Soft Tissue Responses to Orthodontic Treatment: Impact of Premolar Extraction on Diverse Growth Patterns.

INTRODUCTION: Alteration in facial soft tissue plays an important role in the esthetics of an individual. The first thing a patient wants from orthodontic treatment is how well he/she looks. The degree of soft tissue changes brought about by the retraction of teeth can be influenced by factors such as extraction pattern, muscle function, age, gender, weight, etc. Aim: The aim of the study was to compare post-orthodontic soft tissue changes among different facial growth patterns in orthodontic patients undergoing extraction of first premolar teeth. METHODOLOGY: Pre-treatment and post-treatment lateral cephalograms of 45 orthodontic patients who underwent therapeutic extraction of the first premolars were included in the study. They were divided into three equal groups based on their facial growth pattern, that is, average, horizontal, and vertical. Eight soft tissue cephalometric measurements were done in all the lateral cephalograms. Paired Student t-tests and analysis of variance (ANOVA) were conducted to statistically analyze the results. The significance level was set as 0.05. RESULTS: The paired Student t-test showed a P-value > 0.05 for lower anterior facial height in all three groups and for facial angle in vertical growers alone. ANOVA comparing the mean soft tissue changes among the three groups resulted in a P-value > 0.05 for all the measured parameters. CONCLUSIONS: Facial growth patterns do not influence the extent of soft tissue profile changes in orthodontic patients treated with extraction of first premolars.

Evaluation of Orthodontic Mini-Implant Placement in the Maxillary Anterior Alveolar Region in 15 Patients by Cone Beam Computed Tomography at a Single Center in South India.

BACKGROUND In this study, we aimed to evaluate orthodontic mini-implant placement in the maxillary anterior alveolar region by cone beam computed tomography (CBCT) in 15 patients at a single center in South India. MATERIAL AND METHODS A total of 15 CBCT scans of orthodontic patients after completion of leveling and aligning stage were included. The thickness of labial alveolar bone, labio-palatal bone, and inter-radicular distance between the maxillary central incisors (U1-U1), maxillary central and lateral incisor (U1-U2), and maxillary lateral incisor and canine (U2-U3) at vertical levels 4 mm, 6 mm, and 8 mm above the interdental cementoenamel junction were measured. Descriptive statistics, ANOVA, and Tukey post hoc tests were done to assess the differences among the groups. An independent t test was done to analyze differences by sex. RESULTS The thickness of cortical bone in the labial region was higher in the U2-U3 site than in the U1-U1 site, at a height of 4 mm. Also, there was a significant difference between 4 mm and 8 mm heights in the U2-U3 region. No significant difference was noted in bone dimensions among men and women and in the labio-palatal bone thickness among the different sites. The inter-radicular distance was the highest between the U2-U3 site, while it was the lowest in the U1-U2 site. CONCLUSIONS The findings from this center showed that when CBCT was used to evaluate orthodontic mini-implant placement in the maxillary anterior alveolar region, the U2-U3 and U1-U1 locations at heights between 6 mm to 8 mm apical to the interdental cementoenamel junction were optimal for placement of the mini-implants.

Evaluating the Effect of Denosumab in Preventing Anchorage Loss: A Split-mouth Randomized Controlled Trial.

AIM: The trial was focused on assessing the effect of Denosumab in preventing anchorage loss during en-masse anterior retraction and evaluating its effect on the retraction. MATERIALS AND METHODS: This was a split-mouth randomized controlled trial. Ten subjects were randomly allocated with equal probability for Denosumab and control interventions in the contralateral quadrants using computer-generated randomization sequence. During the start of retraction, Denosumab (5 mg/0.2 mL) and injectable sterile water were administered locally on the intervention and control sides, respectively. Lateral cephalograms taken during the start of retraction and later in the 3rd and 6th months into retraction were used to evaluate anchorage loss and retraction. Independent sample t-test and Mann-Whitney U test compared anchorage loss and retraction between the two groups in the maxilla and mandible. Paired t-test and Wilcoxon signed-rank test assessed the anchorage loss and retraction during the first and the second 3 months of retraction. RESULTS: In the maxilla, Denosumab was effective in preventing anchorage loss with a p-value of 0.001 whereas it was not effective in the mandible (p-value-0.172). A significant reduction in anchorage loss was observed with Denosumab in the second 3 months of retraction compared to the first 3 months. There was no significant difference in the retraction among both groups. CONCLUSION: Denosumab was effective in minimizing the anchorage loss in the maxilla without affecting the anterior retraction. CLINICAL SIGNIFICANCE: Denosumab can be effectively used for reinforcing anchorage in the maxilla during en-masse anterior retraction.

A 3D comparison of dimension of infrazygomatic crest region in different vertical skeletal patterns: A retrospective study.

INTRODUCTION: Infrazygomatic crest (IZC) dimension is an important factor in the safety and stability of bone screws. The dimension is known to vary according to the dimensions of the maxillary sinus, which in turn depends on the vertical facial skeletal pattern. OBJECTIVE: The objective of the study was to compare the infrazygomatic crest thickness (IZC) above the mesiobuccal root of the first and second maxillary molar in different vertical skeletal patterns. MATERIALS AND METHODS: This was a retrospective study conducted in Saveetha Dental College, Chennai. Cone beam computed tomography (CBCT) and lateral cephalograms of 36 subjects were collected and divided into 3 groups (12 subjects in each group) depending on their vertical skeletal pattern, namely normal, low and high angle. Vertical skeletal pattern was assessed using lateral cephalogram whereas IZC thickness was measured using CBCT. Mann Whitney U test was done to compare the bone thickness in the right and left sides and also to compare the same above the mesiobuccal root of the first and second molar. Kruskal Wallis and post hoc tests were done to compare bone thickness among the three groups. P-value was set at 0.05 for all the analysis. RESULTS: Significant difference in IZC bone thickness above the first molar region was noted between high angle and average angle groups (P-value 0.001) and high angle and low angle (P-value 0.001). Above the second molar region, a significant difference was seen between high angle and average angle groups (P-value 0.001). Significant difference in bone thickness was also observed among the first molar and second molar region in all the three groups (P-value<0.05). CONCLUSION: IZC thickness was the least in high-angle subjects. Clinically, it is desirable to place the IZC screw above the mesiobuccal root of the maxillary second molar especially in high-angle subjects.

Comparison of accuracy of mesiodistal tooth measurements made in conventional study models and digital models obtained from intraoral scan and desktop scan of study models.

OBJECTIVE: To compare the measured values obtained from the plaster model, digital models created by scanning the plaster models and direct intraoral scanning with the values obtained from direct intraoral measurements. DESIGN: This was a prospective clinical study. SETTING: The study was conducted in Department of Orthodontics, Saveetha Dental College and Hospital, Tamil Nadu, India. PARTICIPANTS: Ten patients before the start of orthodontic treatment were selected for the study. METHODS: A computer-aided design and manufacturing (CAD-CAM) system is an advanced technology that is being adopted in the field of orthodontics for diagnosis, treatment planning and documentation of patient records. Mesiodistal tooth width measurements of first premolars, canines, lateral incisors and central incisors, and transverse width measurement from mesial pit of right first premolar to mesial pit of left first premolar in both maxilla and mandible were obtained from direct intraoral measurement (gold standard), study model obtained from alginate impression, intraoral scanned image, and desktop scanned image of the study model. Descriptive statistics and ANOVA was performed to find the difference in mean among the groups. RESULTS: A P value > 0.05 was obtained in ANOVA indicating that there is no statistically significant difference in the measurements obtained by either of the methods. CONCLUSION: Conventional stone models and digital models obtained from intraoral scan and desktop scanning of plaster models are clinically reliable as the variations in measurements obtained from these methods were clinically negligible.

Comparison of bone thickness in infrazygomatic crest area at various miniscrew insertion angles in Dravidian population - A cone beam computed tomography study.

INTRODUCTION: Infrazygomatic crest miniscrews are an important advancement in the field of orthodontics for anchorage reinforcement. The size of the miniscrews and the site of placement depend on the bone thickness in the infazygomatic crest area. The bone morphology and the thickness vary among different ethnicities of population. OBJECTIVES: To assess the bone thickness in the infrazygomatic crest area around the distobuccal root of the maxillary first molar using cone beam computed tomography and determine the best possible site and angulation for the placement of the miniscrew. Therefore, to determine the size of the implant that will suit the Dravidian population. METHODS: The infrazygomatic crest bone thickness was evaluated on 10 patients using cone beam computed tomography. The measurements were made along the distobuccal root of maxillary first molar at different angulations ranging from 75° to 40° to the occlusal surface of the molar. RESULTS: The infrazygomatic crest bone thickness was of 4.5mm to 9mm for the Dravidian population, when measured at an angle of 40° to 75° to the maxillary first molar occlusal plane and of 11 to 17mm above the occlusal plane. Student t-test (confidence interval 95%) was done to determine gender variation and compare the bone thickness of right and left side. ANOVA and post-hoc test were done to find the statistical difference between the bone thickness measured at different insertion angles. CONCLUSIONS: The best possible site for miniscrew insertion is 12 to 17mm above the occlusal plane at an angle of 65° to 70°, with no injury to the adjacent anatomical structures, no mucosal irritation and adequate stability for the miniscrew. The ideal infrazygomatic crest screw length for Dravidian population is 9 to 11mm.