Alveolar cortical plate changes associated with incisor retraction and its influence on the limits of orthodontic tooth movement.

OBJECTIVE: The extent to which the modelling behaviour of the anterior alveolus limits tooth movement remains unclear. Will the labial and lingual cortical plates model as incisors retract, or will they remain unchanged, therefore limiting the extent of possible tooth movement? SETTING AND SAMPLE POPULATION: Pre- and post-treatment lateral cephalometric radiographs of 29 bimaxillary protrusive patients of South Korean descent were examined. Treatment consisted of two premolar extractions in one or both arches with en masse retraction of the incisors using miniscrew anchorage. MATERIALS AND METHODS: Pre- and post-treatment measurements of both tooth and cortical plate position were made at various increments along the length of the root and then compared using paired t tests. RESULTS: Despite the use of miniscrew anchorage, the incisors were retracted by controlled tipping. The labial cortical plates in both arches modelled to follow tooth movement. Following retraction of the incisors in the maxilla, the incisor root approached the lingual cortical plate, which remained unchanged. In the mandible, the lingual cortical plate position was unchanged except at the level closest to the cementoenamel junction. CONCLUSIONS: The maxillary and mandibular lingual cortical plates did not model to follow the incisor movement while the labial cortical plates did. These findings suggest that lingual cortical plates may act as limitations to planned orthodontic tooth movement.

Bimaxillary transverse constriction in adults: Short-term follow-up of non-surgical arch expansion.

OBJECTIVE: Concurrent maxillary and mandibular expansion is a treatment option for patients with maxillary and mandibular transverse constriction. These patients do not present with crossbite but require expansion due to narrow arches and associated crowding, dark buccal corridors and decreased anterior arch contour. The objective of the study is to first establish Bimaxillary Transverse Constriction as an under-recognized malocclusion and second to evaluate whether in adults the maxillary and mandibular arches can be successfully and safely expanded. SETTING AND SAMPLE POPULATION: Pre- and post-treatment study models and lateral cephalograms of 31 adults with Bimaxillary Transverse Constriction expanded non-surgically were analysed. Thirty adult orthodontic patients who did not require expansion served as a control. Expanders were turned no more frequently than every other day in the maxilla and every third day in the mandible. MATERIALS AND METHODS: Measurements in both arches made on OrthoCAD models were transarch widths, molar and premolar axial angulation, clinical crown height of posterior teeth and cuspids, and mandibular divergence. Retrospective comparison of the 2 groups used independent Student's t tests for mean differences between groups. RESULTS: At pre-treatment, the expansion group demonstrated significant transverse constriction compared with the control. Increased widths were achieved in the expansion group (4 mm in the maxilla and 2.5 mm in the mandible), while the control group was unchanged. The mandibular plane was unchanged. There was no buccal attachment loss. CONCLUSION: Non-surgical expansion in the maxilla and mandible is a viable treatment option for adult patients with Bimaxillary Transverse Constriction.

Quantitative measures of gingival recession and the influence of gender, race, and attrition.

BACKGROUND: Gingival recession in dentitions with otherwise healthy periodontium is a common occurrence in adults. Recession is clinically measured using a periodontal probe to the nearest millimeter. The aim of this study is to establish quantitative measures of recession, the clinical crown height, and a new measure the gingival margin-papillae measurement. The latter is seen as the shortest apico-coronal distance measured from the depth of the gingival margin to a line connecting the tips of the two adjacent papillae. METHODS: Measurements on all teeth up to and including the first molar were performed on pretreatment study models of 120 adult Caucasian and African-American subjects divided into four groups of 30 by gender and race. RESULTS: Both the clinical crown height and the gingival margin-papillae measurements gave a true positive result for changes associated with gingival recession. Tooth wear shortens the clinical crown, and therefore, the measure of clinical crown height can give a false negative result when gingival recession is present. However, the gingival margin-papillae measurement was not affected by tooth wear and gave a true positive result for gingival recession. Tooth wear (attrition) was not associated with an increase in gingival recession. These measures are also useful in detecting recession prior to cemental exposure. Measures for recession and tooth wear were different for the four demographic groups studied. CONCLUSIONS: These measures can be used as quantitative standards in both clinical dentistry, research, and epidemiological studies.

ROC surface assessment of the ANB angle and Wits appraisal's diagnostic performance with a statistically derived 'gold standard': does normalizing measurements have any merit?

OBJECTIVE: To assess the ANB angle's and Wits appraisal's diagnostic performance using an extended version of Receiver Operating Curve (ROC) analysis, which renders ROC surfaces. These were calculated for both the conventional and normalized cephalometric tests (calculated by exchanging the patient's reference landmarks with those of the Procrustes superimposed sample mean shape).The required 'gold standard' was derived statistically, by applying generalized Procrustes superimposition (GPS) and principal component analysis (PCA) to the digitized landmarks, and ordering patients based upon their PC2 scores. METHODS: Digitized landmarks of 200 lateral cephalograms (107 males, mean age: 12.8 years, SD: 2.2, 93 females, mean age: 13.2 years, SD: 1.7) were subjected to GPS and PCA. Upon calculating the conventional and normalized ANB and Wits values, ROC surfaces were constructed by varying not just the cephalometric test's cut-off value within each ROC curve, but also the gold standard cut-off value over different ROC curves in 220 steps between -2 and 2 standard deviations along PC2. The volume under the resulting ROC surfaces (VUS) served as a measure of overall diagnostic performance. The statistical significance of the volume differences was determined using permutation tests (1000 rounds, with replacement). RESULTS: The diagnostic performance of the conventional ANB and Wits was remarkably similar for both Class I/II (81.1 and 80.75% VUS, respectively, P > 0.05). Normalizing the measurements improved all VUS highly significantly (91 and 87.2 per cent, respectively, P < 0.001). CONCLUSION: The conventional ANB and Wits do not differ in their diagnostic performance. Normalizing the measurements does seem to have some merit.

Prognostic factors associated with the success rates of posterior orthodontic miniscrew implants: A subgroup meta-analysis.

OBJECTIVE: To systematically review previous studies and to assess, via a subgroup meta-analysis, the combined odds ratio (OR) of prognostic factors affecting the success of miniscrew implants (MIs) inserted into the buccal posterior region. METHODS: Three electronic searches that were limited to articles on clinical human studies using MIs that were published in English prior to March 2015 were conducted. The outcome measure was the success of MIs. Patient factors included age, sex, and jaw of insertion (maxilla vs. mandible), while the MI factors included length and diameter. A meta-analysis was performed on 17 individual studies. The quality of each study was assessed for non-randomized studies and quantified using the Newcastle-Ottawa Scale. The meta-analysis outcome was a combined OR. Subgroup and sensitivity analyses based on the study design, study quality, and sample size of miniscrews implanted were performed. RESULTS: Significantly higher success rates were revealed for MIs inserted in the maxilla, for patients ≥ 20 years of age, and for long MIs (≥ 8 mm) and MIs with a large diameter (> 1.4 mm). All subgroups acquired homogeneity, and the combined OR of the prospective studies (OR, 3.67; 95% confidence interval [CI], 2.10-6.44) was significantly higher in the maxilla than that in the retrospective studies (OR, 2.10; 95% CI, 1.60-2.74). CONCLUSIONS: When a treatment plan is made, these risk factors, i.e. jaw of insertion, age, MI length, and MI diameter, should be taken into account, while sex is not critical to the success of MIs.

The Relationship between Caries and Malocclusion in Chinese Migrant Workers' Children in Shanghai.

OBJECTIVE: To evaluate the relationship between caries and malocclusion in the early and late mixed dentition in a population of children of Chinese migrant workers in Shanghai. METHODS: Dental charts were obtained for 646 children in the mixed dentition, aged between 6 and 13 years old. The decayed, missing, and filled teeth (DMFT) index and interproximal tooth structure lost due to caries (ITSLC) were evaluated. RESULTS: In the early mixed dentition, overbite was more likely to be ideal in subjects with DMFT > 0. In the late mixed dentition, crowding in both arches was greater in subjects with DMFT > 0. In the total sample, crowding in the lower arch only was greater in subjects with DMFT > 0. In the early mixed dentition, upper crowding was lower in subjects with ITSLC in the upper arch and in both arches and the rate of anterior crossbite was higher in subjects with ITSLC in the upper arch. In the late mixed dentition, overjet was more likely to be ideal in subjects with ITSLC in the upper arch and upper crowding was greater in subjects with ITSLC in both arches. In the total sample, overjet was more likely to be ideal in subjects with ITSLC in the upper arch and lower crowding was greater in subjects with ITSLC in both arches. CONCLUSION: A relationship exists between caries and malocclusion, and between ITSLC and malocclusion, and some relationships may change with dental age.

Force decay evaluation of thermoplastic and thermoset elastomeric chains: A mechanical design comparison.

OBJECTIVES: To compare the following over a period of 8 weeks: (1) force decay between thermoplastic (TP) and thermoset (TS) elastomeric chains; (2) force decay between light (200-g) and heavy (350-g) initial forces; and (3) force decay between direct chains and chain loops (stretched from one pin around the second pin and back to the first pin). MATERIALS AND METHODS: TP and TS chains were obtained from American Orthodontics™ (AOTP, AOTS) and ORMCO™ (OrTP, OrTS). Each of the four chain groups was subdivided into four subgroups with 10 specimens per subgroup: (1) direct chains light force, (2) direct chains heavy force, (3) chain loops light force, and (4) chain loops heavy force. The experiment was performed in artificial saliva (pH of 6.75) at 37°C. RESULTS: A significant difference was found between TP and TS chains, with an average mean difference of around 20% more force decay found in the TP chains (P < .001, α  =  .05). There was no significant difference between direct chains and chain loops except in OrTP, in which direct chains showed more force decay. There was also no significant difference in force decay identified when using light vs heavy forces. CONCLUSIONS: TS chains decayed less than TP chains, and chain loop retraction was beneficial only when using OrTP chains. Contrary to the interchangeable use of TP and TS chains in the published literature and in clinical practice, this study demonstrates that they perform differently under stress and that a clear distinction should be made between the two.

Nasal outcomes of presurgical nasal molding in complete unilateral cleft lip and palate.

Objective. Short-term nasal forms following primary lip repair were compared between presurgical nasal molding and control groups. Aim. To compare nasal symmetry between patients that had nasal molding and lip repair with those that had only lip repair. Design. Retrospective case-control study Patients. Complete unilateral CL+P patients had basilar and frontal photographs at two time points: (1) initial (2) postsurgical. 28 nasal molding patients and 14 control patients were included. Intervention. Presurgical nasal molding was performed prior to primary lip repair in intervention group. No nasal molding was performed in control group. Hypothesis. Nasal molding combined with lip surgery repair according to the Millard procedure provides superior nasal symmetry than surgery alone for nostril height-width ratios and alar groove ratios. Statistics. Shapiro-Wilk test of normality and Student's t-tests. Results. A statistically significant difference was found for postsurgical nostril height-width ratio (P < .05). No other statistically significant differences were found. Conclusions. Nasal molding and surgery resulted in more symmetrical nostril height-width ratios than surgery alone. Alar groove ratios were not statistically significantly different between groups perhaps because application of nasal molding was not early enough; postsurgical nasal splints were not utilized; overcorrection was not performed for nasal molding.

Severity of occlusal disharmonies in down syndrome.

Objective. To quantify the severity of malocclusion and dental esthetic problems in untreated Down syndrome (DS) and untreated non-Down syndrome children age 8-14 years old using the PAR and ICON Indices. Materials and Methods. This retrospective study evaluated pretreatment study models, intraoral photographs, and panoramic radiographs of 30 Down syndrome and two groups of 30 non-Down syndrome patients (private practice and university clinic) age 8-14 years. The models were scored via PAR and ICON Indices, and descriptive characteristics such as Angle classification, missing or impacted teeth, crossbites, open bites, and other dental anomalies were recorded. Results. The DS group had significantly greater PAR and ICON scores, as well as 10 times more missing teeth than the non-DS group. The DS group possessed predominantly Class III malocclusions, with the presence of both anterior and posterior crossbites in a majority of the patients. The non-DS group had mostly Class I or II malocclusion with markedly fewer missing teeth and crossbites. The DS group also had more severe malocclusions based upon occlusal traits such as open bite and type of malocclusion. Conclusion. The DS group had very severe malocclusions, while the control group from the university clinic had more severe malocclusions than a control group from a private practice.

Phantom bite: a survey of US orthodontists.

AIM: In 1976, Marbach described the term phantom bite as a patient's perception of an irregular bite when the clinician could identify no evidence of a discrepancy. Typically, the patient presents with a history of bite-altering procedures, hyperawareness of occlusion, and a persistent complaint of an uncomfortable bite, usually with an absence of pain. Patients with phantom bite complaints often undergo lengthy, expensive, irreversible, invasive, and unnecessary treatments in search of a resolution of their symptoms. The objectives of the study were: (1) to gauge orthodontists' awareness of phantom bite and its associated signs and symptoms, (2) to identify the most common types of treatments rendered for this phenomenon, (3) to determine if regional differences or length of practice experience affected the aforementioned factors, and (4) to determine sex characteristics of patients with phantom bite. METHODS: The study consisted of a 14-item survey administered electronically using SurveyMonkey software. Using the American Association of Orthodontists (AAO) directory, 4,124 orthodontists were recruited to participate via email; 337 completed the survey. RESULTS: Approximately 50% of the responding orthodontists were unfamiliar with the term "phantom bite"; however, many reported seeing patients with phantom bite complaints. Demographic differences, such as geographic region of practice or years in practice, did not affect familiarity with this condition or its treatment. CONCLUSION: The results suggest a need for increasing awareness of this condition among orthodontic practitioners to provide patients with appropriate care.

A comparison of traditional and computer-aided bracket placement methods.

OBJECTIVE: To test the hypothesis that there is no difference in the accuracy of bracket placement produced by OrthoCAD iQ indirect bonding (IDB) and that of an in-house fabricated IDB system by measuring the quality of intra-arch dental alignment at the end of simulated orthodontic treatment. MATERIALS AND METHODS: Twenty-eight artificial teeth were arranged to resemble a typical preorthodontic malocclusion. Forty-six sets of models were duplicated from the original malocclusion and randomly divided into two sample groups. Half of the models had their bracket positions selected by OrthoCAD, while the others were completed by a combination of faculty and residents in a university orthodontic department. Indirect bonding trays were fabricated for each sample and the brackets were transferred back to the original malocclusion following typical bonding protocol. The individual teeth were ligated on a .021 × .025-inch stainless steel archwire to simulate their posttreatment positions. The two sample groups were compared using the objective grading system (OGS) originally designed by the American Board of Orthodontics. RESULTS: The mean total OGS score for the OrthoCAD sample group was 39.25 points, while the traditional IDB technique scored 41.00 points. No statistical difference was found between total scores or any of the four components evaluated. Similar ranges of scores were observed, with the OrthoCAD group scoring from 30 to 52 points and the traditional IDB group scoring from 33 to 53 points. CONCLUSIONS: The hypothesis is not accepted. OrthoCAD iQ does not currently offer a system that can position orthodontic brackets better or more reliably than traditional indirect bonding techniques.

Evaluation of incisor position and dental transverse dimensional changes using the Damon system.

OBJECTIVES: To test the hypotheses that the Damon system will maintain intercanine, interpremolar, and intermolar widths. To test subsequent hypotheses that the Damon system will not produce a significant difference in maxillary and mandibular incisor position/angulation when compared with control groups treated with conventional fixed orthodontic appliances for similar malocclusion. MATERIALS AND METHODS: Subjects treated with the Damon system (N  =  27) were compared with subjects treated with a conventionally ligated edgewise bracket system (N  =  16). Subjects' pretreatment and posttreatment lateral cephalometric radiographs and dental models were scanned, measured, and compared to see whether significant differences exist between time points and between the two groups. RESULTS: Results did not support the claimed lip bumper effect of the Damon system and showed similar patterns of crowding alleviation, including transverse expansion and incisor advancement, in both groups, regardless of the bracket system used. CONCLUSIONS: Maxillary and mandibular intercanine, interpremolar, and intermolar widths increased significantly after treatment with the Damon system. The mandibular incisors were significantly advanced and proclined after treatment with the Damon system, contradicting the lip bumper theory of Damon. Posttreatment incisor inclinations did not differ significantly between the Damon group and the control group. Patients treated with the Damon system completed treatment on average 2 months faster than patients treated with a conventionally ligated standard edgewise bracket system.

Biologic markers for odontogenic periradicular periodontitis.

INTRODUCTION: The diagnosis and assessment of apical periodontitis by traditional periapical radiographs can be challenging and might yield false-negative results. The aim of this study was to determine whether interleukin-1beta (IL-1beta) and dentin sialoprotein (DSP) in gingival crevicular fluid (GCF) can be used as biological markers for apical periodontitis. METHODS: Forty healthy patients with teeth diagnosed with apical periodontitis of pulpal origin were included in the study. GCF samples were obtained from the diseased tooth and from a healthy contralateral control tooth. Total protein concentration in each sample was determined by using the Bio-Rad protein assay. Enzyme-linked immunosorbent assay was used to analyze the concentration of IL-1beta and DSP in the samples. RESULTS: Protein content of the GCF was statistically significantly higher in the disease group compared with the control group. The levels of IL-1beta and DSP were not statistically different between disease and control groups. CONCLUSIONS: Although this study was unable to demonstrate a significantly higher level of IL-1beta or DSP in the GCF of teeth with apical periodontitis, the observed presence of a significantly higher level of total protein in the GCF of diseased teeth suggests the possible role of total protein level as a marker for periapical disease.

Rapid palatal expansion for spontaneous Class II correction.

INTRODUCTION: Palatal expanders have been advocated for spontaneous correction of some Class II malocclusions. However, little research has been done to determine whether correction or improvement actually occurs with expansion. Past research has not shown whether an anterior functional shift is achieved in patients who have Class II improvement. The objective of this study was to determine whether maxillary expansion causes spontaneous correction or improvement of a Class II malocclusion. METHODS: This was a retrospective study of subjects from an orthodontic office in which models are mounted (articulator) in centric occlusion and maximum intercuspation before and after treatment. The sample included Class II patients (n = 13; mean age, 10 years 3 months) who, during the preceding 2 years, had been treated with expansion alone. Study models made before and after expansion were measured to compare the centric occlusion to the maximum intersuspation position. Condyle position indicator paper was also used to determine whether there was a functional shift after expansion. RESULTS: The only measurements with statistically significant changes from pretreatment to postexpansion were the maxillary intermolar widths. Seven of the 13 patients showed Class II improvement, but none had an anterior functional shift after expansion. CONCLUSIONS: Maxillary expansion does not predictably improve Class II dental relationships.

Stability of open bite correction with sagittal split osteotomy and closing rotation of the mandible.

PURPOSE: To determine the long-term stability of bilateral sagittal split osteotomies with counterclockwise (closing) rotation of the mandible combined with rigid internal fixation in the correction of anterior open bite deformities. MATERIALS AND METHODS: A total of 28 patients who had completed orthodontic therapy and had at least 1 year of postoperative follow-up were evaluated using cephalometric analysis for dental and skeletal changes. We evaluated 7 angular and 6 linear measurements cephalometrically at 3 points for each patient: immediately preoperatively, immediately postoperatively, and after a minimum of 1 year of postoperative follow-up. RESULTS: Of the 28 patients, 12 exhibited some degree of opening rotation (range 1% to 64%, mean 16%), and 16 showed no open rotation or continued to experience bite closure. However, all patients had a positive overbite at 1 year of follow-up, indicating that even though skeletal relapse was observed postoperatively, dental compensation resulted in the maintenance of the occlusal relationships. CONCLUSIONS: Bilateral sagittal split osteotomies and closing rotation of the mandible using rigid fixation is a relatively stable procedure and a viable surgical treatment option for the correction of anterior open bite in instances in which maxillary osteotomies are not indicated to improve or enhance facial esthetics.

How well does Invisalign work? A prospective clinical study evaluating the efficacy of tooth movement with Invisalign.

INTRODUCTION: The purpose of this prospective clinical study was to evaluate the efficacy of tooth movement with removable polyurethane aligners (Invisalign, Align Technology, Santa Clara, Calif). METHODS: The study sample included 37 patients treated with Anterior Invisalign. Four hundred one anterior teeth (198 maxillary and 203 mandibular) were measured on the virtual Treat models. The virtual model of the predicted tooth position was superimposed over the virtual model of the achieved tooth position, created from the posttreatment impression, and the 2 models were superimposed over their stationary posterior teeth by using ToothMeasure, Invisalign's proprietary superimposition software. The amount of tooth movement predicted was compared with the amount achieved after treatment. The types of movements studied were expansion, constriction, intrusion, extrusion, mesiodistal tip, labiolingual tip, and rotation. RESULTS: The mean accuracy of tooth movement with Invisalign was 41%. The most accurate movement was lingual constriction (47.1%), and the least accurate movement was extrusion (29.6%)- specifically, extrusion of the maxillary (18.3%) and mandibular (24.5%) central incisors, followed by mesiodistal tipping of the mandibular canines (26.9%). The accuracy of canine rotation was significantly lower than that of all other teeth, with the exception of the maxillary lateral incisors. At rotational movements greater than 15 degrees, the accuracy of rotation for the maxillary canines fell significantly. Lingual crown tip was significantly more accurate than labial crown tip, particularly for the maxillary incisors. There was no statistical difference in accuracy between maxillary and mandibular teeth of the same tooth type for any movements studied. CONCLUSIONS: We still have much to learn regarding the biomechanics and efficacy of the Invisalign system. A better understanding of Invisalign's ability to move teeth might help the clinician select suitable patients for treatment, guide the proper sequencing of movement, and reduce the need for case refinement.

Differences in clinical decision making: a comparison between specialists and general dentists.

OBJECTIVE: The aim of this study was to compare clinical decision making choices of general dentists, prosthodontists, endodontists, oral surgeons,and periodontists when presented with endodontics-related patient scenarios. STUDY DESIGN: A survey instrument with 5 patient scenarios was mailed to 1,250 randomly selected dentists, 250 in each group noted above. The participants were asked to choose from different treatment options and to assess the difficulty of making their choice. The answers were analyzed to identify differences in clinical decision making between groups. RESULTS: A total of 293 surveys were returned, for an overall response rate of 23.4%. Significant differences in treatment planning decisions between the 5 groups were found. Practitioners expressed more difficulty and more variation in making treatment recommendations in cases involving previously endodontically treated teeth than initial treatment scenarios. CONCLUSIONS: Dental specialty status has a significant influence on a clinician's recommendation to perform root canal therapy or extract a tooth.

Preferences for vertical position of the maxillary lateral incisors.

AIM: To evaluate the preferences for vertical position of the maxillary lateral incisors among orthodontists, general dentists, and laypeople. METHODS: The study group consisted of 120 judges, 40 in each of 3 study groups. Judges were asked to give their preference for maxillary lateral incisor position while viewing an animation of an idealized smile. Perceptometrics software animated the photograph and collated responses. Each judge participated in 2 similar experiments, 1 to determine what he/she found to be the most pleasing position and another to define that position's range of acceptability. The processed data were analyzed with ANOVA (analysis of variance) and post-hoc Scheffé tests to determine mean differences among the 3 study groups. RESULTS: The most pleasing protocol revealed no significant difference (P >.05) in the mean preferences of the 3 groups. The average preference was 0.6 mm above the incisal plane. No subjects chose a level incisal plane as being most pleasing. Orthodontists and general dentists had a smaller range of acceptability than laypeople. The means for lower and upper limits of acceptability for all subjects were 0.3 mm and 1.0 mm, respectively, above the incisal plane. CONCLUSIONS: The judges in this study preferred that the maxillary lateral incisor to be set about 0.5 mm above the incisal plane, slightly offset from the incisal plane, and not level. The lateral incisors were best perceived when they were offset slightly from the incisal plane, and there was an acceptable range within which the lateral incisors may be placed.

Outcome of one-visit and two-visit endodontic treatment of necrotic teeth with apical periodontitis: a randomized controlled trial with one-year evaluation.

The choice of one-visit versus two-visit root canal therapy for necrotic teeth with apical periodontitis is a source of current debate. The primary objective of this randomized controlled clinical trial was to compare radiographic evidence of periapical healing after root canal therapy completed in one visit or two visits with an interim calcium hydroxide/chlorhexidine paste dressing. Ninety-seven patients met the inclusion criteria and consented to participate in this study. Patients were randomly assigned to either the one-visit or two-visit group, and root canal therapy was performed with a standardized protocol. Patients in the two-visit group received an intracanal dressing of calcium hydroxide/chlorhexidine paste. Sixty-three patients, 33 in the one-visit group and 30 in the two-visit group, were evaluated at 12 months. The primary outcome measure was change in apical bone density by using the periapical index (PAI). Secondary outcome measures were proportion of teeth healed or improved in each group. Both groups exhibited equally favorable periapical healing at 12 months, with no statistically significant differences between groups.

Bond strength analysis of custom base variables in indirect bonding techniques.

INTRODUCTION: Various methods are used to prepare the cured composite-adhesive interface for orthodontic indirect bonding. The intent of this study was to determine the effect on the shear bond strength of the following variables: use of a filled flowable composite resin as an adhesive, light air-abrasion of the cured composite bracket pad, and wetting the cured composite bracket pad with an unfilled resin. METHODS: The sample of 240 brackets was divided into 2 groups of 120 each. The first group was further divided into 4 groups of 30 each. Brackets were bonded to bovine incisors with a filled flowable composite resin (Filtek, 3M ESPE, St Paul Minn), but the bracket pads were prepared differently in the 4 groups: unfilled resin was applied (Orthosolo, Ormco, Glendora, Calif), the surface was air abraded, the surface was air abraded followed by application of an unfilled resin (Orthosolo), and a control group. A matching sample of 120 brackets was bonded without the flowable composite as an adhesive. The different bracket pad preparations were chosen to represent the various techniques clinicians use in indirect bonding. The shear bond strength was measured on a universal testing machine. RESULTS: Two-way ANOVA analysis showed significant differences in the shear bond strength among the different surface preparations, but not between the use and nonuse of flowable composite. The Scheffé test showed that the mean shear bond strength of the air-abraded surface was significantly higher than all other surface preparations. CONCLUSIONS: Air abrading orthodontic bracket-pad composite surfaces in indirect bonding increased the shear bond strength, whereas the use of flowable composite did not affect bond strengths.