Analyses of oligodontia phenotypes and genetic etiologies

Oligodontia is the congenital absence of six or more teeth and comprises the more severe forms of tooth agenesis. Many genes have been implicated in the etiology of tooth agenesis, which is highly variable in its clinical presentation. The purpose of this study was to identify associations between genetic mutations and clinical features of oligodontia patients. An online systematic search of papers published from January 1992 to June 2021 identified 381 oligodontia cases meeting the eligibility criteria of causative gene mutation, phenotype description, and radiographic records. Additionally, ten families with oligodontia were recruited and their genetic etiologies were determined by whole-exome sequence analyses. We identified a novel mutation in WNT10A (c.99_105dup) and eight previously reported mutations in WNT10A (c.433 G > A; c.682 T > A; c.318 C > G; c.511.C > T; c.321 C > A), EDAR (c.581 C > T), and LRP6 (c.1003 C > T, c.2747 G > T). Collectively, 20 different causative genes were implicated among those 393 cases with oligodontia. For each causative gene, the mean number of missing teeth per case and the frequency of teeth missing at each position were calculated. Genotype–phenotype correlation analysis indicated that molars agenesis is more likely linked to PAX9 mutations, mandibular first premolar agenesis is least associated with PAX9 mutations. Mandibular incisors and maxillary lateral incisor agenesis are most closely linked to EDA mutations.

Finding Appropriate Nickel-Titanium Instruments for Lingual Canals in Mandibular First Premolars with Two Canals: A Micro-CT Study

Background: To find appropriate Nickel-Titanium instruments for lingual canals in mandibular first premolars with two canals.Methods: A total of 42 extracted mandibular first premolars with two canals were selected after micro-CT scanning. The teeth were matched and divided into three groups, and three types of Nickel-Titanium instruments (M3, HyFlex CM and XP-endo Shaper) were used to prepare the lingual canals of the sample teeth. After instrumentation, micro-CT scanning was used again to reconstruct the three-dimensional (3D) teeth model, and then it was geometrically aligned with the original model before instrumentation. Two-dimensional (2D) and three-dimensional parameters of teeth models were measured to evaluate the ability of cleaning and maintaining the original canal shape by the three different instruments. Results: Compared with HyFlex CM and XP-endo Shaper, the apical transportation of M3 was significantly greater within the apical 3 mm (P < 0.05), while there was no significant difference between HyFlex CM and XP-endo Shaper (P > 0.05). There was no significant difference in centering ability among three types of instruments (P > 0.05). In general, HCM group and XPS group performed better than M3 group in the 2D and 3D analysis (P < 0.05). Conclusions: Preparation of the lingual canal in mandibular first premolar was more challenging than that of the main buccal canal. All the three nickel-titanium instruments are safe for canal preparation, and generally, the HyFlex CM and XP-endo Shaper performed better than the M3.

Bypassing a Separated Instrument in Mandibular First Premolar with Two Canals – A Case Report

Fracture of an endodontic instrument will impair the debridement procedure and thus affects the endodontic outcome. This case report focuses on the management of separated instrument and highlights the anatomical variation of mandibular first premolar. An in-depth knowledge on the internal anatomy of this particular tooth as well as following a proven and safe technique as a guideline is important in preventing these endodontic mishaps.

Digital Assessment of Gingival Dimensions of Healthy Periodontium

The aim of the present study was to re-visit the gingival dimension using digital scanning in a healthy Korean population. Forty-eight periodontally healthy volunteers (38 males and 10 females, mean age: 24.3 ± 2.2 years) were included. The mucogingival junction was highlighted using 2.5% diluted iodine solution. Then, the facial gingiva and mucosa of both jaws were digitally scanned using an intraoral digital scanner. Using computer software and periodontal probing, the heights and areas of keratinized gingiva (KG) and attached gingiva (AG) were measured. Similar distribution patterns in the gingival heights were noted in the maxilla and mandible. The maxilla showed substantially greater gingival values than the mandible. The heights of the KG and AG were notably smaller on the mandibular first premolar (2.37 mm and 1.07 mm, median value) and second molar (3.28 mm and 1.78 mm) than on the other teeth. The area of the KG was the largest in the canine (63.74 mm2 and 46.85 mm2) and first molar (64.14 mm2 and 58.82 mm2) in each jaw. Mandibular first and second molars, mandibular canine, and maxillary canine showed the highest value of the area under the receiver operation characteristics curve (>0.7) for differentiating between males and females. The gingival dimensions recorded using intraoral scanner demonstrated similar distribution patterns as in previous studies.

The Proximity of Mental Foramen to Mandibular First Premolar Teeth: Cone Beam Computed Tomography Analysis in Turkish Population

SummaryBackground/Aim: The aim of this study was to evaluate the proximity of the mental foramen (MF) to the roots of the mandibular first premolar teeth in the Turkish population according to gender and different age groups.Material and Methods: The study was conducted on 385 samples of 242 patients who presented at the Dicle University, Faculty of Dentistry, Department of Dentomaxillofacial Radiology. The proximity of the MF to mandibular first premolar teeth was examined on cone beam computed tomography (CBCT) images. Two-way Anova variance analysis was used in the statistical analyses of the data.Results: According to the analysis results, no statistically significant difference was determined between the age and gender groups (p>0.05). In the evaluation of the gender groups, the mean value was 6.6997 mm for females and 6.5445 mm for males.Conclusions: With 3-dimensional imaging technology, the CBCT system provides detailed information about the MF localization. This method has shown that the localization of the MF could change associated with variables such as age and gender.

Nonsurgical Root Canal Treatment of a Mandibular First Premolar with Taurodontism Managed with Minimally Invasive Endodontics: A Case Report

A 67-year-old male patient was referred for further treatment of a mandibular left first premolar. The tooth presented with slight percussion tenderness and the periodontal probing depth was normal. There was no soft tissue swelling. The radiographic image exhibited a temporary restoration in the previously initiated access cavity of the mandibular left first premolar. The diagnosis of the mandibular left first premolar was previously initiated therapy associated with symptomatic apical periodontitis. The tooth presented four root canals and the characteristics of taurodontism. Two buccal root canals bifurcated at the apical third. The pulpal floor was examined under a dental operating microscope and four canal orifices were identified. TruNatomy Glider was used for glide path preparation. TruNatomy Prime file was selected for final root canal preparation in order to maximally preserve the radicular dentin. Root canal irrigation was achieved by using RC-Prep and 2.5% NaOCl between each file application. Canal blockage was avoided by multiple recapitulations with K-files (#10) between changing each rotary file. Obturation of the canals were performed by using TruNatomy Conform Fit® Gutta-Percha cones and AH Plus® root canal sealer via the warm lateral condensation technique. CBCT was arranged for confirmation after root canal treatment of the mandibular left first premolar and showed a good outcome. The clinical procedures and instruments could provide the practitioners for reference while managing such a difficult case.