The impacted maxillary canine. Further observations on aetiology, radiographic localization, prevention/interception of impaction, and when to suspect impaction

Influence of alveolar bone thickness and bucco-palatal inclination on root resorption of lateral incisors in unilateral maxillary impacted canines: a retrospective observational study

BACKGROUND

This study aimed to investigate the potential associations between alveolar bone thickness, bucco-palatal inclination of maxillary lateral incisors, and lateral incisor root resorption in patients with unilateral maxillary impacted canines (UMICs).

METHODS

A total of three hundred and five subjects (120 males, 185 females; mean age, 16.39 years; standard deviation, 4.04) with UMICs were included. Canine position and root resorption were assessed using CBCT. UMICs were divided into palatal, buccal and mid-alveolus groups (PICs, BICs and MAICs), with 117, 137 and 51 subjects, respectively. Alveolar bone thickness and bucco-palatal inclination of lateral incisors were measured using the Dolphin software.

RESULTS

The prevalence of lateral incisor root resorption was significantly lower in the BICs (13.9%) than MAICs (29.4%) and PICs (29.1%). Alveolar bone thickness of the apical area was smaller in UMICs with lateral incisor root resorption than no resorption in both PICs (8.33 ± 1.64 vs 10.53 ± 2.55 mm) and BICs (8.94 ± 1.85 vs 10.76 ± 2.28 mm). Furthermore, lateral incisors on the impacted side were more buccally inclined in PICs with lateral incisor root resorption than no resorption, while in both BICs and MAICs, there was no statistical difference between lateral incisor root resorption than no resorption. Moreover, alveolar bone thickness of the apical area, rather than bucco-palatal inclination of lateral incisors, was significantly correlated with lateral incisor root resorption both in PICs and BICs.

CONCLUSIONS

Lateral incisor root resorption is less common in BICs. Thinner alveolar bone thickness at the apical area of lateral incisors can be considered as a potential risk factor for lateral incisor root resorption in UMICs.

Maxillary canine position of patients with non-syndromic craniofacial disorder: a retrospective evaluation of panoramic radiographs

BACKGROUND

The study evaluates the position and displacement tendency of unerupted maxillary canines in orthodontic patients with non-syndromic craniofacial disorders (CD) compared to a control (C) group.

METHODS

Canine position and displacement tendency were evaluated using panoramic radiographs (PAN) examined with parameters such as sector classification (sectors 1-5) and inclination angles (α and β). The displacement tendency was defined as the positioning of the tip in sectors 1 or 2, as well as its combination with increased angles (α > 30° and β > 39°). In addition, the correlation of the tooth position and agenesis, cleft side, and sex was assessed.

RESULTS

A total of 116 pre-treatment PAN, divided into the CD group (n = 50; mean age 8.32 ± 2.27 years) and the C group (n = 66; mean age 10.80 ± 2.82 years), were evaluated in this study. The sector classification showed no displacement tendency in both groups. Inclination angles α/β showed a statistically significant higher displacement tendency (p = 0.01) of the CD group (n = 5) on the right side, compared to healthy subjects (n = 1). Male CD patients had a statistically significant higher displacement tendency on the right side (p = 0.03). A statistically significant correlation between cleft and non-cleft-side (p = 0.03) was found.

CONCLUSION

Patients with CD showed a statistically significant higher displacement tendency of the maxillary canine affected by the cleft side. The inclination angle was found to be the better predictor compared to the sector classification which should be considered in the orthodontic treatment planning.

Factors That Guide the Diagnosis and Treatment Planning for Impacted Canines Using Three-Dimensional Cone-Beam Computed Tomography: A Cross-Sectional Study

Objective. Impacted canines are one of the significant challenges in orthodontics that should be appropriately assessed to provide the best treatment to the patients. Materials and Methods. In the present study, 57800 patients were examined over six years to investigate the prevalence, diagnostic procedures, and treatment methodologies for impacted canine cases. Prevalence and diagnosis were tested using history taking, clinical examination, and three-dimensional cone-beam radiographs. The cases were tested for impaction site, gender, age, signs, and symptoms. The groups were classified for impaction location according to Mupparapu’s classification. Result. The causative factors and the treatment methodology selected were plotted according to age and gender distribution. The total prevalence was 3.9% of canine impaction cases in relation to the total sample cases. The results showed a strong correlation between the site of impaction toward the upper arch and with distribution following Mupparapu’s classification. The pain was the most detectable complication in all age groups, while root resorption was the least. Conclusion. Most of the younger age groups were sent for exposure and orthodontic traction, while the mid-aged groups elected for observation, and follow-up as their primary concern was esthetics. However, the adult patients were into exposure and traction to improve their function.

3D Analysis of maxillary incisor root inclinations in cases of unilateral maxillary canine impaction

OBJECTIVES

To evaluate the association between maxillary incisor root inclinations and unilateral canine impaction.

METHODS

A retrospective cross-sectional study of 59 pre-treatment CBCT scans (23 palatal impactions, 10 buccal impactions, and 26 comparison patients). Using Dolphin 3-D Imaging software (Chatsworth, CA), relative incisor angulations to a 3D palatal plane and the shortest distance between the canine crown and the root of the closest lateral incisor were calculated. A one-way analysis of variance was used to determine whether there were any differences between the three independent groups of impactions concerning the four continuous dependent variables incisor root inclination for each maxillary incisor.

RESULTS

Patients with unilaterally impacted maxillary canines demonstrate significant differences in the root inclination position on the ipsilateral (0.0001 > P = 0.002) but not contralateral side. While palatal impactions (PIC) are associated with buccally positioned roots of the ipsilateral lateral (-9.05 degrees) and central incisors (-7.91 degrees), buccal impactions (BIC) are only associated with palatally positioned roots of the ipsilateral lateral incisors (+10.40 degrees) alone. A more labial position of the lateral incisor root was correlated with a more proximally located, coronally positioned, and medially displaced adjacent PIC (0.013 > P < 0.026).

LIMITATIONS

This is a retrospective cross-sectional convenience sample.

CONCLUSIONS

Patients with impacted maxillary canines, whether PIC or BIC, do not show generalized retroclination or proclination of all four maxillary incisor roots. Instead, changes in incisor root inclination were only ipsilateral to the impacted canine. BIC is only associated with palatal displacement of the ipsilateral lateral incisor root, whereas PIC is associated with labial root displacement of both ipsilateral incisors.

WITHDRAWN: Extraction of primary (baby) teeth for unerupted palatally displaced permanent canine teeth in children

BACKGROUND

The permanent canine tooth in the maxillary (upper) jaw sometimes does not erupt into the mouth correctly. In about 1% to 3% of the population these teeth will be diverted into the roof of the mouth (palatally). It has been suggested that if the primary canine is removed at the right time this palatal eruption might be avoided. This is an update of a Cochrane review first published in 2009.

OBJECTIVES

To evaluate the effect of extracting the primary maxillary canine on the eruption of the palatally ectopic maxillary permanent canine.

SEARCH METHODS

We searched the following electronic databases: the Cochrane Oral Health Group's Trials Register (to 20 April 2012), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2012, Issue 1), MEDLINE via OVID (1946 to 20 April 2012) and EMBASE via OVID (1980 to 20 April 2012). There were no restrictions regarding language or date of publication.

SELECTION CRITERIA

Trials were selected if they met the following criteria: a randomised or quasi-randomised controlled trial, involving the extraction of the deciduous maxillary canine and assessing eruption/non-eruption of the palatally displaced maxillary permanent canine.

DATA COLLECTION AND ANALYSIS

Data extraction was undertaken independently by two review authors. The primary outcome was the reported prevalence of eruption or non-eruption of the ectopic permanent canine into the mouth following observation or intervention. Results were to be expressed as risk ratios for dichotomous outcomes with 95% confidence intervals and mean differences for continuous outcomes. Heterogeneity was to be investigated, including both clinical and methodological factors. Authors of trials were contacted to request unpublished data.

MAIN RESULTS

Reports of two randomised controlled trials previously excluded from an earlier version of the review due to "deficiencies in reporting, insufficient data" have now been included. These two trials included approximately 128 children, with more than 150 palatally displaced canine teeth, and both were conducted by the same research group. Data presented in the trial reports are either incomplete or inconsistent. Both trials are at high risk of bias. It must be emphasised that both trials have serious deficiencies in the way they were designed, conducted, and reported, and attempts to contact the authors to obtain detailed information and clarify inconsistencies have been unsuccessful. Allocation to treatment appears to be at the level of the individual, but outcomes of successful treatment relate to included teeth and data are not reported for each treatment group. Adverse effects are not reported. Neither trial provides any evidence to guide clinical decision making.

AUTHORS' CONCLUSIONS

There is currently no evidence of the effects of extraction of primary canine teeth in 10-13 year old children with one or two palatally displaced permanent canine teeth.

Systematic review and meta-analysis of congenitally missing permanent dentition: Sex dimorphism, occurrence patterns, associated factors and biasing factors

PURPOSE

We aimed to summarize/analyze, comprehensively and for the first time, the literature on the prevalence of congenitally missing teeth (CMT) in males and females and the CMT pattern, taking various associated and biasing factors into account.

METHODS

A search was performed independently by two authors during September 2012 till June 2013 to find all the available literature regarding CMT-associated factors and patterns comprising sex dimorphism, arches, anterior/posterior regions, unilateral/bilateral patterns, and involved teeth. The data were statistically analyzed.

RESULTS

Seventy-four studies were included. The mean CMT prevalence was 6.42±2.76% in males and 7.55±2.67% in females. Overall, CMT is more prevalent in females but only in epidemiological samples, and not in orthodontic or dental patients. Enrolling orthodontic/dental patients might increase the observed CMT in boys and/or reduce it in girls. Gender dimorphism was not affected by any of the factors: time, regions, or the biasing factors. There is not a significant predominance of maxillary or mandibular involvement, although the anterior segment is more likely to be affected.

CONCLUSIONS

CMT is more common in girls and in the anterior segment, regardless of the date of publication. Contrary to the commonly held belief regarding more CMT prevalence in female orthodontic patients, it was shown that in dental/orthodontic patients, CMT prevalence is higher in boys.

Predictive variables derived from panoramic radiographs for impacted maxillary cuspids treated with easy cuspid system

The aim of the current study was to find, by means of panoramic radiographs, a viable statistical method to forecast the duration of orthodontic traction of impacted maxillary cuspids. The treatment sample consisted of 51 palatal impacted cuspids (19 unilateral and 32 bilateral) in 35 patients (aged between 10.5 and 17.5 y) with a cervical vertebral maturation between cervical stage 1 and 4. Each patient underwent the same combined surgical-orthodontic technique. Anamnestic data as well as pretreatment panoramic radiograph and cephalogram with European Board of Orthodontics analysis were recorded for each case. Eight radiographic indicators were derived from panoramic films to define the reliable position of the impacted cuspid. Multiple regression analysis was used. All cuspids were successfully treated with an average traction time of 99 days (range, 33-188 d). The pretreatment radiographic features assessed on the panoramic radiographs did not significantly affect the duration of traction. The formula based on α angle, d1 distance, and S sector forecasted an average traction time of 123 days (range, 63-210 d), which is longer than the real time. No relevant correlations were found between orthodontic traction time and pretreatment radiograph parameters derived from panoramic film at the beginning of the treatment. The classic formula elaborated by Crescini could not be applied to the patients of this study, who were treated with the Easy Cuspid method.

Congenitally missing teeth (hypodontia): A review of the literature concerning the etiology, prevalence, risk factors, patterns and treatment

Congenitally missing teeth (CMT), or as usually called hypodontia, is a highly prevalent and costly dental anomaly. Besides an unfavorable appearance, patients with missing teeth may suffer from malocclusion, periodontal damage, insufficient alveolar bone growth, reduced chewing ability, inarticulate pronunciation and other problems. Treatment might be usually expensive and multidisciplinary. This highly frequent and yet expensive anomaly is of interest to numerous clinical, basic science and public health fields such as orthodontics, pediatric dentistry, prosthodontics, periodontics, maxillofacial surgery, anatomy, anthropology and even the insurance industry. This essay reviews the findings on the etiology, prevalence, risk factors, occurrence patterns, skeletal changes and treatments of congenitally missing teeth. It seems that CMT usually appears in females and in the permanent dentition. It is not conclusive whether it tends to occur more in the maxilla or mandible and also in the anterior versus posterior segments. It can accompany various complications and should be attended by expert teams as soon as possible.

Three-dimensional localization of impacted canines and root resorption assessment using cone beam computed tomography

The purpose of this study was to develop a new way to localize the impacted canines from three dimensions and to investigate the root resorption of the adjacent teeth by using cone beam computed tomography (CBCT). Forty-six patients undergoing orthodontic treatments and having impacted canines in Tongji Hospital were examined. The images of CBCT scans were obtained from KaVo 3D exam vision. Angular and linear measurements of the cusp tip and root apex according to the three planes (mid-sagittal, occlusal and frontal) have been taken using the cephalometric tool of the InVivo Dental Anatomage Version 5.1.10. The measurements of the angular and linear coordinates of the maxillary and mandibular canines were obtained. Using this technique the operators could envision the location of the impacted canine according to the three clinical planes. Adjacent teeth root resorption of 28.26 % was in the upper lateral incisors while 17.39% in upper central incisors, but no lower root resorption was found in our samples. Accurate and reliable localization of the impacted canines could be obtained from the novel analysis system, which offers a better surgical and orthodontic treatment for the patients with impacted canines.

Prevalence of impacted and supernumerary teeth in the North Indian population

Objectives: Dental impaction is a very frequent problem. Supernumerary teeth, or hyperdontia, are the presence of additional teeth to the normal series in the either of the dentition. The presence of impacted and/or supernumerary teeth can cause various complications. The objective of the present study was to determine the prevalence of impacted and supernumerary teeth in the North Indian population. Study Design: The panoramic radiographic records of 4750 patients attending the Department of Oral Medicine and Radiology, Jodhpur Dental College General Hospital between September 2008 to December 2012 were examined for this retrospective study. The ages of the patients ranged from 8 to 72 years, with a mean of 34.6 years. Results: A total of 798 (16.8%) patients presented with 1126 impacted teeth. Impacted canines were the most prevalent (9.7%), followed by impacted premolars (4.3%). Supernumerary teeth (1.6%) and impacted molars (1.2%) were less prevalent. Among the 842 impacted teeth, the most frequently affected teeth were the canines (56.7%), followed by premolars (27.8%), and supernumerary teeth (9.3%), while the prevalence of impacted molars was quite lower (6.2%). Conclusion: The most frequently impacted teeth were maxillary canines and the mesiodens were the most common supernumerary tooth. The early diagnosis of supernumerary and impacted teeth is essential to prevent malocclusion and malalignment of permanent teeth demonstrating the importance of panoramic radiographs in their detection.

Key words:Impacted, supernumerary, prevalence, canines, mesiodens.

Mechanism of human tooth eruption: review article including a new theory for future studies on the eruption process

Human eruption is a unique developmental process in the organism. The aetiology or the mechanism behind eruption has never been fully understood and the scientific literature in the field is extremely sparse. Human and animal tissues provide different possibilities for eruption analyses, briefly discussed in the introduction. Human studies, mainly clinical and radiological, have focused on normal eruption and gender differences. Why a tooth begins eruption and what enables it to move eruptively and later to end these eruptive movements is not known. Pathological eruption courses contribute to insight into the aetiology behind eruption. A new theory on the eruption mechanism is presented. Accordingly, the mechanism of eruption depends on the correlation between space in the eruption course, created by the crown follicle, eruption pressure triggered by innervation in the apical root membrane, and the ability of the periodontal ligament to adapt to eruptive movements. Animal studies and studies on normal and pathological eruption in humans can support and explain different aspects in the new theory. The eruption mechanism still needs elucidation and the paper recommends that future research on eruption keeps this new theory in mind. Understanding the aetiology of the eruption process is necessary for treating deviant eruption courses.

Etiologic factors for buccal and palatal maxillary canine impaction: a perspective based on cone-beam computed tomography analyses

INTRODUCTION

The aim of this research was to identify the etiologic factors associated with palatally impacted canines and buccally impacted canines in a Chinese population by using the cone-beam computed tomography technique.

METHODS

Pretreatment cone-beam computed tomography scans of 170 Chinese subjects with impacted maxillary canines and 170 age- and sex-matched subjects without impaction were used. Impacted canine subjects were divided into 2 groups: those with palatally impacted canines and those with buccally impacted canines. One rater analyzed the cone-beam computed tomography data for qualitative and quantitative variables of the teeth, dental arch, and skeletal components. The measurements were compared by using analytical statistical methods.

RESULTS

The mesiodistal dimension of the lateral incisor was significantly smaller in the palatally impacted canine group than in the other group (by an average of 0.4-0.5 mm; analysis of variance [ANOVA], P <0.001). Both anterior maxillary dental (interpremolar) width and skeletal width (interjugal points) in the buccally impacted canine group were significantly smaller than in the palatally impacted canine and control groups (ANOVA, P <0.001), whereas the intermolar widths and posterior mandibular widths were similar among the groups. The groups with palatally impacted or buccally impacted canines had significantly increased prevalence values of peg-shaped lateral incisors and incisor impaction, respectively (chi-square or Fisher exact tests, P <0.001). After excluding subjects who also had lateral incisor anomalies, the prevalence values of supernumerary teeth, missing premolars, or third molars combined were not different among the impaction and control groups. The average mesiodistal location of the canine cusp tip was significantly different between the buccally impacted canines and the palatally impacted canines groups; it was distal and mesial to the lateral incisor long axis, respectively.

CONCLUSIONS

In Chinese subjects, buccal canine impaction is mostly associated with anterior transverse (dental and skeletal) deficiency and incisor impaction, whereas palatal impaction is mostly associated with small or missing lateral incisors, consistent with the guidance theory. Likely, preimpaction migrations of the canines are mainly buccal for buccal impactions and excessively mesiopalatal for palatal impactions.

Extraction of primary (baby) teeth for unerupted palatally displaced permanent canine teeth in children

BACKGROUND

The permanent canine tooth in the maxillary (upper) jaw sometimes does not erupt into the mouth correctly. In about 1% to 3% of the population these teeth will be diverted into the roof of the mouth (palatally). It has been suggested that if the primary canine is removed at the right time this palatal eruption might be avoided. This is an update of a Cochrane review first published in 2009.

OBJECTIVES

To evaluate the effect of extracting the primary maxillary canine on the eruption of the palatally ectopic maxillary permanent canine.

SEARCH METHODS

We searched the following electronic databases: the Cochrane Oral Health Group's Trials Register (to 20 April 2012), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2012, Issue 1), MEDLINE via OVID (1946 to 20 April 2012) and EMBASE via OVID (1980 to 20 April 2012). There were no restrictions regarding language or date of publication.

SELECTION CRITERIA

Trials were selected if they met the following criteria: a randomised or quasi-randomised controlled trial, involving the extraction of the deciduous maxillary canine and assessing eruption/non-eruption of the palatally displaced maxillary permanent canine.

DATA COLLECTION AND ANALYSIS

Data extraction was undertaken independently by two review authors. The primary outcome was the reported prevalence of eruption or non-eruption of the ectopic permanent canine into the mouth following observation or intervention. Results were to be expressed as risk ratios for dichotomous outcomes with 95% confidence intervals and mean differences for continuous outcomes. Heterogeneity was to be investigated, including both clinical and methodological factors. Authors of trials were contacted to request unpublished data.

MAIN RESULTS

Reports of two randomised controlled trials previously excluded from an earlier version of the review due to "deficiencies in reporting, insufficient data" have now been included. These two trials included approximately 128 children, with more than 150 palatally displaced canine teeth, and both were conducted by the same research group. Data presented in the trial reports are either incomplete or inconsistent. Both trials are at high risk of bias. It must be emphasised that both trials have serious deficiencies in the way they were designed, conducted, and reported, and attempts to contact the authors to obtain detailed information and clarify inconsistencies have been unsuccessful. Allocation to treatment appears to be at the level of the individual, but outcomes of successful treatment relate to included teeth and data are not reported for each treatment group. Adverse effects are not reported. Neither trial provides any evidence to guide clinical decision making.

AUTHORS' CONCLUSIONS

There is currently no evidence of the effects of extraction of primary canine teeth in 10-13 year old children with one or two palatally displaced permanent canine teeth.

Impaction of both maxillary central incisors and a canine

This case report describes the treatment of a 14-year-old adolescent patient who had 2 impacted maxillary central incisors with distoangular root dilacerations. He also had an impacted maxillary left canine, with the crown completely overlapping the root of the lateral incisor, and insufficient space. The general dentist referred this patient because the maxillary central incisors had still not erupted 2 years after extraction of the retained deciduous incisors. A unilateral expander with a modified vestibular arch and an attachment spring on the right side was used to correct the posterior crossbite on the right side and improve the positions of the teeth. The expansion appliance was also applied as a high anchorage device to move the central incisors and the left canine into position during the initial stages. After this phase, fixed appliances were used to redistribute the space in the anterior maxillary region to create enough space for repositioning the impacted teeth. This procedure restored the normal appearance of the maxillary arch, with good periodontal health and without evidence of root resorption, apart from the distoangular root dilacerations of the 2 maxillary central incisors.

A retrospective study on the influence of maxillary canine impaction on premolar root morphology

OBJECTIVES

The root morphology of the maxillary first premolar differs from the other premolars by presenting a high incidence of separated roots. This study addressed the spatial conditions during root development as a possible influencing factor. Therefore, maxillary computed tomographic (CT) scans of patients with regularly erupted or impacted permanent canines were evaluated on the root morphology of the premolars.

METHODS

The following parameters were retrospectively analysed in 250 maxillary CT scans (100 patients with regular erupted permanent canines, 150 patients with at least one impacted permanent canine): sex, status of the canines (erupted/impacted), position of the impacted canines (buccal/palatal; vertically inclined inside/outside the dental arch/horizontally inclined) and root morphology of the premolars.

RESULTS

Of the patients, 68% with at least one impacted canine were female; the canine was impacted palatally in 75.6% and in a horizontally inclined position in 58.4%. In patients with an impacted canine, the number of first and second premolars with separated roots was significantly reduced on the ipsilateral as well as on the contralateral side (all p values < 0.01).

CONCLUSIONS

The present study detected an influence of maxillary canine impaction on the root morphology of all premolars, in that impaction and the associated surplus of space resulted in decreased root separation. This supports the hypothesis that root development is at least partly influenced by increased spatial conditions of the dental arch. However, root development can be regarded as a multifactorial event, influenced by space, direct mechanical interferences, as well as genetic predetermination. The retrospective nature of this observational study did not allow for conclusive differentiation between these factors. Alternatively, root separation and the mesial concavity of the first premolar may represent a path for canine eruption similar to the lateral incisor.

CLINICAL RELEVANCE

A single-rooted maxillary first premolar might represent an additional risk factor for canine impaction.

Panoramic radiological study to identify locally displaced maxillary canines in Bangladeshi population

Purpose

This study was performed to determine the prevalence of maxillary canine impaction on a basis of a single panoramic radiograph in Bangladeshi population.

Materials and Methods

A random sample of seven hundred panoramic radiographs was collected from the patient record of a dental clinic. All the selected panoramic radiographs were taken from January 2009 to August 2010 by a single panoramic radiograph machine with the same exposure time (19 seconds) for all radiographs. One hundred and twenty panoramic radiographs were excluded to minimize the selection bias. In a dim lit room, an observer assessed the radiographs on a standard radiographic light box. The position of the impacted maxillary canine was recorded in line with the longitudinal axis of a tooth using the edge of a metal ruler. Data were subsequently put on SPSS 11.5 software and chi-square (χ²) tests were applied to find out the association.

Results

Among 580 panoramic radiographs it was found that impacted maxillary canines were present in only 7 (1.2%) radiographs. A statistical significant difference was found between the age of the patients and the vertical position of the impacted canines (p=0.000) and between the age of the patients and the horizontal position of the impacted canines (p=0.003).

Conclusion

The prevalence was found to be low compared with the present study from the limitation of panoramic image. Further study needs to include three-dimensional imaging modality.

Incidence and effects of genetic factors on canine impaction in an isolated Jewish population

INTRODUCTION

The etiology of palatal canine impaction is multifactorial and includes a genetic contribution. The aim of this study was to find the incidence and effects of genetic factors on palatally impacted canines in a genetically isolated community of ultraorthodox Hassidic Jews of Ashkenazi decent.

METHODS

For this study, we retrospectively evaluated 1000 charts of Hassidic Jewish patients. Their distribution was 58% female and 42% male, with a mean age of 14 years.

RESULTS

From those patients, 49 (4.9%) were determined to have canine impaction. Of these 49, 69.4% had unilateral palatal impaction, 26.5% had bilateral palatal impaction, and 4.1% had unilateral labial impaction. The z-test of proportion showed that female patients have a greater percentage than males for unilateral palatal impaction (P <0.01) with left-side dominance (P <0.01).

CONCLUSIONS

Our results imply that genetics plays a significant role in maxillary canine palatal impaction. A genetically isolated Hassidic Jewish community can be a useful group to study the effects of genetic factors on various dental anomalies, including palatally displaced canines.

Extraction of primary (baby) teeth for unerupted palatally displaced permanent canine teeth in children

BACKGROUND

The permanent canine tooth in the upper (maxillary) jaw sometimes does not erupt into the mouth correctly. In about 1% to 3% of the population these teeth will be diverted into the roof of the mouth (palatally). It has been suggested that if the deciduous canine is removed at the right time this palatal eruption might be avoided.

OBJECTIVES

To evaluate the effect of extracting the primary maxillary canine on the eruption of the palatally ectopic maxillary permanent canine.

SEARCH STRATEGY

We searched the Cochrane Oral Health Group's Trials Register (to April 2008); CENTRAL (The Cochrane Library 2008, Issue 3); MEDLINE (1966 to April 2008); EMBASE (1980 to April 2008). There were no language restrictions. Authors of trials were contacted for further data.

SELECTION CRITERIA

Trials were selected if they met the following criteria: a randomised or quasi-randomised controlled trial, involving the extraction of the primary maxillary canine and assessing eruption/non-eruption of the palatally displaced maxillary permanent canine.

DATA COLLECTION AND ANALYSIS

Seven review authors independently, in duplicate, examined the studies found in the search. The primary outcome was the reported prevalence of eruption or non-eruption of the ectopic permanent canine into the mouth following observation or intervention. Results were to be expressed as risk ratios for dichotomous outcomes with 95% confidence intervals and mean differences for continuous outcomes. Heterogeneity was to be investigated, including both clinical and methodological factors.

MAIN RESULTS

The search identified 324 publications of which 295 were excluded after reviewing the abstract. Full articles were obtained for the remaining 31, of which 19 were non-English and required translation. Three reports of two randomised controlled trials were identified for possible inclusion in the review; however, the data in the publications were not presented in a form that could be usable and the authors have been contacted for further details.

AUTHORS' CONCLUSIONS

There is currently no evidence to support the extraction of the deciduous maxillary canine to facilitate the eruption of the palatally ectopic maxillary permanent canine. Two randomised controlled trials were identified but unfortunately, due to deficiencies in reporting, they cannot be included in the review at the present time.

Localization of impacted maxillary canines and observation of adjacent incisor resorption with cone-beam computed tomography

OBJECTIVE

The aim of this study was to investigate with cone-beam computed tomography (CBCT) the locations of impacted maxillary canines and resorption of neighboring incisors.

STUDY DESIGN

Two hundred ten impacted maxillary canines were analyzed using CBCT images. The locations of the impacted canines were assessed and angular and linear measurements were taken using NewTom proprietary software. In addition, root resorption of neighboring incisors was investigated.

RESULTS

Among these impactions, 45.2% were impacted buccal-labially, 40.5% were impacted palatally, and 14.3% in the midalveolus. The locations varied: mesial-labial impaction (n = 67), mesial-palatal impaction (n = 74), in situ impaction (n = 31), distal impaction (n = 12), horizontal impaction (n = 18), and inverted impaction (n = 8). Quantitive measurements further depicted these variations. Root resorption was present in 27.2% of lateral and 23.4% of central incisors, and 94.3% of these resorptions occurred where the impacted canines were in close contact with the incisors.

CONCLUSION

The location of impacted maxillary canines varies greatly in 3 planes, and the resorption of neighboring permanent incisors is common.

Palatal displacement of canines and maxillary skeletal width

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.

Periodontal concerns associated with the orthodontic treatment of impacted teeth

Impacted teeth are common and are often treated with orthodontic eruption, but periodontal problems associated with the process can evade detection. Profound destruction of the periodontium of an impacted tooth or adjacent teeth can occur. This case report describes the orthodontic eruption of 4 impacted canines in a 19-year-old woman. An open surgical approach was used. Within 6 months of treatment, the maxillary right canine and the lateral incisor experienced severe periodontal destruction, resulting in questionable prognoses for the teeth. Plaque control, periodontal architecture, and subgingival microflora were examined as local etiologic factors of periodontal destruction associated with orthodontic eruption of impacted teeth. Plaque control measures were evaluated, and the consequences of orthodontic tooth movement in the presence of inadequate plaque control were considered. Areas of periodontal architecture made vulnerable by the surgical exposure of the impacted teeth were identified, and the effect of orthodontic force on the periodontium was explored. An increase in putative periopathogens in the subgingival microflora after orthodontic appliance placement was observed. Microbiologic monitoring for pathologic levels of periopathogens and antibiotic therapy were considered. Orthodontic treatment of impacted teeth might require additional professional and personal plaque control measures, 3-dimensional diagnostic imaging, and control of putative periopathogens to preserve the health of the periodontium.

Radiographic factors affecting the management of impacted upper permanent canines

The aim of the investigation was to evaluate which radiographic factors influenced the orthodontists' decision whether to expose or remove an impacted upper permanent canine and was a retrospective, cross-sectional design. The sample consisted of all radiographic records of patients referred to the Orthodontic Department at Manchester University Dental Hospital with impacted upper permanent canines between 1994-1998 (n = 44). The following canine position measurements were made from the OPG: angulation to the midline, vertical height, antero-posterior position of the root, overlap of the adjacent incisor, and presence of root resorption of adjacent incisor(s). The labio-palatal position of the impacted canine was assessed from the lateral skull radiograph. Whether the impacted canine had been exposed and orthodontically aligned or removed was also recorded. Stepwise logistic regression analysis showed that the labio-palatal position of the crown influenced the treatment decision, with palatally positioned impacted canines more likely to be surgically exposed and those in the line of the arch, or labially situated, removed (P < 0.05). Additionally, as the canine angulation to the midline increased, the canine was more likely to be removed (P < 0.05). The orthodontists' decision to expose or remove an impacted upper permanent canine, based on radiographic information, seems to be primarily guided by two factors: labio-palatal crown position and angulation to the midline.

Treatment options for impacted teeth

BACKGROUND

A compilation of treatment options for impacted teeth is presented to assist dentists in discussing the sequelae of impacted teeth as well as the complications of treatment with their patients.

OVERVIEW

A differential diagnosis for an impacted tooth is not possible without clinical assessment. However, an ankylosed tooth or a tooth with failure of its eruption mechanism may be mistaken for an impacted tooth. This review of national and international dental texts, journals and publications concerning impacted teeth spans more than 50 years.

PRACTICE IMPLICATIONS

Treatment options for the management of impacted teeth are separated into four categories: observation, intervention, relocation and extraction. The indications, contraindications and complications of each option are presented. This information will help the clinician identify developmental conditions associated with an increased probability of tooth impaction and assess available treatment options.

Localization of the unerupted maxillary canine: how to and when to

Reasons for localizing impacted maxillary canines are outlined and methods of localization described. The favored method of radiographic localization is the parallax method (image/tube shift method). Tube shifts can be carried out in both the horizontal and the vertical planes. For a horizontal tube shift, two occlusal radiographs are recommended; for a vertical tube shift, a rotational panoramic radiograph and an occlusal radiograph are recommended. This latter combination is usually the combination of choice because the panoramic radiograph, which provides information about all the teeth in both arches, the two jaws, and the surrounding structures, is often taken as an initial radiograph and this combination only requires one additional exposure, the occlusal radiograph. To facilitate the interpretation of a vertical tube shift, the angle of the tube in the occlusal radiograph should be increased from the customary 60 degrees to 65 degrees to 70 degrees to 75 degrees. Less accurate methods of radiographic localization are to use (1) image magnification of the impacted maxillary canines and (2) image superimposition of the impacted maxillary canines on the central or lateral incisor. Reasons why periapical radiographs are not recommended to be used for a horizontal tube shift or for a vertical tube shift in combination with a panoramic radiograph are explained. Indications to suspect palatal impaction may occur in the future if the patient is less than 10 years of age, and indications to suspect impaction may have occurred if the patient is more than 10 years of age are discussed. Patient questionnaires are advocated to aid the clinician in anticipating palatal impaction, the most frequent impaction.