First-in-Human Study to Investigate the Safety Assessment of Peri-Implant Soft Tissue Regeneration with Micronized-Gingival Connective Tissue: A Pilot Case Series Study.

Background: We have recently proposed an alternative strategy of free gingival graft (FGG) and connective tissue graft (CTG) using micronized-gingival connective tissues (MGCTs). The advantage of this strategy is that MGCTs from a small piece of maxillary tuberosity can regenerate the keratinized tissue band. However, safety and efficacy have not yet been established in patients. This clinical study was a pilot case series, and the objective was to assess the safety and the preliminary efficacy of MGCTs on peri-implant mucosa regeneration. Methods: This was a pilot interventional, single-center, first-in-human (FIH), open (no masking), uncontrolled, and single-assignment study. A total of 4 patients who needed peri-implant soft tissues reconstruction around dental implants received transplantation of atelocollagen-matrix with MGCTs micronized by the tissue disruptor technique. The duration of intervention was 4 weeks after surgery. Results: This first clinical study demonstrated that using MGCTs did not cause any irreversible adverse events, and it showed the preliminary efficacy for peri-implant soft tissues reconstruction in dental implant therapy. Conclusions: Though further studies are needed on an appropriate scale, as an alternative strategy of FGG or CTG, MGCTs might be promising for peri-implant mucosa reconstruction without requiring a high level of skills and morbidity to harvest graft tissues.

Long-term clinical and radiographic evaluation after maxillary sinus floor augmentation with octacalcium phosphate-collagen composite: A retrospective case series study.

The purpose of this study was to evaluate, using clinical and radiological assessments, the stability of dental implants 5 years after maxillary sinus floor augmentation with octacalcium phosphate-collagen composite (OCP/Col). Maxillary sinus floor augmentation was performed through a lateral window approach. Depending on the height of the host bone, a simultaneous approach (≥5 mm) or a staged approach (less than 5 mm) was employed. The primary outcome was the evaluation of clinical dental implant conditions such as infection, peri-implantitis, dental implant stability, pain, and paresthesia. Secondary outcomes were the evaluation of the augmented bone volume, change rate of augmented bone volume, vertical bone height, and marginal bone loss around dental implant fixture. The conditions of all dental implants were uneventful throughout the follow-up period. Augmented bone volume and changing rate of augmented bone volume were essentially unchanged following maturation of the OCP/Col-derived new bone. The change rate of new bone volume was 21.9% in the simulated approach and 16.8% in the staged approach at 1 year and 5 years postoperatively. The reduction rate in vertical bone height was 7.1% in the simultaneous approach and 7.5% in the staged approach between 1 year and 5 years postoperatively. Mean marginal bone loss was 1.76 mm with the simultaneous approach, and 0.50 mm with the staged approach at 5 years postoperatively. In conclusion, the success of dental implants 5 years after sinus floor augmentation by OCP/Col implantation was clarified by both clinical and radiological evaluations.

Assessment of safety and efficacy of antimicrobial photodynamic therapy for peri-implant disease.

BACKGROUND: There is no reliable treatment procedure for peri-implant disease, despite the rise in its incidence. This study sought to evaluate the short-term safety and efficacy of antimicrobial photodynamic therapy (a-PDT) on peri-implantitis by assessing the volume of pus discharge after a-PDT. METHODS: Patients with pus discharge from a peri-implant pocket were recruited from December 1st, 2019 to April 30th, 2020. The enrolled implants were randomly assigned to one of two groups, the irrigation and a-PDT groups. Their peri-implant pocket was irrigated with normal saline in the irrigation group, and a saline irrigation and subsequent a-PDT with toluidine blue (TB) was performed in the a-PDT group. The safety and efficacy of a-PDT were assessed 7 days after treatment. RESULTS: Twenty-five implants in 21 patients (irrigation group; 13 implants, a-PDT group; 12 implants) were registered. No complication was observed after a-PDT. Pus discharge was decreased in 7 of 12 implants (58.3 %) in the a-PDT group, and in 2 of 13 implants (15.4 %) in the irrigation group. According to Fisher's exact test, a-PDT resulted in a statistically significant decrease in pus discharge compared to irrigation alone (p = 0.0414). CONCLUSIONS: a-PDT was confirmed to be a safe treatment for peri-implantitis, and the short-term efficacy of a-PDT with TB on peri-implantitis was clarified. Nevertheless, its efficacy remains restricted, and a new combination therapy of a-PDT and decontamination procedures is expected to be developed in future.

Full Regeneration of Maxillary Alveolar Bone Using Autogenous Partially Demineralized Dentin Matrix and Particulate Cancellous Bone and Marrow for Implant-Supported Full Arch Rehabilitation.

Autogenous partially demineralized dentin matrix (APDDM) has been reportedly used as a superior bone graft material. A 52-year-old Japanese man who exhibited severe periodontitis was referred for oral rehabilitation. He underwent wide-range anterior maxillary alveolar bone and bilateral sinus floor augmentation by grafting of a mixture of APDDM and particulate cancellous bone and marrow (PCBM); subsequently, he underwent implant-supported full arch rehabilitation. He has been followed up for 4 years after placement of the final restoration without any complications, and his physiological bone volume has been maintained. APDDM constitutes an alternative treatment that may increase the volume of graft material and might prevent rapid resorption of PCBM, because APDDM served as a scaffold for osteoblasts from PCBM. When possible, it may be useful to apply APDDM as a graft material with PCBM for large-volume alveolar bone regeneration.

Alveolar bone preservation by a hydroxyapatite/collagen composite material after tooth extraction.

OBJECTIVE: The aim of this study was to assess the effectiveness of a hydroxyapatite/collagen composite material (HAp/Col) for preservation of alveolar bone after tooth extraction. MATERIALS AND METHODS: HAp/Col was applied to the alveolus bone ridge preservation after tooth extraction, because of subsequent dental implant placement in 35 regions of 24 patients (mean age, 59.3 years; range, 25-81 years). Cone beam computed tomography was used to assess changes in alveolar bone at the extraction site before and at 3 months (mean, 13.7 weeks; range, 10-17 weeks) after tooth extraction. Changes in height and width of the alveolar bone were measured to evaluate bone reduction after surgery. Bone biopsy was performed at 11 regions of dental implant placement to observe bone regeneration and remaining material in the extraction socket. RESULTS: The alveolar bone height was decreased by 0.00 ± 2.44 mm at the buccal side and 0.35 ± 1.73 mm at the lingual side, while the width was decreased by 1.02 ± 1.64 mm at 3 months after surgery. The middle of the socket floor was elevated by 5.71 ± 3.45 mm at 3 months after surgery. Bone biopsy specimens revealed no remaining implanted material, and approximately 49.79 ± 14.41% of the specimens were occupied by bone tissue. CONCLUSIONS: According to the result of this study, HAp/Col is a reliable material to presearve alveolar bone after tooth extraction. CLINICAL RELEVANCE: HAp/Col contributes dental implant treatment due to maintain the alveolar bone after tooth extraction.

Soft tissue engineering with micronized-gingival connective tissues.

The free gingival graft (FGG) and connective tissue graft (CTG) are currently considered to be the gold standards for keratinized gingival tissue reconstruction and augmentation. However, these procedures have some disadvantages in harvesting large grafts, such as donor-site morbidity as well as insufficient gingival width and thickness at the recipient site post-treatment. To solve these problems, we focused on an alternative strategy using micronized tissue transplantation (micro-graft). In this study, we first investigated whether transplantation of micronized gingival connective tissues (MGCTs) promotes skin wound healing. MGCTs (≤100 µm) were obtained by mincing a small piece (8 mm3 ) of porcine keratinized gingiva using the RIGENERA system. The MGCTs were then transplanted to a full skin defect (5 mm in diameter) on the dorsal surface of immunodeficient mice after seeding to an atelocollagen matrix. Transplantations of atelocollagen matrixes with and without micronized dermis were employed as experimental controls. The results indicated that MGCTs markedly promote the vascularization and epithelialization of the defect area 14 days after transplantation compared to the experimental controls. After 21 days, complete wound closure with low contraction was obtained only in the MGCT grafts. Tracking analysis of transplanted MGCTs revealed that some mesenchymal cells derived from MGCTs can survive during healing and may function to assist in wound healing. We propose here that micro-grafting with MGCTs represents an alternative strategy for keratinized tissue reconstruction that is characterized by low morbidity and ready availability.