Maxillary Lateral Incisor Agenesis Research Articles

Great expectations of patients with missing lateral incisors: when are space opening and space closure appropriate?

On average, 2% of the UK population have agenesis of the permanent maxillary lateral incisors. Reopening the space for restorative replacement or closing the space and subsequent reshaping of the canine depends on a number of factors. Among these are the aesthetics of the canines, level of the smile line, gingival architecture and occlusion. Joint orthodontic and restorative planning to determine the appropriateness of space opening or space closing, with a discussion of these in context with the expectations of the patient/parent, is important before commencing treatment. Despite advances in materials and techniques within both restorative and orthodontic specialties resulting in improvements in the aesthetic outcomes of hypodontia cases, the management of patient/parent expectations is key to overall success. This paper details the contemporary restorative–orthodontic treatment options for the management of missing lateral incisors, the orthodontic biomechanics and restorative approaches involved in treatment.

Prevalence of maxillary lateral incisor agenesis and associated skeletal characteristics in an orthodontic patient population

Objectives: This study was aimed to investigate the prevalence of maxillary lateral incisor agenesis and associated skeletal characteristics in an orthodontic patient population.Materials and methods: The records of the 1066 patients seeking orthodontic treatment were screened for maxillary lateral incisor agenesis (MLIA). The following data were recorded for each subject: age; gender; unilateral or bilateral agenesis of MLI and side. The lateral cephalogram of each subject with MLIA was digitally traced. The data were compared to age-matched control orthodontic patients with skeletal Class I.Results: The prevalence of maxillary lateral incisor agenesis was 4.9% (52 patients) in which 63.5% were females. There was a significant difference between MLIA patients and controls in sagittal relationships (ANB, Wits, AB plane, angle of convexity and Co-A/Co-Gn differential analyses) p < 0.05.Conclusions: Patients with maxillary lateral incisor agenesis showed a significant tendency for skeletal Class III compared with the Class I control. This could be attributed to maxillary hypoplasia/retrognathia.

Agenesis of Maxillary Lateral Incisors: Treatment Involves Much More Than Just Canine Guidance.

Objective:In this study, we aimed highlight some clinical features present in patients whose maxillary lateral incisors are missing, and proposed more logical, rational and predictable solutions to inform decision making in rehabilitation procedures.Methods:Literature review and discussion.Conclusion:Choosing the best possible treatment for congenital absence of maxillary lateral incisors depends on the multidisciplinary diagnosis of facial, occlusal, functional and periodontal features. It also depends on the individual long-term stability, and it does not only rely on canine-guided disocclusion.

Esthetic perception of maxillary lateral incisor agenesis treatment by canine mesialization.

The objective of this study was to evaluate perception of the smile in maxillary lateral incisor agenesis (MLIA) cases treated by mesialization of a canine. Nine images were digitally modified from the same frontal intraoral photograph to simulate various treatment options for space closure in MLIA. A questionnaire was submitted to laypersons (303), general dentists (215), prosthodontists (55) and orthodontists (81). Statistical tests with a significance level of P<0.05 were used. The views of MLIA treatment judged to be most attractive showed unilateral dental and gingival reshaping. All study groups considered the simple dental reshaping of the mesial edge of the canine to be attractive. In the analysis of the images grouped together for both unilateral and bilateral MLIA, the view showing dental and gingival reshaping was considered the most attractive whereas unmodified mesialization was considered the least attractive. Regarding the space closure treatments, although all groups regarded simple dental reshaping of the canine to be attractive, the dental professionals considered gingival and crown reshaping to be more esthetic. In contrast, laypersons were not significantly responsive to this dental and gingival modification as compared to only slight reshaping of the mesial edge of the cusp of the mesialized canine in MLIA.

Implant-Prosthetic Rehabilitation in Bilateral Agenesis of Maxillary Lateral Incisors with a Mini Split Crest.

The reported clinical case describes the surgical procedure of ridge augmentation by using a “split crest” technique with a partial thickness flap and a subsequent implant-prosthetic rehabilitation aimed at treating a bilateral agenesis of the upper lateral incisors. In such cases with vestibule-palatal and mesial-distal scarce bone thicknesses associated with the need of a proper functional and aesthetic rehabilitation, the split crest technique is particularly suitable. In the case we reported, because of the poor bone thicknesses, we performed a minimally invasive split crest which allowed a correct insertion of the fixtures. This technique allowed us to achieve an optimal functional and aesthetic rehabilitation; moreover, we obtained a good emergency profile, ensuring the vitality of the close teeth and ensuring a good primary stability and the following osseointegration of dental implants.

Maxillary lateral incisor agenesis and its relationship to overall tooth size

Statement of problemAgenesis of the maxillary lateral incisor has been linked to differences in the size of the remaining teeth. Thus, the mesiodistal space required for definitive esthetic restoration in patients with missing maxillary lateral incisors may be reduced. PurposeThe purpose of this study was to determine whether a tooth size discrepancy exists in orthodontic patients with agenesis of one or both maxillary lateral incisors. Material and methodsForty sets of dental casts from orthodontic patients (19 men and 21 women; mean 15.9 years of age; all of European origin) were collected. All casts had agenesis of one or both maxillary lateral incisors. Teeth were measured with a digital caliper at their greatest mesiodistal width and then compared with those of a control group matched for ethnicity, age, and sex. Four-factor ANOVA with repeated measures of 2 factors was used for statistical analysis (α=.05). ResultsOrthodontic patients with agenesis of one or both maxillary lateral incisors exhibited smaller than normal tooth size compared with the control group. The maxillary arch had a larger tooth size difference between the control and test groups than the mandibular arch (there was a significant Jaw×Group interaction [F=4.78, P=.032]). ConclusionsAgenesis of one or both maxillary lateral incisors is significantly associated with tooth size discrepancy, which may affect the space remaining for restoration of the remaining teeth.

Presurgical Unilateral Cleft Lip Anthropometrics and the Presence of Dental Anomalies

To investigate associations between cleft lip anthropometrics and dental anomalies in the permanent dentition in unilateral cleft lip patients. Retrospective cross-sectional study. Children with unilateral clefts of the lip, with or without cleft palate. Anthropometric lip measurements, made immediately prior to lip repair, were available for each patient. The presence of dental anomalies in the permanent dentition was assessed radiographically. The presence of associations between anthropometric lip measurements and prevalence rates of different dental anomalies were determined using logistic regression analyses. In the 122 included patients, the cleft lateral lip element was deficient in height in 80% and in transverse length in 84% of patients. Patients with more deficient cleft side lateral lip height and less deficient cleft side lateral lip transverse length were more likely to present with cleft side maxillary lateral incisor agenesis. On the other hand, patients with a less deficient cleft side lateral lip height and more deficient cleft side lateral lip transverse length were more likely to present with a cleft side supernumerary maxillary lateral incisor. When looking only at incomplete clefts, the cleft side lateral lip transverse length deficiency was more predictive of the presence of supernumerary maxillary lateral incisors (P = .030), while for complete clefts, the cleft side lateral lip height deficiency was more predictive of the presence of maxillary lateral incisor agenesis (P = .035). In patients with unilateral clefts, cleft lip anthropometrics have a predictive role in determining the occurrence of dental anomalies.

Patterns of bilateral agenesis of maxillary third molars and agenesis of other teeth.

The purpose of this study was to investigate the patterns of bilateral agenesis of maxillary third molars and other tooth agenesis in Japanese orthodontic patients. A group of 262 subjects with bilateral agenesis of maxillary third molars (group A) was divided into three subgroups: group 1A consisting of 114 subjects without agenesis of mandibular third molars; group 2A, 31 subjects with unilateral agenesis of mandibular third molars; and group 3A, 117 subjects with agenesis of all third molars. As controls, 926 other subjects without third molar agenesis were selected (group C). Panoramic radiographs were mainly used to examine for tooth agenesis. The Chi square test and odds ratio were used to make statistical comparisons. The prevalence rates of agenesis of maxillary lateral incisors, mandibular incisors and maxillary and mandibular second premolars, and bilateral agenesis of maxillary lateral incisors and second premolars were significantly higher in any one of the third molar agenesis groups than in the control group. Characteristically, no significant increase in occurrence of bilateral agenesis of mandibular second premolars was demonstrated by the subjects with bilateral agenesis of maxillary third molars. Irrespective of whether unilateral or bilateral agenesis of mandibular third molars is present or not, the Japanese orthodontic patients with bilateral agenesis of maxillary third molars exhibited a significantly increased occurrence of unilateral or bilateral agenesis of maxillary lateral incisors, mandibular incisors and maxillary and mandibular second premolars, except for bilateral agenesis of mandibular incisors and second premolars.

Congenitally missing maxillary lateral incisors: update on the functional and esthetic parameters of patients treated with implants or space closure and teeth recontouring.

Maxillary lateral incisor agenesis (MLIA) is a condition that affects both dental esthetics and function in young patients, and represents an important challenge for clinicians. Although several treatment options are available, the mesial repositioning of the canines followed by teeth recontouring into lateral incisors; or space opening/maintenance followed by implant placement have recently emerged as two important treatment approaches. In this article, the current and latest literature has been reviewed in order to summarize the functional and esthetic outcomes obtained with these two forms of treatment of MLIA patients in recent years. Indications, clinical limitations and the most important parameters to achieve the best possible results with each treatment modality are also discussed. Within the limitations of this review, it is not possible to assert at this point in time that one treatment approach is more advantageous than the other. Long-term followup studies comparing the existing treatment options are still lacking in the literature, and they are necessary to shed some light on the issue. It is possible, however, to state that adequate multidisciplinary diagnosis and planning are imperative to define the treatment option that will provide the best individual results for patients with MLIA.

Case Report: The Clinical Application of a Surgical Navigation System for Implant-Prosthetic Rehabilitation of the Patient with Maxillary Lateral Incisors Agenesis

Introduction: A precise transfer of planned procedures to a real operative field can be provided by surgical robots. This technology, still unique, is increasingly applied in new medical specialties. The aim of this paper was to describe the clinical application of an active navigation in the dental implant treatment. Case Report: The patient was imaged by CBCT computed tomography Gendex GXCB-500/i-CAT while wearing an individually fitted interfacing acrylic splint. Thereafter, CT data were imported to the Image Guided Implantology System and precise 3-dimensional implant treatment plan was contemplated. This system allows real-time interactive carrying out of implantological procedures with three-dimensional visualization of the anatomical structures during the procedure. Conclusions: The system of active navigation ensures the coordination of prosthetic and surgical treatment which guarantees optimal surgical and prosthetic effect of the therapy, including both anatomical structures and prosthetic requirements.

WNT10A coding variants and maxillary lateral incisor agenesis with associated dental anomalies.

Congenital maxillary lateral incisor agenesis (MLIA) is one of the most common subtypes of dental agenesis. Because little is known with regard to the aetiology of this anomaly, the aim of the study was to determine the contribution of nucleotide variants in wingless-type MMTV integration site family, member 10A (WNT10A), msh homeobox 1 (MSX1), and paired box 9 (PAX9) to the risk of MLIA in a Polish population. Coding regions of the selected genes were analysed by direct sequencing in a group of 20 individuals with unilateral and bilateral MLIA, associated or not with other dental anomalies. The frequencies of the identified nucleotide variants were assessed in an additional cohort of patients with isolated dental agenesis (n = 147) and in 178 controls. Mutation screening showed four non-synonymous substitutions located in the highly conserved coding sequence of WNT10A in five (25%) of the 20 patients. Analysis of genotyping results revealed that three of these variants--p.Arg113Cys, p.Phe228Ile, and the newly identified p.Arg171Leu--may represent aetiological mutations underlying MLIA with associated dental anomalies. No mutations that were potentially aetiologic were identified in MSX1 and PAX9. In conclusion, this is the first report implicating coding variants in the WNT10A gene in the aetiology of MLIA. These results will require further confirmation using larger-scale studies.

Esthetic Assessment of the Effect of Gingival Exposure in the Smile of Patients with Unilateral and Bilateral Maxillary Incisor Agenesis.

The aim of this study was to determine the dental esthetic perception of the smile of patients with maxillary lateral incisor agenesis (MLIA); the perceptions were examined pre- and post-treatment. Esthetic determinations were made with regard to the gingival exposure in the patients' smile by orthodontists, general dentists, and laypersons. Three hundred eighty one people (80 orthodontists, 181 general dentists, 120 laypersons) rated the attractiveness of the smile in four cases before and after treatment, comprising two cases with unilateral MLIA and contralateral microdontia and two with bilateral MLIA. For each case, the buccal photograph was adjusted using a computer to apply standard lips to create high, medium, and low smiles. A numeric scale was used to measure the esthetic rating perceived by the judges. The resulting arithmetic means were compared using an ANOVA test, a linear trend, and a Student's t-test, applying a significance level of p < 0.05. The predictive capability of the variables, unilateral, or bilateral MLIA, symmetry of the treatment, gingival exposure of the smile, group, and gender were assessed using a multivariable linear regression model. In the pre- and post-treatment cases, medium smile photographs received higher scores than the same cases with high or low smiles, with significant differences between them. In all cases, orthodontists were the least-tolerant evaluation group (assigning lowest scores), followed by general dentists. In a predictive linear regression model, bilateral MLIA was the more predictive variable in pretreatment cases. The gingival exposure of the smile was a predictive variable in post-treatment cases only. The medium-height smile was considered to be more attractive. In all cases, orthodontists gave the lowest scores, followed by general dentists. Laypersons and male evaluators gave the highest scores. Symmetrical treatments scored higher than asymmetrical treatments. The gingival exposure had a significant influence on the esthetic perception of smiles in post-treatment cases.

Facial Biotype and Mandibular Growth Adaptation in Maxillary Lateral Incisors Agenesis

El objetivo fue verificar la eventual relacion entre la agenesia de los incisivos lLaterales maxilares (AILM) y los biotipos faciales establecidos en clinica. Se realizo un analisis en tres grupos de sujetos: (i) pacientes afectos de AILM, (ii) sus familiares y (iii) una poblacion control no afecta, definida como normal. Entre los grupos tambien se comparo a los sujetos en periodo de crecimiento con los adultos. El biotipo dolicofacial fue descrito principalmente en ninos con agenesias bilaterales, mientras que los pacientes con agenesias unilaterales y la poblacion control presentaban mayoritariamente un patron mesofacial. El patron braquifacial fue prevalente en ninos no afectos de agenesia pero miembros de la familia de pacientes afectos de agenesia. Lo mismo se observo en todos los pacientes adultos, aunque la prevalencia del biotipo braquifacial resulto similar a la del biotipo mesofacial en pacientes no afectos de agenesia, pero con relacion familiar a pacientes afectos. La notable variabilidad en el grupo sometido a estudio, evidente por los elevados valores de DE obtenidos en cada grupo, no permite establecer de manera definitiva una correlacion positiva entre la AILM y un biotipo morfologicos facial, al menos con los datos hasta ahora disponibles.

Agenesis of maxillary lateral incisor and tooth replacement: cost-effectiveness of different treatment alternatives.

To evaluate the long-term cost-effectiveness of five treatment alternatives for maxillary lateral incisor agenesis where space maintenance and tooth replacement are indicated. The following treatment modalities were considered: single-tooth implant-supported crown, resin-bonded fixed partial denture (FPD), cantilever FPD, full-coverage FPD, and autotransplantation. The cost-effectiveness for each treatment modality was determined as the ratio of the outcome of each modality divided by the cost. Direct costs, clinical and laboratory, were calculated based on national fee schedules and converted to international dollars using purchasing power parity exchange rates. Outcomes were based on the most recently published long-term (10-year) survival rates. Sensitivity analyses were carried out, testing the robustness of the cost-effectiveness analysis. The five treatment modalities ranked in the following order from most to least cost-effective: autotransplantation, cantilever FPDs, resin-bonded FPDs, single-tooth implants and implant-supported crowns, and full-coverage FPDs. Sensitivity analysis illustrated that the cost-effectiveness analysis was reliable in identifying autotransplantation as the most and full-coverage FPDs as the least cost-effective treatment modalities. When replacing a missing maxillary lateral incisor, the most costeffective, long-term treatment modality is autotransplantation, whereas the least cost-effective is full-coverage FPDs. However, factors such as patient age, the state of the dentition, occlusion, and tooth conservation should also influence the choice of restoration.

Smile attractiveness of patients treated for congenitally missing maxillary lateral incisors as rated by dentists, laypersons, and the patients themselves

Esthetic judgments can help dental professionals better understand how attentive people are to their own smiles and those of others. The purpose of this study was to evaluate the smile attractiveness of patients treated for maxillary lateral incisor agenesis compared with that of individuals with a complete dentition. Photographs were made of the smiles of patients with maxillary lateral incisor agenesis who were treated with space closure and teeth recontouring (n=26) or space opening and implants (n=20) and of a control group with a complete dentition (n=22). Both laypersons and dentists assessed smile attractiveness by using a visual analog scale. Patients and controls also assessed the level of satisfaction with their own smile. Assessments were performed twice, and the reliability of the method was determined with Cronbach α and intraclass correlation. Multifactorial and 1-way ANOVA were used to analyze smile attractiveness and participant satisfaction, followed by the Bonferroni post hoc test (α=.05). Attractiveness ratings by dentists and laypersons did not differ significantly among the study groups (P=.64). The ratings of male dentists and female laypersons differed significantly from those of other evaluators (P=.01). Patients with space closure and teeth recontouring were significantly more satisfied than controls (P=.002). No significant differences were found between the patients with implants and controls or between the patients with implants and those with space closure and teeth recontouring. The smiles of patients with maxillary lateral incisor agenesis were judged to be as attractive as those ofthecontrols. Male dentists were the most critical raters, closely followed by female laypersons. All participants had highlevels of satisfaction with their own smile; patients treated with space closure and teeth recontouring were the most satisfied.

Identification of Genetic Risk Factors for Maxillary Lateral Incisor Agenesis

Tooth agenesis affects 20% of the world population, and maxillary lateral incisors agenesis (MLIA) is one of the most frequent subtypes, characterized by the absence of formation of deciduous or permanent lateral incisors. Odontogenesis is a complex mechanism regulated by sequential and reciprocal epithelial-mesenchymal interactions, controlled by activators and inhibitors involved in several pathways. Disturbances in these signaling cascades can lead to abnormalities in odontogenesis, resulting in alterations in the formation of the normal teeth number. Our aim was to study a large number of genes encoding either transcription factors or key components in signaling pathways shown to be involved in tooth odontogenesis. We selected 8 genes—MSX1, PAX9, AXIN2, EDA, SPRY2, TGFA, SPRY4, and WNT10A—and performed one of the largest case-control studies taking into account the number of genes and variants assessed, aiming at the identification of MLIA susceptibility factors. We show the involvement of PAX9, EDA, SPRY2, SPRY4, and WNT10A as risk factors for MLIA. Additionally, we uncovered 3 strong synergistic interactions between MLIA liability and MSX1-TGFA, AXIN2-TGFA, and SPRY2-SPRY4 gene pairs. We report the first evidence of the involvement of sprouty genes in MLIA susceptibility. This large study results in a better understanding of the genetic components and mechanisms underlying this trait.

Prevalence of mesiodens in orthodontic patients with deciduous and mixed dentition and its association with other dental anomalies

To determine the prevalence of mesiodens in deciduous and mixed dentitions and its association with other dental anomalies. Panoramic radiographs of 1,995 orthodontic patients were analyzed retrospectively, obtaining a final sample of 30 patients with mesiodens. The following aspects were analyzed: gender; number of mesiodens; proportion between erupted and non-erupted mesiodens; initial position of the supernumerary tooth; related complications; treatment plan accomplished; and associated dental anomalies. The frequency of dental anomalies in the sample was compared to reference values for the general population using the chi-square test, with a significance level set at 5%. The prevalence of mesiodens was 1.5% more common among males (1.5:1). Most of the mesiodens were non-erupted (75%) and in a vertical position, facing the oral cavity. Extraction of the mesiodens was the most common treatment. The main complications associated with mesiodens were: delayed eruption of permanent incisors (34.28%) and midline diastema (28.57%). From all the dental anomalies analyzed, only the prevalence of maxillary lateral incisor agenesis was higher in comparison to the general population. There was a low prevalence of mesiodens (1.5%) in deciduous and mixed dentition and the condition was not associated with other dental anomalies, except for the maxillary lateral incisor agenesis.

Cone-beam computed tomography evaluation of alveolar ridge width and height changes after orthodontic space opening in patients with congenitally missing maxillary lateral incisors

The purpose of this study was to evaluate the alveolar bone dimensional changes with cone-beam computed tomography after space-opening procedures for an endosseous implant in patients with unilateral or bilateral maxillary lateral incisor agenesis. A pilot retrospective cohort study was conducted of 11 patients (13 sites) in whom the canines had erupted less than 2 mm distally to the central incisors. Pretreatment and posttreatment scans obtained from 3 private practice offices were evaluated for changes in alveolar bone width, height, and labial concavity. A fiducial line representing the ideal location of the longitudinal axis of an endosseous dental implant was used as a reference for the spatial location of the alveolar bone at the lateral incisor site in reference to the adjacent tooth roots at posttreatment. The posttreatment width and height measurements scans were compared with normative data from the contralateral incisor in patients with unilateral agenesis (n= 6). Alveolar bone width was significantly decreased on average from 17% to 25% along the height of the ridge (2-10 mm) (P<0.05). The labial concavity was significantly increased compared with the initial dimensions (P<0.05). No significant changes were found in alveolar bone ridge height. Significant alveolar bone width decreases and increases in labial concavity were found after implant ridge development in patients with maxillary lateral incisor agenesis. The alveolar bone ridge was located more lingually than the adjacent teeth, suggesting a need for bone grafting to achieve proper fixture placement.

Analysis of dental agenesis patterns of the oligodontia patients using the method of tooth agenesis code

To analyze the common dental agenesis patterns of the oligodontia patients. The information of 64 oligodontia patients was collected, including the histories, oral examinations and panoramic radiographs. The Tooth Agenesis Code (TAC) procedure was used to analyze the agenesis pattern of each quadrant. In the maxilla, 63% (40/64) (right side) and 58% (37/64) (left side) could be described using eight different patterns. The most common pattern was agenesis of the maxillary lateral incisor, canine and both premolars.In the mandible, 52% (33/64) (right side) and 53% (34/64) (left side) of the patients could be described using only five different patterns, the most common pattern was agenesis of both mandibular premolars. Common patterns of tooth agenesis were successfully identified in non-syndromic oligodontia patients.

Is the presence of Simonart's band in patients with complete unilateral cleft lip and palate associated with the prevalence of missing maxillary lateral incisors?

The aim of this study was to compare the prevalence of agenesis of the maxillary lateral incisors in the cleft area of patients with unilateral cleft lip and palate with and without Simonart's band. A sample of panoramic radiographs of 121 patients with a mean age of 7 years was divided into 2 groups: group 1 included 60 patients with Simonart's band, and group 2 included 61 patients without Simonart's band. Patients with syndromes were not included. Chi-square tests were used for intergroup comparisons (P<0.05). In the pooled subgroup, the prevalences of maxillary lateral incisor agenesis, supernumerary maxillary lateral incisors, 1 maxillary lateral incisor mesial to the cleft, and 1 maxillary lateral incisor distal to the cleft were 40.5%, 12.5%, 8.2%, and 38.8%, respectively. In group 1, these frequencies were 35%, 10%, 6.7%, and 48.3%; in group 2, they were 45.9%, 13.1%, 11.5%, and 29.5%. There was a statistically significant difference between the groups for the prevalence of a maxillary lateral incisor distal to the cleft. The presence of Simonart's band is associated with a higher frequency of maxillary lateral incisor development in the maxillary process.