Human Stem Cells and Tissue Responses to Xenogeneic Bone Block: An In Vitro and Histologic Study

PURPOSE

Premature loss of a tooth element causes extensive local bone atrophy. Block biomaterials are used in patients with an atrophic maxilla to reshape the premaxilla bone. This study aimed to evaluate the responses to xenogeneic bone blocks at cellular and tissue levels.

MATERIALS AND METHODS

Viability of human periodontal ligament stem cells (hPDLSCs) submitted to culture medium-containing substances leached from a xenogeneic block biomaterial (Orthogen) was assessed by the MTT assay. Cells grown in a fresh medium were used as the control. Cell viability was measured at 24, 48, and 72 hours. The results were statistically compared (α ≤ .05). Tissue response to the biomaterial was evaluated by the placement of xenogeneic blocks anchored with miniscrews in six patients with atrophic maxillae and a remaining cortical bone tissue thickness of 2.0 to 3.0 mm. After 8 months, specimens were collected from the grafted areas and analyzed under a light microscope for evaluating the types of collagen fibers and amount of newly formed bone tissue, using the Image-Pro Plus software program.

RESULTS

The number of viable cells was similar in both groups. The histologic sections revealed remaining biomaterial in 10.12% of the patients and newly formed bone in 21.57%.

CONCLUSION

The xenogeneic block biomaterial tested proved to be biocompatible in vitro, and the porosity of the block favored the in vivo formation of new bone matrix deposits.

Current evidence of tissue engineering for dentine regeneration in animal models: a systematic review

Aim: The aim of this study is to verify the type of scaffold effect on tissue engineering for dentine regeneration in animal models. Materials & methods: Strategic searches were conducted through MEDLINE/PubMed, Web of Science and Scopus databases. The studies were included with the following eligibility criteria: studies evaluating dentine regeneration, and being an in vivo study. Results: From 1392 identified potentially relevant studies, 15 fulfilled the eligibility criteria. All studies described characteristics of neoformed dentine, being that the most reported reparative dentine formation. Most of included studies presented moderate risk of bias. Conclusion: Up to date scientific evidence shows a positive trend to dentine regeneration when considering tissue engineering in animal models, regardless the type of scaffolds used.

The importance of prosthetic planning for implant-supported dentures in esthetic zones - A case report

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Prosthetic planning prior to surgical treatment is crucial for the success of implant-supported prostheses.

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Poor rehabilitation planning can lead to gingival retraction and fracture of prosthetic components.

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A multidisciplinary approach is of utmost importance to achieve the desired results.

Introduction

Implant-supported dentures in esthetic zones pose a great challenge to dental surgeons, since important factors are involved in treatment success, such as positioning of the implants, morphology of soft tissues, dental esthetics, and biomechanics of the prosthetic structure.

Presentation of case

This clinical report describes the case of a patient previously subjected to dental surgery for implant placement on tooth #11 and subsequent prosthetic crown placement. The patient reported poor esthetics due to gingival retraction and changes on the surface of the ceramic material. After proper multidisciplinary planning, the prosthesis was remanufactured, with the selection of new components and periodontal surgery using a modified technique for the handling of soft tissues. After nine postoperative months, the patient had a better gingival alignment and reported esthetic and functional satisfaction.

Discussion

After assessing the positioning of implants, it is important to select prosthetic components that are suitable to each clinical case, as they will guarantee clinical success for long time periods. In order to obtain a better gingival contour and avoid an extensive surgical procedure, two techniques were used: the pinhole surgical technique, in which the gingiva is repositioned without the use of grafts; and Tarnow’s technique, in which a semilunar incision is made in soft tissues.

Conclusion

The multidisciplinary approach, combining prosthetic and periodontal procedures, proved to be efficient, improving esthetic outcomes.

Evaluation of the effectiveness of peracetic acid in the sterilization of dental equipment

PURPOSE

To evaluate the effectiveness of peracetic acid in the microbiological sterilisation of dental materials.

METHODS

Peracetic acid solution was evaluated at concentrations of 800, 1500 and 2500 ppm. At these concentrations, it was determined whether peracetic acid caused corrosion to dental instruments and induced cellular mutagenicity and cytotoxicity. In addition, the minimum inhibitory concentration (MIC), the minimum bactericidal concentration (MBC), agar diffusion and diffusion by well method, were also verified.

RESULTS

The corrosion rate, calculated from potentiodynamic assays was 10(-6) cm/year, indicating that the product does not damage equipment. The sterilisation capacity of peracetic acid at 2500 ppm was the best. The comet assay indicated genotoxic activity at 2500 ppm.

CONCLUSIONS

This study demonstrated the effectiveness of peracetic acid for sterilizing dental equipment, providing another alternative for the prevention of infections in clinics.