Alignment of Impacted Maxillary Canines: Critical Analysis of Eruption Path and Treatment Time

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.

Open vs closed surgical exposure of palatally displaced canines: a comparison of clinical and patient-reported outcomes-a multicentre, randomized controlled trial

OBJECTIVES

To compare treatment time, patients' perceptions during orthodontic treatment, dental fear and side effects, between open and closed surgical exposures in patients with palatally displaced canines (PDCs).

TRIAL DESIGN

Multicentre, randomized controlled trial, with random 1:1 allocation of two parallel groups.

MATERIALS AND METHODS

One hundred and twenty patients from three different orthodontic centres were randomized into one of the two intervention arms, open or closed surgical exposure. Both techniques had mucoperiosteal flaps raised and bone removed above the PDCs. In open exposure, tissue was removed above the canine, and glass ionomer - reaching above soft tissue - was built on the crown. The canine was then left to erupt spontaneously, prior to orthodontic alignment. At closed exposure, a chain was bonded to the canine and orthodontic traction was applied under the mucosa until eruption. Orthodontic alignment of the canines was undertaken after eruption into the oral cavity, with fixed appliances in both groups. All participants were treated according to intention to treat (ITT).

BLINDING

Due to the nature of this trial, only outcome assessors could be blinded to the intervention group.

RESULTS

One hundred and seventeen patients completed the trial. All PDCs were successfully aligned. Total treatment time was equal in the two techniques, mean difference -0.1 months (95% CI -3.2 to 2.9, P = 0.93). The closed group experienced more pain and discomfort during the active orthodontic traction. Dental fear, root resorption and periodontal status did not show any clinically significant differences between the groups.

GENERALIZABILITY

Results of this randomized controlled trial (RCT) can be generalized only to a similar population aged 9-16 years, if exclusion criteria are met.

CONCLUSION

The closed exposure group experienced more pain and discomfort mostly during active orthodontic traction. All other studied outcomes were similar between the two exposure groups.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov, ID: NCT02186548 and Researchweb.org, ID: 127201.

CBCT and Intra-Oral Scanner: The Advantages of 3D Technologies in Orthodontic Treatment

BACKGROUND

The aim is to demonstrate the validity of the monitoring through intraoral scanner of the dental movements and the real impact, advantages, and convenience, in terms of treatment time and efficiency gain, to frequently monitor a patient with the scanner application.

METHODS

A movement control of palatally impacted canines was performed, surgically treated with laser opercolectomy. Three-dimensional models of the patient's dental arch were obtained with intraoral scanner during a monitoring time of 4 months. The STL (Standard Triangle Language) files were superimposed with the 3D models extrapolated from the pre-operative CT (Computerized Tomography). The measurements of eruption, exposed palatal and vestibular areas, and distances between the canines and the incisors were performed, using digital technologies and with a digital caliber.

RESULTS

Descriptive and inferential statistical analysis of the data obtained from both conventional and digital monitoring has been realized and performing the T Student Test for paired data.

CONCLUSION

The advantages of digital monitoring are numerous, like the possibility to reduce the error of method caused by manual measurement on plaster casts and the possibility to compare the pattern and amount of eruption of the canine in the same patient overtime.

Interventions for impacted maxillary canines: A systematic review of the relationship between initial canine position and treatment outcome

BACKGROUND

The objective of this review was to critically assess the existing literature on the relationship between the initial position of impacted canines and treatment outcomes.

METHODS

We performed a systematic review of the available literature until February 2020 using the MEDLINE, Cochrane Central, Web of Science and PubMed databases. Prospective and retrospective studies (randomized controlled trials [RCTs], cohort studies, longitudinal follow-up studies) considering impacted maxillary canines that were orthodontically and/or surgically treated, and clearly reporting the initial position using 2D and/or 3D classifications, were included if they assessed at least one of the following: treatment success, treatment duration, number of treatment visits, radiographic outcome, periodontal health, esthetics and/or treatment complications. The included studies were assessed for risk of bias according to the Cochrane guidelines.

RESULTS

Seventeen studies were reviewed (2 RCTs and 15 non-RCTs). The included studies enrolled a total of 1247 patients with an average age of 14.1 years and a total of 1597 impacted canines. Various causal relationships were detected between the success of treatment modalities and the initial state of the impacted canine (bucco-palatal position, vertical position, canine angulation, root development).

DISCUSSION

Evidence, though limited, suggests that a higher alpha angle, higher vertical position and more mesial sector of the impacted canine are related to less successful interceptive and active treatment solutions, prolonged treatment time and inferior outcomes.

Comparative analysis of panoramic radiography and cone-beam computed tomography in treatment planning of palatally displaced canines

INTRODUCTION

The objective of this research was to compare the predictive value of panoramic radiographs (PRs) and cone-beam computed tomography (CBCT) scans for the estimation of root resorption, spontaneous eruption of a canine, and time for orthodontic traction.

METHODS

CBCT scans and PR images of 88 patients (27 male and 61 female; aged between 11 and 44 years) with 106 palatally displaced maxillary canines were retrieved from a database. Predictive values of several radiographic parameters, including the 3-dimensional angle of the canine, were analyzed using the area under the curve and multiple regression analysis.

RESULTS

The angle to the midline and canine position category had a discriminative ability for root resorption of the central incisors with area under the curve values of 0.63 (95% confidence interval, 0.56-0.79) and 0.83 (95% confidence interval, 0.75-0.91), respectively. PR measurements were not reliable predictors of resorptions, except severe resorptions, of the lateral incisors and the premolars. The measurements describing the position of the canine in relation to the midline could predict spontaneous eruption of the canine, regardless of the imaging method. The canine angle to the midline assessed on CBCT was significantly associated with traction time of the canine, producing the following equation: canine traction time = 49.6 - 0.24 × canine angle to the midline (r² = 0.360).

CONCLUSIONS

Only severe resorptions of roots can be predicted with PRs. The use of CBCT is indicated in cases of impacted canines.

Forced-eruption time for palatally impacted canines treated with and without ostectomy-decortication technique

OBJECTIVES

To compare forced-eruption times for palatally impacted canines treated with and without the ostectomy-decortication technique and to assess the influence of palatally impacted canine pretreatment position and angle on forced-eruption time.

MATERIALS AND METHODS

The sample was composed of 118 patient-subjects with 151 palatally impacted canines treated with the ostectomy-decortication technique (n = 72) and without (n = 79). The orthopantomogram radiographs (OPGs) were analyzed for palatally impacted canine angle and horizontal and vertical position. Recovery time was measured from the start of forced eruption until the canine was within ±1 mm of final dental arch position.

RESULTS

The time of forced canine eruption with ostectomy-decortication technique was significantly shorter than without (6.6 vs 21.0 months). Pretreatment canine position significantly increased forced-eruption time in the ostectomy-decortication group but not in the control sample.

CONCLUSIONS

Forced-eruption time of palatally impacted canines using the ostectomy-decortication technique was 3.2 times more rapid than without. Forced-eruption time increased significantly as a function of pretreatment palatally impacted canine position severity in the ostectomy-decortication group but not in the control.

Reliability of different radiographic methods for the localization of displaced maxillary canines

INTRODUCTION

The purpose of this study was to evaluate the reliability of the radiographic images of the main conventional x-ray techniques compared with the information from cone-beam computed tomography (CBCT).

METHODS

Twenty patients with unilateral or bilateral impaction of the maxillary canines had radiographic examinations by means of periapical x-rays, occlusal x-rays, panoramic x-rays, and CBCT scans. Three experienced orthodontists examined all x-rays from each patient and evaluated the radiographic images of the impacted canines. The examiners were asked to detect resorption in adjacent teeth and the buccal-palatal position of the impacted canines. Agreement between examiners was statistically tested.

RESULTS

Different diagnoses were produced by the 3 examiners regarding localization of the impacted canines and the presence or absence of root resorption of the adjacent teeth in conventional radiographic images. It appears that whereas panoramic x-ray is more sensitive in detecting resorption and tooth position, occlusal and periapical imaging have higher specificity and positive predictive value. The examiners were in good or excellent agreement when occlusal and periapicals were used for the definite diagnosis of resorption and tooth position. There was no disagreement of the examiners in CBCT images, which were used as the gold standard.

CONCLUSIONS

Conventional radiographic methods demonstrated a more subjective diagnostic procedure compared with CBCT images. CBCT is a more accurate and precise examination method compared with conventional radiography for the localization of impacted teeth and root resorption of the adjacent teeth.

Successful treatment of multiple bilateral impactions - a case report

BACKGROUND

Successful treatment of patients with multiple bilateral impactions can be an orthodontic challenge, but few reports on treatment planning and execution exist.

CASE PRESENTATION

In this case report, we describe the successful orthodontic treatment of a 16.3-year old female patient without systemic or genetic disease with initially nine persisting deciduous and nine impacted permanent teeth with complete root formation and closed apices in both jaws. After extraction of the deciduous and surgical exposure of the impacted permanent teeth, the Easy-Way-Coil™ system was used in conjunction with a skeletal anchorage (maxilla, BENEfit™ system) to guide the eruption of all impacted teeth. After a total treatment time of only 22.8 months all impacted teeth could be aligned successfully and a stable and functional class I occlusion was achieved. In addition, there were no adverse treatment effects such as anchorage loss, root resorptions or periodontal problems and an esthetic result could be achieved.

CONCLUSIONS

The presented treatment approach thus proved to be highly effective in cases with multiple bilateral impactions with minimal side effects and considerably reduced treatment time.

Early prediction of maxillary canine impaction

OBJECTIVES

The aim of this study was to establish prediction criteria for maxillary canine impaction in young patients, based on angular and linear measurements on panoramic radiographs.

METHODS

From 828 records having at least 2 panoramic radiographs, both taken between the ages of 7 and 14 years, with a minimum 1-year and maximum 3-year interval (T1 and T2), a training data set consisting of 30 subjects with unilateral canine impaction (12 males and 18 females) was selected. The patients' mean age was 10.1 years [standard deviation (SD) 1.3 years] at T1 and 11.9 years (SD 1.1 years) at T2. The training data set also consisted of 30 maxillary canines from the contralateral sides and an additional 60 normal erupted canines from 30 subjects. Those 30 subjects of a test data set were selected based on displaying bilateral maxillary canine eruption at T2 and being matched for gender and age with the subjects of the training data set [12 males and 18 females; mean age at T1, 10.1 years (SD 1.3 years) and at T2, 11.1 years (SD 1.2 years)]. Angular and linear measurements were performed separately by two observers on the total study sample at T1. Linear measurements were expressed as a multiplication of the maxillary central incisor width at the non-impacted side.

RESULTS

Significant differences for linear and angular measurements and radiographic factors were found between the maxillary impacted canine and erupted maxillary canine. The three best-discriminating parameters were canine to first premolar angle, canine cusp to midline distance and canine cusp to maxillary plane distance. These three parameters were combined in a multiple logistic regression model to calculate the probability of impaction, yielding a high area under the curve (AUC) equal to 0.97 (95% confidence interval: 0.94-0.99), with 90% sensitivity and 94% specificity.

CONCLUSIONS

Prediction of maxillary canine impaction from a combination of parameters relating to angles and distances measured in panoramic radiographs is weak. However, the final prediction model, based on canine-first premolar angle, canine cusp tip to midline distance and canine cusp tip to maxillary occlusal plane distance, might be useful to discriminate canine impaction for early intervention or regular follow-up.

Predictors of root resorption associated with maxillary canine impaction in panoramic images

OBJECTIVES

The aim was to identify a prediction model for root resorption (RR) caused by impacted canines based on radiographic variables assessed on 2D panoramic radiographs with the intention to reduce the need for additional cone beam computed tomography (CBCT) imaging.

MATERIALS AND METHODS

Three hundred and six patients (188 female, 118 male; mean age, 14.7 years; standard deviation, 5.6; range, 8.4-47.2 years) were included in the study. In total, 406 impacted maxillary canines were studied, from 206 patients with unilateral impaction and from 100 patients with bilateral impaction. Initial 2D panoramic radiography was available, and 3D CBCT imaging was obtained upon clinical indication. The generated radiographic variables and specific features investigated were collected on 2D panoramic imaging and were correlated to the presence/absence of RR detected on CBCT. A validation sample consisting of 55 canines from 45 patients with maxillary canine impactions was collected to validate the outcome of the present study.

RESULTS

The incidence of RR of the adjacent teeth was 33.8%. A prediction model using panoramic images for the possible presence of RR was established [area under the curve (AUC) = 0.74, 95% confidence interval (CI): 0.69-0.79] and validated by applying leave-one-out cross-validation (AUC = 0.71, 95% CI: 0.66-0.77). For the subgroup of presence of severe RR the discriminative ability increased to 0.80. In this prediction model, patient gender, canine apex, vertical canine crown position, and canine magnification were the strongest predictors for RR.

CONCLUSIONS

The final prediction model for RR based on available panoramic radiographs could be a helpful tool in justifying the need of additional CBCT examination.

The effect of using CBCT in the diagnosis of canine impaction and its impact on the orthodontic treatment outcome

Aim:

To investigate the added-value of using CBCT in the orthodontic treatment method of maxillary impacted canines and treatment outcome.

Materials and Methods:

The sample consisted of 118 treated patients. The CBCT group (n = 58) (39 females/19 males with the mean age of 14.3 years) included those with conventional treatment records consisting of panoramic and cephalometric radiographs, intra-and extra-oral photographs, and dental casts and complemented with a CBCT scan for additional diagnostic information. The conventional group (n = 60) (31 females/29 males with mean age 13.1 years) included those with similar conventional treatment records but without CBCT imaging.

Results:

There were significant differences in the canine-related variables between both groups. The CBCT group had the higher level of difficulty and more severely displaced canines when compared with the conventional group. However, no significant difference was found between groups either in the number of treatment methods used or in the use of interceptive methods combined with other treatment modalities or choice of extraction versus non-extraction. In terms of treatment success and interval duration, no significant differences were found. However, treatment duration was significantly (4 months) shorter in the CBCT group compared with the conventional group (P = 0.023).

Conclusion:

CBCT has been used in cases with more severe symptoms of maxillary canine impaction. The use of CBCT improved the diagnostic capabilities and improved the chances of success in the more difficult cases to a level similar to that of simpler cases treated on the basis of 2D information.

Palatally impacted maxillary canine with congenitally missing lateral incisors and midline diastema

Multiple treatment options are available for patients who have impacted canines in addition to congenitally missing lateral incisors. This article describes the treatment of a 13-year-old postpubertal girl with bilaterally impacted permanent maxillary canines, missing lateral incisors, retained deciduous canines, and a midline diastema. The orthodontic treatment plan included extraction of the deciduous canines. A lingual and labial approach (1-couple force system) was used to move the permanent canines into the arch. Through a collaborative team effort, including an orthodontist and a periodontist, the outcome was excellent esthetically and functionally.

Perfuração do esmalte para o tracionamento de caninos: vantagens, desvantagens, descrição da técnica cirúrgica e biomecânica

INTRODUÇÃO: a tração de dentes não irrompidos sempre foi considerada um procedimento de risco na prática ortodôntica. Com essa perspectiva, é indispensável a busca por eficiência nos procedimentos adotados para esse mister, o que justifica a proposta do presente artigo. Ao perfurar, vazamos uma estrutura natural, cuja restauração com material artificial é uma ação que está no escopo da área de maior evolução da Odontologia, não havendo justificativa para se evocar procedimentos de maior risco, como a colagem ou laçada com fios. OBJETIVO: este artigo objetiva apresentar protocolos para a Perfuração do Esmalte para o Tracionamento de Caninos (PETC), especificamente os caninos superiores, mais acometidos pelas anomalias de posicionamento, também denominadas disgenesias. Serão abordadas as vantagens e desvantagens da PETC em relação à Colagem de Acessório para o Tracionamento de Caninos (CATC), apresentando-se casos clínicos de diferentes níveis de complexidade, tendo como ponto de partida a literatura e a experiência clínica de 30 anos com elevado índice de sucesso.

The topography of displaced canines: a 3D-CT study

AIM

This study investigated the development of a three-dimensional (3D) coordinate system for radiologic volumetric data, allowing the analysis of the tooth axis of displaced teeth in relation to the occlusal, frontal, and sagittal reference planes.

PATIENTS AND METHODS

The data basis consisted of multislice computed tomography (MSCT) data of 37 patients with displaced upper canines. A total of 20 patients displayed unilateral displacement and 17 patients bilateral displacement (n = 54). The non-displaced canines of the opposite side served as the reference group (n = 20), together with MSCT data of 6 patients with non-displaced canines (n = 12). Three reference planes were constructed in the VoXim®5.6 program using landmarks (apex point and tip of the canine, incision point of the lower jaw, mesiobuccal tip of the lower left and right first molar, A-point). The tooth axis of the canines was analyzed in relation to these planes.

RESULTS

The angle to the frontal plane was only slightly smaller in non-displaced canines (mean: 17.53°) than in palatally displaced canines (mean: 19.62°), which however exhibited a considerably greater range (0.40-38.00°). In contrast, the mean angle in buccally displaced canines was 32.79°. Both the differences between the reference group and buccally displaced canines and those between the palatally and buccally displaced canines were statistically significant. The angles for buccal (55.16°) and palatal (56.63°) displacement relative to the occlusal plane were significantly smaller than for the non-displaced teeth (70.95°). However, the range of palatal displacement was high (27.3-80.6°). The inclination towards the sagittal plane was slight for non-displaced canines (mean 6.07°) and for buccally displaced canines (mean 8.25°). The mean angle of palatally displaced canines was significantly larger (23.28°) than that in the other groups, with a much greater range (6.70-50.80°).

CONCLUSION

The 3D coordinate system developed in this study allows the exact measurement of tooth position relative to three spatial planes, thus, enabling tooth position to be objectively determined.