David A. Covell

Relapse of anterior open bites treated with orthodontic appliances with and without orofacial myofunctional therapy

INTRODUCTION Closure and long-term retention of anterior open bites are significant concerns for orthodontists and their patients. In this study, we investigated the efficacy of orofacial myofunctional therapy (OMT) for maintaining closure of open bites in conjunction with orthodontic treatment. METHODS The sample included 76 subjects with dental anterior open bites referred for OMT before, during, or after relapse of orthodontic treatment. The experimental cohort consisted of 27 subjects who received OMT and orthodontic treatment or retreatment. The control cohort comprised 49 subjects who had a history of orthodontic treatment with open-bite relapse. Overbite was evaluated by an OMT professional or orthodontist 2 months to 23 years after removal of the fixed appliances. Measurements were compared with t tests. RESULTS Overbite relapse means were 0.5 mm (range, 0.0-4.0 mm) in the experimental group and 3.4 mm (range, 1.0-7.0 mm) in the control group, a difference that was clinically and statistically significant (P <0.0001). CONCLUSIONS This study demonstrated that OMT in conjunction with orthodontic treatment was highly effective in maintaining closure of anterior open bites compared with orthodontic treatment alone.

A novel biomimetic orthodontic bonding agent helps prevent white spot lesions adjacent to brackets

OBJECTIVE To compare changes in enamel microhardness adjacent to orthodontic brackets after using bonding agents containing various compositions of bioactive glass compared to a traditional resin adhesive following a simulated caries challenge. MATERIALS AND METHODS Extracted human third molars (n  =  10 per group) had orthodontic brackets bonded using one of four novel bioactive glass (BAG)-containing orthodontic bonding agents (BAG-Bonds) or commercially available Transbond-XT. The four new adhesives contained BAG in varying percentages incorporated into a traditional resin monomer mixture. Teeth were cycled through low-pH demineralizing and physiologic-pH remineralizing solutions once each day over 14 days. Microhardness was measured on longitudinal sections of the teeth 100, 200, and 300 µm from the bracket edge and beneath the brackets, at depths of 25 to 200 µm from the enamel surface. Normalized hardness values were compared using three-way analysis of variance. RESULTS Significantly less reduction in enamel microhardness was found with the experimental adhesives at depths of 25 and 50 µm at all distances from the bracket edge. In all groups, there were no significant changes in enamel microhardness past 125-µm depth. Results varied with the different BAG-Bonds, with 81BAG-Bond showing the smallest decrease in enamel microhardness. CONCLUSIONS The BAG-Bonds tested in this study showed a reduction in the amount of superficial enamel softening surrounding orthodontic brackets compared to a traditional bonding agent. The results indicate that clinically, BAG-Bonds may aid in maintaining enamel surface hardness, therefore helping prevent white spot lesions adjacent to orthodontic brackets.

Editor's Summary, Q & A, Reviewer's Critique

INTRODUCTION Enamel decalcification is a common problem in orthodontics. The objectives of this randomized clinical study were to enumerate and compare plaque bacteria surrounding 2 bracket types, self-ligating (SL) vs elastomeric ligating (E), and to determine whether adenosine triphosphate (ATP)-driven bioluminescence could be used for rapid assessment of bacterial load in plaque. METHODS Patients (ages, 11-17 years) were bonded with SL and E brackets in 14 maxillary and 12 mandibular arches by using a split-mouth design. Recall visits were at 1 and 5 weeks after bonding. Plaque specimens were assayed for oral bacteria and subjected to ATP-driven bioluminescence determinations with a luciferin-based assay. RESULTS In most patients, teeth bonded with SL attachments had fewer bacteria in plaque than did teeth bonded with E brackets. At 1 and 5 weeks after bonding, the means for SL vs E brackets were statistically lower for total bacteria and oral streptococci (P <0.05). ATP bioluminescence values were statistically correlated to the total oral bacteria and oral streptococci, with correlation coefficients of 0.895 and 0.843, respectively. CONCLUSIONS SL appliances promote reduced retention of oral bacteria, and ATP bioluminescence might be a useful tool in the rapid quantification of bacterial load and the assessment of oral hygiene during orthodontic treatment.

Measurement and comparison of bracket transfer accuracy of five indirect bonding techniques

OBJECTIVE To measure and compare bracket transfer accuracy of five indirect bonding (IDB) techniques. MATERIALS AND METHODS Five IDB techniques were studied: double polyvinyl siloxane (double-PVS), double vacuum-form (double-VF), polyvinyl siloxane vacuum-form (PVS-VF), polyvinyl siloxane putty (PVS-putty), and single vacuum-form (single-VF). Brackets were bonded on 25 identical stone working models. IDB trays were fabricated over working models (n  =  5 per technique) to transfer brackets to another 25 identical stone patient models. The mesiodistal (M-D), occlusogingival (O-G), and faciolingual (F-L) positions of each bracket were measured on the working and patient models using digital photography (M-D, O-G) and calipers (F-L). Paired t-tests were used to compare bracket positions between working and patient models, and analysis of variance was used to compare bracket transfer accuracy among the five techniques. RESULTS Between the working and patient models, double-VF had the most teeth with significant differences (n  =  6) and PVS-VF the fewest (n  =  1; P < .05). With one exception, all significant differences were ≤0.26 mm and most (65%) were ≤0.13 mm. When the techniques were compared, bracket transfer accuracy was similar for double-PVS, PVS-putty, and PVS-VF, whereas double-VF and single-VF showed significantly less accuracy in the O-G direction. CONCLUSIONS Although overall differences in bracket position were relatively small, silicone-based trays had consistently high accuracy in transferring brackets, whereas methods that exclusively used vacuum-formed trays were less consistent.

Periosteal migration in the growing mandible: An animal model

Migration of mandibular periosteum and attached musculature was tracked along the inferior border of the ramus in growing and nongrowing guinea pigs (Cavia porcellus) over a 6-week period. Particulate metallic growth-tracing implants were placed through the bony mandible and adjacent musculature at two anteroposterior locations and two bony reference markers were placed anteriorly. Quantification from weekly radiographs of growing animals showed marked posterior migration of the periosteum, whereas in nongrowing animals there was negligible periosteum movement. Significantly greater migration occurred in posterior (6.37 +/- 0.76 mm) implants relative to the anterior implants (3.45 +/- 0.86 mm, p < 0.001). The neutral zone, where little periosteal migration occurs, was calculated to be approximately at the anteroposterior center of the molar tooth row. Analysis of the orientation of the medial pterygoid muscle relative to the mandible showed that muscle fibers on average become more horizontal. Thus, the study found differential anteroposterior migration of the mandibular periosteum in growing animals and correlative changes in orientation of the medial pterygoid muscle.