Pulp vitality after rapid palatal expansion.

INTRODUCTION: Although it has been suggested that orthodontic treatment might lead to changes in the dental pulp, no clinical study has attempted to investigate the incidence of pulp necrosis after orthodontic therapy. The purpose of this clinical trial was to determine whether pulp testing response is altered after rapid palatal expansion (RPE). METHODS: Twenty-five adolescent patients (9 boys, 16 girls; ages, 10-16 years) participated in the study. A hyrax appliance was cemented on the first permanent molars and first premolars (when fully erupted). The appliance was activated twice daily (0.5 mm) for 2 weeks. An electric pulp tester (EPT) was used to test at the buccal cusp tips of the molars and premolars. Teeth that did not respond to the EPT were subsequently tested thermally with Endo Ice (Hygienic Corporation, Akron, Ohio). RESULTS: All maxillary molars and erupted premolars of the 25 patients responded positively to pulp tests before cementation of the hyrax appliance. Of the 49 molars tested, 46 responded positively to the EPT, and 3 responded positively to the cold testing (CT). Of the 42 first premolars tested, 40 responded positively to the EPT and 2 to the CT. Of the 38 second premolars tested, 35 responded positively to the EPT and 3 to the CT. Two weeks after the initial activation of the hyrax appliance, 93 teeth in 17 subjects were tested. Of the 93 teeth, 73 teeth responded positively to the EPT and 20 to the CT. Three to 6 weeks after hyrax activation was discontinued, 59 teeth were tested; 48 tested positively to the EPT and 10 to the CT. One tooth (maxillary left first molar) did not respond to either EPT or CT. Finally, 3 to 9 months into retention, all molars and premolars of 23 subjects tested positive to pulp tests, 92 teeth to the EPT and 25 to the CT. The maxillary left first molar that had not responded to the tests at the 3-to-6 week check responded positively to the CT at the final check. CONCLUSIONS: After RPE therapy in children and adolescents, the pulp of the posterior permanent teeth examined in this study was vital.

Comparison of space analysis evaluations with digital models and plaster dental casts.

INTRODUCTION: Diagnostic measurements have traditionally been made on plaster dental casts. Now, 3-dimensional digital dental models can be used. The purpose of this study was to compare space analysis measurements made on digital models with those from plaster dental casts. METHODS: Two sets of 25 alginate impressions were taken of patients who had a permanent Class I crowded dentition. Each impression was made into a plaster cast and a 3-dimensional virtual orthodontic model (OrthoCad, Cadent, Fairview, NJ). Measurements of tooth widths at their greatest mesiodistal dimension and arch length were recorded for both types of models. Tooth widths were measured on the plaster models with a digital caliper, and arch length was measured with a piece of brass wire and a millimeter ruler. The virtual models were measured by using OrthoCad's dedicated software. The space analysis measurements were calculated for both types of models, and the extrapolated amount of crowding for each type of model was accessed. All measurements were made by 2 examiners. The resulting values were compared with nonparametric statistics, and method errors were calculated. RESULTS: When comparing digitized models with conventional plaster dental study models, we found a slight (0.4 mm) but statistically significant difference in the space analysis measurements on the maxillary models; measurements on the mandibular models were not significantly different. No significant difference was found between the measurements of the 2 examiners. CONCLUSIONS: The accuracy of the software for space analysis evaluation on digital models is clinically acceptable and reproducible when compared with traditional plaster study model analyses.

Comparison of levels of inflammatory mediators IL-1beta and betaG in gingival crevicular fluid from molars, premolars, and incisors during rapid palatal expansion.

INTRODUCTION: Previously, we reported fluctuation of the levels of the inflammatory mediators interleukin-1beta (IotaL-1beta) and beta-glucuronidase (betaG) in gingival crevicular fluid (GCF) from the maxillary first molars in adolescents undergoing rapid palatal expansion. In this study, we compared the responses of IL-1beta and betaG in the GCF of the maxillary first molars, first premolars, and central incisors during palatal expansion at the same patients. METHODS: Nine patients requiring palatal expansion were selected at the postdoctoral orthodontic clinic at Columbia University College of Dental Medicine. Each patient received periodontal prophylaxis and instructions in proper home care including rinsing with chlorhexidine. Four weeks after periodontal prophylaxis, a modified hyrax appliance was placed. The jackscrew was activated twice daily until the appropriate expansion was achieved. GCF samples were collected before and after periodontal prophylaxis and during passive wearing of the appliance, active orthodontic treatment, and retention. Fluid samples were collected with filter paper strips and analyzed by ELISA and time-dependent fluorometry for IL-1beta and betaG, respectively. The values recorded after periodontal prophylaxis were used as the baseline. Paired t tests were used to compare mediator levels at baseline with the levels obtained at each subsequent observation. RESULTS: The results validate that IL-1beta and betaG are present in the GCF of adolescents, and, although their level decreases after a strict regimen of plaque control, it increases during orthodontic or orthopedic movement. Moreover, this study demonstrates that both heavy and light forces evoke increased levels of IL-1beta and betaG, stronger forces cause higher levels of inflammatory mediators, and both IL-1beta and betaG respond to direct and indirect application of mechanical force to teeth. CONCLUSIONS: This investigation corroborates previous findings that an inflammatory process occurs during application of mechanical force to teeth. Although this inflammation is considered relatively aseptic, additional inflammation, such as that induced by plaque accumulation, must be avoided during orthodontic or orthopedic treatment.

Evaluation of Class II treatment by cephalometric regional superpositions versus conventional measurements.

INTRODUCTION: The aims of this study were (1) to evaluate cephalometric changes in subjects with Class II Division 1 malocclusion who were treated with headgear (HG) or Fränkel function regulator (FR) and (2) to compare findings from regional superpositions of cephalometric structures with those from conventional cephalometric measurements. METHODS: Cephalographs were taken at baseline, after 1 year, and after 2 years of 65 children enrolled in a prospective randomized clinical trial. The spatial location of the landmarks derived from regional superpositions was evaluated in a coordinate system oriented on natural head position. The superpositions included the best anatomic fit of the anterior cranial base, maxillary base, and mandibular structures. RESULTS: Both the HG and the FR were effective in correcting the distoclusion, and they generated enhanced differential growth between the jaws. Differences between cranial and maxillary superpositions regarding mandibular displacement (Point B, pogonion, gnathion, menton) were noted: the HG had a more horizontal vector on maxillary superposition that was also greater (.0001 < P < .05) than the horizontal displacement observed with the FR. This discrepancy appeared to be related to (1) the clockwise (backward) rotation of the palatal and mandibular planes observed with the HG; the palatal plane's rotation, which was transferred through the occlusion to the mandibular plane, was factored out on maxillary superposition; and (2) the interaction between the inclination of the maxillary incisors and the forward movement of the mandible during growth. CONCLUSIONS: Findings from superpositions agreed with conventional angular and linear measurements regarding the basic conclusions for the primary effects of HG and FR. However, the results suggest that inferences of mandibular displacement are more reliable from maxillary than cranial superposition when evaluating occlusal changes during treatment.

Evaluation of the accuracy of digital model analysis for the American Board of Orthodontics objective grading system for dental casts.

INTRODUCTION: In 1999, after 3 years of field testing, the American Board of Orthodontics (ABO) implemented a grading system for posttreatment orthodontic models and panoramic radiographs, to make the phase III examination both fair and objective. In the ABO's objective grading system, 7 occlusal criteria (tooth alignment, vertical positioning of marginal ridges, buccolingual inclination of posterior teeth, occlusal relationship, occlusal contacts, overjet, and interproximal contacts) are measured on plaster models to assess a patient's final occlusion. To date, no study has evaluated the ABO grading system for use on digital models. The purpose of this study was to determine whether digital models can be used with reasonable accuracy and reliability for assessing patients' final occlusions. METHODS: Plaster and digital (OrthoCAD, Cadent Inc, Carlstadt, NJ) posttreatment models of 24 patients were gathered from the postgraduate orthodontic clinic at Columbia University School of Dental and Oral Surgery. The plaster models were scored by using the ABO measuring gauge and the 7 criteria of the ABO grading system. A second analysis was done on the digital models. To determine interexaminer error, a fourth-year dental student at Columbia University served as a second examiner and repeated all the analyses. RESULTS: The means of the total score and those for marginal ridges, occlusal contacts, occlusal relationships, overjet, and interproximal contacts were not significantly different between plaster and digital models. However, the means for alignment and buccolingual inclination were significantly different. In addition, the scorings of 2 examiners differed for the 2 methods. CONCLUSIONS: This finding suggests that alignment and buccolingual inclination should be reevaluated with both methods, and adequate calibration of the examiners is essential to achieve repeatability in both methods. Digital models might be acceptable for use in the ABO model examination.