Treatment duration by morphology and location of impacted maxillary canines: A cone-beam computed tomography investigation.

INTRODUCTION: This study aimed to identify whether patients with impacted maxillary canines take longer to treat than orthodontic patients without an impacted canine. We also sought to identify factors that are predictive of increased treatment duration in patients with impacted maxillary canines and treated by surgical exposure. METHODS: A retrospective investigation of 37 patients with an impacted maxillary canine, treated by surgical exposure and fixed appliance therapy, was undertaken. In addition, an age- and sex-matched control group of 39 patients (without impacted canines) was also collected. Patient age, sex, and total treatment duration were recorded. For patients with an impacted canine, patient records and pretreatment cone-beam computed tomography datasets were assessed. Point coordinates identifying relevant landmarks were recorded, and a geometric method was used to calculate variables describing canine location, orientation, and apical morphology. RESULTS: Controlling for age and sex, linear regression identified a statistically significant increase in treatment duration of 46.7 and 41.5 weeks for palatal and labial/midalveolar impacted canines, respectively, vs controls (P <0.002). Age and sex of patients with impacted canines collectively affected treatment duration (P = 0.04), with females of increased age being treated faster than younger males. Rotation of the impacted canine crown had a highly significant effect on treatment duration, with every degree of rotation increasing treatment duration by 0.32 weeks (P <0.001). There was a significant degree of multicollinearity between the other radiographic variables. Collectively, radiographic variables describing canine displacement significantly prolonged treatment duration (P <0.001) and explained 29.8% of the variability in total treatment time. The apical morphology of impacted maxillary canines was significantly associated with increased treatment duration (P = 0.01) and explained 11.3% of the overall treatment variability (P = 0.01). CONCLUSIONS: Increased total treatment duration of surgically exposed impacted maxillary canines is associated with increasing mesiopalatal canine crown rotation, worsening displacement, and hooked apical morphology.

Individualized intervention to reduce anxiety in adult orthodontic patients based on Q methodology.

INTRODUCTION: In this study, we used Q methodology to assess the concerns of adults seeking orthodontic treatment and to determine individualized interventions to reduce their anxiety. METHODS: Statements of concern were derived by in-depth interviews with 70 adult patients. Q sorting methodology was then used to identify the main factors associated with anxiety in a cohort of 40 adults who had not been involved in the first part of the study. The final stage involved a randomized study in which 160 new adult patients were recruited and randomized into intervention and control groups. Participants in the intervention group sorted the statements, after which individualized interventions were implemented. Participants in the control group received routine treatment. The State-Trait Anxiety Inventory was used to measure changes in participants' anxiety levels before and during treatment. RESULTS: In total, 41 statements were identified, and participants were classified according to 5 factors. Factor 1 participants were concerned about the lack of treatment information; factor 2 represented concerns about cost and other people's opinions; factor 3 represented concerns about impact on work related to wearing braces; factor 4 encompassed concerns about treatment effects, pain, and dental fears; and factor 5 reflected concerns about side effects and finding a partner. The mean state anxiety inventory scores for both the intervention and control groups were highest 24 hours after bonding (intervention group, 44.63 ± 4.49; control group, 49.43 ± 5.42). The intragroup state anxiety inventory scores differed significantly across the 6 time points (P <0.01), with the state anxiety inventory scores of the intervention group significantly lower than those of the control group (P <0.01) at all time points except baseline. No significant intergroup or intragroup differences were found in relation to trait anxiety. CONCLUSIONS: Adult orthodontic patients expressed diverse concerns. Individualized interventions based on Q methodology may reduce anxiety in this patient population.

Morphology of palatally impacted canines: A case-controlled cone-beam volumetric tomography study.

INTRODUCTION: The aim of this study was to investigate the relationships between an apical curvature or a hook and the crown/root ratio in subjects with and without palatally impacted maxillary canines. METHODS: An experimental group of 44 patients (17 boys, 27 girls; mean age, 13.6 years) with 59 palatally impacted maxillary canines was selected from the records of patients referred to a radiology practice for cone-beam imaging. If a patient had bilateral palatally impacted canines, 1 canine was randomly selected for analysis. The palatally impacted canine group was matched for age and sex with 49 normal subjects (25 boys, 24 girls; mean age, 13.2 years) with 98 canines. Cone-beam DICOM files were imported into In Vivo imaging software (version 5.3; Anatomage, San Jose, Calif) for analysis. The angulations and linear variables of the maxillary canines were measured by using the software measurement tools. Chi-square and independent t tests were used to test for differences between the groups. RESULTS: The presence of a hook at the apical third and other root curvature were significantly different between the 2 groups (P <0.001 and P <0.05, respectively). Of the 44 palatally impacted canines, 16 (36.4%) had an apical hook and only 1 canine in the control group had an apical hook (1.0%). The mean root length of the palatally impacted canines was 2.66 mm shorter (P <0.001), and the mean crown/root ratio was significantly greater for the palatally impacted canines compared with the nonimpacted group (P <0.001). CONCLUSIONS: Palatally impacted canines have a greater tendency to develop apical hooks and are less likely to develop other root curvatures than are nonimpacted canines. Also, they have shorter roots resulting in larger crown/root ratios compared with the control group.

Orthodontic considerations for impacted and ectopic teeth.

This review article describes the changing approach to the management of various impacted teeth. Currently, more third molars are being retained, and it is likely that more patients will develop impactions than a generation ago because of non-extraction orthodontic treatment plans. There are still valid reasons for the surgical removal of selected third molars during the teenage years, during which time impaction can be anticipated to avoid the higher rate of morbidity associated with later removal. Palatally-impacted canines (PIC] can now often be managed with interceptive and non-surgical approaches, which are attractive options. The various approaches addressed in the literature are discussed.

Associations between palatally displaced canines and maxillary lateral incisors.

INTRODUCTION: The purpose of this research was to investigate relationships among the location and orientation of palatally displaced canines and the dimension and orientation of the maxillary lateral incisor. METHODS: An experimental group of 40 patients with 46 palatally displaced canines (20 from boys, 26 from girls; mean age of the subjects, 13.9 years; age range, 10.5-15.9 years) was selected from the records of patients referred to a radiology practice specializing in cone-beam volumetric tomography imaging. This group was age- and sex-matched with 30 normal subjects with 60 canines (26 from boys, 34 from girls; mean age of the subjects, 13.8 years; age range, 10.4-15.7 years). Digital cone-beam volumetric tomography images were imported into an imaging software and were reoriented and reconstructed into several radiographic images in coronal and sagittal sections; a maxillary arch occlusal view was also produced. The angular and linear variables of the canines and the maxillary lateral incisors were measured by using software measurement tools. Independent t tests or Mann-Whitney U tests were used accordingly based on normality of the data to compare the variables between the palatally displaced canine and the control groups. Multiple linear regressions were used to examine the relationships between the canine variables (dependent variables) and the maxillary lateral incisor variables together with confounding variables (independent variables). RESULTS: The maxillary lateral incisors in the palatally displaced canine group tended to be more upright in the sagittal and coronal planes. Generally, the most significant independent variables according to backward examination of linear regression for canine variables (coronal and sagittal angulations, and distance to the occlusal plane of palatally displaced canines) were the coronal and sagittal angulations of the maxillary lateral incisors, the length and buccolingual root width of the maxillary lateral incisors, and age. CONCLUSIONS: The orientation and location of palatally displaced canines were associated with changes in the angulations of maxillary lateral incisors and small lateral incisors.

Maxillary lateral incisor morphology and palatally displaced canines: a case-controlled cone-beam volumetric tomography study.

INTRODUCTION: The goal of this study was to compare the dimensions of maxillary lateral incisors in subjects with and without palatally displaced canines. METHODS: An experimental group of 40 patients with 46 palatally displaced canines (20 in boys, 26 in girls; mean age, 13.9 years; range, 10.5-15.9 years) was selected from the records of patients referred to a radiology practice specializing in cone-beam volumetric tomography imaging. The palatally displaced canine group was age- and sex-matched with 30 normal subjects with 60 canines (26 in boys, 34 in girls; mean age, 13.8 years; range, 10.4-15.7 years). Cone-beam volumetric tomography DICOM files were imported into Dolphin Imaging software (version 11.0; Dolphin Imaging & Management Solutions, Chatsworth, Calif), and the volumetric images were reoriented with the long axis of the lateral incisor vertical and then reconstructed into images of a sagittal slice through the maxillary lateral incisors and 3 axial slices across the maxillary lateral incisor root. The linear variables of the maxillary lateral incisors were measured by using digital measurement tools. The widths of the maxillary lateral incisor roots were registered at the cementoenamel junction level, 4 mm apical to the cementoenamel junction level and 8 mm apical to the cementoenamel junction level. An independent t test was used to test for differences between the groups, because the data were normally distributed. RESULTS: In the group with palatally displaced canines, the mean length of the maxillary lateral incisors was 2.1 mm shorter (P <0.001), and the mean root width was smaller, especially in the buccolingual dimension, by 0.7 mm (P <0.001). CONCLUSIONS: Lateral incisors adjacent to palatally displaced canines were smaller compared with those adjacent to normal canines.

Comparison of surgical and non-surgical methods of treating palatally impacted canines. I. Periodontal and pulpal outcomes.

BACKGROUND: Inferior periodontal and pulpal outcomes may follow surgical exposure of palatally impacted maxillary canines. OBJECTIVES: To compare the periodontal and pulpal health of palatally impacted maxillary canines following either surgical exposure and assisted eruption (SE) or unassisted eruption following extraction of the overlying deciduous canine and orthodontic creation of space in the arch (OT). METHODS: Twenty-eight subjects (OT group: N = 14; SE group: N = 14) with unilateral palatally impacted canines were examined at least six months after orthodontic treatment. The gingival index score, plaque index score, pocket depth, attachment loss, tenderness to percussion, pulpal responses to stimuli and radiographic assessment of changes in the pulpal cavities and peri-radicular areas were collected on the maxillary canines, lateral incisors and premolars. The contralateral teeth were used as controls. RESULTS: There were no significant differences in the plaque index scores, the gingival index scores or the periodontal outcomes between the impacted canines in the two groups (SE and OT). More impacted canines than control canines had lost some periodontal attachment in the SE group (p = 0.004). Although more lateral incisors, canines and premolars on the impacted side had partially obliterated pulps than the corresponding teeth on the control side, the teeth in both groups had similar pulpal responses (p = 0.064). CONCLUSIONS: Natural eruption and conservative surgical exposure with orthodontic alignment have minor effects on the periodontium. Impacted canines treated surgically and non-surgically had a higher prevalence of pulpal changes than the control canines. Ultimately, the choice of treatment may depend on the clinical indications, the patient's and the orthodontist's preferences.

Comparison of surgical and non-surgical methods of treating palatally impacted canines. II. Aesthetic outcomes.

BACKGROUND: Palatally impacted maxillary canines may appear unsightly after treatment because of changes in position and colour. AIM: To determine if palatally impacted canines treated either by surgical exposure and orthodontic repositioning or by creation of space in the arch and unassisted eruption have different aesthetic outcomes. METHODS: Twenty eight subjects with unilateral palatally impacted canines who had completed orthodontic treatment at least 6 months previously were recruited from three specialist practices. In 14 subjects the canines had been treated by surgical exposure, orthodontic extrusion and repositioning in the arch (SE group) and in the remainder the deciduous canines were extracted and excess space created in the arch for the canines to erupt naturally (OT group). The contralateral canines were used as controls. The mean pretreatment ages of the subjects in the SE and OT groups were 13.5 (SD:1.6) years and 13.5 (SD:1.3) years respectively. The position and colour of the canines were assessed on post-treatment study models and 35 mm slides using the American Board of Orthodontics Objective Grading System (ABO OGS) and subjective appraisal by two orthodontists. Each subject used a semantic scale to rate the aesthetic outcome of treatment. RESULTS: Sixty four per cent of the treated canines in the SE group were significantly more 'intruded' than the treated canines in the OT group (p = 0.004) and the control canines (p = 0.004). The ABO OGS grades of the canines in the SE and OT groups were similar (p = 0.173). While the assessors detected a lack of labial root torque and gingival margin changes in the canines in the SE group, the subjects in both groups were satisfied with the appearance of the canines post-treatment. CONCLUSIONS: Palatally impacted canines treated by surgical exposure, extrusion and orthodontic treatment were more likely to be displaced vertically ('intruded') after treatment than palatally impacted canines treated by extraction of the overlying deciduous canines and creation of excess space in the arch. Small occlusal and aesthetic changes detected by the orthodontists, but not the ABO OGS, did not appear to detract from the satisfaction of the subjects with the results of orthodontic treatment.

Factors influencing the non-surgical eruption of palatally impacted canines.

BACKGROUND: Many palatally impacted canines in children do not require surgical exposure prior to the start of orthodontic treatment. They erupt in mid-alveolar positions providing excess space is made for them in the arch. The time required for an impacted tooth to emerge under these conditions is highly variable. AIM: To determine the factors influencing the time required for a palatally impacted canine to spontaneously disimpact following orthodontic treatment to create excess space in the arch. METHOD: Thirty palatally impacted canines, which emerged following orthodontic treatment to open excess space in the arch, were used. The impacted teeth were present in 28 children. No canines were surgically exposed. The positions of the impacted canines before treatment, the mesiodistal widths and rotations of the adjacent and contralateral lateral incisors, age and gender of the subjects, subjects' dental ages, presence of either incisor or premolar hypodontia, number of subjects with bilaterally impacted canines, and number of siblings with impacted canines were recorded. Canines that erupted in less than nine months of treatment were compared with canines that required more than nine months of treatment. The canines were grouped by severity of impaction (sectors II - IV) and compared. RESULTS: There were significantly more severe (sector IV) impactions in the long duration group compared with the short duration group. Significantly more cases of incisor-premolar hypodontia were found in the short duration group. Canines impacted in sector IV emerged after 21 months of treatment and canines in sectors II and III emerged after eight months of treatment. Lateral incisors adjacent to the impacted teeth were rotated mesiolabially to a greater extent in the sector IV group compared with lateral incisors in the sector II group. Differences in rotation of the adjacent and contralateral lateral incisors were significantly less in the sector II group compared with the lateral incisors in the sector III and IV groups. CONCLUSIONS: The sector of impaction was the best guide to the duration of treatment prior to emergence.

A longitudinal index study of orthodontic stability and relapse.

BACKGROUND: Previous studies of stability and relapse after orthodontic treatment report short-term stability is generally followed by slow relapse to the original condition. What these studies do not report is whether this relapse is continuous or interspersed with periods of improvement or stability. METHODS: A subjective 0-10 index of malocclusion was used to record post-treatment stability and relapse over 10 to 12 years following fixed appliance orthodontic treatment of 24 patients. The severity scores were plotted on timelines. RESULTS: Episodes of change, both favourable and unfavourable, were interspersed with episodes of stability. CONCLUSIONS: Changes in the first 3 and 12 months post-treatment are indicative of the 10 to 12 years post-treatment outcomes. This index may provide a useful instrument to analyze patients and/or their study models longitudinally.

Orthodontic treatment of palatally impacted maxillary canines.

The aim of this study was to determine the feasibility of treating children with impacted maxillary canines by orthodontic treatment alone. The subjects were 28 children (mean age: 13.5 years, range 11.4-16.1 years) with between them 32 palatally impacted canines. The overlying primary canines were extracted between 0 and 42 months before the start of appliance treatment to open space in the arches for the impacted teeth. No other surgical procedures were carried out prior to the start of appliance treatment. Appliance treatment was deferred for at least six months if an impacted canine was the main reason for treatment, otherwise treatment was commenced according to the needs of the patient. In 94% of the cases, the severity of impaction lessened following extraction of the overlying primary canines and orthodontic treatment. The deepest impactions tended to occur in the oldest children. The majority (75%) of the canines emerged following orthodontic treatment to create space for them in the arch; the remainder were surgically exposed. Appliance treatment tended to take longer in children with the deepest impactions. It is concluded that fixed appliance treatment to create space for a palatally impacted canine is an effective management option for children with impacted maxillary canines.