Palatal Canines Research Articles

172 Embryological and Developmental Understanding in Improving Outcomes of Canine Exposure

Abstract Aim 85% cases of canine impaction are palatal. This presentation reviews the surgical factors to consider in predicting outcomes for canine exposure. Age - Apexogenesis of the canine root completes by 16 years. Exposures should be considered before root completion. Where the patient is over 16y, a bracket & chain should be considered. Vertical level of impaction - Mcsherry’s rule of thirds suggests the Orthopantomogram can be used to grade the vertical level of impaction. Grade 2 and 3 impactions will most likely require a closed approach. Role of the follicle – The follicle is a source of RANK, CSF-1 and progenitor cells involved in bone remodelling and formation of root-bone surface. Therefore, during surgical exposure, the follicle should not be stripped. Ankylosis may occur from radical removal of dental follicle as bone deposition occurs in the created space. Orthodontic mobilisation should be considered within 4-6 weeks of exposure whilst the woven bone is to mineralise. Method Surgical outcomes were reviewed to assess these theories. Data was collected for the canine exposures done in the department over a 7-year period. The re-exposure rates is compared to the National re-exposure rate reported by Spencer et al. Results Over 500 palatal canines were exposed. 90% were successfully aligned. 0.6% cases required re-exposure. Spencer et al. reported a re-exposure rate of 3% for open exposures. Conclusions By applying the follicle preservation theory and considering age and level of impaction in surgical decision making, our service demonstrates that canine exposure can be carried out with predictable outcomes.

Association between sella turcica bridging and the impaction severity of palatally displaced canines: A retrospective study

This retrospective study aimed to investigate the association between the extent of the bridging and dimensions of sella turcica and the impaction severity of palatally displaced canines. Secondarily, any possible association between skeletal age and gender was evaluated. Panoramic and cephalometric radiographs of 94 patients (63 female, 31 male; 19 pre-peak, 75 post-peak) with palatally displaced canines were evaluated. Sector classification and α angle were used to determine the impaction severity of palatally displaced canines on panoramic radiographs. The distance from the cusp tip of the palatally displaced canines to the occlusal plane (d) and the extent of the bridging and dimensions of the sella turcica were evaluated on cephalometric radiographs. Sella turcica bridging and dimensions did not vary regarding the impaction severity of palatally displaced canines, but a significant association was found between sella turcica bridging and skeletal age (P= 0.038). Class II (33.3%) and Class III (12.0%) bridging was higher in postpubertal patients. No differences between females and males were detected for the extent of bridging and dimensions of the sella turcica. These findings indicate no association between sella turcica bridging and dimensions and the impaction severity of palatally displaced canines. Sella turcica bridging is more frequent in the postpubertal period, whereas gender does not influence sella turcica bridging. More studies are needed to evaluate if the extent of sella turcica bridging may be indicative of severely impacted palatal canines, which in turn would allow for careful monitoring of patients from an early age and for the clinician to take preventive measures.

3-D assessment of skeletal and dentoalveolar bilateral dimensions in unilateral impacted palatal canine cases - A CBCT study.

The aim of this study was to compare skeletal and dentoalveolar dimensions in subjects with maxillary unilateral impacted palatal canines versus the unaffected contralateral side using CBCT. Skeletal and dentoalveolar variables (Anterior alveolar ridge height, Anterior dentoalveolar height , nasal cavity width, basal nasal width, Lateral angulation of long axis of the incisors and canines with respect to the nasal horizontal plane, premolar to median raphe width, dimensions of lateral incisor and canine, root resorption of lateral incisors, crown-root angulation of lateral incisor, and sector classification of canine) were compared between the impacted and the contralateral sides. As the data had normal distribution, means were compared using students t test. The significance was set at p<0.05. The root resorption in lateral incisor was compared using Chi square test. Lateral angulation of long axis of canines, nasal cavity width, basal lateral width, and premolar to median raphe width were found to be significantly different. Maximum number fell in sector 4 (n = 23, 38.3%) in sector classification. Root resorption of lateral incisor on impacted side was insignificant. Skeletal and dento-alveolar dimensions vary between the impacted and non-impacted sides in unilateral palatal canine impaction cases. Canines on the impacted side were more mesially angulated compared to the non-impacted side. The nasal cavity width, basal lateral width and premolar to median raphe width were significantly less on the impacted side compared to the non- impacted side. Key words:Impacted canine, CBCT, skeletal dimensions, diagnosis, orthodontic treatment.

Comparison between Digital Casts and Cone Beam Computed Tomography for Measuring Maxillary Transverse Dimensions in Patients with Impacted Canines.

Cone beam computed tomography (CBTCT) scans (n = 45) and digital dental casts (n = 45) were both used to measure the maxillary transverse dimensions in patients with impacted maxillary canines. The objectives were to explore the associations of these dimensions with the impaction and patient characteristics, and to compare the measurements between these techniques. The maxillary width was measured on scans and casts at the Walaridge, and the intermolar width and interpremolar width levels were measured at the first and second premolars (measured from the buccal grooves and the palatal cuspids, and the palatal and lingual amelocemental junctions). Two examiners independently compared the measurements between the control quadrants (without impaction) and the case quadrants (with impaction) in patients with unilateral impactions, and between the unilateral and bilateral impaction groups. The interclass correlation coefficient (ICC) was calculated to assess the interexaminer reliability and paired or independent Student’s t-tests and ANOVAs were used for comparisons. The ICCs were 0.887 and 0.919, globally, for the measurements on the CBCT scans and casts, respectively, which indicates the excellent interexaminer reliability. On the CBCT scans, statistically significant differences were found between the case and control quadrants in the transverse measurements at the lingual level on the upper first molars, and at the WALA ridge level on the upper second premolars (p < 0.05) in the unilateral impaction group. Significant differences were found between the case quadrants in the unilateral versus the bilateral groups at the WALA ridge on the second premolars in casts (p < 0.05), and at the lingual point on the first molars on the CBCT scans (p < 0.05). No statistically significant differences in the transverse measurements were observed between the impacted buccal and palatal canines on either the casts or CBCT scans. To the best of our knowledge, this is the first study to compare the transverse measurements between digital models and CBCT scans.

Interarch Traction Strategy for Palatal Cuspid Impactions

To disimpact a palatally impacted canine using a novel, compliance-dependent technique. Orthodontic traction of palatally impacted teeth warrants careful mechanical strategies to avoid complications that include r oot damage to adjacent teeth and r esorptions. Sound biomechanical control to avoid these side effects is considered paramount in planning the traction. The palatally impacted canine was pulled into the arch with the aid of a modified power arm on the exposed canine and a miniscrew on the lower arch. The impacted canine was successfully brought into occlusion within 11 months. This paper highlights the use of a simple strategy using interarch mechanics and temporary anchorage devices (TADs) to aid in the safe mechanical eruption of impacted palatal canines without the need to bend complex wire designs.

LOCALISATION OF IMPACTED MAXILLARY CANINES USING PANORAMIC RADIOGRAPHS; A NOVEL TECHNIQUE THAT USES BICONDYLAR LINE AS REFERENCE

Purpose: To localize the impacted maxillary canines in the alveolus using panoramic radiographs.&#x0D; Methods: The present study was a retrospective radiographic chart review of 81 patients with 92 impacted maxillary canines from the Department of oral and maxillofacial surgery, PMS College of Dental Science and Research, Trivandrum. Of the 92 impacted maxillary canines, 57 were impacted buccally and 35 were impacted palatally. The ratio formed between the distance from the crown tips of impacted maxillary canine and ipsilateral central incisors were measured. We used these measurements to predict the position of the tooth and correlate this prediction with the actual approach used during surgery.&#x0D; Results: The ratio of the canines in the buccal group was 1.35± 0.144(range, 1.04 to 1.88). Palatal group has got little higher values with the mean ratio of 1.93± 0.52 (range, 1.29 to 3.22). The ratios were distributed over a scatter plot (Figure 2). The diagnostic test characteristics for the values greater than 1.45, greater than 1.50 and greater than 1.55 were taken. These values were used for constructing a receiver operating curve. There was a better sensitivity and specificity for the values greater than 1.50(sensitivity: 94.29%, specificity: 91.38%). Logistic regression showed that if the ratio is more than 1.50, there is a chance of 19.3 times to get a canine palatally impacted.&#x0D; Conclusion: There is significant difference in the vertical position of buccal and palatal canines in the alveolus. Based on our values we found that palatally impacted canines are restricted more superiorly.&#x0D; Keywords: Localization, impacted maxillary canines, panoramic radiographs, bicondylar line

Open versus closed surgical exposure of canine teeth that are displaced in the roof of the mouth.

Palatally displaced canines or PDCs are upper permanent canines, commonly known as 'eye' teeth, that are displaced in the roof of the mouth. This can leave unsightly gaps, cause damage to the surrounding roots (which can be so severe that neighbouring teeth are lost or have to be removed) and, occasionally, result in the development of cysts. PDCs are a frequent dental anomaly, present in 2% to 3% of young people.Management of this problem is both time consuming and expensive. It involves surgical exposure (uncovering) followed by fixed braces for two to three years to bring the canine into alignment within the dental arch. Two techniques for exposing palatal canines are routinely used in the UK: the closed technique and the open technique. The closed technique involves uncovering the canine, attaching an eyelet and gold chain and then suturing the palatal mucosa back over the tooth. The tooth is then moved into position covered by the palatal mucosa. The open technique involves uncovering the canine tooth and removing the overlying palatal tissue to leave it uncovered. The orthodontist can then see the crown of the canine to align it. To assess the effects of using either an open or closed surgical method to expose canines that have become displaced in the roof of the mouth, in terms of success and other clinical and patient-reported outcomes. Cochrane Oral Health's Information Specialist searched the following databases: Cochrane Oral Health's Trials Register (to 24 February 2017), the Cochrane Central Register of Controlled Trials (CENTRAL) (in the Cochrane Library, 2017, Issue 1), MEDLINE Ovid (1946 to 24 February 2017), and Embase Ovid (1980 to 24 February 2017). The US National Institutes of Health Ongoing Trials Register (ClinicalTrials.gov) and the World Health Organization International Clinical Trials Registry Platform were searched for ongoing trials. No restrictions were placed on the language or date of publication when searching the electronic databases. We included randomised and quasi-randomised controlled trials assessing young people receiving surgical treatment to correct upper PDCs. There was no restriction on age, presenting malocclusion or type of active orthodontic treatment undertaken. We included unilaterally and bilaterally displaced canines. Two review authors independently screened the results of the electronic searches, extracted data and assessed the risk of bias in the included studies. We attempted to contact study authors for missing data or clarification where feasible. We followed statistical guidelines from the Cochrane Handbook for Systematic Reviews of Interventions for data synthesis. We included three studies, involving 146 participants. Two studies were assessed as being at high risk of bias.The main finding of the review was that the two techniques may be equally successful at exposing PDCs (risk ratio (RR) 0.99, 95% confidence interval (CI) 0.93 to 1.06; three studies, 141 participants analysed, low-quality evidence).One surgical failure was due to detachment of the gold chain (closed group). One study reported on complications following surgery and found two in the closed group: a post-operative infection requiring antibiotics and pain during alignment of the canine as the gold chain penetrated through the gum tissue of the palate.We were unable to pool data for dental aesthetics, patient-reported pain and discomfort, periodontal health and treatment time; however, individual studies did not find any differences between the surgical techniques (low- to very low-quality evidence). Currently, the evidence suggests that neither the open or closed surgical technique for exposing palatally displaced maxillary canine teeth is superior for any of the outcomes included in this review; however, we considered the evidence to be low quality, with two of the three included studies being at high risk of bias. This suggests the need for more high-quality studies. Three ongoing clinical trials have been identified and it is hoped that these will produce data that can be pooled to increase the degree of certainty in these findings.

Can radiographic features predict the difficulty of open exposure of palatal canines?

AbstractAimThe aim of this study is to determine if radiographic features are predictive of surgical difficulty of open exposure of palatal canines using a tissue sacrifice method.Materials and methodsThis is a prospective case series comparing features observed on preoperative panoramic radiographs and other variables to both surgical duration and the surgeons reported difficulty. Radiographic features included height, sector (overlap of adjacent incisor) and angulation of the impacted canine. Clinical variables recorded were patient age and gender, side of impaction, anaesthetic choice, if the canine was palpable, and patient cooperation. A stepwise linear regression analysis was used to relate clinical and radiographic variables to treatment duration and assessed difficulty. Inter‐ and intra‐examiner reliability were assessed with Kappa statistics.ResultsForty‐nine patients with a total of 55 palatal canine exposures were included. The mean duration of exposure was 4 min and 5 s with a range of 45 s to 8 min and 50 s. Surgical duration was correlated to a subjective grade of surgical difficulty recorded on a visual analogue scale by the surgeon (Pearson's correlation coefficient 0.76). Three predictors of increased surgical duration were identified as anaesthetic choice, height and angulation of impaction. The linear regression had an accuracy of 30.5%.ConclusionsRadiographic features had a small predictive value in determining duration of open palatal canine exposure. Both increased height and angulation to the midline were associated with longer procedures. The use of local anaesthetic was associated with a longer surgical duration compared with general anaesthetic.

Comparison of methods for localization of impacted maxillary canines by panoramic radiographs

The objective of this study was to compare three methods for localization of impacted maxillary canines using only conventional panoramic radiographs. The panoramic radiographs of 94 patients (102 impacted maxillary canines) were reviewed and evaluated using the methods magnification, angulation and superimposition. The actual positions of them were decided with cone beam CT images. The predicted positions of impacted canines from the magnification and angulation methods were compared using the McNemar χ(2) test. Sensitivity, specificity, accuracy, positive-likelihood ratio and negative-likelihood ratio were calculated. The canine-incisor index values and α angles of palatally and bucally non-rotated impacted canines were compared using the Mann-Whitney U test. The statistical analysis revealed that there was a significant difference between the magnification and angulation methods (p < 0.01). Using the magnification method, 68.00% of buccal canines and 69.57% of palatal canines could be localized correctly. The results of the angulation method were 28.57% and 84.91%, respectively. The sensitivity of the angulation method for buccal canines was very low. In the superimposition method, 82.98% of the superimposing samples were palatal. The magnification and angulation methods were not reliable methods for locating the impacted canine with a single panoramic radiograph. Magnification was more successful than the angulation method. Further research is needed on the magnification method. The image superimposition method could be used as an adjunct to others.

Orthodontic treatment for a patient with hypodontia involving the maxillary lateral incisors

Developmental absence of maxillary lateral incisors is not uncommon in orthodontic patients. Treatment depends on a number of factors, including skeletal pattern, type of malocclusion, overjet, and the shape and color of the canines. Management can be broadly divided into space closure, space opening or redistribution, and prosthetic replacement. The purpose of this article was to report the treatment of a girl with an Angle Class I malocclusion with missing maxillary lateral incisors and severe crowding in the mandibular labial segment. Treatment included preadjusted fixed appliances, extraction of the mandibular first premolars, and space closure of the maxillary labial segment space with the canines substituted for the maxillary lateral incisors.

How to…mechanically erupt a palatal canine

Management of ectopic permanent maxillary canines represents one of the greatest challenges to orthodontists. This paper outlines a variety of techniques and mechanics which may facilitate expedient, predictable and safe eruption of palatal canines. While each method may be useful in isolation, the varying presentations of palatal canines ensure that the ability to apply an array of techniques is essential if successful outcomes are to be consistently achieved.

Anaesthetic choice for palatal canine exposure

AbstractAim: To determine if predicted difficulty of exposure of palatally displaced, unerupted canines assessed by radiographic score had influenced the choice between a local or a general anaesthetic procedure in adolescents.Materials and methods: This was a retrospective analysis of patients undergoing surgical exposure of palatal canines between December 2005 and June 2008 in a dental hospital setting. A total of 56 subjects, for whom complete records were available, aged 16 years or under and assessed and treated by one surgeon, were included. The predicted degree of difficulty of exposure was graded from preoperative radiographs based on three criteria; the horizontal and vertical position of the crown, and the canine angulation (possible score range 3–11: higher score = more difficulty). The radiographic scores and patient age for the local anaesthetic and general anaesthetic groups were compared using Student's unpaired t‐tests. Other variables including gender, other surgical treatment required and unilateral or bilateral exposure were evaluated by chi‐squared analysis.Results: Thirty‐one (55%) patients were treated with local anaesthetic and 25 (45%) with general anaesthetic, the mean age was 13.7 years. The mean radiographic scores did not differ between groups being 7.53 and 7.36 for the local anaesthetic and general anaesthetic groups, respectively. Chi‐squared analysis showed concurrent other surgical treatment to be the only statistically significant factor in anaesthetic choice.Conclusions: Difficulty of canine exposure is not a significant factor in anaesthetic choice for adolescents, other concurrent surgical treatment appears a more significant factor in anaesthetic choice in this group.

Exposure of unerupted palatal canines: A survey of current practice in the United Kingdom, and experience of a gingival-sparing procedure

Patients with impacted ectopic canines often present to Orthodontic and Oral and Maxillofacial units, with 85% being displaced palatally. Current orthodontic opinion suggests that the creation of adequate space ultimately allows the spontaneous eruption of most impacted canines, but we are often requested to operate to facilitate their eruption. There are several approaches, techniques that vary depending on whether orthodontically assisted or spontaneous eruption is expected. There are few publications that describe either the techniques or their merits. We have used a gingival-sparing technique for more than 10 years in this unit. To determine current practice, we carried out a national postal survey of consultant oral and maxillofacial surgeons and staff grade/associate specialists. A total of 564 questionnaires were sent, and 353 replies were received (63%). There was considerable variation in the design of mucosal flaps used for exposure of the canines. Only 9% of clinicians avoided the gingival margin of the adjacent erupted teeth during operation. We describe this unit's practice of sparing the gingival margins, and highlight the merits of this technique.

Dental Anomaly Patterns (DAP)

Dental Anomaly Patterns (DAP)

Influence of Radiographic Position of Ectopic Canines on the Duration of Orthodontic Treatment

To investigate the influence of radiographic position of palatally impacted canines on the length of treatment for orthodontic alignment. Treatment records of 45 consecutive successfully treated patients (36 unilateral, 9 bilateral) with ectopic palatal canines treated with surgical exposure and orthodontic traction were analyzed. The sample was based on orthodontic referrals over a 3-year period in Kent and Canterbury Hospital, UK. The duration of treatment was related to radiographic parameters including the height of the impacted canine, angulation of the long axis to the upper midline, mesiodistal position of the canine tip relative to the midline and adjacent incisors, and the anteroposterior position of the canine root apex. Using multiple stepwise regression analysis, the horizontal position of the canine crown relative to adjacent teeth and maxillary dental midline showed a statistically significant correlation with the duration of treatment (P =.042), explaining 7.7% of the overall variance. However, treatment duration was found to be independent of the initial canine angulation (P = .915), vertical height (P =.065), and position of the canine apex (P = .937). Accurate prediction of treatment duration for orthodontic alignment of palatally impacted maxillary canines is difficult. However, the mesiodistal position of the canine may be a useful predictor of treatment duration.

An audit of referral practice for patients with impacted palatal canines and the impact of referral guidelines

To assess referral practice for patients presenting with impacted palatal maxillary canines, and to develop and evaluate the effectiveness of referral guidelines. Prospective clinical audit. Southend and Basildon district general hospitals. The 'gold' standard was identified as regular dental attenders with unerupted palatal canines being referred by 12 years old, with a wait of no longer than 20 weeks from referral to assessment. Data were collected and compared to the defined standard. An algorithm outlining the correct management was developed and distributed to all local dentists. The cycle was repeated for a similar time period. Ninety-eight per cent of patients were seen within 20 weeks during both cycles while the referrals increased from 85 to 109 patients. The percentage of patients referred by 12 years of age increased from 16.5% to 27% (p = 0.09). During the first cycle 82% of patients presented with retained deciduous maxillary canines. This was reduced to 76% during the second cycle (p = 0.29). Referral practice was generally poor when compared to the recommended good practice. More patients were referred after distribution of the guidelines, but the percentage referred by the recommended age was not statistically significantly improved.

Reliability of a method for the localization of displaced maxillary canines using a single panoramic radiograph.

The present study was initiated to determine the validity and reproducibility of a method previously reported for localization of displaced maxillary canines by panoramic radiographs. Eleven dental specialists (five orthodontists, five surgeons, and one radiologist) and five (final year) dental students were asked to interpret initial panoramic radiographs of 20 patients with 26 unerupted canines. The method contends that, provided that the radiographic image of the unerupted canines superimposes on the root of the lateral incisor at a height coronal to the apical third, a ratio between the widest mesiodistal dimension of the affected canine and the homolateral central incisor [Canine-Incisor Index (CII)] of more than 1.15 indicates palatal displacement. Among the observers, the measurement error was small, insufficient to cause overlap between the ranges of values for the CII of buccal and palatal canines. Inter-observer reproducibility was high. Without exception, all observers correctly diagnosed the location of each of the impacted canines. The CII cut-off point of 1.15, which was arbitrarily chosen in the previous work, was shown to be valid to differentiate buccal from palatal displacement. The present method is rapid, simple, accurate, and easily taught to dental students or dental specialists, with the simplest of initial instruction. While confirmations with other radiographic techniques is strongly advised before a definitive treatment is undertaken, this method has merit in providing more information than has been available from the panoramic radiograph hitherto, to satisfy the needs of an initial orthodontic consultation.

The use of panoramic radiographs to localize displaced maxillary canines

Objective. The purpose of this investigation was to develop a reliable method of diagnosing the position of a displaced maxillary canine on the basis of a single panoramic radiograph. Study design. A total of 115 panoramic radiographs depicting 164 displaced maxillary canines were evaluated. The ratio of the width of the displaced canine to the width of the homolateral central incisor (the canine-incisor index) and the ratio of the width of the displaced canine to the width of the contralateral canine (the canine-canine index) were calculated. The height of the crown of each displaced canine was classified in the vertical plane, relative to the adjacent incisor, as apical, middle, or coronal. Results. There was an overlap in the canine-incisor index ranges of the buccal (0.94-1.45) and palatal (1.15-1.29) canines in the apical zone. In the middle and coronal zones, a clear difference could be seen between the canine-incisor indices of labially (0.78-1.11) and palatally (1.15-1.7) located canines. A cut-off point of 1.15 was determined. Conclusions. Provided that vertical restriction and the canine-incisor index are used, the panoramic radiograph can serve as a useful indicator for determining the position of an unerupted maxillary canine. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1999;88:511-6)

Eruption of palatal canines following surgical exposure: a review of outcomes in a series of consecutively treated cases.

The records of a consecutive series of 72 patients who had undergone excisional exposure of one or both palatally displaced canines were reviewed. The purpose was to ascertain whether the canine(s) erupted spontaneously following surgery, whether orthodontically-assisted eruption was required or whether the procedure failed completely indicating the need for re-exposure. The results of the study suggest that the majority of canines will erupt once exposed and of those that fail to erupt completely most will still remain exposed to a sufficient extent to allow attachments to be bonded to the palatal surface.

The palatal canine and the adjacent lateral incisor: a study of a west of Scotland population.

The hypothesis that palatally-displaced canines are associated with smaller than average lateral incisors or with congenital absence of adjacent lateral incisors was tested on a West of Scotland population. A retrospective study of the records of orthodontic patients attending Glasgow Dental Hospital was carried out. One-hundred-and-eighty-two subjects with palatally displaced canines were identified. The tooth length of lateral and central incisors was measured on radiographs and the crown widths of lateral incisors were measured on study casts. One-hundred-and-six extracted maxillary lateral incisors were examined to allow more accurate measurement of crown width and root length than was possible from radiographs. An association was sought between the size of the lateral incisor or its absence, the position of the adjacent maxillary canine, and between crown size and root length of the lateral incisor. The conclusions supported the hypothesis that there is a weak association between palatally displaced maxillary canines and lateral incisors of smaller than average crown width. There was weak support for the association between palatal canines and absence of the adjacent lateral incisor. There was no correlation between lateral incisor crown width and root length.