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Introduction: This study aimed to identify significant factors affecting the spontaneous angular changes of impacted mandibular third molars as a result of second molar protraction. Temporary skeletal anchorage devices in the missing mandibular first molar (ML-6) or missing deciduous mandibular second molar (ML-E) with missing succedaneous premolar spaces provided traction., Methods: Forty-one mandibular third molars of 34 patients (10 male and 24 female; mean age 18.3 ± 3.7 years) that erupted after second molar protraction were included in this study. They were classified into upright (U) and tilted (T) groups. Linear and angular measurements were performed at the time of treatment initiation (T1) and of ML-6 or ML-E space closure (T2). Regression analyses were used to identify significant factors related to third molar uprighting., Results: Nolla stage (odds ratio [OR] 4.1), sex (OR 0.003 for male), third molar angulation at T1 (OR 1.1), missing tooth space (OR 0.006), rate of third molar eruption (OR 23.3), and rate of second molar protraction (OR 0.2) significantly affected third molar uprighting. Age, third molar angulation at T1, rate of third molar eruption, and rate of second molar protraction were significant factors for predicting third molar angulation at T2., Conclusions: Available space for third molar eruption before and after second molar protraction is not associated with uprighting of erupting third molars. Older patients whose third molars are in greater Nolla stage, are in a more upright position at T1, and have a greater eruption rate have a greater chance for third molar uprighting. Alternatively, an increase in second molar protraction rate results in mesial tipping of the third molars., (Copyright © 2019 American Association of Orthodontists. Published by Elsevier Inc. All rights reserved.)

Introduction: The aim of this study was to compare the root resorption (RR) of maxillary incisors after traction of unilateral vs bilateral impacted canines with reinforced anchorage., Methods: This retrospective longitudinal study included 60 cone-beam computed tomography scans of patients with maxillary impacted canines: 30 scans taken before and 30 taken after orthodontic traction with nickel-titanium coil springs. Two groups were formed according to the impaction condition: 15 with unilateral maxillary impacted canines and 15 with bilateral maxillary impacted canines. Three trained orthodontists made the measurements. Demographic variables, occlusal characteristics, skeletal class, and measurements related to canine impaction were collected from the clinical history, dental models, and radiographs of each patient. RR (mm and mm 2 ) for each maxillary incisor was measured in 3 dimensions. Independent t or Mann-Whitney U tests were used, depending on data normality. Multiple linear regression analyses were used to evaluate the influence of all variables (predictors) on RR (α = 0.05)., Results: RR did not show significant differences between groups in any section (P > 0.05). No subject had RR greater than 2 mm or 5 mm 2 . The specific influence of some predictor variables varied depending on the type of maxillary incisor., Conclusions: RR of maxillary incisors after traction of unilateral vs bilateral impacted canines with reinforced anchorage was similar and is not a risk to the integrity of the maxillary incisor root., (Copyright © 2018 American Association of Orthodontists. Published by Elsevier Inc. All rights reserved.)

A 22-year-old woman came with a unilateral missing mandibular first molar and buccal crossbite. The open space was closed by protraction of the mandibular left second molar and uprighting and protraction of the horizontally impacted third molar using temporary skeletal anchorage devices, and her buccal crossbite was corrected with modified palatal and lingual appliances. The total active treatment time was 36 months. Posttreatment records after 9 months showed excellent results with a stable occlusion., (Copyright © 2016 American Association of Orthodontists. Published by Elsevier Inc. All rights reserved.)

Introduction: The aim of this study was to evaluate the effect of malocclusion severity on oral health-related quality of life and food intake ability in adult patients, controlling for sex, age, and the type of dental clinic visited., Methods: The sample consisted of 472 Korean patients (156 male, 316 female) with a mean age of 21.1 (SD, 8.6) years in a dental hospital and a private clinic. The correlations between the Korean version of the Oral Health Impact Profile-14 (OHIP-14K), subjective food intake ability (FIA) for 5 key foods, and Index of Orthodontic Treatment Need-Dental Health Component (IOTN-DHC) were investigated., Results: The mean IOTN-DHC and OHIP-14K scores were significantly higher for the dental hospital patients than for the private clinic patients (IOTN-DHC, P <0.001; OHIP-14K, P <0.05). Malocclusion severity was significantly higher in male than in female subjects (P <0.001). Older patients perceived their oral health-related quality of life more negatively than did the teens (P <0.001). As the severity of the malocclusion increased, oral health-related quality of life and masticatory function worsened (OHIP-14K, P <0.001; FIA, P <0.05)., Conclusions: As the severity of the malocclusion and the age of the patients increased, oral health-related quality of life and masticatory function relatively deteriorated. This finding provides evidence that severe malocclusions are associated with lower quality of life and less masticatory efficiency in older patients., (Copyright © 2016 American Association of Orthodontists. Published by Elsevier Inc. All rights reserved.)

The aim of the present study was to investigate the influences of the presence and position of a lower third molar (M3) on the fragility of mandibular angle and condyle, using finite element analysis. From computed tomographic scans of a human mandible with normally erupted M3, two additional virtual models were generated: a mandibular model with partially impacted M3 and a model without M3. Two cases of impact were considered: a frontal and a lateral blow. The results are based on the chromatic analysis of the distributed von Mises and principal stresses, and calculation of their failure indices. In the frontal blow, the angle region showed the highest stress in the case with partially impacted M3, and the condylar region in the case without M3. Compressive stresses were dominant but caused no failure. Tensile stresses were recorded in the retromolar areas, but caused failure only in the case with partially impacted M3. In the lateral blow, the stress concentrated at the point of impact, in the ipsilateral and contralateral angle and condylar regions. The highest stresses were recorded in the case with partially impacted M3. Tensile stresses caused the failure on the ipsilateral side, whereas compressive stresses on the contralateral side., (Copyright © 2015 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.)

Background: There is no consensus regarding the prophylactic removal of mandibular third molars (TM) in fracture lines to facilitate healing. Recent evidence suggests that poor healing is attributed to the limited use of antimicrobials, delayed care and semi-rigid fixation as a treatment method, favoring retention of TM., Study Design: A retrospective cohort study of all patients presenting with mandibular angle fractures at the Hippokration General Hospital of Athens (2006-2011) was designed to examine the association between the presence versus absence of TMs in the line of mandibular fractures and the fracture healing process. Development of complications during the healing process was the outcome of interest. Additional factors considered were patient age, sex, and fracture etiology., Materials and Methods: Data were extracted from a retrospective chart review, including information from clinical and radiological examinations. The analytical sample included 112 patients with 121 angle fractures. Bivariate methods including Fisher's exact and chi-square tests were used to test the association between TM presence in the fracture line and healing complications., Conclusion: This study found no association between the presence of mandibular TM in the fracture line and postoperative complications and the healing process when combined with light intermaxillary fixation for 15 days., (Copyright © 2014 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.)

Delayed tooth eruption can affect the accuracy of orthodontic diagnosis and treatment planning and could delay overall treatment. A girl, aged 7 years 4 months, who had unilateral delayed eruption of several teeth was successfully treated. The evaluation of delayed tooth eruption should be considered by the orthodontist because the role of these teeth can affect the overall treatment of malocclusion. In patients with delayed tooth eruption, careful and accurate diagnosis and treatment planning will allow the orthodontist to start treatment at the proper stage and might reduce the overall orthodontic treatment time., (Copyright © 2013 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.)

Objective: A tooth with a dentigerous cyst (DC) does not always erupt by marsupialization. The eruption duration and conditions of DC-associated premolars were examined to predict such eruption following marsupialization., Study Design: The eruption and conditions including depth, root formation, inclination, and eruption space were examined retrospectively in 21 DC-associated mandibular premolars using dental and panoramic radiograms., Results: Fifteen of 21 premolars erupted half within 3 months and all 15 erupted completely within 10 months after marsupialization, without orthodontic traction. The age of the patients, tooth depth, and inclination were significantly different between the erupted and non-erupted groups, whereas there was no significant difference in the root formation or the eruption space between the 2 groups., Conclusions: The successful eruption of a DC-associated premolar can be predicted within 3 months after marsupialization. Furthermore, the eruption may be affected by the patient's age, tooth depth, and tooth inclination.

Introduction: The purpose of this study was to determine whether a clinically significant association exists between maxillary skeletal width and palatal canine impaction, also known as palatally displaced canine (PDC)., Methods: Seventy-nine patients with PDC were matched for age, sex, and malocclusion to 79 controls. Maxillary and mandibular skeletal widths and nasal cavity widths were measured on posteroanterior cephalograms; maxillary and mandibular intermolar widths were measured on dental casts; and maxillary interalveolar arch widths at 3 levels (canine, premolar, and first molar) were measured on occlusograms., Results: Only maxillary alveolar arch width at the canine level was significantly different between the 2 groups. However, further analysis showed that the presence of erupted deciduous or permanent canines, rather than their absence in the canine area (whether due to extraction, exfoliation, impaction, or not yet having erupted), was strongly associated with maxillary intercanine alveolar arch width., Conclusions: The additional finding in this study that the eruptive status of canines significantly affects maxillary alveolar arch width in this area suggests that maxillary intercanine alveolar arch width as measured in this or other studies is not a good predictor of PDC.

Intraosseous migration of impacted teeth across the midline to the opposite side of the jaw is a rare dental anomaly of unknown etiology. Transmigration of an impacted mandibular canine through the symphysis to the contralateral side of the arch has been documented. Transmigration of an impacted maxillary canine across the midpalatal suture to the opposite side of the maxilla has not been previously observed and is reported here for the first time.

The aim of this study was to investigate the eruption of teeth associated with dentigerous cysts in the mandibular premolar and maxillary canine regions in preadolescents. Fifty-eight cyst-associated teeth, including 47 mandibular premolars and 11 maxillary canines, were examined retrospectively by using normalized panoramic radiographs and histological materials. The subjects were divided into 2 groups: the erupted group, in which the teeth had erupted successfully after marsupialization, and the nonerupted group, in which the teeth had undergone orthodontic traction or cystectomy with removal of the cyst-associated tooth. Eighty-one percent of the mandibular premolars and 36% of the maxillary canines in the cysts erupted successfully about 100 days after marsupialization without traction. The eruption of a mandibular premolar was significantly related to a shallow position in the alveolar bone, shallow angulation of the tooth, and young age of the patient but not to cyst size and dental space for the eruption. The eruption of the maxillary canine was significantly related to the small size of the cyst and the patient's age. The cyst walls of the erupted group showed severe inflammatory cellular infiltration. These findings present a treatment guideline for dentigerous cysts associated with mandibular premolars and maxillary canines in preadolescents.

Objective: To evaluate the possibility of applying the Third Molar Eruption Predictor to all panoramic radiographs., Study Design: Panoramic radiographs were retrospectively analyzed from a 4-year follow-up study of third molars carried out at the University of Copenhagen, Denmark. The radiographs, taken at a mean age of 20.6 years, included 45 unerupted or partially erupted mandibular third molars in 28 subjects. Because the device was calibrated both with simple proportions and by use of the methods of Bayes' Decision Theory, the separation point of the device was therefore adjusted at 12 mm from the distal surface of the second molar., Results: The predictions of future eruption or impaction made with the calibrated device and the actual clinical outcome 4 years later were in conformity for 80% of the mandibular third molars., Conclusion: The Third Molar Eruption Predictor may be applied to all panoramic radiographs, but it seems to require calibration before use.

The purpose of this study was to investigate the eruption speed and rate of angulation change of a cyst-associated mandibular second premolar after marsupialization of a dentigerous cyst in preadolescents. Premolars on the cyst and noncyst sides and size of the cyst were retrospectively examined with a total of 42 pairs of normalized panoramic radiographs in 20 patients who underwent neither extraction nor orthodontic traction of the cyst-associated mandibular second premolar after marsupialization. Sixteen premolars at the intraosseous eruption stage in a total of 9 preadolescents without cysts were also examined. The eruption speed and rate of angulation change of the cyst-associated mandibular second premolar were significantly faster than those of the premolars without cysts, and significantly correlated with the diminishing rate of the cyst size, which rapidly decreased for the first 3 months after marsupialization. In addition, the eruption speed of the cyst-associated mandibular second premolar correlated with that of the premolar on the noncyst side, and the rate of angulation change inversely correlated with the level of root formation. The results suggest that a cyst-associated permanent tooth erupts more rapidly regardless of the level of root formation and size and type of the cyst, and the abnormally tilted tooth axis improves more rapidly for the first three months after marsupialization of a dentigerous cyst in preadolescents.

Objective: To measure changes in angular position and eruption status of mesially impacted mandibular third molars (M3) during 4-year follow-up period., Study Design: Standardized panoramic radiographs were taken at the start of the study (the average age of the subjects was 19.7 years) and 4 years later. Angulation and degree of impaction of M3 were determined by their sagittal relationships to the adjacent second molars. The impacted M3 were either partially erupted or unerupted., Results: Initial examination showed that among a total of 59 mesioangular M3, 49 (83%) had inclination between 5 and 30 degrees. The proportion of M3 that became upright (zero tilt) was 76% (13/17) with initial angulations of 5 to 10 degrees, 61% (11/18) with initial angulations of 15 to 20 degrees, and 14% (2/14) with initial angulations of 25 to 30 degrees. None of the M3 originally presented at 35 degrees or more became upright, but an average decrease of 12 degrees in angulation was registered. In total, 26 M3 of 59 (44%) became upright during the follow-up period. Initial examination of levels of eruption showed that among 59 M3, 13 (22%) were partially erupted and the rest were unerupted. Of the 46 M3 initially unerupted, 17 (37%) became fully erupted and 7(15%) erupted partially during the 4-year follow-up. Of the total sample, 25 (42%) had erupted to full occlusion during the observation period., Conclusion: A significant proportion of mesially impacted mandibular M3 had changed their angulation and became fully erupted by the time the individual reached 24 years of age. Positional changes and eruption of impacted M3 are unpredictable phenomena.

This study was designed to create a transparent device to be superimposed on a panoramic tomogram taken of a patient at age 20 years to make predictions of future eruption or impaction of lower third molars. The device was developed from data on 40 lower third molars initially retained at age 20 years; one half of these remained impacted, and the other half of them erupted by age 26 years. Tracings were made from panoramic tomograms taken at age 20 years. The critical point for prediction in the overlay was the intersection of a horizontal reference line and the anterior border of the ascending ramus. To estimate this critical separation line, Bayes' Decision Theory was used. The sum of false negatives and false positives was least at a distance of 14.5 mm from the distal surface of the second molar. Mesial from this point, the probability of impaction was 76%; distal from this point, the probability of eruption was 72%. Tested against 35 initially unerupted lower third molars, the predictions made by the device and the actual clinical findings were in conformity in relation to 97% of the test teeth. It could thus be concluded that the method was simple to use and may prove a good addition for predicting lower third molar development.