Assessment of orthodontic treatment efficacy of Clarity Aligners using the Peer Assessment Rating index and the American Board of Orthodontics Cast-Radiograph Evaluation.

INTRODUCTION: 3M Oral Care Solutions (St Paul, Minn) has recently introduced Clarity Aligners into the market. This cohort study evaluated the orthodontic treatment efficacy of this clear aligner system using the Peer Assessment Rating (PAR) index and the American Board of Orthodontics Cast-Radiograph Evaluation (CR-Eval). METHODS: Pretreatment and posttreatment dental models of 87 subjects who had undergone orthodontic treatment using Clarity Aligners in both arches to align their teeth to a target setup were independently evaluated by 4 examiners using the PAR index and the American Board of Orthodontics CR-Eval. Changes in CR-Eval and PAR scores from pretreatment to posttreatment were calculated, with PAR score reductions also expressed as percentages. RESULTS: Treatment with Clarity Aligners reduced the CR-Eval scores from 39.05 ± 14.98 to 30.34 ± 8.76, resulting in a statistically significant difference of 8.76 ± 11.45 between pretreatment and posttreatment scores. Similarly, aligner treatment reduced the weighted PAR scores from 13.40 ± 9.26 to 5.80 ± 4.84, resulting in a statistically significant difference of 7.50 ± 7.56 between pretreatment and posttreatment scores. The overall median PAR reduction was 53%, with 94% of the subjects having reduced PAR scores after treatment. Seventy-eight percent of subjects had >30% PAR reduction, 57% had >50% PAR reduction, and 33% had >70% PAR reduction. CONCLUSIONS: The results suggest that Clarity Aligners may be an effective treatment modality in mild to moderate malocclusions.

Three-dimensional cone-beam computed technology evaluation of skeletal and dental changes in growing patients with Class II malocclusion treated with the cervical pull face-bow headgear appliance.

INTRODUCTION: This study aimed to 3-dimensionally quantify and compare the outcomes of growing patients with Class II malocclusion treated with the cervical pull face-bow headgear appliance in combination with full fixed orthodontic appliances. METHODS: The study sample consisted of 22 patients with Class II malocclusion with the following inclusion criteria: ANB >4.75°, Class II molar relationship, and SN-GoGn <37°. The mean age of patients was 12.5 ± 1.1 years at baseline. The average treatment time was 27.7 ± 7.3 months. Cone-beam computed tomography scans were superimposed in the cranial base, maxillary regional, and mandibular regional to evaluate growth, treatment displacements, and bone remodeling. RESULTS: Relevant statistically and clinically significant skeletal changes included average decreases in ANB (2.1 ± 1.1°) and SNA (1.8 ± 1.1°); posterior (1.3 ± 1.4 mm) and inferior (4.6 ± 2.2 mm) displacement of A-point; inferior displacements of B-point (5.4 ± 2.8 mm) and Pogonion (5.8 ± 2.6 mm); superior displacement of Condylion (6.9 ± 2.4 mm); increase in mandibular length (5.4 ± 2.0 mm); and clockwise rotation of palatal plane (1.9 ± 1.9°). Significant proclination of the maxillary incisors (9.8 ± 11.1°) and nonsignificant proclination of the mandibular incisors (4.7 ± 9.6°) were also noted. CONCLUSIONS: Class II skeletal correction was primarily achieved by posterior, inferior displacement of the sagittal position of the maxilla. Change in the sagittal position of the mandible/chin (B-point, Pogonion) was not significant; rather, mandibular displacement was significant in an inferior vertical direction without backward rotation, as seen from marked condylar and ramus growth.

Midpalatal suture density ratio: Assessing the predictive power of a novel predictor of skeletal response to maxillary expansion.

INTRODUCTION: Rapid maxillary expansion (RME) is a common orthodontic treatment to correct maxillary transverse deficiency; however, the inability to determine the precise timing of fusion of the midpalatal suture creates difficulty for clinicians to prescribe the appropriate treatment, surgical or nonsurgical expansion. The purpose of this study was to assess the predictive power of the midpalatal suture density ratio (MPSD) for a skeletal response to RME. METHODS: Pre- and posttreatment cone-beam computed tomography scans were obtained from 78 orthodontic patients aged from 8 to 18 years treated with RME. MPSDs were calculated from pretreatment scans, and a prediction was made for the amount of skeletal expansion obtained at the level of the palate after comprehensive orthodontic treatment. Predicted values were compared with actual outcomes as assessed from posttreatment scans, followed by regression analyses to investigate correlations between MPSD and skeletal expansion and equivalence testing to analyze the performance of the predicted measurements. RESULTS: The MPSDs were not statistically significantly (P >0.05) correlated with the amount of skeletal expansion achieved. In addition, the predicted skeletal expansion using MPSD was not statistically equivalent to the skeletal expansion achieved using an equivalence margin of ±0.05. CONCLUSIONS: The results suggest that the MPSD obtained from pretreatment cone-beam computed tomography scans were not correlated well enough with the amount of skeletal expansion achieved to be an effective predictor of the amount of long-term skeletal expansion after RME.

Three-dimensional condylar changes from Herbst appliance and multibracket treatment: A comparison with matched Class II elastics.

INTRODUCTION: The purpose of this study was to quantify and qualify the 3-dimensional (3D) condylar changes using mandibular 3D regional superimposition techniques in adolescent patients with Class II Division 1 malocclusions treated with either a 2-phase or single-phase approach. METHODS: Twenty patients with Herbst appliances who met the inclusion criteria and had cone-beam computed tomography (CBCT) images taken before, 8 weeks after Herbst removal, and after the completion of multibracket appliance treatment constituted the Herbst group. They were compared with 11 subjects with Class II malocclusion who were treated with elastics and multibracket appliances and who had CBCT images taken before and after treatment. Three-dimensional models generated from the CBCT images were registered on the mandible using 3D voxel-based superimposition techniques and analyzed using semitransparent overlays and point-to-point measurements. RESULTS: The magnitude of lateral condylar growth during the orthodontic phase (T2-T3) was greater than that during the orthopedic phase (T1-T2) for all condylar fiducials with the exception of the superior condyle (P <0.05). Conversely, posterior condylar growth was greater during the orthopedic phase than the subsequent orthodontic phase for all condylar fiducials (P <0.05). The magnitude of vertical condylar development was similar during both the orthopedic (T1-T2) and orthodontic phases (T2-T3) across all condylar fiducials (P <0.05). Posterior condylar growth during the orthodontic phase (T2-T3) of the 2-phase approach decreased for all condylar fiducials with the exception of the posterior condylar fiducial (P <0.05) when compared with the single-phase approach. CONCLUSIONS: Two-phase treatment using a Herbst appliance accelerates condylar growth when compared with a single-phase regime with Class II elastics. Whereas the posterior condylar growth manifested primarily during the orthopedic phase, the vertical condylar gains occurred in equal magnitude throughout both phases of the 2-phase treatment regime.

Comparative assessment of bonding time and 1-year bracket survival using flash-free and conventional adhesives for orthodontic bracket bonding: A split-mouth randomized controlled clinical trial.

INTRODUCTION: A new flash-free adhesive promises to eliminate the flash removal step in bonding and to reduce bonding time by as much as 40% per bracket, with a bond failure rate of less than 2%. The aim of this trial was to compare bonding time and bracket failure rate over a 1-year period between the flash-free adhesive and a conventional adhesive for orthodontic bracket bonding. METHODS: Forty-five consecutive patients had their maxillary incisors, canines, and premolars bonded with ceramic brackets (Clarity Advanced; 3M Unitek, Monrovia, Calif) using a flash-free adhesive (APC Flash-Free Adhesive Appliance System; 3M Unitek) on 1 side and a conventional adhesive (APCII Adhesive Appliance System; 3M Unitek) on the other side. The side allocation was randomized. Bonding was timed to the nearest second. Bond failure was recorded at standardized intervals of 4 weeks. The primary outcome was bonding time (average per tooth for each patient and per quadrant). Secondary outcomes were bracket failure rate within 1 year, time to first-time failure of a bracket, and bond failure type (adhesive remnant index score). Bonding times and adhesive remnant index scores upon bond failure were compared using paired t tests, with P <0.05 considered statistically significant. The adhesives were considered equivalent if the confidence interval for the difference between bracket failure rates fell within a margin of equivalence of ±5%. RESULTS: The bonding times were significantly shorter with the flash-free adhesive than with the conventional adhesive, both per tooth (P <0.001) and per quadrant (P <0.001). Compared with the conventional adhesive, the average bonding times per tooth and per quadrant with the flash-free adhesive were 37.3% and 32.9% shorter, respectively. The bracket failure rates at 1 year were 3.7% for the flash-free adhesive and 0.9% for the conventional adhesive. This was statistically equivalent. The average times to first-time failure of a bracket were 25 weeks for the flash-free adhesive and 11 weeks for the conventional adhesive. Although there were no significant differences in the adhesive remnant index scores upon failure (P >0.05), the flash-free adhesive tended to fail more often at the enamel-adhesive interface than did the conventional adhesive. CONCLUSIONS: The use of the flash-free adhesive may result in bonding time savings of approximately one third compared with the conventional adhesive. With regard to bracket survival, a statistically significant difference was not found between the 2 adhesives when ceramic brackets were bonded. REGISTRATION: This trial was registered on December 3, 2013 (ClinicalTrials.gov ID, NCT02030002). PROTOCOL: The protocol was not published before trial commencement.

Alternative cone-beam computed tomography method for the analysis of bone density around impacted maxillary canines.

INTRODUCTION: Genetic and environmental etiologic factors have been described for maxillary canine impaction, except for the trabecular bone characteristics in the impacted area. The aim of this study was to evaluate the surface area and fractal dimension of the alveolar bone on cone-beam computed tomography (CBCT) images of patients with maxillary impacted canines. METHODS: The sample comprised preorthodontic treatment CBCT images of 49 participants with maxillary impacted canines (31 unilateral and 18 bilateral). CBCT images were acquired in portrait mode (17 × 23 cm high field of view) at 120 kV, 5 mA, 8.9-seconds exposure time, and 0.3-mm voxel size. Coronal slices (0.3 mm) were obtained from the right and left alveolar processes between the first and second maxillary premolars. We collected 64 × 64-pixel regions of interest between the premolars to assess maxillary bone area and fractal dimension using ImageJ software (National Institutes of Health, Bethesda, Md). Comparisons were made using paired t tests and linear regression. Repeated measurements were obtained randomly from about 20% of the sample. RESULTS: In subjects with unilateral impactions, the maxillary bone area (P = 0.0227) was higher in the impacted side, with a mean difference of 245.5 pixels (SD, 569.2), but the fractal dimension (P = 0.9822) was not, -0.0003 pixels (SD, 0.082). Comparisons of unilateral and bilateral subjects using a general linear mixed model test confirmed the increased bone area in the impacted side (P = 0.1062). The repeated measurements showed similar results. CONCLUSIONS: The maxillary alveolar bone area is increased in the impacted side compared with the nonimpacted side.

Comparing Stability of Mandibular Setback Versus 2-Jaw Surgery in Class III Patients With Minimal Presurgical Orthodontics.

PURPOSE: The aim of this study was to compare treatment time and skeletal stability between mandibular setback surgery (MS) and 2-jaw surgery (2J) with minimal presurgical orthodontics (MPO) in patients with skeletal Class III. MATERIALS AND METHODS: One hundred ninety-five patients who underwent orthognathic surgery were enrolled in this retrospective cohort study. Consecutive patients were selected based on standardized inclusion criteria: Class III malocclusion with mandibular prognathism, surgery type, and presurgical orthodontics with non-extraction for less than 6 months (MPO). Lateral cephalograms were taken before surgery (T0), 1 month after surgery (T1), and at debonding (T2). To evaluate surgical changes (T0 to T1) and postsurgical changes (T1 to T2) in skeletodental tissue, linear, angular, and dental measurements were analyzed using paired t test and independent t test. RESULTS: Thirty-one patients were allocated to the MS-MPO group (n = 16) and the 2J-MPO group (n = 15). The 2J-MPO group showed a shorter duration of postsurgical orthodontic and total surgical and orthodontic treatment than the MS-MPO group. Although the 2J-MPO group exhibited advancement and superior impaction of the maxilla from T0 to T1, posterior movement with clockwise rotation of the mandible between the 2 groups did not show a statistical difference. In addition, from T1 to T2, the MS-MPO and 2J-MPO groups presented forward and upward movement and counterclockwise rotation of the mandible, but no intergroup difference was found. CONCLUSIONS: The MS-MPO and 2J-MPO groups showed similar horizontal and vertical mandibular stability. However, the 2J-MPO group presented a shorter surgical and orthodontic treatment time than the MS-MPO group.

Conservative interdisciplinary treatment of a case with multiple facial and condyle fractures.

The purpose of this case report is to describe an interdisciplinary approach for a 51-year-old male who underwent multiple facial fractures including bilateral condyle fractures. The patient underwent emergency surgery, which included open reduction of the maxilla and mandibular symphysis and closed reduction of the bilateral condyle fractures. Although the patient recovered a comfortable range of mouth opening and alleviation of the temporomandibular joint (TMJ) symptoms after surgery, he suffered from a large anterior-posterior discrepancy due to less stability on the condyle-fossa relationships and from open bite with contacts only on both second molars and right second premolars. In this case, first, to increase the occlusal contact, comprehensive orthodontic treatment was completed. Second, occlusal equilibration was selectively performed to relieve the interferences and establish a stable range of mandibular movement without any changes in the vertical dimension. Third, both the upper central incisors and left lateral incisor were minimally restored with splinted and single zirconia crowns, which had modified lingual contours to provide adequate anterior guidance permitting the anterior-posterior discrepancy of the posterior teeth during protrusion. This conservative interdisciplinary treatment, including open and closed reduction, orthodontic treatment, occlusal adjustment, and minimal prosthetic restorations, resulted in a stable mandibular position and recovery of mastication function.

Midpalatal suture density ratio: A novel predictor of skeletal response to rapid maxillary expansion.

INTRODUCTION: During adolescence, increasing interdigitation of the midpalatal suture increases resistance to rapid maxillary expansion (RME); this decreases its skeletal effect. In this study, we aimed at determining whether a novel measure of midpalatal suture maturity, the midpalatal suture density ratio, can be used as a valid predictor of the skeletal response to RME. METHODS: The midpalatal suture density ratio, chronologic age, cervical vertebral maturation, and the stage of midpalatal suture maturation were assessed before treatment for 30 patients (ages, 12.9 ± 2.1 years) who underwent RME as part of comprehensive orthodontic treatment. Measurements on cone-beam computed tomography scans were used to determine the proportions of prescribed expansion achieved at the greater palatine foramina, the nasal cavity, and the infraorbital foramina. RESULTS: There was a statistically significant negative correlation between the midpalatal suture density ratio and both the greater palatine foramina and the infraorbital foramina (r = -0.7877 and -0.3647, respectively; P <0.05). In contrast, chronologic age, cervical vertebral maturation, and stage of midpalatal suture maturation were not significantly correlated to any of the assessed measures of skeletal expansion (r range, -0.2209 to 0.0831; P >0.05). CONCLUSIONS: The midpalatal suture density ratio has the potential to become a useful clinical predictor of the skeletal response to RME. Conversely, chronologic age, cervical vertebral maturation, and stage of midpalatal suture maturation cannot be considered useful parameters to predict the skeletal effects of RME.

Evaluation of Soft Tissue Changes Around the Lips After Mandibular Setback Surgery With Minimal Orthodontics Using Three-Dimensional Stereophotogrammetry.

PURPOSE: Most reports on the surgery-first approach in skeletal Class III malocclusion have focused on the skeletal changes. The present study evaluated the soft tissue changes around the lips over time after mandibular setback surgery (MS) with minimal orthodontics (MO) using 3-dimensional (3D) stereophotogrammetry. MATERIALS AND METHODS: We performed a retrospective study of patients with mandibular prognathism who had undergone MS-MO. Lateral cephalograms and 3D photographs were taken before (T0) and 1 (T1) and 6 months (T2) after surgery and were superimposed. A paired t test, independent t test, and simple linear regression analysis were used to evaluate the hard and soft tissue changes and their correlation. RESULTS: The sample included 15 patients (7 males and 8 females). The soft tissue landmarks on the X-axis (left-right) showed no significant positional changes. The landmarks of the lips and oral commissure on the Y-axis (vertical) moved downward until T2; however, most of these changes did not differ significantly over time (T1 compared with T0 and T2 compared with T0). The landmarks in the lower lip, oral commissure, and soft tissue chin on the Z-axis (anterior-posterior) showed posterior movement at T1 and T2. In contrast, the lower lip (labiale inferius, 1.67 mm) and soft tissue chin (soft tissue B point, 1.28 mm; soft tissue pogonion, 1.61 mm) moved significantly forward from T1 to T2, but had no correlation with the anterior relapse of the mandible. CONCLUSIONS: Protrusion of the lower lip and soft tissue chin with forward and upward relapse of the mandible during postoperative orthodontics was observed. The results from the present study suggest that 3D stereophotogrammetry can be useful for evaluating the perioral soft tissue changes over time in orthognathic surgery patients.

Comparison of the Stability After Mandibular Setback With Minimal Orthodontics of Class III Patients With Different Facial Types.

PURPOSE: Most studies on the surgery-first approach focused on skeletal relapse compared with conventional surgery. The objective of this study was to compare the stability of skeletal Class III patients with 2 different vertical facial types after mandibular setback surgery (MS) with minimal orthodontic preparation (MO). MATERIALS AND METHODS: In this retrospective study, the patients were recruited from a population that had undergone MS. Consecutive patients were selected based on the following inclusion criteria: skeletal Class III malocclusion with mandibular prognathism, MO without extraction for less than 6 months, and sagittal split ramus osteotomy. The vertical facial types of the patients were classified based on the Frankfort mandibular-plane angle (FMA). Lateral cephalograms were taken at the presurgical stage, at 1 month after surgery (T1), and at the debonding stage (T2). To evaluate surgical changes (T1 - presurgical stage) and relapse (T2 - T1), the linear, angular, and dental measurements were analyzed using a paired t test and an independent t test. RESULTS: The 26 patients were divided into 2 groups: normal-angle group (n = 14; mean FMA, 23.58°) and high-angle (HA) group (n = 12; mean FMA, 30.26°). From T1 to T2, the normal-angle and HA groups showed significant forward and counterclockwise rotation of the mandible (distance between pogonion and perpendicular line to Frankfort horizontal plane from sella, 1.71 mm and 1.51 mm, respectively; distance between menton and perpendicular line to Frankfort horizontal plane from sella, 1.91 mm and 1.60 mm, respectively; angle between articulare-menton line and Frankfort horizontal plane, -0.55° and -0.89°, respectively). The HA group showed a significant upward movement of the mandible (distance from Frankfort horizontal plane to pogonion, -1.13 mm; distance from Frankfort horizontal plane to menton, -0.78 mm). However, there was no significant difference in the skeletal-dental changes between the 2 groups from T1 to T2. CONCLUSIONS: The vertical facial types of Class III patients with similar prognathic mandible and dental patterns may not cause any differences in the relapse pattern after MS-MO.

Debonding and adhesive remnant cleanup: an in vitro comparison of bond quality, adhesive remnant cleanup, and orthodontic acceptance of a flash-free product.

BACKGROUND/OBJECTIVES: A new flash-free adhesive promises to eliminate the need to clean up excess adhesive upon orthodontic bracket bonding. This study evaluated this new adhesive with regard to microleakage at the enamel-bracket interface, amount of adhesive remaining on the tooth after bracket debonding, time required for adhesive remnant cleanup, and clinical practitioners' preference in comparison to a conventional adhesive. MATERIALS/METHODS: A total of 184 bovine incisors were bonded with ceramic brackets using either the flash-free adhesive (APC Flash-Free Adhesive Coated Appliance System, 3M Unitek [3M], Monrovia, California, USA) or a conventional adhesive (APCII Adhesive Coated Appliance System, 3M). Twenty-four of the teeth were scanned using microcomputed tomography to quantify microleakage into the adhesive layer. Twenty orthodontists debonded the brackets, removed the remaining adhesive, and then completed a survey regarding their preference for one of the two adhesives. The adhesive remnant was quantified and the time required for its removal recorded. Differences between the adhesives were tested for statistical significance. RESULTS: For both adhesives, the microleakage was minimal with no significant differences between the two adhesives. The adhesive remnant was significantly larger for the flash-free adhesive, whereas there was no significant difference in adhesive cleanup time. Fourteen out of the 20 orthodontists preferred the flash-free adhesive over the conventional adhesive. LIMITATIONS: In vitro testing cannot replicate the actual clinical situation during in vivo debonding. CONCLUSIONS: With regard to bond quality and adhesive remnant cleanup, the new flash-free adhesive performs just as well as the conventional adhesive, and, of the two products, is the one preferred by most orthodontists.

Clinical use of a direct chairside oral scanner: an assessment of accuracy, time, and patient acceptance.

INTRODUCTION: Chairside oral scanners allow direct digital acquisition of the intraoral situation and can eliminate the need for conventional impressions. In this study, we aimed to assess accuracy, scan time, and patient acceptance of a chairside oral scanner when used for full-arch scans; these are critical factors for acceptance of this technology in the orthodontic setting. METHODS: Fifteen patients had digital models made from both intraoral scans (Lava COS; 3M ESPE, St Paul, Minn) and alginate impressions. Each procedure was timed, and patient preference was assessed with a survey. In addition, digital models were made from 5 plaster model pairs using the intraoral scanner and an orthodontic model scanner. Model pairs were digitally superimposed, and differences between models were quantified. Accuracy was assessed using the Bland-Altman method. Time differences were tested for statistical significance with the Student t test. RESULTS: Digital models made using the chairside oral scanner and either impressions or the orthodontic model scanner did not differ significantly. The chair time required to take impressions was significantly shorter than the time required for the intraoral scans. When processing time was included, the time requirement did not differ significantly between methods. Although 73.3% of the patients preferred impressions because they were "easier" or "faster," 26.7% preferred the scan because it was "more comfortable." CONCLUSIONS: Despite the high accuracy of chairside oral scanners, alginate impressions are still the preferred model acquisition method with respect to chair time and patient acceptance. As digital technology continues to progress, intraoral scanning may become more accepted for use in orthodontics.

Accuracy, reproducibility, and time efficiency of dental measurements using different technologies.

INTRODUCTION: Historically, orthodontists have taken dental measurements on plaster models. Technological advances now allow orthodontists to take these measurements on digital models. In this study, we aimed to assess the accuracy, reproducibility, and time efficiency of dental measurements taken on 3 types of digital models. METHODS: emodels (GeoDigm, Falcon Heights, Minn), SureSmile models (OraMetrix, Richardson, Tex), and AnatoModels (Anatomage, San Jose, Calif) were made for 30 patients. Mesiodistal tooth-width measurements taken on these digital models were timed and compared with those on the corresponding plaster models, which were used as the gold standard. Accuracy and reproducibility were assessed using the Bland-Altman method. Differences in time efficiency were tested for statistical significance with 1-way analysis of variance. RESULTS: Measurements on SureSmile models were the most accurate, followed by those on emodels and AnatoModels. Measurements taken on SureSmile models were also the most reproducible. Measurements taken on SureSmile models and emodels were significantly faster than those taken on AnatoModels and plaster models. CONCLUSIONS: Tooth-width measurements on digital models can be as accurate as, and might be more reproducible and significantly faster than, those taken on plaster models. Of the models studied, the SureSmile models provided the best combination of accuracy, reproducibility, and time efficiency of measurement.

Dosimetry of a cone-beam computed tomography machine compared with a digital x-ray machine in orthodontic imaging.

INTRODUCTION: Cone-beam computed tomography (CBCT) has become a routine imaging modality for many orthodontic clinics. However, questions remain about the amount of radiation patients are exposed to during the scans. This study determined the amounts of radiation potentially absorbed by a patient during orthodontic imaging with a CBCT machine with various scan settings compared with a conventional 2-dimensional digital x-ray machine. METHODS: The radiation exposures delivered by a next generation i-CAT CBCT machine (Imaging Sciences International, Hatfield, Pa) at various scan settings and orthopantomograph OP100/OC100 digital x-ray machine (Instrumentarium Dental, Tuusula, Finland) during panoramic and cephalometric radiography were recorded using thermoluminescent dosimeters placed inside a head and neck phantom. The manufacturer-recommended settings for an average adult male were used for both types of machines. Effective doses were calculated using the tissue-weighting factors recommended by the 2007 International Commission on Radiological Protection. RESULTS: The effective doses at various voxel sizes and field of view settings ranged from 64.7 to 69.2 µSv for standard resolution CBCT scans (scan time 8.9 s) and 127.3 to 131.3 µSv for high resolution full field of view scans (scan time 17.8 s), and measured 134.2 µSv for a high-resolution landscape scan with a voxel size as would be used for SureSmile (OraMetrix, Richardson, Tex) therapy (scan time 26.9 s). The effective doses for digital panoramic and lateral cephalometric radiographs measured 21.5 and 4.5 µSv, respectively. CONCLUSIONS: CBCT, although providing additional diagnostic and therapeutic benefits, also exposes patients to higher levels of radiation than conventional digital radiography.

Orbital volume changes during growth and development in human children assessed using cone beam computed tomography.

OBJECTIVES: To measure growth-related changes in orbital volume from childhood to the late teenage years using cone-beam computed tomography (CBCT) scans. METHODS: This retrospective cohort study involved 65 (24 male, 41 female) healthy Caucasian children (ages 6-18 years) with existing serial craniofacial CBCT scans. CBCT scans were available for 292 orbits. Each orbit was transformed into a closed space with well-defined boundaries, and orbital volume was measured using manual segmentation. A novel statistical analysis was applied to extract the maximum amount of longitudinal information from the data. Intra- and inter-operator correlation coefficients were calculated from replications performed on a random subset of 10% of the sample. RESULTS: Orbital volume increased at a rate of 1-2% annually until the late teenage years. Intra- and inter-operator agreement between repeated measurements were >90%. CONCLUSIONS: Orbital volume increases by 1-2% per year throughout childhood continuing until the late teenage years. This annual increase is large enough to be clinically relevant as it may lead to less-than-optimal long term surgical outcomes when reconstructive surgery for the pediatric anophthalmic socket is required.

Effect of neonatal capsaicin treatment on orthodontic tooth movement in male Sprague-Dawley rats.

INTRODUCTION: In this study, we examined the effect of neonatal administration of capsaicin on the magnitude of orthodontic tooth movement in rats. METHODS: Twelve timed pregnant Sprague-Dawley rats were randomized between the capsaicin group and the vehicle group. The pups received treatment with either capsaicin or vehicle on day 2 of life. Capsaicin treatment has been shown to produce a selective destruction of fine myelinated and unmyelinated Aδ and C sensory nerve fibers, causing an inhibition of the effects from neurogenic inflammation. Tooth-movement experiments began at 12 weeks of age. A mesial tipping force was applied to the maxillary first molar by using a 3-mm length of Sentalloy closed-coil spring (Dentsply GAC Intl, Bohemia, NY) activated from a bonded molar cleat to the maxillary incisors; this appliance delivers a constant tipping force of 50 g. Diastema measurements between the first and second molars were made at 2 and 4 weeks after appliance placement. Measurements were made indirectly from stone models by using a charge-coupled device microscope camera and Optimas 5.2 measurement software (Media Cybernetics, Bethesda, Md). Two-way repeated-measures analysis of variance (ANOVA) was used to analyze the differences between the groups. RESULTS: The capsaicin-treated rats and the controls did not differ in the amount of tooth movement at the collected time points (P >0.05). Similarly, the magnitude of change of tooth movement from 2 to 4 weeks did not differ between the groups (P >0.05). An increase in average diastema size was observed between 2 and 4 weeks after appliance activation in both treatment groups (P <0.0001). CONCLUSIONS: These results suggest that neonatal capsaicin desensitization in the rat does not affect the rate of orthodontic tooth movement after the application of a 50-g tipping force to the maxillary first molar. This might be due in part to the development of compensatory mechanisms in the chronically desensitized rat. Further studies are necessary to determine the reproducibility and histologic characteristics of this treatment.

Evaluation of transverse maxillary growth on cone-beam computed tomography images.

This study aimed at quantifying the annual transverse growth of the maxilla using skeletal landmarks in three different regions on cone-beam computed tomography (CBCT) scans. CBCT scans taken before and after orthodontic treatment of 100 child and adolescent patients (50 male, 50 female) without maxillary transverse deficiencies were used to determine the transverse linear distances between the greater palatine foramina (GPFd), the lateral walls of the nasal cavity (NCd), and the infraorbital foramina (IOFd). We found that all distances increased significantly with growth in both genders (p < 0.001). The overall average annual change was 0.5 mm for GPFd, 0.3 mm for NCd, and 0.7 mm for IOFd. Males generally had greater annual changes than females for GPFd and IOFd, but not NCd. There were weak, statistically not significant (p > 0.05) correlations between patient age and the annual changes in GPFd, NCd, and IOFd. These results suggest that the positions of the greater palatine foramina, the lateral walls of the nasal cavity, and the infraorbital foramina change consistently with maxillary transverse growth. Clinicians can use the growth rates as population averages to more confidently estimate the amount of skeletal transverse deficiency or evaluate the long-term effects of maxillary expansion treatment.