Root and root canal variations of the human maxillary and mandibular third molars in a Chinese population: A micro-computed tomographic study

Furcation Involvement in Periodontal Disease: A Narrative Review

Furcation-involved teeth, commonly seen in dental practice, have a higher likelihood of needing extraction as the severity of periodontal furcation involvement increases. Studies consistently show that periodontitis in teeth with multiple roots significantly increases the risk of tooth loss, especially in the area where the furcation is involved. These furcation defects pose a major problem for dentists because of their location, accessibility issues, and the unpredictable healing process. The biggest hurdle in treating furcation defects is their irregular shape, which makes it hard to achieve complete debridement. While various treatments have been explored, non-surgical methods have not shown much success. This article comprehensively provides a review and discussion on the classification, assessment, and treatment options, including surgical and non-surgical management of furcation-involved molar teeth. Properly understanding the severity of the disease and its confounding factors and managing and treating the lesions appropriately have been shown to impart satisfactory survival rates for these teeth. Enhancing the understanding of managing these teeth can also lead to better outcomes for patients.

Effectiveness evaluation of autotransplanted teeth after performing extraoral endodontic surgery instead of conventional root canal therapy

PURPOSE

The aim of this study was to examine the viability and efficacy of utilizing extraoral apicoectomy and retrograde filling in combination to seal the root canal system of mature molars without the need for root canal therapy (RCT) during the autotransplantation of teeth (ATT).

MATERIALS AND METHODS

This study screened 27 patients who received ATT at the Department of Oral Surgery in the Hospital of Stomatology from 2019 to 2021. Extraoral apicoectomy and retrograde filling were performed, while RCT was temporarily not performed. The study analysed the periodontal status and masticatory function of transplanted teeth one to three years postoperation and used cone-beam computed tomography (CBCT) and periapical radiograph (PA) to evaluate the integrity of the periodontal space and intra/periapical inflammation. The potential predictors of survival/success were analysed statistically. We also conducted questionnaires and chewing efficiency tests.

RESULTS

In this study, 27 TTs from 27 patients were found to be fully functional in terms of chewing ability. The overall survival rate was 100% (27/27), and the success rate was 70.4% (19/27). A total of 90.9% (20/22) of patients reported being satisfied or very satisfied with their TTs. Additionally, the chewing efficiency of the transplantation side was on average 82.0% of that of the healthy side, with a significant difference between the two sides (P < 0.05). None of the potential predictors were found to significantly affect the success or survival of the transplanted tooth (TT).

CONCLUSION

The combination of extraoral apicoectomy and retrograde filling in TT showed promising outcomes, but further clinical cases and longer follow-up times are still required to validate the treatment plan.

Effect of impaction on third molar development and age estimation-A study in a Lebanese population

BACKGROUND

The effect of impaction on third molar development is disputable as the scientific literature is not uniform. In parallel, population-specific studies have been encouraged in dental age estimation. This study aimed to investigate the effect of impaction on third molar formation in a sample of Lebanese individuals.

MATERIALS AND METHODS

The sample consisted of 518 panoramic radiographs of females (n=229) and males (n=289) between 15 and 23.9 years. Mandibular third molars were classified based on their position as non-impacted and impacted (with horizontal, vertical, mesioangular, and distoangular impaction). Dental development was classified according to Demirjian's 8-level staging system.

RESULTS

Most teeth presented mesioangular impaction (#38=29.7%, #48=33%). Developing third molars were predominantly distributed between stages D and G. The mean age of most developmental stages was higher among impacted teeth, meaning that third molar mineralization could be slower in the presence of impaction. In general, the delayed dental development did not have statistically significant effects (P<0.05). However, descriptive data pointed out differences between (impacted and non-impacted) mean ages of >12 months-suggesting a potential clinical significance (despite the lack of a statistical one). Furthermore, differences changed based on sex and side (#38/#48).

CONCLUSION

Therefore, dental age estimation from third molars in the selected Lebanese population should preferably be performed in non-impacted third molars whenever available.

[Microanatomy features in third molars roots adjacent to mandibular canal]

THE PURPOSE

Of the study is to reduce the risk of postoperative neuropathy of the inferior alveolar nerve by improving diagnostic methods, assessment of individual topographic and anatomical features and extraction technique of impacted teeth adjacent to the mandibular canal.

MATERIALS AND METHODS

According to the CBCT examination, orthopantomography and macroscopic examination of removed third molars roots (n=140) the relative position of the mandibular canal and the roots of the third molars were studied.

RESULTS

Three variants of close mandibular canal and third molars position have been identified. In the lateral and apical nerve position, the root surface depressions were detected. With inter-radicular position fit, the mandibular canal and the nerve bundle form a «bed» in between impacted tooth roots.

CONCLUSION

The injury of neurovascular bundle prognosis during extraction with an interadicular mandibular position depends on roots anatomy and their convergence degree. If the interradicular distance is less than the diameter of the mandibular canal, nerve injury during tooth extraction is inevitable, in such cases coronectomy is indicated.

Root and Root Canal Configuration Characterization Using Microcomputed Tomography: A Systematic Review

This systematic review’s objective was to conduct a complete analysis of the literature on the root canal morphology using advanced micro-computed tomography. The electronic web databases PubMed, Scopus, and Cochrane were examined for research papers concerning the chosen keywords, evaluating the root canal morphology using Micro-CT, published up to 2021. The articles were searched using MeSH keywords and searched digitally on four specialty journal websites. DARE2 extended (Database of Attributes of Reviews of Effects) was used to assess bias risk. The information was gathered from 18 published studies that strictly met the criteria for inclusion. In the included studies, a total of 6696 samples were studied. The studies were conducted on either maxillary (n-2222) or mandibular teeth (n-3760), permanent anteriors (n-625), and Third molars (n-89). To scan samples, a Scanco Medical machine in was used in 10 studies, Bruker Micro-CT in 34, and seven other machines were utilized in the rest. Bruker Micro-CT software from Kontich, Belgium, VG-Studio Max 2.2 software from Volume Graphics, Heidelberg, Germany, was the most commonly used software. The minimum Voxel size (resolution) adopted in the included studies was 11.6 µm. However, 60 µm was the maximum. Most studies classified the root canal morphology using Vertucci’s classification system (n-16) and the four-digit system (n-6).

Periprosthetic biomechanical response towards dental implants, with functional gradation, for single/multiple dental loss

The differences in shape and stiffness of the dental implants with respect to the natural teeth (especially, dental roots) cause a significant alteration of the periprosthetic biomechanical response, which typically leads to bone resorption and ultimately implant loosening. In order to avoid such clinical complications, the implant stiffness needs to be appropriately adapted. In this study, hollow channels were virtually introduced within the designed implant screws for reduction of the overall stiffness of the prototype. In particular, two opposing radial gradients of increasing hollow channel diameters, i.e., outside to inside (Channel 1) and inside to outside (Channel 2) were considered. Two clinical situations of edentulism were addressed in this finite element-based study, and these include a) loss of the first molar, and b) loss of all the three molars. Consequently, two implantation approaches were simulated for multiple teeth loss - individual implantation and implant supported dental bridge. The effects of implant length, approach and channel distribution on the biomechanical response were evaluated in terms of the von Mises stress within the interfacial periprosthetic bone, under normal masticatory loading. The results of our FE analysis clearly reveal significant variation in periprosthetic bone stress between the different implant designs and approaches. An implant screw length of 11 mm with the Channel 2 configuration was found to provide the best biomechanical response. This study also revealed that the implant supported dental bridge approach, which requires lower bone invasion, results in favorable biomechanical response in case of consecutive multiple dental loss.

Molecular biological and histological effects of Er:YAG laser irradiation on tooth movement

The aim of this study was to evaluate the effects of a fiberotomy-like procedure using Er:YAG laser irradiation on the velocity of orthodontic tooth movement. To produce experimental tooth movement in rats, orthodontic force was applied to the upper first molars with a nickel-titanium closed coil. The right molars were irradiated with an Er:YAG laser while the non-irradiated left molars were used as controls. The rats were sacrificed at 4 weeks after the start of tooth movement and the distance between the mesial side of the second molar and the distal side of the upper first molar was measured on CT images. The amount of tooth movement was significantly greater in the irradiation group than in the control group. The TRAP-positive nuclei count at the pressure site was higher in the laser-irradiation group than in the control group. Expression of RANKL and ALP was higher at the mesial-coronal pressure site in the laser-irradiation group than in the control group. In addition, expression of OPG was higher at the pressure site in the control group than in the laser-irradiation group. These results suggest that a fiberotomy-like procedure using an Er:YAG laser stimulates osteoclasts and osteoblasts and may promote bone metabolism in the context of experimental tooth movement.