Critical considerations when planning experimental in vivo studies in dental traumatology

Methods and applications of finite element analysis in dental trauma research: A scoping review

Finite Element Analysis (FEA) is vital for understanding dental traumatology (DT) biomechanics, aiding diagnosis, treatment planning, and outcome prediction. This review explores FEA applications in DT research, evaluates their quality and outcomes, and assesses methodological aspects. Accordingly, recommendations for future researchers are provided. The study adhered to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines for scoping reviews and registered in Open Science framework. A comprehensive search using relevant text-words and MeSH terms was performed in established databases. The inclusion criteria encompassed all Finite element analysis (FEA)-based Dental traumatology (DT) studies without language or publication year restrictions. Risk of bias was assessed with the Risk of bias tool for the use of finite element analysis in dentistry (ROBFEAD) tool. Forty-six studies published from 2001 to 2023 were included in the qualitative synthesis. The studies were categorized into five domains and six subdomains based on objectives. Maxillary central incisors and surrounding structures were commonly modelled (n = 27). Most studies utilized Computed tomography (CT), Cone Beam CT, or micro CT. Traumatic injury forces ranged from 100 N to 2000 N, and occlusal forces ranged from 150 N to 350 N. All studies were rated as high risk of bias. Fory-six studies were categorized, with most focusing on stress distribution and fracture patterns in dento-alveolar structures under various conditions, while few assessed displacements. Methodological quality lacked robustness in model development and substructure properties. Future studies should address these limitations and enhance reporting practices.

The Role of Dendritic Cells during Physiological and Pathological Dentinogenesis

The dental pulp is a soft connective tissue of ectomesenchymal origin that harbors distinct cell populations, capable of interacting with each other to maintain the vitality of the tooth. After tooth injuries, a sequence of complex biological events takes place in the pulpal tissue to restore its homeostasis. The pulpal response begins with establishing an inflammatory reaction that leads to the formation of a matrix of reactionary or reparative dentin, according to the nature of the exogenous stimuli. Using several in vivo designs, antigen-presenting cells, including macrophages and dendritic cells (DCs), are identified in the pulpal tissue before tertiary dentin deposition under the afflicted area. However, the precise nature of this phenomenon and its relationship to inherent pulp cells are not yet clarified. This literature review aims to discuss the role of pulpal DCs and their relationship to progenitor/stem cells, odontoblasts or odontoblast-like cells, and other immunocompetent cells during physiological and pathological dentinogenesis. The concept of “dentin-pulp immunology” is proposed for understanding the crosstalk among these cell types after tooth injuries, and the possibility of immune-based therapies is introduced to accelerate pulpal healing after exogenous stimuli.

Low-intensity pulsed ultrasound attenuates replacement root resorption of avulsed teeth stored in dry condition in dogs

This study aimed to investigate the effects of low-intensity pulsed ultrasound (LIPUS) on replacement root resorption after replantation of avulsed teeth stored in a dry condition in dogs. A total of 73 premolar roots from four male mongrel dogs were intentionally avulsed with forceps and divided into four groups—HN, HL, DN, and DL—according to storage conditions and whether or not they received LIPUS treatment. Thirty-eight roots were kept in Hanks’ Balanced Salt Solution for 30 min (HN and HL groups), whereas the remaining 35 roots were left to dry in the air for an hour (DN and DL groups) prior to replantation. Following replantation, the roots in the HL and DL groups (21 and 18 roots, respectively) received a 20-min daily LIPUS treatment for 2 weeks. The animals were euthanized 4 weeks after the operation. Micro-computed tomography images were acquired for each root and the amount of replacement root resorption was measured three-dimensionally. Histological assessments were also carried out. There was significantly less replacement root resorption for the roots in the DL group compared to the DN group (p < 0.01). Histological findings in the DN group demonstrated evident replacement root resorption, whereas the DL group revealed less severe resorption compared to the DN group. Within the limitations, these results suggest that LIPUS could attenuate the replacement resorption of avulsed teeth stored in a dry condition, thereby improving their prognosis.

Cell-Based Therapy for Tooth Replantation Following Avulsion: A Systematic Review

The management of avulsed teeth undergoing delayed replantation remains a clinical challenge as there are currently no effective interventions that can improve periodontal healing and prevent replacement root resorption. While several preclinical studies have reported varied success using cell-based tissue engineering to improve periodontal healing, a consensus is required before further clinical translation. Therefore, this systematic review seeks to evaluate the efficacy of cell-based therapy in promoting periodontal healing following delayed replantation in animal models. MEDLINE (PubMed) and Embase were searched on September 27, 2020. Ten studies involving rodent and dog models met the inclusion criteria. Cell sources included gingiva, periodontal ligament (PDL), bone marrow, and adipose tissues. Generally, cell-based therapy had increased the proportion of root surfaces displaying periodontal healing and concomitantly reduced the proportion presenting with replacement root resorption and ankylosis. The best outcomes were observed following treatment with PDL-derived cells of various potency. Future preclinical studies will benefit from adopting measures to minimize bias during the conduct of animal experiments and the standardization of the outcome measures reporting. This will facilitate future reviews with possible pooling of results in the form of meta-analyses, allowing a consensus to be obtained from the literature. In addition, further research will be required to shed light on the implications of using allogeneic cells as well as the optimization of cell delivery protocols. The findings of this systematic review demonstrated the therapeutic potential of certain cell-based therapies in promoting periodontal healing following delayed replantation, thus highlighting their prospective clinical benefits and translational value.

The effect of cathepsin K inhibitor surface treatment on delayed tooth replantation in dogs

BACKGROUND/AIM

Continuous research efforts have been focusing on promoting healing of delayed replantation of avulsed teeth. The aim of this in vivo study was to assess the effect of cathepsin K inhibitor surface treatment on delayed tooth replantation.

MATERIALS AND METHODS

Thirty-four premolar roots of 4 beagle dogs were extracted, and conventional root canal treatment was performed. The canals were filled with gutta-percha and cement. All extracted teeth were air-dried for 1 hour. Teeth were divided into 2 groups according to the root surface treatment prior to replantation: control (n = 13) and cathepsin K inhibitor (n = 21). Treated teeth were replanted in their original sockets and stabilized with a resin-wire splint for 1 week. After 12 weeks, the dogs were euthanized and micro-computed tomography was performed. Tissues were then further processed as resin-embedded specimens stained with hematoxylin and eosin. In each evaluation, data were analyzed using the Mann-Whitney U test (P < .05).

RESULTS

In the micro-computed tomography evaluation, inflammation scores of both groups were not statistically different (P > .05). In the histological evaluation, the mean proportions of inflammatory resorption and replacement resorption in the control group were similar to those in the cathepsin K inhibitor group (P > .05).

CONCLUSIONS

Cathepsin K inhibitor did not demonstrate significant inhibitory effects on root resorption after delayed replantation in vivo.

An experimental model for studies on delayed tooth replantation and ankylosis in rabbits

AIM

To develop an experimental in vivo model to study dentoalveolar ankylosis and osseous replacement resorption after delayed replantation.

MATERIALS AND METHODS

The maxillary right incisors of eight rabbits were extracted and replanted, while the maxillary left incisors served as controls. A special technique for extraction was used, luxating the incisor laterally prior to extraction. Extra-oral root canal treatment was performed. In four of the eight replanted teeth, periodontal ligament was removed using gauze. All teeth were replanted after one-hour dry storage. A horizontal line was drilled on the labial enamel surface of the incisors to enable registration of possible subsequent infraposition. The rabbits were sacrificed after 1 week or 4 weeks, respectively. Percussion test of the teeth was carried out and infraposition was registered. Histological processing and evaluation were performed.

RESULTS

Percussion sound was normal after 1 week and high in the 4 week group; infraposition was noted in all replanted teeth in the 4-week group. Fusion between the bone and dentin was seen in some areas on the root already after 1 week, but there was little or no osseous replacement. Larger areas of ankylosis were seen in the 4-week group although not significant, but deeper progressive osseous replacement was noted in this group. There was no significant difference in ankylosis with regard to periodontal ligament removal or not. Pulp and periodontal tissues were normal in all control teeth.

CONCLUSION

The rabbit tooth model may be useful for experimental in-vivo studies on delayed replantation, subsequent ankylosis, osseous replacement and infraposition.

Effect of indomethacin on surface treatment and intracanal dressing of replanted teeth in dogs

PURPOSE

This study evaluated the healing process of teeth replanted after root treatment and intracanal dressing with indomethacin alone or indomethacin with calcium hydroxide (Ca[OH]2).

MATERIALS AND METHODS

Through a case-control study, 24 teeth of 6 adult dogs were extracted, dried, and divided into 4 groups according to the root surface treatment protocols performed before replantation and the intracanal medication used after replantation. In group 1 (negative control), root surfaces were treated by immersion in a 0.9% saline solution and then replanted. In the other groups, the roots were immersed for 10 minutes in Ca(OH)2 (group 2), indomethacin (group 3), or a solution of indomethacin and Ca(OH)2 (group 4). After 2 weeks, group 1 teeth were subjected to single-visit root canal treatment and obturation with gutta-percha and sealer consisting of zinc oxide and eugenol. The teeth in the other groups were subjected to intracanal dressing with the same material used for immersion. After an additional period of 28 weeks, the animals were euthanized and the jaws containing the replanted teeth were processed for histologic analysis. Histometric values were statistically analyzed, with significance set at a P value less than or equal to .05.

RESULTS

Group 1 exhibited significantly more normal periodontium than group 4 (P = .02). Total resorption was greater in group 4 than in group 1 (P = .02). No statistically significant difference in the percentage of surface resorption or in total inactive resorption was observed between the groups.

CONCLUSIONS

The findings of this study suggest that intracanal dressing and topical root treatment with Ca(OH)2 with or without indomethacin is not recommended for teeth dried for 50 minutes, but the use of indomethacin alone as root surface treatment for delayed tooth replantation deserves further study using longer drying periods. In addition, the present results suggest that a single-visit root canal, performed up to 2 weeks after replantation, might be indicated for teeth dried for up to 50 minutes.

Histologic and micro-computed tomographic analyses of replanted teeth stored in different kind of media

INTRODUCTION

Coconut water (CW) and soy milk (SM) have been proposed as storage media for avulsed teeth because of their nutrients that preserve cell viability. The present study investigated the periodontal healing process of dog teeth replanted after storage in CW, SM, and whole milk (WM) using micro-computed tomographic (μCT) and histologic analyses compared with immediate tooth replantation.

METHODS

Forty roots of 10 adult beagle dogs were extracted and subjected to the following protocols: immediate replantation after extraction (control), stored in CW with an adjusted pH, and SM and WM for 50 minutes before replantation. The animals were euthanized 28 days postoperatively, and the obtained specimens were scanned using a μCT scanner and subjected to routine processing for histometric analyses under an optical microscope.

RESULTS

CW and SM performed similarly to WM; however, SM showed significantly higher ankylosis than the control group.

CONCLUSIONS

Additionally, this study showed that the combined use of histologic analysis and μCT is a promising method to better identify tooth resorption and the repair process and to evaluate the total extension of the periodontium. CW as a storage medium is a promising transport media for avulsed teeth.