The purpose of this study was to examine the precise anatomical location of the lower labial branches (LLBs) of the mental nerve as they run beneath the oral vestibular mucosa (OVM), in order to prevent the complication of injury to the LLB during oral implant-related surgery.
Fifty-one mental neurovascular bundles were dissected from 26 cadavers to determine the course and depth of the LLBs between the mental foramen (MF) and the lower lip. The following items were measured:1) the number of LLBs, 2) the angle between the main branch of the LLB and the inferior border of the mandible (IBM), 3) the distance between the MF and the shallowest point of a LLB beneath the OVM, and 4) the depth from the shallowest point of the LLB to the OVM.
The results of the anatomical investigations were:
1) the number of LLB, 1～3 and 1.39±0.60 (mean±S.D.); 2) the main branch of the LLB-IBM angle, 25.00～70.00° and 50.40±12.40°; 3) the MF-LLB distance, 2.00～28.00 mm and 12.10±6.80 mm; and 4) the LLB-OVM depth, 0.05～5.40 mm and 0.90±1.03 mm.
These measurement results show that the LLB, upon exiting from the MF, runs in an anterosuperior direction at approximately 50°relative to the IBM and travels at an extremely shallow level directly beneath the OVM near the mandibular canine area.
Although dental implant bodies are currently cut by machine to the appropriate shape, this method is not suitable for those with a complicated morphology. One way to overcome this problem is the metal injection molding method (MIM), which is considered to yield excellent results as a method to produce large amounts of identical, morphologically precise products. In this study, using Ti-6Al-4V alloy powder, whose use as a material for implant bodies is increasing, we produced test specimens by MIM and evaluated their characteristics.
The tensile strength of Ti-6Al-4V wire rods was 57 MPa higher than that of MIM specimens. The proof stress was 45 MPa higher in the MIM specimens. Elongation was 9% greater in the wire rods than in the MIM specimens. Hardness was greater in the MIM specimens than in the wire rods. As a result of observing the metal structure, the test specimens produced using the MIM showed pores during sintering. The MIM specimens had sufficient mechanical properties according to the JIS standard, and thus the MIM method is thought to be suitable as an implant material.
The purpose of this study was to determine whether clinical success can be achieved with immediate loading in the edentulous maxilla and mandible with Brånemark implants (Nobel Biocare, Gotebörg, Sweden) at three years after placement of the implants.
The study sample consisted of 30 patients who were edentulous or about to lose all remaining teeth. A total of 186 implants were placed in 9 maxillae and 22 mandibles, including one bimaxillary patient. One hundred and fifty-four of the 186 implants were immediately loaded and 32 implants were submerged. Five to 7 implants (mean of 5.8 implants) supported the prostheses in the maxilla and 4 or 5 implants (mean of 4.6 implants) in the mandible. All implants immediately loaded were placed in the incisor and premolar regions of both maxilla and mandible. The mean lengths of the implants in the maxillae and mandibles were 14.6±1.8 mm and 16.3±2.3 mm,respectively. All of 52 immediate loaded implants in the maxillae showed placement torque of more than 30 Ncm. Although 5 of 102 implants in the mandibles showed placement torque of 30 Ncm, the remaining implants showed more than 35 Ncm. Provisional implant-supported fixed prostheses were fabricated in a laboratory from an impression and were placed on the next day after the surgery. After 4 to 7 months, definitive prostheses were fabricated and placed. One implant, although still osseointegrated, was removed owing to bone resorption. In the patient, the provisional prosthesis was supported by the remaining 4 implants; thus the cumulative survival rates for implants and prostheses were 99.4% and 100%, respectively, after three years.
This clinical report suggests that immediate loading of implant-supported fixed prostheses in the edentulous maxilla and mandible can be a safe and successful treatment as long as patients are carefully and strictly selected.