Relationship of maxillary 3-dimensional posterior occlusal plane to mandibular spatial position and morphology.

INTRODUCTION: The purpose of this study was to examine the relationship of the 3-dimensional (3D) posterior occlusal plane (POP) and the mandibular 3D spatial position. The relationship of the POP to mandibular morphology was also investigated. METHODS: Retrospective data from a convenience sample of pretreatment diagnostic cone-beam computed tomography scans were rendered using InVivo software (Anatomage, San Jose, Calif). The sample consisted of 111 subjects (51 male, 60 female) and included growing and nongrowing subjects of different races and ethnicities. The 3D maxillary POP was defined by selecting the cusp tips of the second premolars and the second molars on the rendered images of the subjects. The angles made by this plane, in reference to the Frankfort horizontal plane, were measured against variables that described the mandibular position in the coronal, sagittal, and axial views. The POP was also compared with bilateral variables that described mandibular morphology. RESULTS: There were significant differences of the POP among the different skeletal malocclusions (P <0.0001). The POP showed significant correlations with mandibular position in the sagittal (P <0.0001), coronal (P <0.05), and axial (P <0.05) planes. The POP also showed a significant correlation with mandibular morphology (P <0.0001). CONCLUSIONS: These findings suggest that there is a distinct and significant relationship between the 3D POP and the mandibular spatial position and its morphology.

Variables affecting orthodontic tooth movement with clear aligners.

INTRODUCTION: In this study, we examined the impacts of age, sex, root length, bone levels, and bone quality on orthodontic tooth movement. METHODS: Clear aligners were programmed to move 1 central incisor 1 mm over the course of 8 weeks. Thirty subjects, ages 19 to 64, were enrolled, and measurements were made on digital models (percentage of tooth movement goal achieved). Morphometric features and bone quality were assessed with cone-beam computed tomography. Data from this study were combined with data from 2 similar studies to increase the power for some analyses. RESULTS: The mean percentage of tooth movement goal achieved was 57% overall. Linear regression modeling indicated a cubic relationship between age and tooth movement, with a decreasing rate of movement from ages 18 to 35 years, a slightly increasing rate from ages 35 to 50, and a decreasing rate from ages 50 to 70. The final decreasing trend was not apparent for women. As would be expected, the correlation was significant between the percentage of the goal achieved and the cone-beam computed tomography superimposed linear measures of tooth movement. A significant negative correlation was found between tooth movement and the measurement apex to the center of rotation, but bone quality, as measured by fractal dimension, was not correlated with movement. CONCLUSIONS: The relationship between age and tooth movement is complex and might differ for male and female patients. Limited correlations with cone-beam computed tomography morphology and rate of tooth movement were detected.

A more accurate method of predicting soft tissue changes after mandibular setback surgery.

PURPOSE: To propose a more accurate method to predict the soft tissue changes after orthognathic surgery. PATIENTS AND METHODS: The subjects included 69 patients who had undergone surgical correction of Class III mandibular prognathism by mandibular setback. Two multivariate methods of forming prediction equations were examined using 134 predictor and 36 soft tissue response variables: the ordinary least-squares (OLS) and the partial least-squares (PLS) methods. After fitting the equation, the bias and a mean absolute prediction error were calculated. To evaluate the predictive performance of the prediction equations, a 10-fold cross-validation method was used. RESULTS: The multivariate PLS method showed significantly better predictive performance than the conventional OLS method. The bias pattern was more favorable and the absolute prediction accuracy was significantly better with the PLS method than with the OLS method. CONCLUSIONS: The multivariate PLS method was more satisfactory than the conventional OLS method in accurately predicting the soft tissue profile change after Class III mandibular setback surgery.

Intrarater agreement about the etiology of Class II malocclusion and treatment approach.

INTRODUCTION: The management of patients with Class II malocclusion has been an ongoing discussion in orthodontics. The aim of this study was to determine whether orthodontists agree among themselves and with each other about the etiology, timing, and difficulty of treating subjects with Class II malocclusion. METHODS: The initial records of 159 Class II subjects were sent to 8 orthodontists. In this sample, duplicate records of 18 subjects were dispersed. A questionnaire was sent with the records. RESULTS: The intrarater consistency values were 65% when determining the type of malocclusion, 60% when deciding which arch was at fault, and 81% when determining the need for immediate treatment. Consistency values were 33% regarding case difficulty and 77% regarding phase 2 treatment need. There was a significant negative correlation between the consistency of the orthodontists' responses and the peer assessment rating score. CONCLUSIONS: We found that practitioners had only moderate agreement among themselves when diagnosing a patient's type of malocclusion and which arch was at fault when a skeletal discrepancy was noted. Intrarater agreement improved as the peer assessment rating score increased, but the correlation was weak, and this was not consistent for all examiners. Because of insufficient intrarater agreement, interrater agreement was not examined.

A randomized, placebo-controlled clinical trial on the effects of recombinant human relaxin on tooth movement and short-term stability.

INTRODUCTION: Moving teeth rapidly and avoiding posttreatment relapse are fundamental goals of orthodontic treatment. In-vitro and animal studies suggest that the human hormone relaxin might increase the rate of movement and the stability through its effect on the periodontal ligament. The purpose of this study was to compare relaxin and a placebo with regard to tooth movement and stability in human subjects. METHODS: A single-center, blinded, placebo-controlled, randomized clinical trial was used to examine the effect of relaxin on tooth movement and stability. Forty subjects were randomized 1:1 and received weekly injections of 50 µg of relaxin or a placebo for 8 weeks. Aligners programmed to move a target tooth 2 mm during treatment were dispensed at weeks 0, 2, 4, and 6. Movement was measured weekly on polyvinyl siloxane impressions that were scanned and digitized. The subjects were followed through week 12 to assess relapse. RESULTS: Tooth movement over the 8-week treatment period did not differ by treatment group (P = 0.995). By using an intent-to-treat analysis, we found that the mean tooth movement for both groups was 0.83 mm (SE, 0.08 for relaxin and 0.09 for the placebo). Relapse from weeks 8 to 12 was the same in both groups (P = 0.986), and the mean was -0.75 (SE, 0.07 for relaxin and 0.08 for theplacebo). CONCLUSIONS: No differences in tooth movement over 8 weeks of treatment or relapse at 4 weeks posttreatment were detected when comparing subjects who received weekly injections of relaxin with those who received a placebo. In both groups, an average of less than half of the programmed tooth movement was obtained after 8 weeks of treatment. The local doses of relaxin might have been too low to affect tooth movement or short-term relapse.

Effect of early Class II treatment on the incidence of incisor trauma.

INTRODUCTION: Many researchers have examined the prevalence of dental injuries in children and adolescents. The purpose of this study was to examine the prevalence and incidence of incisor trauma in subjects who participated in a randomized clinical trial designed to investigate early growth modifications in the treatment of Class II malocclusion. METHODS: The subjects were randomized to 3 treatment groups during the initial phase of the study: (1) headgear or biteplane, (2) bionator, and (3) observation (no treatment). All 3 groups underwent phase 2 treatment with fixed appliances. Incisor injury was scored at every data collection point with the Ellis index by a blinded examiner using dental casts, intraoral photos, and panoramic and periapical x-rays. RESULTS: Twenty-five percent of the subjects had incisor trauma at the baseline examination, and 28% experienced new or worsening maxillary incisor injury during the study. No significant differences were found with regard to sex and prevalence of injury at baseline. No differences in incidence of trauma were found between the 3 treatment groups throughout the study (P = 0.19); however, boys were more likely to experience maxillary incisor injury (odds ratio estimate, 2.37; 95% CI, 1.33, 4.21), and those with an injury at baseline were more likely to experience an additional injury (odds ratio estimate, 1.81; 95% CI, 1.03, 3.17). CONCLUSIONS: Early orthodontic treatment did not affect the incidence of incisor injury. The majority of the injuries before and during treatment were minor; therefore, the cost-benefit ratio of orthodontic treatment primarily to prevent incisor trauma is unfavorable.

Effects of analgesics on orthodontic pain.

INTRODUCTION: Our objective was too assess the effectiveness of 3 analgesics (ibuprofen, naproxen sodium, and acetaminophen) and a placebo administered before and after the placement of separators in reducing the severity of postseparator placement pain. We also examined the impact of treatment on chewing efficiency at 24 hours after separator placement. METHODS: Twenty-four subjects participated in the study. Each subject received 3 of 4 treatments: ibuprofen, naproxen sodium, acetaminophen, or placebo in random order at monthly intervals. The dosing times were 1 hour before separator placement and 3 and 7 hours after separator placement. Before placement, the subjects completed a masticatory efficiency test and a visual analog scale (VAS) for expected pain and pain experienced. A VAS pain diary was kept for 24 hours. Subjects returned to the clinic after 1 week for separator removal. RESULTS: VAS pain summary scores after separator placement were significantly affected by the administration of ibuprofen (P = 0.0298) and the time after separator placement (P <0.0001). Administering ibuprofen before and after separator placement significantly reduced pain compared with the placebo. The analgesic effects diminished by day 2, resulting in peak pain levels and decreased chewing efficiency. The expected pain after separator placement also played a role in experienced pain; subjects expecting more pain experienced more pain. CONCLUSIONS: Ibuprofen was superior to the placebo in relieving postseparator pain as measured by the VAS pain summary scores, whereas acetaminophen and naproxen sodium did not significantly differ from the placebo.

Method to classify dental arch forms.

INTRODUCTION: The aim of this study was to propose a method to classify dental arch forms of subjects with normal occlusion into several types that can ensure both goodness of fit and clinical application. METHODS: We selected 306 subjects with normal occlusion from 15,836 young adults, recorded 14 reference points that defined the distance between 2 arch forms as the area between 2 arches, and then classified the dental arch forms by using the partitioning around medoids clustering and silhouette method. We measured tooth size, arch width, basal arch width, arch depth, mesiodistal angulations, and buccolingual inclinations. RESULTS: We identified 3 types of arch forms, and cross-classification of the maxillary by mandibular arch forms showed a more frequent distribution in the diagonal elements than in the off-diagonal elements. The 3 arch forms showed differences in tooth size, arch width, basal arch width, and inclination of the posterior teeth. CONCLUSIONS: By defining area discrepancies as distance measures and applying them to the cluster method by using medoids, the dental arch form can be classified keeping control for the extremes without bias. It is hoped that this method will have possible clinical applications in determining the shape and number of preformed orthodontic arch forms.

Effects of preoperative ibuprofen on pain after separator placement.

INTRODUCTION: Many patients experience pain with orthodontics, but there is no widely accepted standard of care for controlling orthodontic pain. Previous studies were inconclusive as to the most effective way to manage orthodontic pain. The purpose of this study was to assess the effectiveness in reducing pain of preemptive ibuprofen added to an ibuprofen regimen administered after separator placement. We also examined the contributions of psychological factors and sex to the experience of pain. METHODS: The subjects were randomly assigned to group A, 400 mg of ibuprofen 1 hour before separator placement (D1), 3 hours after placement (D2), and 7 hours after placement (D3); group B, placebo at D1, 400 mg of ibuprofen at D2 and D3; or group C, placebo at D1, D2, and D3. Before separator placement, the subjects completed 2 psychological surveys, a masticatory efficiency test, and a visual analog scale for expected pain and experienced pain during the masticatory efficiency test. After placement, the subjects recorded their actual pain, kept a pain diary for 24 hours after separator placement, and performed a 24-hour follow-up masticatory efficiency test. RESULTS: Group A, receiving ibuprofen before and after separator placement, experienced significantly less pain (P <0.05) at 6 hours, at bedtime, and at awakening on the second day. No contributions to pain were found for psychological factors or sex. CONCLUSIONS: Preemptive administration of analgesics should be recommended to orthodontic patients before separator placement.

Comparison of arch dimension changes in 1-phase vs 2-phase treatment of Class II malocclusion.

INTRODUCTION: We compared arch dimension changes in 1-phase and 2-phase treatment of Class II malocclusion. This was a prospective randomized clinical trial conducted in the Department of Orthodontics at the University of Florida between 1990 and 2003. METHODS: During phase 1 treatment, 86 subjects were treated with a bionator, 93 were treated with headgear/biteplane, and 81 served as the observation group. For phase 2, all subjects were then treated with full orthodontic appliances. Arch dimensions were followed; maxillary and mandibular alginate impressions were taken at baseline, end of early Class II treatment or observation, beginning of fixed appliance treatment, end of orthodontic treatment, and approximately 3 years posttreatment. Alginate impressions were taken of each dental arch at each data collection point. These were poured in orthodontic stone, trimmed, and photocopied from the occlusal aspect. These images were then scanned and measured. RESULTS: Although differences between the treatment groups were found in both the maxillary and mandibular arches after phase 1, these differences were no longer evident by the end of full orthodontic treatment or after posttreatment retention. CONCLUSIONS: There were no differences in arch dimensions after 1-phase or 2-phase treatment of Class II malocclusion.

Effect of early treatment on stability of occlusion in patients with Class II malocclusion.

INTRODUCTION: The purpose of this study was to evaluate the effect of early treatment on the stability of occlusion in patients with Class II malocclusions. The peer assessment rating (PAR) index was used to evaluate changes in occlusion after treatment of subjects treated in 1 phase or 2 phases. This study was a prospective, randomized, controlled clinical trial. METHODS: Dental casts were obtained from the participants, who were randomized into 3 phase-1 early treatment groups: bionator, headgear/bite plane, or observation. Phase 2 consisted of continued treatment of the bionator and the headgear/biteplane subjects and comprehensive treatment of the observation subjects. PAR scores were obtained for 208 subjects at end of treatment; 173 (83%) had at least 1 follow-up visit, with a median follow-up time of 5.0 years. PAR scores were calculated for each subject at key treatment and posttreatment time points. Linear mixed-effect models were used to evaluate the impact of phase-1 treatment group, years posttreatment, end of treatment PAR score, and other covariates that could affect stability on the posttreatment PAR score. RESULTS: Factors significantly affecting posttreatment PAR scores were PAR score at end of treatment (P <.0001), years posttreatment (P =.0064), and PAR score at the start of phase 2. Although phase-1 treatment was not statistically significant, those with early treatment had lower PAR scores at the start of phase 2 than the observation subjects (means [SD]: bionator 17.5 [7.4], headgear/biteplane 15.3 [7.0], observation 22.2 [8.6], P <.0001). Thus, early treatment had an indirect effect. CONCLUSIONS: Factors that affect posttreatment PAR score stability include PAR score at the end of treatment, years posttreatment, and PAR score at the start of phase-2 treatment. The early treatment modalities have limited positive impact on posttreatment stability PAR scores in Class II malocclusion patients due to their effect on PAR scores at the start of phase-2 treatment.

Three-dimensional morphological characterization of malocclusions with mandibular lateral displacement using cone-beam computed tomography.

OBJECTIVE: The purpose of this study was to evaluate the morphologic characteristics of MLD malocclusions using 3D imaging. MATERIALS AND METHODS: MLD characteristics were examined using CBCT data in 40 subjects. A 3D Cephalometric analysis was developed to describe the spatial position of the mandible and temporal bones. RESULTS: Vertical dental heights were shorter and the posterior occlusal plane (POP) presented a steeper sagittal inclination on the shifted side (the side of the laterally displaced bony chin) than on the contralateral side. (p < 0.01). The MLD was related to a superiorly inclined POP Cant in the same direction (r = 0.82; p < 0.01). The shifted side condyle was dislocated medially and was smaller. Temporal bone sagittal inclination showed a more forward and medial inclination on the contralateral side (p < 0.01). CONCLUSIONS: A unilateral decrease in the vertical height of the dentition and the subsequent steeper occlusal plane inclinations correlated with (1) mandibular rotational displacement and condylar lateral displacement, (2) mandibular and condylar morphologic changes (3) changes in temporal bone position.

Timing of Class II treatment: skeletal changes comparing 1-phase and 2-phase treatment.

INTRODUCTION: Previous studies reported small but significant skeletal changes as a result of early treatment of Class II malocclusion with headgear and functional appliances. In this study, we report on the skeletal changes for 1-phase and 2-phase treatment of Class II malocclusion. METHODS: This was a prospective randomized clinical trial conducted sy the Department of Orthodontics at the University of Florida between 1990 and 2000. A total of 261 subjects demonstrating at least a one half-cusp Class II molar relationship and meeting the inclusion criteria were enrolled in the study and had at least 1 follow-up visit. During phase 1, 86 subjects were treated with a bionator, 95 were treated with a headgear/biteplane, and 80 served as the observation group. For phase 2, all subjects were then treated with full orthodontics appliances. Skeletal changes were monitored with cephalograms taken at baseline, at the end of early Class II treatment or observation baseline, at the beginning of fixed appliances, and at end of orthodontic treatment. RESULTS: Overall skeletal changes at the end of phase 1 treatment were as follows: (1) SNA angle increased in the bionator (0.51) and the observation groups (0.67), whereas it decreased (-0.50) in the headgear/biteplane group; (2) SNB angle increased in the bionator (1.36) and the observation groups (0.84), whereas it remained unchanged (0.19) in the headgear/biteplane group; (3) ANB angle decreased in the bionator (-0.85) and the headgear/biteplane groups (-0.72), and was unchanged in the observation group; and (4) the mandibular plane angle increased (1.30) only in the headgear/biteplane group. By the end of full orthodontic treatment, the skeletal differences in all measurements for all 3 groups were within 1 degrees . Linear regression models showed that, during phase 1, baseline value and treatment group were significant. However, when the entire treatment period was considered, treatment group had no effect. CONCLUSIONS: There is temporary skeletal change as a result of phase I treatment with both appliances but no detectible skeletal difference between 1-phase and 2-phase treatment of Class II malocclusion by the end of full orthodontic treatment.

A comparison of treatment impacts between Invisalign aligner and fixed appliance therapy during the first week of treatment.

INTRODUCTION: The aim of this study was to evaluate the differences in quality of life impacts between subjects treated with Invisalign aligners (Align Technology, Santa Clara, Calif) and those with fixed appliances during the first week of orthodontic treatment. METHODS: A prospective, longitudinal cohort study involving 60 adult orthodontic patients (33 with Invisalign aligners, 27 with fixed appliances) was completed by using a daily diary to measure treatment impacts including functional, psychosocial, and pain-related outcomes. A baseline survey was completed before the start of treatment; diary entries were made for 7 consecutive days to measure various impacts of the subjects' orthodontic treatment over time. The data were then analyzed for differences between treatment modalities in terms of the subjects' reported impacts from their orthodontic treatment. RESULTS: The baseline mean values did not differ between groups for pain reports (P = .22) or overall quality of life impact (P = .51). During the first week of treatment, the subjects in the Invisalign group reported fewer negative impacts on overall quality of life (P <.0001). The Invisalign group also recorded less impact in each quality of life subscale evaluated (functional, psychosocial, and pain-related, all P <.003). The visual analog scale pain reports showed that subjects in the Invisalign group experienced less pain during the first week of treatment (P <.0001). The subjects in the fixed appliance group took more pain medications than those in the Invisalign group at days 2 and 3 (both P <.007). CONCLUSIONS: Adults treated with Invisalign aligners experienced less pain and fewer negative impacts on their lives during the first week of orthodontic treatment than did those treated with fixed appliances.

Perceptions of orthognathic surgery patient's change in profile. A five-year follow-up.

OBJECTIVES: To compare pairs of silhouettes generated from presurgical and 5-year postsurgical cephalometric radiographs to evaluate whether orthodontists, oral surgeons, and lay persons perceive changes in profile resulting from orthodontics and mandibular advancement surgical treatment. MATERIALS AND METHODS: A survey-based method of data collection was used to evaluate 15 pairs of silhouettes. These silhouettes included 1 control pair and 14 surgically treated pairs representing mandibular advancements ranging from 0.11 mm to 10.13 mm. Collected data were analyzed to determine whether changes can be perceived and whether these changes were esthetically pleasing. RESULTS: The control silhouette pair was identified by 104 of 127 evaluators. For the 14 surgical treated silhouette pairs, the vast majority of evaluators (N = 127; 53 orthodontists, 32 oral surgeons, and 42 lay persons) were able to identify changes in profile and individual features. At least one group of evaluators was able to perceive significant (P < .05) improvement in the visual analog scale (VAS) score for all these silhouette pairs, except for the pair with 10.13 mm of mandibular advancement. This silhouette pair, which represented the largest mandibular advancement, was perceived to have a significant (P < .05) worsening in the VAS score by the lay person group. There were significant differences among the groups of evaluators. Esthetic improvement in profile was perceived for 13 of 14 surgically treated silhouette pairs. CONCLUSION: In some cases, orthodontists, oral surgeons, and lay persons perceived changes in profile differently.

A prospective randomized clinical trial into the capacity of a toothpaste containing NovaMin to prevent white spot lesions and gingivitis during orthodontic treatment.

BACKGROUND: White spot lesions and gingivitis represent common, yet challenging, dilemmas for orthodontists. Fluoride has shown some benefit as a protective measure against demineralization; however, this is usually insufficient for orthodontic patients with less than ideal oral hygiene. Dentifrices containing calcium sodium phosphosilicate bioactive glass (NovaMin) have been proposed to aid in prevention of white spot lesions and gingival inflammation. Thus, the purpose of this study was to determine if the use of NovaMin reduces the formation of white spot lesions and improves gingival health in orthodontic patients. METHODS: This was a prospective, double-blind, randomized controlled trial. Forty-eight patients undergoing orthodontic treatment were randomly allocated to two groups. The control group consisted of 24 patients who received over-the-counter fluoride toothpaste (Crest®), while the study group consisted of 24 patients who were given the test dentifrice (ReNew™) containing 5 % NovaMin and fluoride. Patients were followed up for 6 months on a monthly basis. Decalcification, gingival health, plaque, and bacteria levels were evaluated every 3 months. Statistical analysis was performed using both parametric and non-parametric tests to identify differences between groups at different time points. RESULTS: There were no significant differences between the groups in regard to changes in white spot lesions, plaque, or gingival health (P > 0.05). There was a trend toward improvement in white spot lesions found in subjects using Crest® at the 3-month time point; however, this was not sustained throughout the study. CONCLUSIONS: Our results indicate that a toothpaste containing NovaMin does not differ significantly compared to traditional fluoride toothpaste for improving white spot lesions and gingivitis in orthodontic patients.

A better statistical method of predicting postsurgery soft tissue response in Class II patients.

OBJECTIVE: To propose a better statistical method of predicting postsurgery soft tissue response in Class II patients. MATERIALS AND METHODS: The subjects comprise 80 patients who had undergone surgical correction of severe Class II malocclusions. Using 228 predictor and 64 soft tissue response variables, we applied two multivariate methods of forming prediction equations, the conventional ordinary least squares (OLS) method and the partial least squares (PLS) method. After fitting the equation, the bias and a mean absolute prediction error were calculated. To evaluate the predictive performance of the prediction equations, a leave-one-out cross-validation method was used. RESULTS: The multivariate PLS method provided a significantly more accurate prediction than the conventional OLS method. CONCLUSION: The multivariate PLS method was more satisfactory than the OLS method in accurately predicting the soft tissue profile change after surgical correction of severe Class II malocclusions.

Orthodontic tooth movement with clear aligners.

Clear aligners provide a convenient model to measure orthodontic tooth movement (OTM). We examined the role of in vivo aligner material fatigue and subject-specific factors in tooth movement. Fifteen subjects seeking orthodontic treatment at the University of Florida were enrolled. Results were compared with data previously collected from 37 subjects enrolled in a similar protocol. Subjects were followed prospectively for eight weeks. An upper central incisor was programmed to move 0.5 mm. every two weeks using clear aligners. A duplicate aligner was provided for the second week of each cycle. Weekly polyvinyl siloxane (PVS) impressions were taken, and digital models were fabricated to measure OTM. Initial and final cone beam computed tomography (CBCT) images were obtained to characterize OTM. Results were compared to data from a similar protocol, where subjects received a new aligner biweekly. No significant difference was found in the amount of OTM between the two groups, with mean total OTM of 1.11 mm. (standard deviation (SD) 0.30) and 1.07 mm. (SD 0.33) for the weekly aligner and biweekly control groups, respectively (P = 0.72). Over eight weeks, in two-week intervals, material fatigue does not play a significant role in the rate or amount of tooth movement.