The effect of maxillary first and mandibular second premolar extractions on the posterior Bolton ratio.

INTRODUCTION: The anterior and overall Bolton ratios and their application in orthodontics are widely known. However, little has been reported about the posterior Bolton ratio, how it is affected by the extraction of posterior teeth, and its application in orthodontic treatment planning. This study aimed to investigate how extracting maxillary first and mandibular second premolars affects the posterior Bolton ratio. METHODS: The sample included 55 patients with Class I occlusion within 1 standard deviation of ideal anterior and overall Bolton ratios. The digitized models were subjected to virtual extraction of maxillary first premolars and mandibular second premolars and setup of posterior teeth in ideal occlusion. If space closure compromised occlusion, the teeth were moved to achieve ideal cusp-fossa or cusp-marginal ridge occlusion. The ideal setups were measured for residual interproximal spacing. Statistical analysis used R statistical software (version 2018; R Core Team, Vienna, Austria). RESULTS: The ideal nonextraction posterior Bolton ratio was determined from the sample to be 105.77 ± 1.99%. The ideal expected posterior Bolton ratio for maxillary first and mandibular second premolar extraction patients was 106.52 ± 2.52%. This significantly differed from the expected posterior Bolton ratio for the 4 first premolar extractions. Patients finished with an average of 1.28 mm net residual spacing between mandibular first premolars and first molars; 38.2% of patients finished with at least 1.5 mm of residual space, and 9.1% of patients finished with at least 2 mm of residual space. CONCLUSIONS: A patient with ideal anterior, posterior, and overall Bolton ratios treated with maxillary first and mandibular second premolar extractions to ideal occlusion will likely finish with some spacing in the mandibular dentition.

Dimensional and morphologic characteristics of unilateral impacted maxillary central incisors.

INTRODUCTION: This cross-sectional study aimed to investigate the crown and root characteristics of impacted central incisors compared with spontaneously erupted contralateral incisors and the influence of etiologic and local factors on their dimensions. METHODS: Forty-five patients (22 boys, 23 girls) who underwent orthodontic treatment for unilateral impaction of maxillary central incisors were referred for cone-beam imaging. Dimensions of the impacted and contralateral incisors were assessed using Dolphin 3D software (Dolphin Imaging & Management Solutions, Chatsworth, Calif). Paired t test and linear regression were used to compare the characteristics of the impacted and contralateral teeth. RESULTS: Contralateral and impacted central incisors showed statistically significant differences for root length (95% confidence interval [CI], 2.32-3.46; P <0.001), mesiodistal crown-root angulation (95% CI, 4.09-15.95; P = 0.001), and labiolingual crown-root angulation (95% CI, -18.69 to -4.70; P = 0.002). Etiologic factors did not alter the dimensions of incisors (95% CI, -1.17 to 0.76; P = 0.672). According to the multiple linear regression the independent variables associated with root length of contralateral and impacted incisors were sex (ß = -0.904; 95% CI, -1.62 to - 0.19; P = 0.014) and the presence of impaction (ß = -2.87; 95% CI, -3.67 to -2.07; P <0.001). CONCLUSIONS: Regardless of their etiology, the impacted incisors showed roots that were 2.89 mm shorter than the contralateral incisors and had greater angulation in the mesiodistal and labiolingual directions. Girls showed a reduction of 0.904 mm (7.6%) on the lengths of roots of both impacted and contralateral central incisors. The presence of impaction led to a reduction of 25% in incisor root lengths. Approximately 30% of the impacted teeth showed crown-root angulations >20° resulting in an increased distal and labial angulation of the root apical portion.

The effect of 4 first premolar extractions on the posterior Bolton ratio.

INTRODUCTION: Overall and anterior Bolton ratios have been well covered in the orthodontic literature; however, little has been reported on posterior Bolton ratios. Considering the frequency of premolar extractions in the specialty, it would be relevant to know how the posterior occlusion is affected by premolar extractions. This study aimed to investigate how the posterior Bolton ratio is affected by the extraction of the 4 first premolars. METHODS: Fifty-five patients with Class I occlusion within 1 standard deviation of ideal anterior and overall Bolton ratios models were selected and digitized. Tooth widths were measured. Virtual extractions of 4 first premolars were performed, and a digital setup of anterior and remaining posterior teeth observing ideal occlusion relationships was executed. When space closure compromised the occlusion, preference was given to the latter. Residual interproximal spacing was digitally measured on the setups. Analysis of variance and linear regression tests were used to identify factors contributing to interproximal spacing. RESULTS: An average of 1.1 mm of net residual spacing between mandibular second premolars and first molars was observed. In 27% of the sample, at least 1.5 mm of residual space was found. In addition, 16% showed at least 2 mm of residual space. The ratio of the maxillary second premolars to the mandibular second premolars and the width of the maxillary second premolars best explain residual space (r = 0.554; r2 = 0.307). A regression equation for predicting residual space is offered. CONCLUSIONS: Ideal anterior, posterior, and overall Bolton ratios treated with extraction of 4 first premolars and ideal occlusion will likely finish with some spacing in the mandible.

Nonsurgical treatment of skeletal maxillary protrusion with gummy smile using headgear for growth control, mini-implants as anchorage for maxillary incisor intrusion, and premolar extractions for incisor retraction.

INTRODUCTION: An adolescent girl, aged 12 years 11 months, was evaluated for orthodontic treatment. Her chief complaints included a difficulty with keeping her lips passively closed and excessive gingival exposure upon smiling. Her treatment plan included (1) restriction of maxillary growth with cervical headgear, (2) extraction of the maxillary first premolars to reduce the maxillary protrusion and the mandibular second premolars to facilitate Class II dental correction, and (3) management of maxillary incisor intrusion via anchoring with mini-implants. When indicated, even in the absence of large space discrepancies, extractions can be beneficial to the patient. The final results showed an attractive smile, passive lip seal, and a more esthetic and balanced facial profile. Retention records confirmed the stability of the treatment. The 5-year follow-up visit revealed that the treatment results were quite stable.

Enamel thickness of maxillary canines evaluated with microcomputed tomography scans.

INTRODUCTION: Enameloplasty of maxillary canines is often needed for aesthetic substitution in patients with congenitally missing lateral incisors. The exact enamel thicknesses for the various canine surfaces are unknown because previous studies failed to employ accurate measurement tools to report and compare detailed enamel thicknesses for each surface at various crown heights. METHODS: Thirty-two extracted maxillary canines were collected and scanned in a microcomputed tomography scanner. The scans were imported into a custom-written MATLAB software (version 9.2; MathWorks, Natick, Mass) and the enamel thickness on the mesial, distal, labial, fossa, cingulum, and incisal edge of each tooth was computed, obtaining the mean value from slices at 0.1 mm intervals. The overall mean enamel thickness for each surface was also calculated, and these values were compared using paired t tests. Incisal wear stage and incisal enamel thickness that was measured were compared using Spearman rank correlation coefficient. RESULTS: The mean enamel thickness was significantly thinner at the gingival level when compared with the incisal for all surfaces that were analyzed (1-tailed, P <0.001). The mean enamel coverage at the mesial was significantly thinner than the distal when measured gingival to the widest mesiodistal area. The mean enamel coverage of the cingulum was particularly thin and therefore requires extreme care in reshaping it. Incisal edge enamel thickness was highly negatively correlated with the wear stage of the scoring system that was used (1-tailed, P <0.001). CONCLUSIONS: The enamel coverage of the maxillary canine varies depending on the tooth surface and the incisogingival measurement location.

Esthetic perception of clear aligner therapy attachments using eye-tracking technology.

INTRODUCTION: The purpose of this research was to assess and compare esthetic perceptions of clear aligner therapy with attachments and esthetic brackets by measuring differences in eye fixations using eye-tracking technology. METHODS: The sample involved 250 adult subjects. The subjects gave verbal consent, then viewed photographs showing 4 variations of orthodontic appliances: clear aligner control with minimal attachments, clear aligner with anterior and posterior attachments, esthetic brackets, and clear aligner with posterior attachments. Images were displayed for 6 seconds each on a computer monitor. Location and time to first fixation, total fixation duration, and total visit count and duration for each type of appliance were measured. Subjects were then asked to complete an online survey. RESULTS: Participants spent the least amount of time looking at the photograph of the control, followed by those of the ceramic brackets, posterior attachments, and anterior and/or posterior attachments. The anterior and/or posterior image had the least number of visits but garnered the longest visit duration (1.32 visits averaging 0.74 seconds per visit). This was followed by the images of the posterior attachments (1.40 visits, 0.70 seconds per visit), ceramic brackets (1.43 visits, 0.65 seconds per visit), and minimal attachments control (1.45 visits, 0.61 seconds per visit). The hierarchy of most preferred appliances across all 250 respondents was as follows: minimal attachments control, ceramic brackets, posterior attachments, and anterior and/or posterior attachments. Overall, 88.4% of subjects would compromise appliance esthetics during treatment for a better outcome (n = 221). CONCLUSIONS: Eye-tracking data show that time to the first fixation was negatively correlated with its survey ranking and that an increase in attachments led to an increase in total fixation duration. There is a general desire for clear aligners without attachments and ceramic brackets over clear aligners with multiple attachments. Survey data suggest that although respondents viewed appliance esthetics as highly important, nearly all would compromise appliance esthetics during treatment if it resulted in a better outcome.

Orthodontic treatment of a patient with maxillary lateral incisors with dens invaginatus: 6-year follow-up.

INTRODUCTION: Dens invaginatus is an anomaly of dental development in which calcified tissues, such as enamel and dentin, are invaginated into the pulp cavity. This morphologic alteration is more frequent in maxillary permanent lateral incisors and makes them more susceptible to carious lesions and pulp alterations. METHODS: This case report describes a patient with maxillary lateral incisors affected by dens invaginatus. The maxillary right lateral incisor had already undergone endodontic treatment, and the maxillary left one had a periapical lesion. Additionally, the patient had a Class II Division 1 malocclusion, with anterior open bite, posterior crossbite, and an impacted mandibular left second molar. RESULTS: The orthodontic treatment involved extraction of the maxillary lateral incisors and 2 mandibular premolars, resulting in proper overjet and overbite with good arch coordination and occlusal stability. CONCLUSIONS: Treatment results were stable, as evaluated in a 6-year posttreatment follow-up.

Three-dimensional evaluation of craniofacial characteristics related to mandibular asymmetries in skeletal Class I patients.

INTRODUCTION: Our objective was to analyze the characteristics that affect skeletal Class I adults with mandibular asymmetries using cone-beam computerized tomography. METHODS: The sample included cone-beam computerized tomography images of 120 subjects. Asymmetry was determined by the deviation of gnathion from the midsagittal plane and classified as relative symmetry, moderate asymmetry, or severe asymmetry. Maxillary and mandibular measurements were made, and the differences between the contralateral side and the deviated side were evaluated, as well as the differences between the categories of asymmetry. RESULTS: For patients with moderate asymmetry, there were significant differences between the contralateral and deviated sides for some measuments in the transverse and vertical planes. For those with severe asymmetry, statistically significant differences were found between the sides for all measurements, except for the measuments that evaluated the position of the mandibular condyle in the transverse and sagittal directions. Furthermore, a strong correlation was found in patients with severe asymmetry, between the deviation of the mandibular dental midline and the lateral displacement of gnathion. CONCLUSIONS: Patients with relative symmetry had a bilateral balance, whereas those with moderate and severe asymmetries showed several skeletal imbalances. A great deviation of the mandibular dental midline may indicate severe skeletal asymmetry in Class I adults.

Longitudinal cephalometric growth of untreated subjects with Class II Division 2 malocclusion.

INTRODUCTION: Our objective was to evaluate the craniofacial growth of subjects with untreated Class II Division 2 malocclusion. METHODS: A mixed longitudinal sample of 39 white Class II Division 2 subjects was analyzed at 5 time points: T1 (6 or 7 years), T2 (9 or 10 years), T3 (12 or 13 years), T4 (15 or 16 years), and T5 (18 or 19 years). They were compared with an age- and sex- matched sample of Class I controls. Seventeen measurements (12 angular, 5 proportional) were computed. Multilevel modeling procedures were used to statistically describe the growth changes and to evaluate group differences. RESULTS: There were no group differences in the relative sizes and anteroposterior positions of the jaws during childhood, adolescence, or early adulthood. Subjects with Class II Division 2 malocclusion demonstrated significantly (P <0.05) smaller mandibular plane angles, smaller palatal-to-mandibular plane angles, larger posterior-to-anterior facial height ratios, smaller gonial angles, smaller cranial base angles, larger interincisal angles, and more retroclined maxillary incisors than did the Class I subjects. The hypodivergent patterns were established early and became more pronounced over time. Group differences in the mandibular plane angle, palatal-to-mandibular plane angle, gonial angle, interincisal angle, and maxillary incisor-to-cranial base angle, as well as the posterior-to-anterior facial height ratio all increased over time; the difference in the cranial base angle remained unchanged over time. Retroclination of the maxillary incisors occurred primarily during the early mixed dentition. CONCLUSIONS: Subjects with Class II Division 2 malocclusion are more hypodivergent and have more upright maxillary incisors than do subjects with Class I occlusion. Hypodivergence establishes itself early and increases progressively through early adulthood; maxillary incisor retroclination occurs early.

Open-bite treatment with vertical control and tongue reeducation.

An open-bite malocclusion with a tongue-thrust habit is a challenging type of malocclusion to correct. A 12-year-old girl came for orthodontic treatment with a severe anterior open bite, extruded posterior segments, a tongue-thrust habit, and lip incompetency. Her parents refused surgical treatment, so a nonextraction treatment plan was developed that used palatal temporary skeletal anchorage devices for vertical control and mandibular tongue spurs to reeducate the tongue. Interproximal reduction was also used to address the moderate to severe mandibular crowding. An abnormal Class I occlusion was achieved with proper overbite and overjet, along with a pleasing smile and gingival display.

Relationship between body mass and dental and skeletal development in children and adolescents.

INTRODUCTION: The purpose of this investigation was to determine whether a relationship exists between body mass and dental and skeletal development in children and adolescents. A sample of 197 orthodontic patients (82 boys, 115 girls) was selected. Ethnicity was recorded, and body mass index (BMI) was calculated according to the standard equation from the Centers for Disease Control and Prevention, and then a BMI percentile according to sex and age was obtained. The panoramic radiographs were used to calculate the dental ages with an index. The chronologic ages were subtracted from the calculated dental ages to determine a "dental age difference" for each subject. The lateral cephalogram radiographs were analyzed for skeletal development using the cervical vertebral maturation stage method. RESULTS: The white population (60%) had an average BMI percentile of 53.6 and was statistically different from the Hispanic/black population (40%), which had an average percentile of 64.3. There were no significant differences for boys and girls for the BMI percentile and dental age difference, or for the BMI percentile and cervical vertebral stages. The multiple regression model showed that BMI percentile and ethnicity were statistically significant explanatory variables for the dental age difference. CONCLUSIONS: A relationship exists between body mass and dental and skeletal development. BMI percentile, dental age difference, and cervical vertebral stage are weakly correlated. No significant differences existed between boys and girls in any variables. BMI percentile and ethnicity are weak predictors of the discrepancy between dental age and chronologic age.

Quantitative assessment of the effectiveness of phase 1 orthodontic treatment using the American Board of Orthodontics Discrepancy Index.

INTRODUCTION: This retrospective study included a sample of 300 randomly selected patients from the archived records of Saint Louis University's graduate orthodontic clinic, St. Louis, Mo, from 1990 to 2012. The objective of this study was to quantify the changes obtained in phase 1 of orthodontic treatment and determine how much improvement, if any, has occurred before the initiation of the second phase. METHODS: For the purpose of this study, prephase 1 and prephase 2 records of 300 subjects were gathered. All were measured using the American Board of Ortodontics Discrepancy Index (DI), and a score was given for each phase. The difference of the 2 scores indicated the quantitative change of the complexity of the treatment. Paired t tests were used to compare the scores. Additionally, the sample was categorized into 3 groups according to the Angle classifications, and the same statistics were used to identify significant changes between the 2 scores. Analysis of variance was applied to compare the 3 groups and determine which had the most change. Percentages of change were calculated for the significant scores. RESULTS: The total DI score overall and the scores of all 3 groups were significantly reduced from before to after phase 1. Overall, 42% improvement was observed. The Class I group showed 49.3% improvement, the Class II group 34.5% and the Class III group 58.5%. Most components of the DI improved significantly, but a few showed negative changes. CONCLUSIONS: Significant reductions of DI scores were observed in the total sample and in all Angle classification groups. This indicates that early treatment reduces the complexity of the malocclusions. Only 2 components of the DI showed statistically significant negative changes.

Long-term stability of rapid palatal expansion in the mixed dentition vs the permanent dentition.

INTRODUCTION: Palatal expansion has been a popular and proven technique for transverse discrepancies used in orthodontics for decades. The short-term effectiveness of the technique is understood, yet questions remain regarding the long-term stability, with much debate surrounding the optimum treatment timing to initiate expansion for the most beneficial and stable results, especially with regard to mixed dentition treatment. The purpose of this study was to determine the long-term stability of palatal expansion performed in the mixed dentition vs the permanent dentition. METHODS: Fifty-four subjects were grouped as follows: 24 in the mixed dentition and 30 in the permanent dentition at the start of treatment. All patients had been treated with the Haas type of palatal expansion appliance followed by nonextraction fixed edgewise mechanics. Digitized dental casts were evaluated at 3 times: before treatment (T1), after treatment (T2), and at the long-term retention (T3). Intermolar widths were computed by subtracting measurements between time points, and comparisons between the groups were made to determine expansion and stability differences. RESULTS: Significant intermolar width increases were observed from T1 to T2 with significant relapses from T2 to T3, and an overall net gain remained at T3 in each group. No significant differences were found for relapse between the mixed and permanent dentitions. CONCLUSIONS: There are no differences for the long-term intermolar width stability in patients treated with palatal expansion in the mixed dentition vs the permanent dentition.

Evaluation of marginal alveolar bone in the anterior mandible with pretreatment and posttreatment computed tomography in nonextraction patients.

INTRODUCTION: Our objectives were to evaluate marginal alveolar bone height in the anterior mandible after orthodontic treatment and to assess any correlations between morphologic and treatment changes. METHODS: We used 57 pretreatment and posttreatment cone-beam computed tomography images (17 male and 40 female subjects; 22 Class I, 35 Class II; average age, 18.7 ± 10.8 years; average treatment time, 22.7 ± 7.3 months) to measure cortical bone thickness, ridge thickness, distance from the apex to the labial cortical bone, and the distance from the cementoenamel junction to the marginal bone crest. Changes in the cementoenamel junction to the marginal bone crest distance were correlated with pretreatment measurements and treatment changes. RESULTS: Although there were great variations, the average facial and lingual vertical bone losses were 1.16 ± 2.26 and 1.33 ± 2.50 mm, respectively. The incisor-mandibular plane angle changes were also highly variable, averaging 2.4°. CONCLUSIONS: Orthodontic treatment causes changes in alveolar bone height and cortical bone thickness around the mandibular incisors. Although pretreatment cortical bone thickness, ridge width thickness, and specific tooth movements all play roles in what happens to the bone during treatment, incisor inclination was not correlated with alveolar bone height changes.

Posttreatment evaluation of maxillary canine positions in 15-year-old subjects.

INTRODUCTION: Esthetic improvement is a primary reason that people seek orthodontic treatment. The maxillary canine is considered by many to have great importance for both function and esthetics. Limited information is available about the position of the maxillary canine in relation to skeletal landmarks and whether the position can influence esthetic perceptions. The purposes of this study were to evaluate the normal maxillary canine position in relation to skeletal landmarks, to determine posttreatment 3-dimensional maxillary canine position with cone-beam computed tomography images, and to see whether maxillary canine position influences esthetic perceptions. METHODS: The Bolton standard template was used as the control sample, and the maxillary canine position was determined by implementing a Cartesian coordinate system. The right and left maxillary canines of 96 treated patients (48 boys, 48 girls; 15 years old) were analyzed by digitization of the cone-beam computed tomography volumes. The subjects' posttreatment smile photographs were ranked and quantified by 9 orthodontic residents who completed a Q-sort. Correlations were determined between canine positions and esthetic outcomes. RESULTS: The only difference between the right and left canine positions was the anteroposterior position of the root apex. Statistically significant sex differences were found for the superoinferior position of the right and left canine cusp tips, the mediolateral right and left canine root apices, and the mediolateral left canine cusp tips. No correlation was determined between the maxillary canine position and the esthetic perception. CONCLUSIONS: The maxillary canine position in relation to skeletal landmarks was determined and does not appear to significantly impact the esthetic perception, according to this study.

Simultaneous Intrusion and Retraction of Maxillary Incisors with a Three Piece Intrusion Arch and Mini-screw Implants: A Case Report.

Orthodontic treatment for a case with hyperdivergent growth pattern, moderate mandibular arch crowding, and maxillary incisor proclination was undertaken. Segmented arch mechanics with a three piece intrusion arch were used for simultaneous intrusion and retraction of maxillary incisors. Miniscrew implants were used to reinforce anchorage.

Extraction vs no treatment: Long-term facial profile changes.

INTRODUCTION: Long-term soft tissue response to extraction orthodontic treatment has been a subject of interest for years. The purposes of this study were to investigate long-term soft tissue profile changes in an extraction sample and to compare them with profile changes in an untreated sample. METHODS: A premolar extraction-treated sample (n = 47) and an untreated control sample (n = 57) were studied. Descriptive statistics were collected, and individual t tests were used for comparison and contrast of the treated and untreated samples. RESULTS: We found that the untreated soft tissue profile changed in the downward and forward direction. The treated soft tissue profile change was similar, but with more of a forward component than in the untreated sample. Most noteworthy was the finding that the soft tissue profiles of both the untreated and the treated samples were similar at the end point. CONCLUSIONS: The following conclusions were derived from the study. (1) There was no substantive difference in the soft tissue profiles of the samples, but there were some differences in the directional changes between them. (2) The changes for the untreated sample were the greatest for the lips and the chin, with the change occurring in the downward and forward direction. (3) The soft tissue profiles of the extraction sample also had the greatest measurable changes in the lips and the chin, but the changes had more of a forward component than they did in the untreated sample. (4) Extraction treatment does not adversely impact soft tissue profile changes over time.

Effect of bone-borne rapid maxillary expanders with and without surgical assistance on the craniofacial structures using finite element analysis.

INTRODUCTION: The aim of this study was to analyze stress distribution and displacement of the craniofacial structures resulting from bone-borne rapid maxillary expanders with and without surgical assistance using finite element analysis. METHODS: Five designs of rapid maxillary expanders were made: a tooth-borne hyrax expander (type A); a bone-borne expander (type B); and 3 bone-borne surgically assisted modalities: separation of the midpalatal suture (type C), added separation of the pterygomaxillary sutures (type D), and added LeFort I corticotomy (type E). The geometric nonlinear theory was applied to evaluate the Von Mises stress distribution and displacement. RESULTS: The surgical types C, D, and E demonstrated more transverse movement than did the nonsurgical types A and B. The amounts of expansion were greater in the posterior teeth in types A and B, but in types C, D, and E, the amounts of expansion were greater in the anterior teeth. At the midpalatal suture, the nonsurgical types showed more anterior expansion than did the posterior region, and higher stresses than with the surgical types. Type B showed the highest stresses at the infraorbital margin, anterior and posterior nasal spines, maxillary tuberosity, and pterygoid plate and hamulus. CONCLUSIONS: The 3 surgical models showed similar amounts of stress and displacement along the teeth, midpalatal sutures, and craniofacial sutures. Therefore, when using a bone-borne rapid maxillary expander in an adult, it is recommended to assist it with midpalatal suture separation, which requires minimal surgical intervention.

Impact of adenotonsillectomy and palatal expansion on the apnea-hypopnea index and minimum oxygen saturation in nonobese pediatric obstructive sleep apnea with balanced maxillomandibular relationship: A cross-over randomized controlled trial.

OBJECTIVE: To determine the impact and best management sequence between adenotonsillectomy (AT) and rapid palatal expansion (RPE) on the apnea-hypopnea index (AHI) and minimum oxygen saturation (MinSaO2) in nonobese pediatric obstructive sleep apnea (OSA) patients presenting balanced maxillomandibular relationship. STUDY DESIGN/METHODS: Thirty-two nonobese children with balanced maxillomandibular relationship and a mean age of 8.8 years, with a graded III/IV tonsillar hypertrophy and maxillary constriction, participated in a cross-over randomized controlled trial. As the first intervention, one group underwent AT while the other underwent RPE. After 6 months, interventions were switched in those groups, but only to participants with an AHI > 1 after the first intervention. OSA medical diagnosis with the support of Polysomnography (PSG) was conducted before (T0), 6 months after the first (T1) and the second (T2) intervention. The influence of sex, adenotonsillar hypertrophy degree, initial AHI and MinSaO2 severity, and intervention sequence were evaluated using linear regression analysis. Intra- and intergroup comparisons for AHI and MinSaO2 were performed using ANOVA and Tukey's test. RESULTS: The initial AHI severity and intervention sequence (AT first) explained 94.9% of AHI improvement. The initial MinSaO2 severity accounted for 83.1% of MinSaO2 improvement changes. Most AHI reductions and MinSaO2 improvements were due to AT. CONCLUSIONS: Initial AHI severity and AT as the first intervention accounted for most of the AHI improvement. The initial MinSaO2 severity alone accounted for the most changes in MinSaO2 increase. In most cases, RPE had a marginal effect on AHI and MinSaO2 when adjusted for confounders.

Apicotomy: surgical management of maxillary dilacerated or ankylosed canines.

This clinical article reports a technique, apicotomy, for managing dilacerated or ankylosed canines. The records of 3 patients successfully treated with apicotomy are presented. Orthodontists observe clinically significant incidences of impacted maxillary canines in their daily practices. Several procedures have been described to bring an ankylosed, impacted tooth into occlusion. Luxation is the most widely used solution, but there are risks involved with that approach, and the success rate is low. Surgical repositioning has also been used, but morbidity is high, and the aggressiveness of the procedure might also contraindicate it. Ankylosis might be related to the anatomic position of the canine's root apex and its adjacent anatomic structures. Apicotomy is a guided fracture of a canine root apex, followed by its orthodontic traction. It is a conservative surgical alternative for treating impacted canines with dilacerations or apical root ankylosis.