Non-syndromic hypodontia of maxillary lateral incisors and its association with other dental anomalies

Shear Bond Strength of Simulated Single-Retainer Resin-Bonded Bridges Made of Four CAD/CAM Materials for Maxillary Lateral Incisor Agenesis Rehabilitation

OBJECTIVES

 Maxillary lateral incisor agenesis (MLIA), treated orthodontically by space opening, requires complimentary aesthetic rehabilitation. Resin-bonded bridges (RBBs) can be equated as interim rehabilitation until skeletal maturity is achieved to place an implant-supported crown or as definitive rehabilitation in case of financial restrictions or implant contraindications. Scientific evidence of the best material must be confirmed in specific clinical situations. Computer-aided design and computer-aided manufacturing (CAD/CAM) materials are promising versatile restorative options. This study aimed to identify a straightforward material to deliver interim or definitive RBBs for nonprepared tooth replacement in MLIA.

MATERIALS AND METHODS

 Single-retainer RBB made from CAD/CAM ceramic blocks (Vita Enamic [ENA], Suprinity [SUP], and zirconia [Y-ZPT]) and a three-dimensional (3D) printed material (acrylonitrile butadiene styrene [ABS]) were evaluated by shear bond strength (SBS) and mode of failure, after adherence to an artificial tooth with RelyX Ultimate used in a three-step adhesive strategy.

STATISTICAL ANALYSIS

 The load to fracture (N) was recorded, and the mean shear stress (MPa) was calculated with standard deviations (SD) for each group and compared between materials using boxplot graphics. One-way analysis of variance (ANOVA) followed by the Tukey-Kramer post hoc test was used to compare the differences (α = 0.05). A meta-analysis focusing on CAD/CAM materials evaluated the magnitude of the difference between groups based on differences in means and effect sizes (α = 0.05; 95% confidence interval [CI]; Z-value = 1.96). Failure mode was determined by microscopic observation and correlated with the maximum load to fracture of the specimen.

RESULTS

 The mean ± SD SBS values were ENA (24.24 ± 9.05 MPa) < ABS (24.01 ± 1.94 MPa) < SUP (29.17 ± 4.78 MPa) < Y-ZPT (37.43 ± 12.20 MPa). The failure modes were mainly adhesive for Y-ZPT, cohesive for SUP and ENA, and cohesive with plastic deformation for ABS.

CONCLUSION

 Vita Enamic, Suprinity, Y-ZPT zirconia, and 3D-printed ABS RBBs are optional materials for rehabilitating MLIA. The option for each material is conditioned to estimate the time of use and necessity of removal for orthodontic or surgical techniques.

Alveolar morphometry in young adults with and without agenesis of the upper lateral incisor: A retrospective study

INTRODUCTION

We aimed to compare alveolar morphometry in young adults with agenesis of the upper lateral incisor versus the side without agenesis and versus matched controls.

MATERIAL AND METHODS

In this observational retrospective study, cone beam computed tomography scans were obtained of 36 upper hemiarches from young adults aged 15 to 30 years. The hemiarches were distributed into three groups: group 1: 12 upper hemiarches presenting agenesis of the upper lateral incisor; group 2: 12 upper hemiarches from the opposite side without agenesis of the upper lateral incisor (control group 1); and group 3: 12 upper hemiarches without agenesis of the upper lateral incisor matched for age and sex with respect to the affected group (control group 2). A trained and calibrated investigator performed all the alveolar measurements at two different times, including sagittal, coronal and axial slices of each hemiarch. Paired Student's t-tests, Chi-square and repeated measures ANOVA with Bonferroni correction were used, (P<0.05).

RESULTS

Apical mesial evaluation of group 1 (4.22±1.19mm) was significantly lower (P<0.001) than that of groups 2 (6.72±1.17mm) and 3 (7.58±1.67mm). Apical distal evaluation also showed differences (P<0.001) among the three groups, with the dimension being smaller in group 1 with agenesis (4.53±1.14mm), followed by group 2 without agenesis (6.23±1.55mm) and the healthy control group 3 (7.73±1.71mm).

CONCLUSIONS

Lateral incisor agenesis significantly reduces the alveolar dimensions of the affected area. In cases of unilateral agenesis, the unaffected side also shows sequelae, with decreased dimensions compared to cases without agenesis. This condition should be taken into account when making therapeutic decisions regarding rehabilitation with implants or canine replacement.

"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.

Characteristics of Unilaterally Impacted Maxillary Canines and Effect on Environmental Tissues: A CBCT Study

BACKGROUND

The prognosis of orthodontic treatment for a patient with impacted canine teeth can be affected by many factors and understanding some of the characteristics of impacted teeth can increase the effectiveness and reduce the duration of treatment. This study aims to explore the effects of positions and dentoalveolar morphological characteristics of impacted maxillary canines on the prognosis of orthodontic treatment.

METHODS

In this study, forty-six adolescent individuals who applied for treatment of impacted teeth were divided into three groups: CC (no impacted maxillary canine group), BC (unilateral buccally positioned impacted maxillary canine group), and PC (unilateral palatally positioned impacted maxillary canine group). The impacted canine and adjacent teeth were evaluated in terms of position, angulation, inclination, mesiodistal and buccolingual widths, root length, dilaceration angle, and root resorption.

RESULTS

The mean values of U3 Ang (angulation of the maxillary impacted canine) and U3/U2 angles (maxillary impacted canine and lateral incisor angle) were statistically significantly higher in the BC and PC groups (p < 0.001). The mean values of U2 RL (lateral incisor root length) and U3 RD (canine root dilaceration angle) were statistically significantly lower in the BC and PC groups.

CONCLUSIONS

The results of this study suggest that shorter root lengths and increased angulation values may lead to the ectopic eruption of canines. The higher canine angulations in the PC group increase the degree of root resorption.

Esthetic Perception of Different Clinical Situations of Maxillary Lateral Incisor Agenesis According to Populations with Dental and Non-Dental Backgrounds: A Systematic Review and Meta-Analysis

Treatment of unilateral or bilateral maxillary lateral incisor agenesis is challenging, time-consuming, expensive, and requires careful treatment planning, predictability, and esthetics. This review aimed to identify differences in esthetic perception among orthodontists, general dentists, differentiated dentists, and laypersons, which may interfere with treatment options. EBSCO, PubMed, ScienceDirect, Cochrane Library databases, and Google Scholar were searched using keyword pairing and a Boolean expression, "(congenitally missing OR agenesis OR hypodontia) AND (maxillary lateral incisors) AND (esthetic perception OR smile) AND (laypersons OR dental professional OR general dentist OR orthodontists)." Reviews and case studies were excluded. A total of 13 studies were selected for qualitative analysis (adapted ROBINS-I) and 11 were selected for meta-analysis (p < 0.05) after being sub-grouped into "Opening vs. Closure" and "No remodeling vs. Dental remodeling vs. Dental and gingival remodeling" groups. A meta-analysis evaluated the magnitude of the difference between groups based on differences in means and effect sizes (α = 0.05; 95% CI; Z-value 1.96), revealing that the esthetic perception of maxillary lateral incisor agenesis treatment remains controversial even among professionals. Gingival remodeling was not valued compared to isolated dental remodeling. Studies lack rigorously comparable methodologies. Discussion with the patient is pertinent in doubtful situations, as the best treatment option remains unclear, and overtreatment should be avoided.