Predictability of intraoral scanner error for full-arch implant-supported rehabilitation.

OBJECTIVES: The present study aimed to analyze the behaviors of three intraoral scanners (IOSs): evaluating the interdistance and axial inclination discrepancies in full-arch scans, predictable errors were searched. MATERIALS AND METHODS: Six edentulous sample models with variable numbers of dental implants were used; reference data were obtained with a coordinate-measuring machine (CMM). Each IOS (i.e., Primescan, CS3600, and Trios3) performed 10 scans per model (180 total scans). The origin of each scan body was used as a reference point to measure interdistance lengths and axial inclinations. Precision and trueness of interdistance measurements and axial inclinations were evaluated to address error predictability. Bland-Altman analysis, followed by linear regression analysis and Friedman's test (plus Dunn's post hoc correction), was performed to evaluate the precision and trueness. RESULTS: Regarding interdistance, Primescan showed the best precision (mean ± SD: 0.047 ± 0.020 mm), while Trios3 underestimated the reference value more than the others (p < 0.001) and had the worst performance (mean ± SD: -0.079 ± 0.048 mm). Concerning the inclination angle, Primescan and Trios3 tended to overestimate angle values, while CS3600 underestimated them. Primescan had fewer inclination angle outliers, but it tended to add 0.4-0.6° to the measurements. CONCLUSIONS: IOSs showed predictable errors: they tended to overestimate or underestimate linear measurements and axial inclinations of scan bodies, one added 0.4-0.6° to the angle inclination values. In particular, they showed heteroscedasticity, a behavior probably related to the software or the device itself. CLINICAL SIGNIFICANCE: IOSs showed predictable errors that could affect clinical success. When performing a scan or choosing a scanner, clinicians should clearly know their behaviors.

The Use of Zirconia for Implant-Supported Fixed Complete Dental Prostheses: A Narrative Review.

The success of implant-supported fixed complete dental prostheses (ISFCDPs) depends on multiple factors: some are related to the fixtures, such as fixture material, surface characteristics, positioning, and type of connection to prosthetic components; others are related to the prostheses, such as design and materials used. Zirconia is a material widely used in fixed prosthodontics, whether on natural teeth or on implants, with excellent results over time. Regarding the use of zirconia for ISFCDPs, the 2018 ITI Consensus Report stated that "implant-supported monolithic zirconia prostheses may be a future option with more supporting evidence". Since CAD/CAM technology and zirconia are being continuously innovated to achieve better results and performances over time, a narrative review of the literature seems necessary to focus research efforts towards effective and durable solutions for implant-supported, full-arch rehabilitations. The objective of the present narrative review was to search the literature for studies regarding the clinical performance of zirconia-based ISFCDPs. According to the results of this review, the use of zirconia for ISFCDPs showed good clinical outcomes, with high survival rates ranging from 88% to 100% and prosthetic complications that were restorable by the clinicians in most cases.

Computer planning and bone density evaluation of jaws reconstructed with bone grafts from living donors.

Bone augmentation to reconstruct atrophic jaws provides the base for sufficient functional and aesthetic implant-supported oral rehabilitation. Although autografts are the standard procedure for bone grafting, the use of homolog bone provides a reasonable alternative because it is safe, cheap, and available in adequate amount. Five patients were grafted with femur bone derived from living donors, and in 2 of them, 16 implants were inserted after 6 months. Pearson χ test was used to investigate the difference in bone density (BD) between native and grafted bone and between peri-implant and bone far from fixtures. The BD of the grafted bone is about double that of the native bone. Peri-implant BD is higher than BD far from fixtures, demonstrating that implant loading increase BD. Computed tomography is a valuable and accurate preoperative and follow-up method to obtain information about bone quality and quantity (ie, volume of available bone). Femur graft has a high density that improves under loading, thus suggesting that early implant loading should be performed whenever possible. However, a larger implant series and a longer observation period are mandatory to have a stronger support to these preliminary data.

A case report of haemorrhagic-aneurismal bone cyst of the mandible.

Haemorrhagic-aneurismal bone cysts (HABCs) are quite rare, benign, non-neoplastic, expansive, and vascular locally destructive lesions. They are generally considered sequelae of an earlier trauma causing an overflow of blood into the bone. HABCs are classified as pseudocysts and they should be differentiated from true cysts because their treatment is different. Since few of these cysts involve subjective symptoms, most are discovered accidentally during radiography, while a sure diagnosis is likely to be obtained only during surgery, on discovery of a non-epithelialised cavity. Here, we report a typical case of a haemorrhagic-mandibular cyst in a 13-year-old girl, which was treated by opening the cavity and scraping its walls following diagnostic arteriography and post-operative transcutaneous intralesional embolization. No further complications were recorded in the post-operative period, although the convalescence lasted for a time longer than expected, because of anemia. No further surgery was performed. She has been disease-free for two years. Evaluation of intralesional blood flow is important for HABCs because of the hemorrhagic risk in surgery. Embolization seems to be a useful procedure in the treatment of HABCs and could be tried as the treatment modality in the standard protocol for the treatment of HABCs.

A case of lipoma of lateral anterior neck treated with surgical enucleation.

Lipoma arise in almost 50% of all soft tumours. The neck lipomas are rare tumours that may present as painless masses with slow growth, in the lateral portions of the neck. Some lipomas, such as the one studied in our case, grow deep in the subcutaneous tissue, in close contact with muscles. Here, we report a case of lipoma extending from pre-tragal region up to the ascending branch of the mandible in a 62 year old man, treated with enucleation. The inferior margin of lipoma involved the pharyngeal and the superior margin was achieved by the top of the skull base. The mass of lipoma caused breathing difficulties in the patient, preventing regular sleep. No complication was recorded in the post-operative period and no further surgery was performed. The complete resolution after one year's follow-up, together with the rarity of the anatomical site, makes this case worthy of description. A correct diagnosis facilitated removal of this lesion with a surgical method.

A case of mandible osteonecrosis after a severe periimplant infection.

The term osteonecrosis has been applied to describe the presence of a persistent inflammation of the mouth, osteomyelitis, delayed healing of extraction sockets, development of sequestra or presence of fistulae from the mouth to the lower skin. Here, we document a case of mandible osteonecrosis that developed in a patient after a severe periimplant infection. Osteonecrosis, severe inflammatory osteolysis, and heavy bacterial colonization were found. Surgical toilette and hyperbaric oxygen therapy permitted complete healing of the case. No complication was recorded in the post-operative period and no further surgery was performed. The clinical follow up and the imaging after one year showed a complete 'restitution ad integrum' of the mandible. Although the risk of developing osteonecrosis of the jaw for oral implants is low, the devastating complications still require caution.