Phillip M. Campbell

Enamel surfaces after orthodontic bracket debonding.

The enamel surfaces of extracted teeth were studied clinically and with a scanning electron microscope following debonding of orthodontic attachments and subsequent polishing. Excess orthodontic resin was removed with tungsten carbide burs and abrasive discs. Several combinations of polishing agents were evaluated. The no. 30 fluted tungsten carbide bur appeared to be the most efficient method of removing highly filled resin, and it produced the least amount of scarring. A polishing sequence was developed which used resin points and cups followed by a water slurry of fine pumice and brown and green cups. This procedure was tested clinically and appeared to return the enamel to an acceptable condition. This procedure is fast, efficient, and comfortable for the patient.

Prevalence of white spot lesion formation during orthodontic treatment

PURPOSE To quantify the prevalence of white spot lesions (WSLs) on the anterior teeth and, secondarily, to evaluate risk factors and predictors. MATERIALS AND METHODS Digital photographs and records of 885 randomly chosen patients were evaluated before and after treatment. Chart information included gender, age, as well as banding and debanding dates. Fluorosis and oral hygiene before and after treatment were also evaluated. Preexisting and posttreatment WSLs were recorded and compared for all 12 anterior teeth. Risk ratios (RR) and absolute risk (AR) were calculated to determine the likelihood and risk of WSL formation. RESULTS Overall, 23.4% of the patients developed at least one WSL during their course of treatment. Maxillary anterior teeth were affected more than mandibular teeth. The maxillary laterals and canines and the mandibular canines were the most susceptible. There was no significant difference in WSLs between genders. Fluorosis, treatment time in excess of 36 months, poor pretreatment hygiene, hygiene changes during treatment, and preexisting WSLs were all significantly (P < .05) related to the development of WSLs. The highest risk of developing WSLs was associated with preexisting WSLs (RR = 3.40), followed by declines in oral hygiene during treatment (RR = 3.12) and poor pretreatment oral hygiene (RR = 2.83). CONCLUSIONS Nearly 25% of the patients developed WSLs while in treatment, depending on fluorosis, treatment time, preexisting WSLs, and oral hygiene. Orthodontists need to be mindful of these risk factors when making treatment decisions.

Effectiveness of Pit and Fissure Sealants in Reducing White Spot Lesions during Orthodontic Treatment

OBJECTIVE A pilot investigation was performed to test the null hypothesis that highly filled (58%) resin sealants do not prevent white spot lesions in patients undergoing active orthodontic treatment. MATERIALS AND METHODS A split-mouth design was applied to 60 healthy patients, with the sealant randomly allocated to either the right or the left side of each jaw. The sealant was applied to the incisors and canines from the gingival surface of the bracket to the free gingival margin. The contralateral teeth had the same type of bracket with no sealant. Sealants were placed on the experimental teeth 2 weeks to 3 months after initial bonding and were removed after 15 to 18 months. Intraoral photographs, visual assessments, and DIAGNOdent (KaVo Dental Corporation, Lake Zurich, Ill) measurements were used to assess white spot lesions after sealant removal. RESULTS Six lesions on the teeth with sealants were identified visually, compared with 22 lesions on the teeth without sealants. The teeth without sealants had 3.8 times the number of white spot lesions than were noted on the sealed teeth. These sealants showed no visible signs of discoloration. The DIAGNOdent measured statistically significant differences between sealed and unsealed teeth in the maxilla (P < .001) and in the mandible (P = .010). DIAGNOdent measurements also showed a difference between sealed and unsealed teeth after the 28 teeth with visible lesions were excluded. CONCLUSION The hypothesis was rejected. Ultraseal XT Plus clear sealant (Ultradent Products, South Jordon, Utah) produced a significant reduction in enamel demineralization during fixed orthodontic treatment and should be considered for use by clinicians to minimize white spot lesions.

Tooth movements in foxhounds after one or two alveolar corticotomies

The aim of this split-mouth experimental study was to determine (1) whether corticotomy procedures increase tooth movement and (2) the effects of a second corticotomy procedure after 4 weeks on the rate of tooth movement. The mandibular third and maxillary second premolars of five skeletally mature male foxhounds, approximately 2 years of age, were extracted. One randomly selected mandibular quadrant had buccal and lingual flaps and corticotomies performed around the second premolar; the other quadrant served as the control. Both maxillary quadrants had initial buccal flaps and corticotomies; one randomly selected quadrant had a second buccal flap surgery and corticotomy after 28 days. Coil springs (200 g force), along with a 0.045 mm diameter tube on a 0.040 mm diameter guiding wire, were used to move the mandibular second and maxillary third premolars. Records, including digital calliper measurements and radiographs, were taken on days 0, 10, 14, 28, 42, and 56. Multilevel statistical procedures were used to model longitudinal tooth movements. The radiographic measurements initially showed increasing mandibular tooth movement rates, peaking between 22 and 25 days, and then decelerating. Total mandibular tooth movements were significantly (P < 0.05) greater on the experimental (2.4 mm) than on the control (1.3 mm) side. The rates of maxillary tooth movement slowed over time, with significantly (P < 0.05) more overall tooth movement on the side that had two (2.3 mm) than one (2.0 mm) corticotomy procedure. Alveolar corticotomy significantly increases orthodontic tooth movement. Performing a second corticotomy procedure after 4 weeks maintained higher rates of tooth movement over a longer duration and produced greater overall tooth movement than performing just one initial corticotomy, but the difference was small.

Antimicrobial Effects of Zinc Oxide in an Orthodontic Bonding Agent

OBJECTIVE To test the null hypothesis that the addition of zinc oxide (ZnO) has no effect on the antimicrobial benefits and shear bond strength of a light-cured resin-modified glass ionomer. MATERIALS AND METHODS ZnO was added to Fuji Ortho LC to create mixtures of 13% ZnO and 23.1% ZnO. Specimen discs of the modified bonding agent were incubated with Streptococcus mutans for 48 hours in a disc diffusion assay that was used to measure zones of bacterial inhibition. In addition, brackets were bonded to bovine deciduous incisors with the modified bonding agents, and shear bond strength was evaluated with a universal testing machine. RESULTS The modified samples showed that antimicrobial activity increased as the concentration of ZnO increased. There were significant differences (P < .05) in antimicrobial activity. Post hoc tests showed that the antibacterial effects were 1.6 times greater with 23.1% ZnO than with 13% ZnO. There was no difference between Transbond and 0% ZnO (the negative control). After 1 month of daily rinsing, the antibacterial effects of 23.1% ZnO and 13% ZnO decreased 65% and 77%, respectively, but both maintained significant effects over the negative controls. There were no significant differences (P = .055) in shear bond strength between any of the mixture comparisons. CONCLUSIONS The incorporation of ZnO into Fuji Ortho LC added antimicrobial properties to the original compound without significantly altering the shear bond strength. ZnO holds potential for preventing decalcification associated with orthodontic treatment.

Transverse dentoalveolar changes after slow maxillary expansion

INTRODUCTION In this study, we evaluated the transverse dentoalveolar changes in the maxillary first molar region after early treatment with the quad-helix appliance. METHODS Seventy-three consecutive patients (39 boys, 34 girls) who had phase 1 quad-helix treatment were evaluated with cone-beam computed tomography scans taken before phase 1 (mean age, 9.2 years) and phase 2 (mean age, 11.9 years) treatments. Buccal bone thickness, buccal cortical plate thickness, lingual bone thickness, alveolar width, palatal width, and intermolar width were measured by using standardized orientations. RESULTS Slow palatal expansion with the quad-helix decreased buccal bone thickness (1.6 mm ± 0.8), and increased lingual bone thickness (1.6 mm ± 1.3) and alveolar width (0.5 mm ± 1.0). Intermolar widths and palatal widths increased 6.5 mm ± 2.9 and 3.9 mm ± 1.8, respectively. At the beginning of phase 2, approximately one third of the patients showed little or no buccal cortical plate on at least 1 side. Patients retained with the Hawley demonstrated some relapse tendencies; patients without retention had the greatest relapse tendencies. CONCLUSIONS Early treatment with the quad-helix appliance proved to be highly effective in increasing intermolar, palatal, and alveolar widths. The teeth moved through the alveolus, leading to substantial decreases in buccal bone thickness and increases in lingual bone thickness.

Long-term stability: Postretention changes of the mandibular anterior teeth

INTRODUCTION Our objectives were to evaluate the long-term posttreatment changes of orthodontically corrected mandibular anterior malalignment and to determine the factors explaining these changes. METHODS The sample consisted of 66 subjects (mean age, 15.4 ± 1.7 years) selected from 7 private practices. The teeth had been retained for approximately 3 years and followed for 15.6 ± 5.9 years posttreatment. Longitudinal study models and cephalograms were analyzed to quantify the malalignment and growth changes that occurred. RESULTS Crowding (1.2 ± 0.9 mm) and irregularity (1.5 ± 1.8 mm) showed only small average increases over the postretention period; only 26% of the sample had more than 3.5 mm of postretention irregularity. Variation in crowding explained 16% of the differences among subjects in irregularity. Growth variables (posterior facial height and mandibular rotation) and interarch variables (incisor-mandibular plane angle, interincisal angle, overbite, and overjet) were not significantly related to malalignment. Postretention malalignment changes were related to posttreatment anterior arch perimeter, intercanine width, and arch form, together indicating that narrower arch forms are likely to show greater posttreatment malalignment changes. Patients treated with extractions showed significantly greater malalignment than those treated without extractions; this was related to arch form. Patients who received interproximal restorations after treatment also showed significantly greater postretention malalignment than patients who did not. CONCLUSIONS Orthodontic treatment is not inherently unstable. Narrow arch forms and interproximal restorations are potential risk factors for the development of postretention malalignment.

Effects of increased surgical trauma on rates of tooth movement and apical root resorption in foxhound dogs

PURPOSE To experimentally determine the effects of increased surgical trauma on the rates of tooth movement and apical root resorption. Two surgical techniques for rapid protraction of multi-rooted teeth in foxhound dogs immediately following premolar extraction were compared. METHODS Split-mouth design to randomly assign two surgical techniques [periodontal ligament distraction (RAP side) and a modified form of dentoalveolar distraction (RAP+ side)] to the maxillary quadrants. First premolars were extracted, and second premolars were protracted 0.5 mm per day for 15 days using a custom made jack-screw distractor. Serial caliper and radiographic measurements were performed to quantify tooth movements and apical root resorption. RESULTS Both techniques demonstrated significant movement of the crown and apex. The second premolar crowns were protracted significantly more on the RAP+ side (2.9 mm) than on the RAP (1.8 mm) side. The premolars on both sides demonstrated significant tipping (4.3 and 3.9 degrees for the RAP+ and RAP sides, respectively). The distal root apex showed almost twice as much apical root resorption than the mesial root apex, but resorption was limited (<0.16 mm) and not statistically different between sides. CONCLUSIONS Increased surgical trauma increased the rate and, ultimately, the amount of tooth movement. The heavy forces used to protract the teeth produced statistically, but not clinically, significant apical root resorption on the mesial and distal roots of the maxillary second premolars.

Bony adaptation after expansion with light-to-moderate continuous forces

INTRODUCTION The purpose of this study was to evaluate the biologic response of dentoalveolar bone to archwire expansion with light-to-moderate continuous forces. METHODS With a split-mouth experimental design, the maxillary right second premolars of 7 adult male dogs were expanded for 9 weeks using passive self-ligating brackets (Damon Q; Ormco, Orange, Calif) and 2 sequential archwires (0.016 × 0.022-in copper-nickel-titanium alloy, followed by 0.019 × 0.025-in copper-nickel-titanium alloy). Intraoral and radiographic measurements were made to evaluate tooth movements and tipping associated with expansion; archwire forces were measured using a force gauge. Microcomputed tomography was used to compare buccal bone height, total tooth height, total root height, and buccal bone thickness. Bone formation was evaluated histologically using tetracycline and calcein fluorescent labels and hematoxylin and eosin stains. RESULTS Buccal expansion was produced by forces between 73 and 178 g. Compared with the control side, which showed no tooth movement, the experimental second premolars were expanded by 3.5 ± 0.9 mm and tipped by 15.8°. Buccal bone thickness was significantly thinner (about 0.2 mm) in the coronal aspects and significantly thicker (about 0.9 mm) in the apical aspects over the mesial roots. The tipping and expansion significantly (P <0.05) reduced buccal bone height (ie, caused dehiscences) at the mesial (about 2.9 mm) and distal (about 1.2 mm) roots. Bony apposition occurred on the trailing edges of tooth movement and on the leading edges of the second premolar apices. The axial microcomputed tomography slices indicated, and the bone histomorphometry and histology demonstrated, newly laid-down bone on the periosteal side of the buccal cortical surfaces. Ordered osteoblast aggregation was also evident on the periosteal surfaces of buccal bone, just cervical to the apparent center of rotation of the tooth. Tooth and root heights showed no significant differences between the experimental and control second premolars. CONCLUSIONS Buccal expansion with light-to-moderate continuous forces produced 3.5 mm of tooth movement, uncontrolled tipping, and bone dehiscence, but no root resorption. Bone formation on the periosteal surfaces of cortical bone indicates that apposition is possible on the leading edge of tooth movements.

Differences in craniofacial and dental characteristics of adolescent Mexican Americans and European Americans

INTRODUCTION The purpose of this study was to compare the soft-tissue profiles of matched Class I adolescent European Americans and Mexican Americans. The secondary aim was to explain profile differences based on group differences in soft-tissue thickness, skeletal morphology, dental position, and tooth size. METHODS The study pertained to 207 untreated Class I adolescents, including 93 Mexican Americans and 114 European Americans. Lateral cephalometric and model analyses were performed to quantify morphologic differences. Two-way analyses of variance were used to evaluate ethnicity, sex, and their interaction. RESULTS Mexican Americans had significantly (P <0.05) greater lip protrusion and facial convexity than did European Americans. Mexican Americans had smaller craniofacial dimensions and larger teeth, resulting in maxillary and mandibular dentoalveolar protrusion. Mexican Americans also had thicker soft tissues and greater maxillary skeletal prognathism than European Americans. The combination of thicker soft tissues, maxillary skeletal prognathism, and dentoalveolar protrusion explained the protrusive lips of Mexican Americans. The greater facial convexity of Mexican Americans was due primarily to maxillary prognathism and mandibular hyperdivergence. Sex differences pertained primarily to size; the linear dimensions of the boys were consistently and significantly larger than those of the girls. CONCLUSIONS European American normative data and treatment objectives do not apply to Mexican Americans. Knowledge of the soft-tissue, skeletal morphology, and dental position differences should be applied when planning treatment for Mexican American patients.