in the quadrant receiving HA. CONCLUSION: There was statistically significant reduction in orthodontic tooth movement magnitude after local HA administration as well as reduction in bone resorptive activity.