Measurement of gap between abutment and fixture in dental conical connection implants. A focused ion beam SEM observation.

BACKGROUND: The aim of the authors was to examine the abutment-fixture interface in Morse-type conical implants in order to verify gaps at this level using a new microscopical approach. MATERIAL AND METHODS: In this in vitro study, 20 abutment-fixture complexes were prepared by sectioning (longitudinal and cross-sectional to the long axis) with a microtome and then with a focused ion beam (FIB). This is a micrometric machine tool that uses gallium ions to abrade circumscribed areas to dig deeper into the cuts obtained with the microtome in order to eliminate cut-induced artifacts. This is because the FIB abrasion is practically free from artifacts, which are normally generated by the action of the microtome blades or other techniques. Samples were then observed by scanning electron microscopy (SEM). RESULTS: The observation of the abraded parts with the FIB permitted measurement of the real gap between the implant-abutment components. A variable amount of gap was retrieved (from 0 to 3 µm) by the observations, confirming the non-hermetic nature of the connection. It has to be pointed out that in approximately 65% of cases, the gap accounted for less than 1 µm. CONCLUSIONS: The reported data confirmed that the analyzed connection system allowed for minimal gap. However, from the evidence of the present analysis, it cannot be assumed that the 2 parts of a Morse-type conical implant are fused in 1 piece, which would create a perfectly matched hermetic connection.

Maxillary ameloblastoma.

Maxillary ameloblastoma is a rare odontogenic neoplasm that is histologically benign and originates from epithelial cells present in bone tissue. If excised through conservative surgery, this tumour has a high relapse rate and is locally aggressive. The risk, in particularly extensive forms, that the ameloblastoma will invade extra-maxillary structures such as the orbit, the pterygomaxillary fossa, the infratemporal fossa and the base of the skull, means that surgical treatment is difficult if it is to be oncologically radical while respecting function and aesthetics. Thus, in these cases a complete and in-depth diagnostic work-up and careful planning of surgical treatment are needed: surgery entails an ablative phase with en-bloc resection of the neoformation to margins free of neoplastic infiltration, and a reconstruction phase that, within a short time-frame, will re-establish functionality and provide a good aesthetic result. Our experience in treating 2 cases of maxillary ameloblastoma is reported.

[Maxillo-mandibular fixation by mono-cortical screws. Clinical indications and surgical methods]. / Il bloccaggio intermascellare con viti transfisse monocorticali. Indicazioni cliniche e note di tecnica chirurgica.

BACKGROUND: Intermaxillary fixation is one of the most reknown and widely used techniques in maxillofacial traumatology. It's carried out usually by means of direct criss-cross teeth wiring or through the wiring of a metallic archbar on the upper and lower jaws. These techniques are time-consuming operations, they can produce dental or periodontal damages, and are not well tolerated by the patient, even under local anesthesia. Recent experiences in oral implantology and in the use of miniscrews for rigid internal fixation suggest the experimentation of new, easy to use and better tolerated systems for bone-anchored intermaxillary fixation. METHODS: 1-0 stainless steel wires and titanium monocortical screws, 2 mm of diameter and 12 and 15 mm of length, have been used as alveolar-bone anchorages for the intermaxillary fixation of 10 mandibular fractures. The fixations have been performed either under general or local anesthesia, with 2, 4 or 6 points of alveolar bone anchorage, maintaining the fixation for 15 days in condylar fractures and for 40 days in all the other cases. RESULTS: A really good compliance of the patient towards all the procedures performed under local anesthesia, with a clear reduction of postoperative discomfort has been observed. Infection or rejection of the implanted screws did not occur as well as cases of alveolar or dentoparodontal damages. CONCLUSIONS: This preliminary report on a new intermaxillary fixation technique didn't point out any significant complication of the procedure, showing at the same time that this technique can be easily performed under local anesthesia on out-patients with a better compliance, lower postoperative discomfort and good skeletal stability.