Palatally Displaced Canines Research Articles

Extraction of the deciduous canine as an interceptive treatment in children with palatal displaced canines - part I: shall we extract the deciduous canine or not?

To analyse whether extraction of the deciduous canines facilitates eruption of the palatal displaced canines (PDCs), and to analyse root resorption in adjacent teeth caused by the PDCs. Eligibility criteria for participants were as follows: children at age 10-13 years with either maxillary unilateral or bilateral PDC, persisting deciduous canine and no previous experience of orthodontic treatment. Sixty-seven patients (40 girls and 27 boys; age: mean ± standard deviation: 11.4±1.0) with unilateral (45) or bilateral (22) PDCs were consecutively recruited and randomly allocated using permuted block randomization method to extraction or non-extraction. No patients dropped out after the randomization or during the study. Patients underwent a clinical examination and cone beam computed tomography at baseline (T0), after 6 (T1) and 12 months (T2). The total observation time was 24 months. Outcome measures were eruption, positional changes, length of time until eruption, and root resorption of adjacent teeth. The baseline images were measured blinded while the 6- and 12-month control images were not, since it was not possible to blind the extracted canine. Significantly more spontaneous eruptions of the PDCs were seen in the extraction group (EG) than in the control group (CG), with rates of 69 and 39 per cent, respectively, with a mean eruption time of 15.6±5.6 months in the EG and 18.8±5.8 months in the CG. Significant differences in changes between the groups, in favour of the EG, were found for all variables except for the sagittal angle. In the EG, the changes in the distances of the canine cusp-tip were larger during the first 6 months, while the change of apex was larger between 6 and 12 months. There were no significant differences in resorption of adjacent teeth between the groups. Imputation values were used for the PDCs who had erupted at T2, since no x-rays were taken for ethical reasons, which might have given uncertainty in the positional changes between T1 and T2. Extraction of the deciduous canine is an effective treatment in patients with PDCs. Significantly more positional changes and shorter mean eruption time were seen in the EG. Resorptions of lateral incisors were seen in both groups, but none exceeded grade 2 (resorption up to half of the dentine thickness to the pulp). This trial was registered in "FoU i Sverige" (http://www.fou.nu/is/sverige), registration number: 40921. The protocol was not published before trial commencement.

A New Appoaroch in Diagnosis of Palatally Impacted Maxillary Canine in Orthodontic Patient by Cone Beam Computed Tomography (CBCT) - A Case Report

In recent years cone beam computed tomography (CBCT) has become a widely accepted radiographic tool for diagnosis, treatment planning and follow-up in dentistry .3D imaging has improved diagnostic efficiency and the practice of dentistry in a variety of ways; from routine evaluation to complex analysis of unusual pathology and congenital deformities, the technology available today makes dentistry better, and easier, and more accurate. The most recognized need for CBCT imaging in orthodontics is that of impacted canine evaluation. In this article a patient having impacted left maxillary canine is evaluated by the 3D CBCT and found beneficial particularly in terms of anatomical detail root resorption and the labiolingual relationships of the impacted tooth with the roots of neighboring teeth, in addition to determining the pathway for biomechanical resolution. Linear and angular measurements on CBCT images are accurate and precise and can be used to assess the exact position of palatal displaced canines.

The management of palatally displaced maxillary canines: Considerations and challenges

This article opens with a recognition that ectopic maxillary canines may lead to frank impactions requiring a coordinated and multidisciplinary approach to their surgical/orthodontic management and the potential benefit of managing canine ectopia, particularly palatally displaced canines, more conservatively in their pre-eruptive ectopic positions in an effort to avoid impaction. The prevalence of palatally displaced canines (PDC) in various populations and corroborating as well as competing or conflicting opinions of etiology are briefly reviewed. Some of the traditional as well as relatively newer strategies and associated investigations of managing pre-eruptive palatally displaced maxillary canines are discussed, and the imaging techniques utilized to identify and locate ectopic maxillary canines are also discussed. Early detection of ectopic canines must include at the very least panoramic and/or periapical radiographs as part of any mixed dentition orthodontic examination and assessment. The sometimes unpredictable continued path of the ectopic maxillary canine poses clinical and ethical issues to the clinician when developing treatment strategies as part of any overall orthodontic treatment plan for young patients presenting with maxillary canine ectopia. The need for more thoughtful and carefully designed randomized clinical trials with a greater emphasis on subject sample scrutiny is strongly recommended to add much needed clarity to the clinical management of ectopic maxillary canines.

Maxillary Impacted Canines: A Clinical Review

Impacted teeth are those with a delayed eruption time or that are not expected to erupt completely based on clinical and radiographic assessment. Palatal displacement of the maxillary canines is defined as the developmental dislocation to a palatal site often resulting in tooth impaction requiring surgical and orthodontic treatments. Impacted permanent maxillary canine occur in 1-2% of the population. The Occurrence of impacted permanent maxillary canines are; 85% palatal and 15% labial. The prevalence of palatally displaced canines (PDC) fluctuates between 0.8-5.2%. Palatally erupting or impacted maxillary canines occur twice often in females than males, and are five times more common in Caucasians than Asians. Of all patients with maxillary impacted canines, 8% have bilateral impactions.DOI: http://dx.doi.org/10.3126/ojn.v3i1.9285 Orthodontic Journal of Nepal, Vol.3, No.1, 2013: 63-68

Cone-beam computed tomography for assessment of palatal displaced canine position: A methodological study

To assess the inter- and intraexaminer reliability of a measurement method for evaluation of eruption angles and position of palatal displaced canines (PDCs) with cone-beam computed tomography (CBCT) images and to test the validity of the measured angles on a dry skull. Twenty patients (eight boys, 12 girls; age 11.4±1.2 years) were randomly chosen among 67 patients from a study evaluating the interceptive effect of extracting the deciduous canine in children with PDCs. In total, 60 images were analyzed, because each patient had three CBCT examinations (baseline, 6-month control, and endpoint). Two observers assessed the following measurements twice: mesioangular and sagittal angle, vertical position, canine cusp tip, and canine apex to dental arch. The validity of the angular measurements was tested against angular measurements on a dry skull using mathematical formulations. The inter- and intraexaminer mean differences for angular and linear measurements were all low and statistically insignificant (P>.05). The mean differences between the physical and 3D measurements were 0.5±0.39 mm for the sagittal angle and 0.22±0.19 mm for the mesioangular angle. Linear and angular measurements on CBCT images are accurate and precise and can be used to assess the precise position of a PDC.

Periodontal health of palatally displaced canines treated with open or closed surgical technique: A multicenter, randomized controlled trial

The aim of this study was to investigate differences in the periodontal outcomes of palatally displaced canines (PDC) exposed with either an open or a closed surgical technique. A multicenter, randomized controlled trial was undertaken in 3 hospitals in the United Kingdom, involving 2 parallel groups. Patients with unilateral PDC were randomly allocated to receive either an open or a closed surgical exposure. Periodontal health was assessed 3 months after removal of fixed appliances. Parameters measured included clinical attachment levels, recession, alveolar bone levels, and clinical crown height. Data from 62 participants (closed, 29; open, 33) were analyzed. There was no difference between PDC exposed with an open vs a closed surgical technique (mean difference, 0.1 mm; 95% confidence interval [CI], -0.2-0.5). There was, however, a statistical difference in mean attachment loss between the operated and unoperated (contralateral) canines (mean difference, 0.5 mm; 96% CI, 0.4-0.7; P<0.001). Twenty of the 62 subjects had some recession on the palatal aspect of the operated canine, whereas only 4 subjects had some visible root surface on the palatal aspect on the unoperated side (P= 0.001). There is a periodontal impact when a unilateral PDC is exposed and aligned. This impact is small and unlikely to have clinical relevance in the short term; however, the long-term significance is unknown. When the open and closed techniques were compared, no difference in periodontal health was found.

Dental arch parameters of the displacement and nondisplacement sides in subjects with unilateral palatal canine ectopia.

To compare arch perimeter and teeth size, number, and shape between the two sides of the dental arch-the canine displacement side (DS) and the nondisplacement side (NDS)-in subjects with unilateral palatally displaced canine (PDC). Orthopantomograms (OPTs) of 240 subjects with unilateral PDC and 240 OPT matching controls were used. Additionally, study casts of 100 study subjects and 100 controls were used. The age of subjects ranged between 14 and 25 years. Dental casts were digitized and several parameters were recorded. The transverse width from midpalatal line to the buccal segment and the palatal area on the DS was larger than that in the NDS (P < .05 to .001), with no difference in tooth size between both sides. Maxillary second premolars, canines, and lateral incisors in the PDC group were smaller than those in control group. Peg-shaped lateral incisors were significantly more frequent in the study group (P < .001). The transverse width of the DS was larger than that of the NDS. Both sides were generally smaller than those of the control group. Tooth size in the DS was comparable to that in the NDS but smaller than those of the control group. A missing or peg-shaped lateral incisor was the most common reported anomaly.

Dental anomalies and clinical features in patients with maxillary canine impaction

To analyze the prevalence, distribution, clinical features, and relationship with dental anomalies of maxillary canine impaction. The complete pretreatment records of 1674 orthodontic patients were examined. Subjects with maxillary impacted canines were divided into two study groups: a palatally displaced canine (PDC) group (114 patients) and a buccally displaced canine (BDC) group (37 patients). These were compared to a control group of 151 patients who were randomly selected from the initial sample without maxillary canine impaction. The significance of associations between canine impaction and dental and clinical features and anomalies was examined with the chi-square test. PDC patients presented with normal overjet and facial profile and a lower degree of dental arch crowding in comparison to the control patients. PDC patients showed a higher prevalence of impaction of other teeth, dental aplasia, transposition, and peg-shaped maxillary lateral incisors (odds ratios 3.3, 2.6, 8.3, and 5.8, respectively). PDC was frequently the only orthodontic problem of patients. BDC group patients did not present with notable differences in clinical and dental features or dental anomalies compared to control subjects.

Palatally displaced maxillary canines: factors influencing duration and cost of treatment

The purpose of this retrospective study was to assess the relationship between the initial position of palatally displaced canines (PDCs) on panoramic radiographs and the duration of the orthodontic treatment and further to estimate the costs of the treatment. Data from panoramic radiographs and patient records of 66 consecutive patients (mean age 14.9 ± 1.7 years) with PDC were analysed. The initial position of the canine, the distance between the canine cusp tip and the occlusal plane, and the inclination of the canine were significantly associated with treatment duration both unadjusted and adjusted for background characteristics. The average estimated cost of the treatment of PDC was €3200 per case. The total annual cost for treatment of PDC in Sweden may therefore be estimated at €600,0000. In this study, duration of treatment averaged 17 months for canines displaced in impaction zone 1 or 2, 2.6 [95% confidence interval (CI) -1.0 to 6.2] months longer for those in impaction zone 3, and 7.6 (95% CI 4.1-11.1) months longer for canines displaced in impaction zone 4 or 5. This information makes it easier, through study of the panoramic radiograph, to estimate the duration of treatment and to give patients more precise information about the expected length of their treatment.

Dental age assessment in patients with maxillary canine displacement

The aims of this study were to investigate the relationship between dental age and maxillary canine displacement with 2 methods, to study differences in dental development between the displaced and nondisplaced sides, and to investigate sex differences in dental development in the studied groups. Two hundred forty subjects were recruited for this study. They were divided into 2 groups: the palatally displaced canine group (87 girls, 33 boys) and the buccally displaced canine group (81 girls, 39 boys). Dental ages were assessed by using the 2 methods. Delayed dental development was associated with subjects with palatally displaced canines only, whereas those with buccally displaced canines had comparable dental development to that of the control group. Sex differences in the 3 groups were found; girls had more pronounced delayed dental development in all groups according to both methods. With unilateral palatally displaced canines, the displacement side showed delayed dental development compared with the side of nondisplacement (P = 0.002). The development rates of the displaced and nondisplaced sides were comparable in the subjects with unilateral buccally displaced canines. Palatal and buccal canine displacements are 2 distinct entities; delayed dental development plays a role in the etiology of palatal canine displacement, but not in buccal canine displacement.

A Controlled Study on Diagnostic and Prognostic Measurements of Palatally Displaced Canines on Lateral Cephalograms

ObjectivesThe aim of this prospective controlled study was to determine the role that the lateral cephalogram can play in the detection of palatally displaced canines (PDCs). Materials and methodsThe study was comprised of 85 subjects in the late mixed dentition. Thirty-five subjects had PDCs (either unilateral or bilateral) identified on the panoramic radiograph (PDC group), and 50 subjects presented with a normal pathway of upper permanent canine eruption as assessed on panoramic radiographs (No-PDC group). Linear and angular measurements on the lateral cephalograms concurrent with panoramic radiographs were compared between the PDC and No-PDC group statistically. ResultsAll angular measurements that incorporated the main axis of the canine (to Frankfort horizontal, to the palatal plane, or to the axis of the central incisor) were significantly smaller in the PDC group (p<0.001). In terms of linear measurements, both the distance from the tip of the canine to the vertical axis of the central incisor parallel to Frankfort horizontal and the distance from the tip of the canine to the anterior alveolar ridge parallel to Frankfort horizontal showed significantly larger values in the PDC subjects than in normal controls. On the contrary, the vertical distance from the tip of the canine to the functional occlusal plane did not reveal any significant difference between the PDC and the No-PDC group. ConclusionsEarly diagnosis of PDC is essential in order to avoid the occurrence of final canine impaction. If 3-D images of a displaced canine cannot be acquired, a lateral cephalogram can be a useful tool for the early detection of PDC in the late mixed dentition. The angle between the vertical axis of the canine and the palatal plane demonstrate diagnostic value when assessing PDCs. Values for this angle smaller than 102 degrees can indicate the presence of PDC.

Dentoskeletal characteristics in patients with palatally and buccally displaced maxillary permanent canines

The aim of this retrospective study was to analyse dentoskeletal characteristics in patients with eruption disturbances of the maxillary permanent canines. Pre-treatment panoramic radiographs and lateral cephalograms of 636 consecutive orthodontic patients were assessed. The control group included 456 patients with physiologically erupted maxillary permanent canines (261 females and 195 males, mean age 12.6 and 12.4 years, respectively). The other groups comprised 144 subjects with palatally displaced canines (PDCs) (92 females and 52 males, mean age 14.2 and 14.7 years, respectively) and 36 patients with buccally displaced canines (BDCs) (16 females and 20 males, mean age 12.4 and 12.8 years, respectively). The selected dentoskeletal parameters were compared with classic cephalometric norms using the method of analysis of variance, chi-square, and Fisher's exact tests. The PDC patients showed a significantly more prognathic maxilla, a significantly more frequent occurrence of skeletal class I, retroinclination of maxillary central incisors, hypodivergent relationship, and mandibular anteriorotation and less frequent posteriorotation. A significantly more frequent retrognathic maxilla and skeletal class III and less frequent retroinclination of the maxillary central incisors were found in the BDC patients. The results of this study indicate the existence of different facial morphology and more likely also etiopathogenesis of eruption disturbances of the canines in the PDC and BDC patients.

Pain, discomfort, and use of analgesics following the extraction of primary canines in children with palatally displaced canines

BACKGROUND. Pain following the extraction of the primary canine in children with palatally displaced canines (PDC) as an interceptive treatment has not been investigated. AIMS. To describe pain, discomfort, dental anxiety, and use of analgesics following the extraction of primary canines in children with PDC. DESIGN. Forty-four children, aged 10-13 with PDC, were included. Pain intensity, discomfort, and analgesic consumption were rated the first evening and 1 week after the extraction of the primary canine. Dental anxiety was assessed pre-extraction, using the dental anxiety scale (DAS). A matched reference group also completed the DAS. RESULTS. No significant differences were found between the study and the reference group regarding the pre-extraction assessments. Post-extraction pain and discomfort was low. The experience of the injection was graded worse than the extraction, and more pain was rated at the evening post-extraction than during the extraction. Analgesics were used only the first evening. High correlation was detected between DAS and pain during injection and extraction. CONCLUSIONS. The experience of pain and discomfort during and after extraction of the primary canines is low, despite that 42% of the children used analgesics. Therefore, appropriate analgesics and recommendation doses pre- and post-extraction should be prescribed.

Effect of rapid maxillary expansion and transpalatal arch treatment associated with deciduous canine extraction on the eruption of palatally displaced canines: A 2-center prospective study

Our aim was to investigate the effect of rapid maxillary expansion and transpalatal arch therapy combined with deciduous canine extraction on the eruption rate of palatally displaced canines (PDCs) in patients in the late mixed dentition in a 2-center prospective study. Seventy subjects were enrolled based on PDCs diagnosed on panoramic radiographs. The treatment group (TG, 40 subjects) underwent RME followed by TPA therapy and extraction of the deciduous canines. The control group (CG, 30 subjects) received no orthodontic treatment. At the start of the trial, panoramic radiographs and dental casts were compared between the TG and the CG with the Mann-Whitney U test (P <0.05). At the second observation (cervical vertebral maturation stage 5 or 6), all subjects were reevaluated, and the eruption of the maxillary permanent canines was assessed. The rates of success in the TG were compared with those in the CG by means of chi-square tests (P <0.05). The association of PDCs with other dental anomalies was reported. No statistically significant difference was found for any measurement at the start of the trial between the 2 groups. The prevalence rates of eruption of the maxillary canines were 80% for the TG and 28% in the CG, a statistically significant difference (chi-square =16.26, P <0.001). The prevalence rate at the start for the pubertal stages of cervical vertebral maturation (63%) was significantly greater in the unsuccessfully treated subjects than in the successfully treated ones (16%). In the CG, all successful subjects had PDCs that overlapped the corresponding deciduous canine or the distal aspect of the lateral incisor. Eruption of PDCs in both groups was associated significantly with an open root apex. Rapid maxillary expansion therapy followed by a transpalatal arch combined with extraction of the deciduous canine is effective in treating patients in the late mixed dentition with PDCs. Pretreatment variables indicating success of treatment on the eruption of PDCs were less severe sectors of displacement, prepubertal stages of skeletal maturity, and open root apices of PDCs. Several dental anomalies were associated significantly with PDCs, thus confirming the genetic etiology of this eruption disturbance.

Current ideas on the management of palatally displaced canines

An adolescent presenting with a palatally displaced canine (PDC) is a fairly common occurrence. The condition is expensive to treat as it involves surgical exposure (usually under general anaesthesia) followed by lengthy fixed orthodontic treatment at an average of two to three years. In the majority of cases alignment is successful. However if orthodontic alignment is unsuccessful and the tooth has to be surgically removed this can leave a large bony defect, which will be difficult to restore with a bridge or implant (see Figure 1). This article aims to give an overview of current principles and problems in the management of PDC.

An RCT on treatment of palatally displaced canines with RME and/or a transpalatal arch

To investigate the effect of rapid maxillary expansion (RME) and/or transpalatal arch (TPA) therapy in combination with deciduous canine extraction on the eruption of palatally displaced canines (PDCs). Hundred and twenty subjects were enrolled in an RCT based on PDCs diagnosed on panoramic radiographs and they were randomly assigned to one of four study groups. Three treatment groups (TGs) (RME followed by TPA therapy plus extraction of deciduous canines, RME/TPA/EC group, 40 subjects; TPA therapy plus extraction of deciduous canines, TPA/EC group, 25 subjects; extraction of deciduous canines, EC group, 25 subjects) were analyzed. A control group (CG, 30 subjects) received no orthodontic treatment. Prevalence rates of eruption of PDCs in the three TGs were compared with the CG at T2. Predictive features at T1 for successful canine eruption were tested in the three TGs. The prevalence of canine eruption was 80 per cent for the RME/TPA/EC group, 79 per cent for the TPA/EC group, 62.5 per cent for the EC group, versus 28 per cent in the CG, with statistically significant differences between all the groups, with the exception of the comparison between RME/TPA/EC and TPA/EC. Predictive pretreatment variables for the success of treatment were less severe sectors of canine displacement, prepubertal stages of skeletal maturity, and an open root apex of PDCs. The use of a TPA in absence of RME can be equally effective than the RME/TPA combination in PDC cases not requiring maxillary expansion, thus reducing the burden of treatment for the patient.

Distally displaced premolars: A dental anomaly associated with palatally displaced canines

The aim of this study was to evaluate the significance of association between distally displaced premolars (DDP) and palatally displaced canines (PDC) in the pattern of associated phenotypes of dental developmental disturbance. A sample of 2811 subjects (mean age, 9 years 7 months +/- 1 year 3 months) was divided randomly into 2 groups. The first group of 500 subjects was the control group. The reference prevalence rates for the examined parameters were calculated for this group: DDP (measured with the distal angle theta and the premolar-molar angle gamma); PDC; and other dental anomalies, specifically, aplasia of the third molars, aplasia of the contralateral mandibular second premolar, aplasia of the maxillary lateral incisors, and small maxillary lateral incisors. Of the remaining 2311 subjects, the first 100 with a diagnosis of DDP of at least 1 mandibular second premolar comprised experimental group 1 (DDP group). In addition to sex distribution, the same variables that were examined in the control group were analyzed. In the subgroup with the concurrent DDP and PDC (experimental group 2, or DDP-PDC group), the presence of other dental anomalies was investigated. The prevalence rate for PDC in experimental group 1 was compared with that in the control group. The same was done for the prevalence rates for the 4 other dental anomalies in the PDC-DDP group (experimental group 2) vs the prevalence rates for these anomalies in the control group. All comparisons were performed with chi-square tests with the Yates correction (P <0.05), as were the comparisons between the sexes in experimental groups 1 and 2. The values for theta and gamma angles in experimental group 1 were compared with the values for these angles in experimental group 2, as well as with those in the control group. These statistical comparisons were made with analysis of variance (ANOVA) with the Bonferroni post-hoc test (P <0.05). The prevalence rate for PDC in experimental group 1 (28%) was significantly greater than in the control group (4.2%) (P <0.01). Significantly greater prevalence rates for aplasia of the second premolars, aplasia of the maxillary lateral incisors, and small maxillary lateral incisors were found in the PDC-DDP group (experimental group 2) compared with the control group. Significant sex differences (P <0.01) were found in both experimental groups. A significant relationship between distal displacement of unerupted mandibular second premolars and PDC was found. Because DDP is diagnosed earlier than PDC, it can be a developmental risk indicator for displaced maxillary permanent canines.

Risk Indicators and Interceptive Treatment Alternatives for Palatally Displaced Canines

The present article reviews diagnostic, prognostic, and therapeutic aspects related to palatal displaced canines (PDCs) and their possible evolution to palatally impacted canines (PICs). Through the analysis of the relevant literature, a series of dental anomalies can be identified that present with a significant clinical association with PDC. Because these tooth disturbances may appear before PDC, they represent risk indicators for the occurrence of the eruption anomaly of the maxillary permanent canine. The second part of this work describes comparatively the effectiveness of several interceptive treatment approaches to PDC to avoid the evolution from PDC to PIC. In particular, the extraction of the deciduous canine, alone or in combination with orthodontic forces aimed to prevent the physiological mesial movement of the upper permanent molar, appears to be able to increase by 2 to 3 times the rate of eruption of PDCs (diagnosed on a panoramic radiograph) with respect to that which occurs in untreated subjects with PDC (spontaneous eruption in about one third of the cases). Rapid maxillary expansion in the early developmental stages may represent a valid alternative for the interceptive treatment of PDCs (diagnosed on a posteroanterior cephalogram). Although genetic factors are known to play a fundamental role in the etiology of PDC (and subsequent PIC), it appears that environmental local factors can be affected by orthodontic/orthopedic approaches during the pathogenetic evolution process leading from PDC to final PIC.

A systematic review of the interceptive treatment of palatally displaced maxillary canines

The aim of this study was to assess whether interceptive treatment in the mixed dentition prevents impaction of palatally displaced canines (PDC) by systematically reviewing the literature. A literature search of PubMed, the Cochrane Library electronic databases, and Scopus was performed covering the period from January 1966 to May 2009. The inclusion criteria were mixed dentition with unilateral or bilateral PDC, randomized controlled trials (RCT), prospective and retrospective studies with untreated controls, and clinical trials comparing at least two treatment strategies. Three reviewers selected and extracted the data independently and evaluated the quality of the studies. Inter-examiner reliability was measured using the intraclass correlation coefficient (ICC). The search strategy resulted in 686 articles, of which two met the inclusion criteria. Because of the unequivocal results and heterogeneity in the study methods, the scientific evidence was too weak to fully evaluate the effect that interceptive treatment might have on PDC and which treatment modalities are most effective. The quality of the studies was rated as low because of inadequate sample selection and deficient description of sample size, confounding factors, uncertainty of randominization, and no blinding in measurements. The ICC value for total scores was >0.80, e.g. perfect agreement. To obtain reliable scientific evidence as to whether interceptive treatment prevents impaction of PDC and which treatment modalities are the most effective, better controlled and well-designed RCTs are needed. Future studies should also include assessment of patient satisfaction and pain experience as well as analysis of the costs and side-effects of treatments.

Increased Occurrence of Dental Anomalies Associated with Infraocclusion of Deciduous Molars

To test the null hypothesis that there is no relationship between infraocclusion and the occurrence of other dental anomalies in subjects selected for clear-cut infraocclusion of one or more deciduous molars. The experimental sample consisted of 99 orthodontic patients (43 from Boston, Mass, United States; 56 from Jerusalem, Israel) with at least one deciduous molar in infraocclusion greater than 1 mm vertical discrepancy, measured from the mesial marginal ridge of the first permanent molar. Panoramic radiographs and dental casts were used to determine the presence of other dental anomalies, including agenesis of permanent teeth, microdontia of maxillary lateral incisors, palatally displaced canines (PDC), and distal angulation of the mandibular second premolars (MnP2-DA). Comparative prevalence reference values were utilized and statistical testing was performed using the chi-square test (P < .05) and odds ratio. The studied dental anomalies showed two to seven times greater prevalence in the infraocclusion samples, compared with reported prevalence in reference samples. In most cases, the infraoccluded deciduous molar exfoliated eventually and the underlying premolar erupted spontaneously. In some severe phenotypes (10%), the infraoccluded deciduous molar was extracted and space was regained to allow uncomplicated eruption of the associated premolar. Statistically significant associations were observed between the presence of infraocclusion and the occurrence of tooth agenesis, microdontia of maxillary lateral incisors, PDC, and MnP2-DA. These associations support a hypothesis favoring shared causal genetic factors. Clinically, infraocclusion may be considered an early marker for the development of later appearing dental anomalies, such as tooth agenesis and PDC.