Effects of barriers on chemical and biological properties of two dual resin cements.

The aim of this study was to investigate the degree of conversion, monomer release, and cytotoxicity of two dual-cure resin cements (Cement-One and SmartCem2), light-cured across two indirect restorative materials in an attempt to simulate in vitro the clinical conditions. The results obtained show that the degree of conversion was influenced by both barriers, but the effect of the composite material was greater than that of the ceramic one. The amount of monomers released from the polymerized materials in the absence of barriers was significantly lower than that released in the presence of either the ceramic or the composite barrier. However, a higher amount of monomers was released in the presence of the ceramic barrier. All materials, in all the experimental conditions employed, induced slight cytotoxicity (5-10%) on human pulp cells. Our examinations showed that the two resin cements had similar chemical and biological properties. The decreased degree of conversion of the dual-curing self-adhesive composite showed that the light-curing component of these materials has an important role in the polymerization process. In clinical practice, it is therefore important to pay attention to the thickness of the material used for the reconstruction.

Retrospective evaluation of mandibular incisor replacement with narrow neck implants.

The authors have retrospectively evaluated the clinical results of mandibular incisors replacement with narrow neck implants (NNI). Thirty-one patients treated consecutively for single or multiple lower incisor replacement with NNI with a mean follow-up of 23 months (range 18-42 months) were included in the study and were divided into three groups: single tooth, multiple unit restoration and restorations on adjacent implants. Survival and success rates and soft tissue parameters such as modified plaque index (mPI), peri-implant probing depth (PPD), bleeding on probing (BOP) and the papilla index were analyzed. Subjective evaluation was performed by patients and clinicians on visual analogue scales. The implants and prostheses showed a survival rate of 100% and an overall success rate of 94%. The distribution of mPI outcomes showed better results for the single tooth group. BOP was present in four of eight implants (50%) in the adjacent implant group, in one out of 20 implants in the single tooth group (5%) and in one out of 16 implants in the multi unit group (6%). The adjacent implant group showed a statistically significant increase in PPD. The Papilla Index showed a better outcome distribution in single tooth and multi unit groups. Patients' evaluation of treatment outcome was satisfactory in all groups, even though the best esthetic and functional results were found in single tooth and multi unit groups. The professional evaluation showed good outcomes for the single tooth and multi unit groups and statistically significant poorer results in the adjacent implants group. With the limitations of this study, it may be concluded that the replacement of lower incisors with NNI leads to favorable functional and esthetic results in cases of single-tooth or multiple-unit replacement. Worse results are achieved if two adjacent mandibular incisors are replaced with adjacent implants.

Retrospective evaluation of complete-arch fixed partial dentures connecting teeth and implant abutments in patients with normal and reduced periodontal support.

STATEMENT OF PROBLEM: The clinical outcome of complete-arch fixed prostheses supported by implants and natural tooth abutments in patients with normal or reduced periodontal support has been reported by few studies, with controversial results. PURPOSE: The purpose of this study was to report on the implant success rate, prosthetic complications, and the occurrence of tooth intrusion, when complete-arch fixed prostheses, supported by a combination of implants and teeth, were fabricated for patients with normal and reduced periodontal support. MATERIAL AND METHODS: Nineteen patients with residual teeth that served as abutments were consecutively treated with combined tooth- and implant-supported complete-arch fixed prostheses and were retrospectively evaluated after a period varying from 24 to 94 months. Nine patients showed reduced periodontal support as a result of periodontal disease and treatment (RPS group), and 10 patients had normal periodontal support of the abutment teeth (more than 2/3 of periodontal support [NPS group]). Ninety implants and 72 tooth abutments were used to support 19 fixed partial dentures. Screw- and cement-retained metal-ceramic and metal-resin prostheses were fabricated with rigid and nonrigid connectors. Implant survival and success rates, occurrence of caries and tooth intrusion, and prosthetic complications were recorded. The number of teeth, implants, prosthetic units, fixed partial dentures, and nonrigid connectors were compared with a t test to assess differences between the 2 groups, while data for the occurrence of intrusions and prosthetic complications were compared with the Fisher exact test (alpha=.05). RESULTS: One of the 90 implants was lost (99% survival rate) over 24 to 94 months, while 3 implants showed more than 2 mm of crestal bone loss (96% success rate) over the same period. No caries were detected, but 5.6% (4/72) of the abutment teeth exhibited intrusion. Intrusion of abutment teeth was noted in 3 patients who had normal periodontal support (13% of teeth in NPS group) of the abutment teeth and was associated with nonrigid connectors. No intrusion of teeth was noted in the patients exhibiting reduced periodontal support regardless of the type of connector or when a rigid connector was used for either group. The number of intruded teeth was significantly greater in patients with intact periodontal support (P=.03). CONCLUSIONS: Complete-arch fixed prosthesis supported by implant and tooth abutments may be associated with intrusion of teeth with intact periodontal support when nonrigid connectors are used to join the implant- and tooth-supported sections of the prostheses. However, fixed partial dentures supported by implants and teeth with reduced periodontal support were not associated with tooth intrusion, regardless of the type of connectors used.

Fracture and displacement of lingual cortical plate of mandibular symphysis following bone harvesting: case report.

This article describes a unique complication after chin bone harvesting. The complication consisted of fracture and posterior displacement of the lingual cortical plate that did not occur at the time of the operation but during the healing phase. The bone was harvested for a bilateral sinus lift procedure. Diagnosis was made by chance with the aid of a postoperative CT scan that was taken to study the sinus area. The mandibular scans revealed a bony fragment 2 to 4 mm in width and 3 cm in length fractured and displaced 1 cm posteriorly. This bony fragment was pedicled to the geniohyoid and genioglossus muscles. The patient was asymptomatic, and no treatment was carried out. The patient is still symptom-free 16 months after the initial diagnosis of the fracture.