Prevalence of tooth agenesis and peg-shaped maxillary lateral incisor associated with palatally displaced canine (PDC) anomaly

Does Current Evidence Support the Discussion Around the Guidance Theory? A Systematic Review and Meta-Analysis on the Association Between Maxillary Lateral Incisor Agenesis and Displacement or Impaction of the Permanent Canine

Palatal impaction of the maxillary canine is commonly considered as a genetic condition, while the lateral incisor root has been suggested to guide maxillary permanent canine eruption. This review assessed whether agenesis of the maxillary lateral incisor is associated with eruption disturbances of the maxillary canine (displacement or impaction). Unrestricted searches in six databases for observational case-control human studies until May 2024 assessing eruption disturbances of the permanent maxillary canine in conjunction with permanent maxillary lateral incisor agenesis were performed. Study selection, data extraction and risk-of-bias assessment with the Joanna Briggs Institute's tool were performed in duplicate. Random-effects meta-analyses of odds ratios (ORs) with their 95% confidence intervals (CIs) were performed, followed by meta-regressions and sensitivity analyses. Seventeen reports pertaining to 17 case-control studies were included covering 10,155 patients (11.6 year-old/46% male on average). Maxillary lateral incisor agenesis was associated with eruption disturbance of the maxillary canine (17 studies; OR = 3.88; 95% CI = 2.05-7.34; p < 0.001; I 2 = 58). Lateral incisor agenesis was more associated with canine displacement (7 studies; OR = 7.56; 95% CI = 2.10-27.18; p = 0.008; I 2 = 57) and to a lesser degree with canine impaction (10 studies; OR = 2.39; 95% CI = 1.28-4.48; p = 0.01). No significant effects of patient age or sex were seen, and the results were robust to study design and precision. The quality of evidence was low due to the inclusion of observational case-control studies with methodological issues and residual confounding. Evidence indicates that permanent maxillary lateral incisor agenesis is associated with eruption disturbances of the permanent maxillary canine, including mainly displacement, but also impaction. Trial Registration: PROSPERO database number: CRD42024549898.

Invisible treatment with preadjusted lingual appliance and monolateral space opening for an adult Class II malocclusion with upper lateral incisors agenesis: An ortho-prosthetic case report

This case report describes the treatment of a Class II malocclusion with upper lateral incisors agenesis in an adult patient, performed by an invisible preadjusted lingual appliance, monolateral space opening and dental Class II correction. The patient had previously been treated by clear aligners with the insertion of an implant in upper right canine position in order to close the remaining space. With the twofold aim of obtaining ideal occlusal relationship and smile aesthetic improvement, it highlights how a fixed orthodontic technique is needed to achieve the planned results, when anterior torque, bodily translations and deep-bite correction are necessary. On the other hand, it underlines how the treatment plan should not be adapted to the limits of the employed appliance, but should aim for the best clinical result for the patient. A prosthetic finalisation was in the end performed in order to obtain the best aesthetic result.

Palatal canine impaction is not associated with third molar agenesis

BACKGROUND/OBJECTIVES

Third molar agenesis and palatally impacted canines (PICs) are two independent dental phenotypes with different developmental backgrounds. Isolated reports indicate a common genetic origin for both, however, current data is inconsistent. The aim of this study was to investigate the presence of third molar agenesis in individuals with PICs, compared to individuals without PICs.

MATERIALS/METHODS

This retrospective case-control study comprised 310 individuals (188 females and 122 males), half of whom presented with unilateral or bilateral PICs. Individuals with other dental anomalies of known genetic origin were excluded. The association between PICs and third molar agenesis was assessed using four regression models, with PIC as the dependent variable and sex, age, and third molar agenesis as predictors. One model treated PIC as a nominal variable (pattern) and the other as ordinal (severity), and both were run testing either third molar agenesis severity or third molar agenesis patterns. All statistical tests were performed assuming a type-1 error of 5%.

RESULTS

There was no significant association between canine impaction and third molar agenesis in any of the four regression models. Neither the severity nor the patterns of palatally impacted canines were associated with either the severity or the patterns of third molar agenesis (P > .05).

LIMITATIONS

Due to the common racial background of all participants, the results of this investigation might not be generalizable to the general population.

CONCLUSIONS/IMPLICATIONS

Palatal canine impaction is not associated to third molar agenesis, after accounting for age, sex, and various patterns of PICs and third molar agenesis. These results indicate that these two dental phenotypes do not share a common biological mechanism for their occurrence.

Eruptive path of maxillary canines in patients with lateral incisor agenesis: a longitudinal follow-up

OBJECTIVES

To evaluate the eruptive angle, mesiodistal position and height of permanent maxillary canines in patients with agenesis of the permanent maxillary lateral incisor (AL) from the mixed to the permanent dentition.

MATERIALS AND METHODS

The sample was composed of orthodontic records of subjects with and without AL. The agenesis group comprised 11 patients, 7 with bilateral and 4 with unilateral AL (8.6 ± 1.6 years, 4 males, 7 females). The control group comprised 9 patients (8.5 ± 1.0 years, 2 males, 7 females) without AL. Panoramic radiographs were analyzed at three timepoints: inter-transitional period (T1), second transitional period (10.1±0.9 years, T2) and permanent dentition (11.9±1.1 years, T3). The long axis angle of the permanent maxillary canine (α and β), the mesiodistal distance (d) in relation to the central incisor, and the height (H) from the cusp tip of the canine to the occlusal plane were evaluated. Intergroup comparisons were performed with t-tests, Mann-Whitney, and Chi-square tests (P < 0.05).

RESULTS

A mesial position of the canine cusp tip relative to the distal of the permanent maxillary central incisor was observed for the agenesis group at T1, T2 and T3. From T1 to T2, the agenesis group showed greater occlusal displacement of the canine tooth germ.

CONCLUSIONS

In patients with AL, canine tooth germs showed more mesial displacement and erupted a mean of 4.5 mm closer to the maxillary central incisors. Eruption of maxillary canines tended to be accelerated during the late mixed dentition in patients with AL.

Palatal canine impaction is associated with craniofacial shape in humans

BACKGROUND/OBJECTIVES

It is unclear whether palatal canine impaction is related to genetic or local/environmental factors. If a genetic origin is assumed, then it could be expected that palatal canine impaction is associated with overall craniofacial development. Within this context, the aim of this study was to evaluate the craniofacial morphology of individuals with palatal canine impaction and compare it to a matched group of normal controls.

MATERIALS/METHODS

The sample for this investigation comprised 404 individuals (232 females and 172 males). Half of these individuals presented with unilateral or bilateral palatal canine impaction confirmed clinically and radiographically. The other half were matched for sex and age with the first half and comprised individuals without tooth impaction, apart from third molars. The shape of the craniofacial structures was outlined on calibrated cephalometric images through 15 curves and 127 landmarks (11 fixed and 116 semi-landmarks). Shape configurations were superimposed using Procrustes Superimposition and the resulting shape coordinates were reduced into principal components for all subsequent analyses. The effect of palatal canine impaction on craniofacial shape was assessed with regression models, separately in females and males. All statistical tests were performed assuming a type-1 error of 5%.

RESULTS

Individuals with palatally impacted canines appear to have a less convex face, a more brachyfacial skeletal pattern, and a sagittally extended premaxilla. In females effect sizes ranged between η2 = 0.136-0.397 (P < 0.05) and in males between η2 = 0.125-0.396 (P < 0.05, apart from the entire craniofacial configuration: P = 0.259).

LIMITATIONS

Palatal canine impaction was not confirmed through cone beam computer tomography images in all patients, however, in those cases, the treatment history confirmed the diagnosis.

CONCLUSIONS/IMPLICATIONS

Palatal canine impaction is related to a distinct craniofacial shape in females and males. These findings allow for speculation that palatal canine impaction is affected by genetic pathways involved in overall craniofacial development.

Periodontal and orthodontic management of impacted canines

The maxillary and mandibular canines are described by many clinicians as the "cornerstone" of the arch. When in their optimal position, they play a critical role in providing a well-balanced occlusal scheme that contributes toward functional as well as neuromuscular stability, harmony, esthetics, and dentofacial balance. When an aberration is noted with the normal eruptive and development process, early diagnosis with strategic intervention is critical and may often require a multidisciplinary approach. A proper diagnosis, risk assessment, and management of the soft tissues, hard tissues, and adjacent structures are vital for a successful outcome. This review highlights the diagnostic and treatment modalities that require consideration for the orthodontic as well as the periodontal management of impacted canines. The reader is guided through the etiology, diagnosis, prevention, and intervention of clinical cases that were managed with different approaches.

Restoration of a Peg Lateral Incisor Using the Putty Index Technique: A Case Report

The restoration of peg lateral incisors poses considerable aesthetic and functional issues. This case report describes the use of a putty index approach for conservatively restoring peg-shaped maxillary lateral incisors with resin composites. A 21-year-old female patient with good periodontal health and appropriate occlusal interactions had treatment at the Department of Conservative Dentistry and Endodontics. The restoration method included initial impressions, shade selection, etching, bonding, and gradual composite application, followed by curing and polishing. The putty index was used as a reference to accurately recreate the palatal enamel. This approach provides a low-cost, minimally intrusive treatment that maintains natural tooth structure while producing satisfactory aesthetic outcomes. Direct adhesive resin restorations are being highlighted as a feasible option, as technology and bonding techniques progress. This case shows the significance of modifying treatment plans based on patient characteristics and practitioner expertise.

Challenges of a two-phase orthodontic treatment of a mandibular lateral incisor-canine transposition and a maxillary palatally displaced canine: A case report

INTRODUCTION

The management of eruption disturbances in orthodontics may be challenging and requires a careful diagnosis and treatment planning. This case report discusses the challenges of a two-phase orthodontic treatment of a patient presenting with a dental eruption pattern anomaly.

PATIENT CONCERNS

A 10-year-old boy presented with no complaints for a routine orthodontic evaluation during the mixed dentition.

PRIMARY DIAGNOSES

The patient was diagnosed with a skeletal Class I malocclusion with unilateral posterior crossbite, incomplete mandibular lateral incisor-canine transposition and a unilateral maxillary ectopic canine.

INTERVENTIONS

Phase 1 started with rapid maxillary expansion to correct the maxillary constriction and the ectopic eruption of the right maxillary canine. In the mandibular arch, phase 1 included the extraction of the left primary lateral incisor and canine, alignment of the left permanent lateral incisor and orthodontic traction of the left permanent canine. The duration of phase 1 was 14 months. Phase 2 involved a comprehensive course of orthodontic treatment and started when the patient was aged 13 years. This phase lasted 18 months.

RESULTS

An adequate dental occlusion was obtained, and the treatment results were stable after an 18-month follow-up.

CONCLUSION

In this case, the early diagnosis of the dental anomalies was valuable as it allowed an early intervention to be undertaken, which resulted in overall treatment simplification and potentially minimised the adverse effects. This case report reinforces the importance of a careful follow-up during mixed dentition.

Craniofacial morphology in patients with impacted canine: a case control-study

BACKGROUND

The objective of this study was to evaluate the risk of maxillary canine impaction through cephalometric evaluation.

METHODS

One hundred and eighty-two Caucasian patients (80 males and 102 females) with a mean age of 12.4±0.5 were retrospectively enrolled in the present study. Ninety patients with impacted canines were compared with ninety-two patients with physiologically erupted canines. The following cephalometric variables were analyzed: SNA, ANB, SN-GOME, GO-ME, SP-CL, SELLA TURCICA DEPHT, A-Pt LINE, B-Pt LINE, A-Pt LINE°, B-Pt LINE°, A1s-Pt, A1i-Pt, A1s-Pt°, A1i-PT°, A-SN, B-SN and SN-U1. When applicable, a paired sample t-test was performed to investigate the difference in means between the two sample groups, while the Mann-Whitney Test was used as a non-parametric test in the case of a non-normal distribution of data. Statistical significance was set at P<0.05.

RESULTS

The group with impacted canines showed an increase in Go-Me distance, SNA angle and A1s-Pt angle compared with the control group. In addition, the same group showed a decrease in A-SN and SP-Cl distance compared with the control group.

CONCLUSIONS

An increase in mandibular length (GO-ME) and SNA angle associated with a reduction in A-Sn distance and interclinoid distance (SP-Cl) were observed in patients with impacted canines.

Local factors relating to mandibular canine impaction: A retrospective study

INTRODUCTION

This study aimed to investigate the characteristics of impacted and transmigrated mandibular canines and the association existing between them and some local factors, such as degrees of axial inclination of mandibular incisors, skeletal Class, and mandibular symphysis width.

METHODS

A retrospective observational study was performed on the medical records and radiographic examination (panoramic radiographs and lateral cephalograms) of 102 orthodontic patients divided into a study group, with at least 1 impacted mandibular canine (51 subjects) and a control group, without mandibular impaction (51 subjects). A chi-square test, t test, and analysis of variance test analysis were used to analyze the data.

RESULTS

Unilateral and buccal impaction and the presence of the deciduous canine were the more prevalent characteristics of impacted canines, whereas 39.2% presented transmigration. Furthermore, the persistence of the deciduous canine on the impaction side (P <0.0001) and the mesial axial inclination of the impacted canine (P <0.0001) were found to be statistically significant characteristics. A statistically significant association was found between the impaction of the mandibular canine and mandibular incisor to the mandibular plane angle (IMPA) (IMPA, 95.8°; P = 0.009). An additional statistically significant association was found with transmigrated canines (IMPA, 96.8°; P = 0.024).

CONCLUSIONS

The mesialization of the canine cusp and the persistence of the mandibular deciduous canine are characteristics frequently found in the impaction of the mandibular canine. An accentuated vestibular inclination of the mandibular incisors is significantly associated with mandibular canine impaction.

Does third molar agenesis influence the second lower molar mineralization?

Different studies have established that the mineralization stages of the second mandibular molar can be used in forensic age estimation. Nowadays, the estimate's accuracy is an ethical concern, producing as few false positives (individuals incorrectly classified as older than a determined threshold) and false negatives (individuals incorrectly classified as younger than a determined threshold) as possible. Some have hypothesized that changes in teeth number may influence tooth mineralization, altering the age estimate process. This paper analyzes whether third molar agenesis affects the second mandibular molar mineralization time frame. To do so, 355 orthopantomograms were evaluated for third molar agenesis, and the second mandibular molar mineralization stage was assessed using the Demirjian stages. Student's t-test was used to compare the difference in the mean age at which the various stages of 37 mineralization were reached in the groups with and without third molar agenesis. The level of statistical significance was set at 5%. The results pointed to a delay in second mandibular molar mineralization in the case of agenesis, suggesting the need to consider this when estimating age using dental techniques.

"Examining the link between tooth agenesis and papillary thyroid cancer: is there a risk factor?" Observational study

BACKGROUND

Mutations in one or multiple genes can lead to hypodontia and its characteristic features. Numerous studies have shown a strong genetic influence on the occurrence of hypodontia, and identified several genes, including AXIN2, EDA, FGF3, FGFR2, FGFR10, WNT10A, MSX1, and PAX9, that are directly associated with dental agenesis and carcinogenesis. The objective of this study was to investigate the occurrence and pattern of tooth agenesis, microdontia, and palatally displaced canine (PDC) in women diagnosed with papillary thyroid cancer (PTC), compared to a control group of women without any malignancy or thyroid disease.

MATERIALS AND METHODS

This case-control study was carried at the Department of Orthodontics, School of Dental Medicine University of Zagreb, and Department of Oncology and Nuclear Medicine Sestre Milosrdnice University Hospital Centre. The study involved a clinical examination and evaluation of dental status, panoramic X-ray analysis, and assessment of medical and family history of 116 female patients aged 20-40 with PTC, as well as 424 females in the control group who were of similar age.

RESULTS

The prevalence of hypodontia, microdontia, and PDC was statistically higher in women with PTC than in the control group. The prevalence rate of hypodontia was 11.3% in the experimental group and 3.5% in the control group. The experimental group showed a higher occurrence of missing upper lateral incisors, lower left central incisors, and all the third molars (except the upper left) compared to the control group. Women with PTC showed the prevalence of PDC significantly higher than the control group (3.5%, 0.7%, p = 0.002). The probability of hypodontia as a clinical finding increases 2.6 times, and microdontia occurs 7.7 times more frequently in women with PTC.

CONCLUSION

Our study suggests a possible link between odontogenesis and PTC. The absence of permanent teeth may increase the likelihood of PTC in women. Leveraging the age-7 orthopantomogram to identify women at high risk for PTC within a critical early detection window could significantly improve oral health outcomes and PTC prognosis through proactive interventions.

Comparisons of Dental Anomalies in Orthodontic Patients with Impacted Maxillary and Mandibular Canines

To assess the presence and possible associations between the type of dental anomalies and maxillary and mandibular canine impactions in orthodontic patients treated for canine impaction, panoramic radiographs of orthodontic patients treated for canine impaction were assessed for the presence of associated dental anomalies. A random sample of orthodontic patients without canine impaction matched for age and gender served as controls. Descriptive and exact inferential statistics were implemented in order to assess potential associations between canine impaction and dental anomalies. A total of 102 orthodontic patients with 70 maxillary (MaxCI) and 32 mandibular (ManCI) canine impactions were assessed. The control group included 117 orthodontic patients. Dental anomalies were present in more than 50% of patients with impacted canines and in 20% of the controls. Tooth agenesis was significantly more common in the MaxCI group when compared to the ManCI group, while supernumerary teeth and canine transmigration were registered more often in the ManCI group. When compared to the control group, peg-shaped maxillary lateral incisors and tooth agenesis were significantly more prevalent in the MaxCI group, while canine transmigration, supernumerary teeth, the agenesis of mandibular incisors and tooth transpositions were significantly more prevalent in the ManCI group. The impaction of other teeth was significantly more common in both canine impaction groups when compared to the controls. The prevalence of dental anomalies in orthodontic patients with impacted canines was higher than in orthodontic patients without canine impaction. Different types of tooth anomalies were found in the MaxCI and ManCI groups.

Association between maxillary canine impaction and other dental anomalies: radiological study of a mixed dentition children's cohort from an orthodontic clinic

PURPOSE

To investigate the significance of association between maxillary impacted canines and various dental anomalies.

METHODS

Files of 874 orthodontic patients were evaluated for the presence of maxillary impacted canines. From this sample, a group of 97 patients (39 males and 58 females) with at least 1 impacted maxillary canine consisted the study group. This group was compared to a control group of 97 patients (42 males and 55 females) that was created by random selection from the initial sample without maxillary canine impaction. The impaction diagnosis was made from the panoramic radiographs. Chi-square test was used to perform the analysis for significant associations. Stepwise discriminant analysis, binary logistic regression and classification tree were used to identify best combinations.

RESULTS

Statistically significant difference was found for peg-shaped maxillary lateral incisors and infraoccluded deciduous molars. The presence of peg-shaped upper lateral incisors arises the probability of impacted canine to 83.3%, a distal displaced unerupted second premolar to 63.16% and the impaction of any other teeth to 80% as showed by the classification tree.

CONCLUSIONS

The presence of peg-shaped maxillary lateral incisors and infraocclusion of deciduous molars can be considered major valuable early risk indicators for maxillary canine impaction, because they manifest before the maxillary canine eruption. Special consideration should be given on distal displaced unerupted second premolar and the impaction of any other teeth. Patients with these dental anomalies are candidates for future interceptive treatment for canine eruption.

Invisible treatment of an asymmetric adult class II malocclusion related to unilateral upper lateral incisor agenesis with a straight wire lingual appliance, mini-screw and premolar extraction: A case report

This case report describes a complex full-step class II malocclusion with unilateral upper lateral incisor agenesis in an adult patient treated with lingual straight-wire appliance and premolar extraction, with the two-fold aim of obtaining ideal occlusal relationship and smile aesthetic improvement. In view of this, it underlines how an appropriate treatment strategy, including extraction choice and anchorage control during space closure, is needed to achieve the planned results with a completely invisible lingual appliance combined with aesthetic veneers.

Predictive Analysis of Maxillary Canine Impaction through Sella Turcica Bridging, Ponticulus Posticus Calcification, and Lateral Incisor Anomalies: A Retrospective Observational Study

Maxillary canine impaction is an increasing dental anomaly and is often related to other dento-skeletal anomalies. The aim of this work is to support the clinician in evaluating the relationship between a displaced maxillary canine and clinical (the features of lateral incisors)/skeletal (ponticulus posticus and sella turcica bridging) anomalies through orthopanoramic radiographs, lateral cephalograms, and plaster casts to identify the parameters that best predict maxillary canine impaction. A retrospective observational study was carried out on the analysis of the medical records, radiographic findings (panoramic radiographs and lateral cephalograms), and plaster casts of 203 orthodontic patients divided into a case group, with at least one impacted maxillary canine, and a control group, without an impaction. A chi-square test and logistic regression analysis were used to analyze the data. A statistically significant association was found between the impaction of the maxillary canine and the female sex, the bridging of the sella turcica, the ponticulus posticus calcification, and the anomaly of the lateral incisor; a logistic regression revealed that these significant variables were found to be positive predictors of impacted maxillary canines, particularly in reference to the impaction in the palatal area. Finding one of these clinical and radiographic elements can represent a predictive sign of the possible impaction of the maxillary canine.

Association between dental agenesis and delay in dental development: a preliminary study in a Spanish paediatric population in relation with Dental Anomaly Pattern (DAP)

Background

The association between dental anomalies has been studied, giving rise to the concept of Dental Anomaly Pattern (DAP). Tooth agenesis has been associated with alterations such as molar infracclusion, taurodontism and delayed dental development. The aim of this study was to evaluate the dental development pattern in patients with non-syndromic dental agenesis, in comparison with a control group.

Methods

Dental and chronological age was analysed in a sample size of 204 orthopantomographs divided into a study group (n = 104) and a control group (n = 100) with the Demirjian Method. Intra and intergroup differences in chronological and dental age, and the correlation between them were calculated by statistical analysis with a 95% confidence level (p < 0.05).

Results

Dental age exceeded chronological age both in the control group and in the study group. Statistically significant differences (p = 0.004) were found when comparing the difference between chronological and dental age in the study (-0.16 ± 1.12) and control group (-0.58 ± 0.90). Regarding sex and age intergroup differences, the results were only statistically significant in the girls’ group (p = 0.017), and the age over 8 years old (p < 0.05). There were no significant differences in tooth development depending on the number of missing teeth or the affected tooth group, but there was a delay in the development of the homologous tooth contralateral to the absent one in 14.9% of patients.

Conclusions

The difference between chronological and dental age in permanent dentition is significantly lower in Spanish children with non-syndromic agenesis compared to a control group, presenting a lower dental age than chronological age than children without non-syndromic agenesis.

Risk Prediction of Maxillary Canine Impaction among 9-10-Year-Old Malaysian Children: A Radiographic Study

BACKGROUND

Early diagnosis and interceptive treatment of the maxillary canine impaction is crucial as it reduces treatment complexity and decreases complications and adverse outcomes. Aim and Objectives. To determine the mean maxillary canine position among 9-10-year-old children and predict the risk of impaction of the maxillary canines. Methodology. Panoramic radiographs (PANs) of 289 healthy children aged between 9 and 10 years were observed where the average position of maxillary canines was related to the lateral incisor, sector locations, and angulations to the bicondylar line were traced. The average position was obtained by using descriptive statistics. One sample Wilcoxon signed-rank test is done to predict the risk of canine impaction by comparing the data obtained to the average position from prior studies.

RESULTS

A total of 289 PANs (126 males and 163 females) were utilized for the analysis. The findings showed that the average position of the maxillary canines in our population was statistically different from the average position of nonimpacted canines in previous studies. However, on average, more than 85% of canines in our population were still located within the safe range of satisfactory position, with females showing slight predominance outside of the acceptable range. The mean scores of the angles between the right canine and lateral incisor were significantly higher among females than males (p = 0.001). Similarly, females had a significantly higher mean angle of the left canine than males (p < 0.001). In regard to the angles between the bicondylar line and permanent maxillary canine, the mean scores were not significantly different (p > 0.05) on both the left and right side.

CONCLUSION

There is a low risk of impaction of maxillary canines in the Malaysian population. However, more retrospective studies using more radiographic and clinical indicators need to be done to confirm the risk of impaction further.

Common dental anomalies in Korean orthodontic patients: An update

Objective

The aim of this study was 1) to investigate the prevalence and pattern of dental anomalies (DAs), 2) to compare DAs according to the type of malocclusion, and 3) to investigate the correlation between tooth impaction and other DAs in the Korean orthodontic population.

Methods

A total of 3,240 orthodontic patients were classified as Class I, Class II, or Class III malocclusion groups. The presence and location of common DAs, including impaction, microdontia, agenesis, supernumerary tooth, transposition, and fusion, were identified by examining diagnostic records. Furthermore, samples were classified as Group 1 without impaction or Group 2 with impaction. The prevalence of other DAs concurrent with impaction was investigated and compared to Group 1.

Results

Impaction was the most prevalent DA, followed by microdontia, agenesis, and supernumerary. Class I and Class III groups showed the same order of prevalence, but agenesis was more frequent than microdontia in the Class II group. The prevalence of the four DAs was lowest in the Class III group. Overall, 8.6% of patients were classified into Group 2. The incidence of DAs other than impaction and the prevalence of multiple concurrent DAs were significantly higher in Group 2. Impaction showed a significant relationship with supernumerary tooth, transposition, and fusion.

Conclusions

The prevalence and pattern of DAs varied depending on the type of malocclusion. As there was a higher risk of other DAs in patients with impacted teeth, early detection of the impacted tooth and a detailed diagnosis of other possible DAs may be essential.

Prosthetic rehabilitation of maxillary lateral incisors agenesis using dental mini-implants: a multicenter 10-year follow-up

Objectives

Implants are used to replace congenitally missing lateral incisors but often the space across the alveolar crest is too narrow to permit their use. This multicenter study (Dental Clinic of the University of Foggia, Odontostomatology Clinic of the University of L’Aquila) evaluated the efficacy of mini-implants in cases of maxillary lateral incisor agenesis with severe osseous atrophy in 10-year follow-up.

Materials and methods

Forty-seven mini-implants have been inserted in 35 patients affected by lateral incisors agenesis (23 single and 12 bilateral ageneses). All patients underwent orthodontic opening of the space of the upper lateral incisors. After the insertion of the implants, the immediate, non-functional loading, positioning of crowns, presence of pain during percussion and mini-implant function, horizontal and vertical movement when a force of 5 N was applied, ridge loss, and plaque index have been evaluated 1 month after loading, 1 year after loading, and then every 5 years in the following 10 years. Little’s test was used to evaluate the assumption that data of loss to follow-up implants are missing completely at random (MCAR) and that a complete-case scenario could be adopted. Wilcoxon test was carried out to look statistically significant differences between the various parameters resulting in the complete-case scenario and those assumed for the worst scenario. The software R (v. 3.6.1, 2019) was employed to perform the statistical analysis.

Results

The results obtained over 10 years range from 89% of success rate in a worst-case scenario to the 100% using a complete-case analysis with satisfactory values of marginal bone resorption and good conditions of the peri-implant tissue. Ten-year follow-up using complete-case analysis shows survival rates of 100% for implants with no signs of peri-implantitis, stability of the marginal bone levels and soft tissue around the dental implants.

Conclusions

The data collected show very good implant stability, absence of progressive peri-implantitis, and satisfactory aesthetical results in time (no signs of infraocclusion).

Clinical relevance

Mini-implants can be considered a valid and stable over time solution in the restorative treatment of maxillary lateral incisors agenesis.

Successful Pulp-Preserving Treatment for Peri-invagination Periodontitis of Double Dens Invaginatus With Oehlers Type IIIA and IIIB: A Case Report

Dens invaginatus (DI), which often occurs in the maxillary lateral incisor, is an important issue in endodontics because the treatment complexity increases depending on the degree of invagination and the vitality or nonvitality of the pulp. An 11-year-old female patient with a sinus tract in the gingiva of the maxillary lateral incisors showed peri-invagination periodontitis and double DI on radiography. Cone-beam computed tomographic imaging was used to examine the structure in the root canal in detail, and Oehlers type IIIA and IIIB DI was found. It was also shown that the patient's bone defect was caused by type IIIA. Because a healthy reaction was observed in the pulp test, the final diagnosis was peri-invagination periodontitis associated with type IIIA of the double DI with vital pulp. We expected the lesion to heal by treating only the type IIIA invaginated pseudo-root canal while preserving the healthy pulp. The invaginated root canal was cleaned under a microscope using ultrasonic instruments and nickel-titanium files to minimize irritation to the pulp. Because the lesion shrinkage was confirmed by cone-beam computed tomographic imaging taken 3 months after the start of treatment, vertical compaction of the warm gutta-percha technique was performed. At the 6-month postoperative recall, the pulp was normal, and the lesions were further improved. Treatment of the main root canal of double DI is complicated. However, proper diagnosis and careful cleaning of the invaginated root canal are essential for healing while preserving the pulp.

Dental anomaly patterns in mixed dentition: Illustrating the role of interceptive orthodontics in the management of mandibular lateral incisor-canine transpositions and palatally displaced maxillary canines

Dental anomalies of size, number, and position have been suggested to have a genetic background and frequently complicate the orthodontic treatment. Early intervention is a paramount step in managing patients with dental anomaly patterns (DAPs) to decrease the complexity of the case during the later stages of comprehensive orthodontic care. This case report highlights the importance of the detailed diagnosis in a case with several dental anomalies (mandibular lateral incisor-canine transposition, palatally displaced canines, small-sized maxillary lateral incisors and congenitally missing second premolar), utilizing interceptive orthodontic management in the mixed dentition stage in order to minimize the complexity and complications of comprehensive orthodontic care in the permanent dentition stage.

Dental anomaly pattern and multiple ectopic teeth

Treatment for a patient with a dental anomaly pattern is challenging and complex. This article presents a rare case with an association of multiple ectopic eruptions treated in 2 phases. An 8-year-old boy in the early mixed dentition showed a Class II, Division 2 malocclusion, and an ectopic eruption of the mandibular right lateral incisor. The treatment plan included extractions of the deciduous mandibular right lateral incisor and canine, followed by partial mandibular fixed appliances and a lingual arch. In the late mixed dentition, the panoramic radiograph showed bilateral ectopic eruptions of the maxillary canines. The deciduous maxillary canines were extracted, and a cervical headgear was installed. Within 12 months, both permanent maxillary canines spontaneously erupted. Comprehensive orthodontic treatment was initiated when the patient was aged 13 years to level the curve of Spee and reduce the overbite. Phase 2 lasted 15 months. In patients with dental anomaly patterns, longitudinal follow-up during the mixed dentition is highly important and might contribute to simplifying comprehensive orthodontic treatment and reducing complications and adverse effects.

Difficulty of palatal impacted canine treatment in different sagittal and vertical skeletal malocclusions: A retrospective 3D evaluation

OBJECTIVE

To evaluate the difficulty of impacted canine treatment in different kinds of sagittal and vertical malocclusion using the KPG index, a novel 3D classification system for canine impaction.

MATERIALS AND METHODS

In this cross-sectional study, 74 cone-beam computed tomography (CBCT) images of subjects with palatally impacted canines were collected from one dental radiographic clinic. Impacted canines were assessed and KPG index of difficulty of treatment was calculated for each tooth. Lateral cephalograms corresponding with each CBCT were also traced and analysed. To assess the relationship between the level of treatment difficulty and type of malocclusion, the Chi² test was used. The Kruskal-Wallis H test was used to assess the difficulty score between the three classes of malocclusion.

RESULTS

There was no correlation between different sagittal skeletal measurements and treatment difficulty of impacted teeth (P>0.05). A positive correlation was shown between KPG index and linear measurements of A to Pn and facial angle (FH-N Pog) (P<0.05). Difficulty of treatment did not differ among various patterns of vertical growth.

CONCLUSION

Treatment of impacted canines is more difficult in patients with maxillary prognathism and it is recommended that these patients be more meticulously evaluated prior to treatment.

Association between maxillary transverse discrepancy and occurrence of potentially impacted maxillary canines in mixed dentition patients

OBJECTIVE

The aim of this study was to determine the association between transverse maxillary discrepancy and occurrence of potentially impacted maxillary canines in mixed dentition patients.

MATERIAL AND METHODS

This cross-sectional analytical study was conducted on 85 Pakistani subjects (32 males and 53 females) aged between 8 to 13 years, having good quality orthopantomographs and dental casts. Maxillary transverse discrepancy was assessed by subtracting the mandibular intermolar width from the maxillary intermolar width on dental cast. Maxillary lateral incisors and canines were traced from orthopantomographs, and canines were placed into sector classification. Chi-square test was used to determine the difference in the occurrence of potentially impacted maxillary canines between patients with maxillary transverse discrepancy and patients without maxillary transverse discrepancy.

RESULTS

There was no significant difference seen in the occurrence of impacted maxillary canines in patients with and without maxillary transverse discrepancy in mixed dentition patients.

CONCLUSION

Patients with maxillary transverse discrepancy may not be at a higher risk of palatal canine impaction. Radiological presence of canine in sector II, III and IV, pose a higher risk of canine impaction.

Genotyping analysis of the Pax9 Gene in patients with maxillary canine impaction

Background: Paired-box gene 9 ( PAX9) mutation is potentially associated with impaction in some patient populations. Here, we analyzed the relationship between PAX9 polymorphism and the occurrence of maxillary canine impaction. Methods: Patients with and without maxillary canine impaction were selected based on specific inclusion criteria, and samples of genomic DNA were obtained from a buccal mucosa swab. DNA was amplified by polymerase chain reaction and sequenced for further bioinformatics analysis to identify single nucleotide polymorphism (SNP) genotypes. Genotype and allele counting was performed in both case and control groups prior to conducting statistical analysis. Results: Four SNPs were identified in patients with maxillary canine impaction, with relative confidence determined based on chromatogram-peak assessment. All SNPs were located in exon 3 of PAX9 and in the region sequenced by the primer pair -197Fex3 and +28Rex3. Three of the SNPs (rs375436662, rs12881240, and rs4904210) were reported previously and are annotated in NCBI (dbSNP version 150), whereas another SNP mapped to chromosome 14 has not been reported. Patients with a CC genotype at SNP 3 [odds ratio (OR): 2.61 vs. TT; 1.28 vs. CT] and a CC genotype at SNP 4 [OR: 0.71 vs. GG; 0.79 vs. CG] were more likely to have maxillary canine impaction. Conclusions: These results demonstrated that the presence of SNPs 3 and 4 is associated with increased likelihood of suffering from maxillary canine impaction.

New perspective for evaluation of tooth widths in patients with missing or peg-shaped maxillary lateral incisors: Quadrant analysis

INTRODUCTION

Missing or peg-shaped maxillary lateral incisors can affect the mesiodistal dimensions of the dentition.

METHODS

The pretreatment casts of patients with bilateral (BMLI, n = 35) or unilateral (UMLI, n = 29) missing maxillary lateral incisors or bilateral peg-shaped maxillary lateral incisors (BPLI, n = 16) were evaluated. The mesiodistal widths of all permanent teeth except the second and third molars were measured, and the sums of total and quadrant tooth widths were calculated. The results were compared with a control group (n = 32) with normal maxillary lateral incisors. A quadrant analysis was performed by comparing the quadrants with lateral incisor agenesis, peg-shaped lateral incisors, and normal lateral incisors with each other. Statistical analysis was performed by 1-way analysis of variance followed by Tukey and Tamhane tests.

RESULTS

In the BMLI and BPLI groups, significant reductions in individual tooth widths and total tooth widths were seen. The size discrepancies were the greatest in the maxillary central incisors and decreased gradually from the incisors to the molars. Compared with the control group, the tooth-size discrepancy was more pronounced in the BPLI group followed by the BMLI and UMLI groups. Due to the variability in clinical presentations of the UMLI group, the association with the reduction of the tooth sizes was not significant. But the quadrant analysis showed that in quadrants with a missing or peg-shaped lateral incisor, the teeth were significantly narrower than in quadrants with normal incisors; this indicates the importance of the contralateral side in unilaterally affected patients during analysis.

CONCLUSIONS

Bilateral missing or peg-shaped maxillary lateral incisors were significantly associated with reduction of individual mesiodistal tooth widths as well as their total and quadrant sums. Patients with a unilaterally missing lateral incisor should be analyzed individually with quadrant analysis, since the variability in the contralateral side would affect the traditional analysis results.

What factors affect the severity of permanent tooth impaction?

BACKGROUND

The aim of this study was to investigate the association between the severity of permanent tooth impaction and a number of predefined factors, including tooth type, age, gender, tooth agenesis, microdontia of maxillary lateral incisor, and retained deciduous predecessors.

METHODS

A sample of 2979 dental patients, aged 15 to 40 years, was surveyed by two calibrated examiners for permanent tooth impaction (excluding third molars). On panoramic radiographs, the impacted teeth were initially ranked based on their vertical, horizontal, and angular positions, and the ranking was then analysed for distribution by the predefined factors. To test the age factor, patients were divided into younger (15 to 25 yr) and older (between 25 and 40 yr) age groups. The statistical significance of the ranked vertical, horizontal, and angular positions of impacted teeth by the investigated factors was determined using the Wilcoxon-Mann-Whitney U test.

RESULTS

The angular position of the impacted teeth was more severe in the older age group (P = 0.012) and in females (P = 0.018). The maxillary canine had more severe horizontal (P = 0.001) and angular (P = 0.003) impactions in females. Tooth agenesis was associated with less severe horizontal impaction (P = 0.041) in the mandibular second premolar. In addition, microdontia of the maxillary lateral incisor was associated with more severe horizontal impaction in general, and more severe horizontal (P = 0.024) and angular (P = 0.010) impaction of the mandibular second premolar in particular. Finally, our results showed that a retained deciduous predecessor was linked to a less severe vertical impaction of the mandibular second premolar (P = 0.030) and horizontal impaction of the maxillary second premolar (P = 0.037) but more severe angular impaction of the mandibular canine.

CONCLUSIONS

This study suggests that the more delayed the treatment, being a female, the presence of maxillary lateral incisor with microdontia, and retained lower deciduous canines might be associated with more severe position of the impacted teeth. Because the severity of tooth impaction would follow different patterns when considering the investigated factors, it is mandatory to include such factors during dental diagnoses and the planning of preventive or interceptive interventions for young patients.

Third molar tooth agenesis and pattern of impaction in patients with palatally displaced canines

OBJECTIVES

To investigate the association between third molar agenesis and pattern of impaction, missing teeth, and peg-shaped lateral incisor with palatal canine displacement (PDC).

MATERIALS AND METHODS

The pretreatment orthodontic orthopantomograms of 438 patients (122 males and 316 females) diagnosed with PDC were included. A total of 338 patients with normally erupted canines who had a preexisting radiograph as part of their orthodontic treatment (125 males and 313 females) served as controls. Orthopantomograms were evaluated for missing third molars, third molar eruption status, and type of impaction, third molar spaces, third molar width, and angulation.

RESULTS

In the PDC group, at least one third molar was missing in 48% and 19% in the upper and lower arches, respectively. Also, 38% and 67% of PDC patients had at least one third molar impaction in the upper and lower arches, respectively. The difference between the PDC and control groups was significant for both missing and impacted third molars ( P < .001 for each). The most common type of third molar impaction in the upper arch was vertical and distoangular in the PDC and control groups, respectively. Upper and lower third molar width and spaces were reduced in PDC patients when compared with the control group ( P < .001). In PDC patients, missing teeth and peg-shaped lateral incisors were recorded in 5.6% and 9.1%, respectively.

CONCLUSIONS

PDC patients showed a high prevalence of third molar agenesis and impaction. Upper and lower third molar width and space were reduced in the PDC patients. There were no significant associations between tooth agenesis (other than third molars) and the PDC anomaly.

Association between maxillary lateral incisors' root volume and palatally displaced canines: An instrumental variables approach to the guidance theory

OBJECTIVES:

To evaluate association and causation between maxillary lateral incisors' (MxI2) apical root volume (ARV) and palatally displaced canines (PDC).

MATERIALS AND METHODS:

In a retrospective cross-sectional study, computed tomography scans of 179 patients with unilateral PDC were analyzed. MxI2 root length and volume on the impaction and eruption side were measured. A mixed logit model was used to infer the association between ARV and PDC and an instrumental variables approach to interpret causality.

RESULTS:

MxI2 root length on the impaction side was shorter in 42%, equal in 33% and longer in 25% of the patients. ARV amounted for 13.5% of total root volume on the impaction and 14.9% on the eruption side. Reduced ARV was significantly associated with the impaction side ( P < .001). The causal effect of ARV on PDC in the instrumental variable approach amounted to less than half of the association in a standard noncausal approach.

CONCLUSIONS:

An association between PDC and reduced MxI2 root length and volume was confirmed. However, the lack of causality did not allow the researchers to draw a conclusion as to whether a reduced ARV is causing PDC or resulting from it; this should be considered in etiologic theories.

Associations between tooth agenesis and displaced maxillary canines: a cross-sectional radiographic study

Background

The aim of present study was to test the association between hypodontia and displaced maxillary canine when compared with a control group.

Methods

The study group was composed of 336 subjects with a mean age of 10.7 ± 1.2 years, presenting with at least one missing tooth. Exclusion criteria included syndromes, craniofacial malformations, extractions and trauma history and previous orthodontic treatment. The control group consisted of 336 subjects with a mean age of 10.7 ± 1.2 years, without agenesis. Stepwise multiple logistic regression using the backwards elimination and the Wald test method was performed to identify the best combination of hypodontia and displaced maxillary canine (P < 0.05).

Results

The most represented category in study group consisted in mild agenesis (86.9%); moderate and severe agenesis groups respectively represented the 11.7 and 1.4% of study group. Agenesis was diagnosed in both arches in 46 subjects. Maxillary hypodontia and mandibular hypodontia was respectively detected in 156 and 134 subjects. The most frequent missing teeth were mandibular second premolars (45.8%), lateral incisors (41.7%) and maxillary second premolars (17.8%). A significant correlation between agenesis and displaced maxillary canine was observed in the study group (P < 0.05). Only the agenesis of maxillary lateral incisors remained in the final model during backward stepwise deletion. Significant association between the severity of dental agenesis and prevalence of displaced maxillary canine was not assessed.

Conclusions

The outcomes revealed no difference related to the severity of dental agenesis and prevalence of displaced maxillary canine. Only the agenesis of maxillary lateral incisors should be considered directly connected with displaced maxillary canine.

Electronic supplementary material

The online version of this article (10.1186/s40510-018-0226-0) contains supplementary material, which is available to authorized users.

"Maxillary lateral incisor partial anodontia sequence": a clinical entity with epigenetic origin

The relationship between maxillary lateral incisor anodontia and the palatal displacement of unerupted maxillary canines cannot be considered as a multiple tooth abnormality with defined genetic etiology in order to be regarded as a “syndrome”. Neither were the involved genes identified and located in the human genome, nor was it presumed on which chromosome the responsible gene would be located. The palatal maxillary canine displacement in cases of partial anodontia of the maxillary lateral incisor is potentially associated with environmental changes caused by its absence in its place of formation and eruption, which would characterize an epigenetic etiology. The lack of the maxillary lateral incisor in the canine region means removing one of the reference guides for the eruptive trajectory of the maxillary canine, which would therefore, not erupt and /or impact on the palate. Consequently, and in sequence, it would lead to malocclusion, maxillary atresia, transposition, prolonged retention of the deciduous canine and resorption in the neighboring teeth. Thus, we can say that we are dealing with a set of anomalies and multiple sequential changes known as sequential development anomalies or, simply, sequence. Once the epigenetics and sequential condition is accepted for this clinical picture, it could be called “Maxillary Lateral Incisor Partial Anodontia Sequence.”

Determinants of maxillary canine impaction: Retrospective clinical and radiographic study

BACKGROUND

The aim of this study is to evaluate determinants of maxillary canine impaction taking into account both canine position related variables and the pattern of facial growth.

MATERIAL AND METHODS

A retrospective clinical and radiographic analysis was carried out on 109 patients aged between 9 and 10 years at the time of first evaluation. At baseline, SN-GoMe angle, the interincisal angle, the canine angle α and the canine distance d were used to characterize canine location and vertical facial growth. At the end of a two years follow up period the eruption state of each canine of each patient was recorded and accordingly classified as erupted or impacted on a clinical and radiographic basis. Univariate and multivariate statistical analyses were performed, including correlation among the studied variables and principal components analysis; several machine learning methods were also used in order to built a predictive model.

RESULTS

At the end of the two years follow up period after the first examination, 54 (24.77%) canines were classified as impacted. Except for Angle α values, there were no statistically significant differences between impacted and erupted canines. The studied variables were not significantly correlated, except for the SN-GoMe Angle and the distance d in the impacted canine group and the angle α and the distance d in erupted canines group. All variables, except for SN-GoMe Angle in erupted canines, have a partial communality with the first two principal components greater than 50%. Among the learning machine methods tested to classify data, the best performance was obtained by the random forest method, with an overall accuracy in predicting canine eruption of 88.3%.

CONCLUSIONS

The studied determinants are easy to perform measurements on 2D routinely executed radiographic images; they seems independently related to canine impaction and have reliable accuracy in predicting maxillary canine eruption. Key words:Canine impaction, Determinants, Facial growth.

Long-term survival of retained deciduous mandibular second molars and maxillary canine incorporated into final occlusion

Orthodontic treatment of a complex case that involves retained deciduous mandibular second molars with missing permanent successors is challenging. Usually, congenitally missing teeth are manifested with other dental anomalies that further complicate orthodontic treatment, such as retained deciduous teeth, impactions, transpositions and peg-shaped lateral incisors. Even though the long term prognosis of the retained deciduous tooth is not fully predictable, if the teeth are in good condition, the patient and clinician may incline towards a decision to preserve the deciduous teeth as long as possible. This case report demonstrates that deciduous teeth, in this case the mandibular second molars and maxillary canine, can be incorporated into final occlusion with clinically stable long-term results.

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

BACKGROUND

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.

OBJECTIVES

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.

SEARCH METHODS

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.

SELECTION CRITERIA

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.

DATA COLLECTION AND ANALYSIS

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.

MAIN RESULTS

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).

AUTHORS' CONCLUSIONS

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.

Dental anomaly patterns associated with tooth agenesis

OBJECTIVE

The objective of this study is to evaluate the relationship between tooth agenesis and the occurrence of other dental anomalies in children and adolescents.

MATERIAL AND METHODS

Panoramic radiographs of 195 subjects with tooth agenesis, except for the third molar, were retrospectively examined and compared with a non-agenesis control group of 600 subjects. Their ages ranged from 7 to 15 years. Panoramic and periapical radiographs were used to analyze the presence of other associated dental anomalies. The occurrences of these anomalies were compared with those in the non-agenesis group.

RESULTS

Subjects with tooth agenesis showed a significantly higher prevalence of a small maxillary lateral incisor (17.7%), distoangulation of the mandibular second premolar (6.5%), delayed development of a permanent tooth (10.8%), and hypo-occlusion of a primary molar (11.8%). In contrast, the prevalence of a supernumerary tooth was higher in the control group, and no difference was observed in the prevalence of ectopic eruption of a first molar. According to the agenesis area, microdontia of the maxillary lateral incisors occurred more often in patients with anterior or premolar agenesis than in the molar agenesis groups. Distoangulation of the mandibular second premolars, delayed tooth development, and hypo-occlusion of the primary molars were associated with premolar tooth agenesis.

CONCLUSIONS

A small maxillary lateral incisor, distoangulation of the mandibular second premolar, delayed development of a permanent tooth, and hypo-occlusion of a primary molar were frequently associated with tooth agenesis, providing additional evidence of a genetic interrelationship in the causes of these dental anomalies.

Impacted Maxillary Canine Prevalence and Its Association with Other Dental Anomalies in a Mexican Population

Objective. We quantified the prevalence of impacted maxillary canines (IMC) and their association with other dental anomalies (DAs). Materials and Methods. A retrospective study was done with 860 patients 12 to 39 years of age. The prevalence of IMC was calculated and compared by sex. The sample was divided into a control group and an impaction group, and the prevalence was calculated in both for a series of anomalies: agenesis, supernumerary teeth, shape anomalies of the upper laterals (microdontia, peg and barrel shape, and talon cusp), fusion, gemination, other impacted teeth, transposition, and amelogenesis imperfecta. The prevalence values for both groups were compared (Pearson's χ² test, p ≤ 0.05). Results. IMC were present in 6.04% of the sample with no difference by sex (p = 0.540). Other DAs occurred in 51.92% of the IMC group and in 20.17% of the controls (p < 0.05). Significant associations (p < 0.05) were identified between IMC and four other DAs: microdontia, barrel shape, other impacted teeth, and transposition. The prevalence of all anomalies was lower in the control group. Conclusion. IMC were seen in 6.04% of patients. Patients with this condition also had a higher prevalence of other DAs. These other anomalies should be used as risk indicators for early diagnosis.

Morphological relationship analysis of impacted maxillary canines and the adjacent teeth on 3-dimensional reconstructed CT images

OBJECTIVE

To examine whether there is a relationship between maxillary canine impaction and the morphologic characteristics of the maxillary dentition, especially the root of the lateral incisor.

MATERIALS AND METHODS

In this study, we selected only patients with unilateral maxillary canine impaction to compare the morphologic characteristics of the dentition on the impaction side and the clinically normal eruption side. The sample size was decided to be 40 based on the pilot study. To minimize bias depending on sex and location of the maxillary canine impaction, we selected equal numbers (20) of boys and girls, and equal cases (20) of buccal impaction and palatal impaction. Under the aforementioned conditions, the mean age was 13.5 ± 2.3 years. The multislice spiral computed tomography images of these 40 subjects were converted into three-dimensional (3D) reconstructed images using the OnDemand 3D program (Cybermed Co, Seoul, Korea). Then we measured the morphologic characteristics of the individual teeth on the obtained 3D teeth images.

RESULTS

Length and volume of the maxillary lateral incisor's roots were significantly smaller on the impaction side compared with the normal eruption side (P = 0.001 and P = 0.006, respectively). The width and volume of the canine's crown were significantly greater on the impaction side compared with the normal eruption side (P = 0.020 and P < .0001, respectively).

CONCLUSION

These results might help to prove the hypothesis that the smaller-sized lateral incisor roots and greater-sized canine crowns are the influential etiologic factors in maxillary canine impaction.

Associations between occlusion, jaw relationships, craniofacial dimensions and the occurrence of palatally-displaced canines

BACKGROUND AND PURPOSE

Cephalometric and arch measurements might predict the occurrence of a palatally-displaced impacted maxillary canine (PDC). Despite their clinical importance, studies in this regard are limited and controversial.

METHODS

In this case-control study, 35 PDC patients and 77 controls aged over 13 years were examined. Eleven cephalometric measurements: N-S, ANS-PNS, ANS-N, S-N-ANS, facial angle (FH/NPog), SNA, SNB, Y-axis (SN/SGn), gonial angle, Go-Gn/SN, and Jarabak Index were performed. The maxillary and mandibular intermolar and interpremolar widths were measured. Patients' sagittal skeletal relationships and centric occlusions (molar) were measured by radiographic and cast examinations. The differences between the two groups in terms of the above-mentioned cephalometric and anatomic variables were assessed using Chi² and Mann-Whitney U-tests (α=0.05).

RESULTS

Chi² showed a significant negative association between dentoalveolar class I (molar) and PDC occurrence (P=0.018), but not between PDC and skeletal sagittal relationships. Facial angle (FH/NPog) and Y-axis (SN/SGn) were more obtuse in patients with PDC (P<0.05). No arch dimensions differed between the two groups.

CONCLUSIONS

PDC tends to accompany molar class II/III but is not associated with upper or lower jaw widths or lengths. Vertical dimensions might be smaller in PDC patients. Some variables were inconclusive and need future assessments.

Risk of developing palatally displaced canines in patients with early detectable dental anomalies: a retrospective cohort study

The early recognition of risk factors for the occurrence of palatally displaced canines (PDC) can increase the possibility of impaction prevention.

Prevalence and distribution of dental anomalies: a comparison between maxillary and mandibular tooth agenesis

INTRODUCTION

The aim of this study was to compare the pattern and prevalence of associated dental anomalies between maxillary and mandibular tooth agenesis (hypodontia).

METHODS

A sample of 3315 dental patients, aged 8.6 to 25.4 years, was surveyed for tooth agenesis (excluding third molars): 106 subjects were diagnosed with maxillary hypodontia (group 1) and 70 with mandibular hypodontia (group 2). Both groups were examined for the following dental anomalies: retained deciduous molars, infraocclusion of deciduous molars, impaction, microdontia of maxillary lateral incisors, supernumerary teeth, transposition, transmigration, and ectopic eruption of the permanent molars. For statistical testing, the chi-square test (P <0.05) was used to compare the occurrences of these anomalies among the groups.

RESULTS

We found that 77.5% of the patients in the mandibular hypodontia group had at least 1 dental anomaly compared with 49.5% in the maxillary hypodontia group (P <0.0001). The only dental anomaly with a significantly increased prevalence in the maxillary hypodontia group compared with the mandibular hypodontia group was microdontia of the maxillary lateral incisors (groups 1, 46.7%; group 2, 12.9%; P <0.0001). On the other hand, the prevalences of retained deciduous molars (group 1, 9.4%; group 2, 60.0%), infraoccluded deciduous molars (group 1, 0.9%; group 2, 7.1%), and impacted teeth (group 1, 22.6%; group 2, 38.6%) were significantly higher in the mandibular hypodontia group. The prevalences of supernumerary teeth, transposition, transmigration, and ectopic eruption of permanent molars were low and not significantly different between the groups.

CONCLUSIONS

Tooth agenesis isolated to the maxilla is frequently associated with microdontia of the maxillary lateral incisors, whereas tooth agenesis isolated to the mandible is frequently associated with retained deciduous molars, infraoccluded deciduous molars, and impacted teeth. The results of this study may provide additional evidence supporting the field-specific genetic control theory for dental development in both jaws.

Simplified treatment mechanics with a miniscrew for a case of canine impaction

With the introduction of miniscrews into the orthodontic field, the efficiency and effectiveness of treating complex cases have significantly improved. Biomechanical considerations, especially relating to anchorage control have become less of a concern and side effects, as a consequence, have become minimal. This article reports on a canine impaction case in which an orthodontic miniscrew has been used to effectively and efficiently pull the canine, thereby reducing anchorage unit side effects and simplifying treatment mechanics.

Epidemiology and genetics of hypodontia and microdontia: a study of twin families

OBJECTIVE

To identify genetic and environmental factors contributing to hypodontia and microdontia by using Korean twin family data.

MATERIALS AND METHODS

A total of 1267 individuals (525 men and 742 women; 180 monozygotic twins [MZ] and 43 dizygotic twins [DZ] from 282 families) underwent an oral examination as part of the Healthy Twin Study in Korea. Dental anomalies classified as hypodontia or microdontia were diagnosed using radiographs and clinical examinations. In order to estimate genetic contributions to dental anomalies, we estimated the pairwise concordance rate (PCR), recurrence risk ratio (RRR), and heritability (h2).

RESULTS

The prevalence of hypodontia and microdontia was 3.55% and 3.00%, respectively. MZ had the highest PCR and RRR (13.0-15.3). The PCR and RRR values for both anomalies were much higher for DZ (5.0-11.9) than for siblings (1.4-2.6), despite the fact that DZ pairs and sibling pairs share 50% genetic identity. Further genetic analysis revealed both an additive genetic effect (0.38 when hypodontia and microdontia were pooled) and a strong "twin effect" (0.52 when hypodontia and microdontia were pooled).

CONCLUSIONS

This twin-based study revealed that the formation of dental anomalies is affected by both genetic and environmental factors, and that the impact of these factors varies according to the specific dental anomaly.

Agenesis of second premolars and delayed dental maturation

AIM

The purpose of this work was to examine the relationship between second-premolar agenesis and how rapidly permanent dentition develops.

METHODS

Panoramic radiographs of 678 girls and boys aged 6-14 years were evaluated. Subjects with syndromes or history of tooth extraction were excluded. The permanent dentition's stages of mineralization (scale 1-10) and eruption (1-7), and the resorption (1-5) of deciduous teeth were assessed.

RESULTS

Adjusted for age and sex, subjects with one or more missing second premolars revealed earlier developmental stages (mineralization: average -0.37 stages per tooth, 95% CI -0.23 to -0.50; eruption: -0.42, 95% CI -0.60 to -0.24; resorption: -0.36, 95% CI -0.49 to -0.24; all p < 0. 001). Canines, premolars, and second molars were particularly affected, regardless of their location in the same or opposing jaw, and independent of the number of missing teeth. Overall dental development was delayed by 8.6 months (95% CI 5.4-11.8) in subjects with missing second premolars.

CONCLUSION

These results have implications for several areas of medicine. Joint biological etiology for the agenesis and late maturation of permanent teeth should be considered in developmental research. Orthodontists should be aware of the delay associated with missing second premolars when timing interventions. Forensic age assessment based on tooth development should adjust for missing teeth to avoid underestimating the subject's age.

Infraocclusion: Dental development and associated dental variations in singletons and twins

OBJECTIVE

The aim of this study was to investigate the prevalence of selected dental variations in association with infraocclusion, as well as determining the effects of infraocclusion on dental development and tooth size, in singletons and twins.

DESIGN

Two samples were analysed. The first sample comprised 1454 panoramic radiographs of singleton boys and girls aged 8-11 years. The second sample comprised dental models of 202 pairs of monozygotic and dizygotic twins aged 8-11 years. Adobe Photoshop CS5 was used to construct reference lines and measure the extent of infraocclusion (in mm) of primary molars on the panoramic radiographs and on 2D images obtained from the dental models. The panoramic radiographs were examined for the presence of selected dental variations and to assess dental development following the Demirjian and Willems systems. The twins' dental models were measured to assess mesiodistal crown widths.

RESULTS

In the singleton sample there was a significant association of canines in an altered position during eruption and the lateral incisor complex (agenesis and/or small tooth size) with infraocclusion (P<0.001), but there was no significant association between infraocclusion and agenesis of premolars. Dental age assessment revealed that dental development was delayed in individuals with infraocclusion compared to controls. The primary mandibular canines were significantly smaller in size in the infraoccluded group (P<0.05).

CONCLUSION

The presence of other dental variations in association with infraocclusion, as well as delayed dental development and reduced tooth size, suggests the presence of a pleiotropic effect. The underlying aetiological factors may be genetic and/or epigenetic.