Rotational path removable partial mandibular resection prostheses: A case series of patients with mandibular symphyseal defects.

Rotational path removable partial mandibular resection prostheses (MRPs) offer advantages in the management of patients with acquired symphyseal defects of the mandible, including enhanced esthetics achieved through a reduced number of clasps, the provision of rigid retainers less prone to distortion compared with flexible alternatives, and the ability to engage prominent proximal undercuts in patients lacking buccal undercuts. Additionally, removable partial MRPs represent a suitable treatment option in scenarios where the cost of implant-retained prostheses is prohibitive or in patients where implant therapy is contraindicated, such as those with a history of head and neck radiation. While the use of rotational path removable prostheses has been well documented in conventional prosthodontics, its application in maxillofacial prosthetics remains less explored. This case series describes 3 patients, all of whom underwent mandibular resections involving the mandibular symphysis and subsequently received prosthetic rehabilitation incorporating rotational path removable partial MRPs.

Cell Type-Specific Effects of Implant Provisional Restoration Materials on the Growth and Function of Human Fibroblasts and Osteoblasts.

Implant provisional restorations should ideally be nontoxic to the contacting and adjacent tissues, create anatomical and biophysiological stability, and establish a soft tissue seal through interactions between prosthesis, soft tissue, and alveolar bone. However, there is a lack of robust, systematic, and fundamental data to inform clinical decision making. Here we systematically explored the biocompatibility of fibroblasts and osteoblasts in direct contact with, or close proximity to, provisional restoration materials. Human gingival fibroblasts and osteoblasts were cultured on the "contact" effect and around the "proximity" effect with various provisional materials: bis-acrylic, composite, self-curing acrylic, and milled acrylic, with titanium alloy as a bioinert control. The number of fibroblasts and osteoblasts surviving and attaching to and around the materials varied considerably depending on the material, with milled acrylic the most biocompatible and similar to titanium alloy, followed by self-curing acrylic and little to no attachment on or around bis-acrylic and composite materials. Milled and self-curing acrylics similarly favored subsequent cellular proliferation and physiological functions such as collagen production in fibroblasts and alkaline phosphatase activity in osteoblasts. Neither fibroblasts nor osteoblasts showed a functional phenotype when cultured with bis-acrylic or composite. By calculating a biocompatibility index for each material, we established that fibroblasts were more resistant to the cytotoxicity induced by most materials in direct contact, however, the osteoblasts were more resistant when the materials were in close proximity. In conclusion, there was a wide variation in the cytotoxicity of implant provisional restoration materials ranging from lethal and tolerant to near inert, and this cytotoxicity may be received differently between the different cell types and depending on their physical interrelationships.