Clinical evaluation of an improved cementation technique for implant-supported restorations: a randomized controlled trial.

BACKGROUND: Cement remnants were frequently associated with peri-implantitis. Recently, a shoulderless abutment was proposed, raising some concern about cement excess removal. AIM: To compare different cementation techniques for implant-supported restorations assessing the amount of cement remnants in the peri-implant sulcus. Additional aim was to compare the effect of these cementation techniques using two different abutment designs. MATERIAL & METHODS: Forty-six patients requiring double implant-supported restoration in the posterior maxilla were randomly divided in two groups according to the cementation modality: intraoral and extraoral. According to the abutment finishing line, implants in each patient were randomly assigned to shoulderless or chamfer subgroup. In the intraoral group, crowns were directly seated onto the titanium abutment. In the extraoral group, crowns were firstly seated onto a resin abutment replica and immediately removed, then cleansed of the cement excess and finally seated on the titanium abutment. After cement setting, in both groups, cement excess was carefully tried to remove. Three months later, framework/abutment complexes were disconnected and prepared for microscopic analysis: surface occupied by exposed cement remnants and marginal gaps were measured. Additionally, crown/abutment complexes were grinded, and voids of cement were measured at abutment/crown interface. Related-samples Friedman's two-way analysis of variance by ranks was used to detect differences between groups and subgroups (P ≤ 0.5). RESULTS: At the end of the study, a mean value of 0.45 mm2 (±0.80), 0.38 mm2 (±0.84), and 0.065 mm2 (±0.13) and 0.07 mm2 (±0.15) described surface occupied by cement remnants in shoulderless and chamfer abutment with intraoral cementation and shoulderless and chamfer abutment with extraoral cementation, respectively. A mean value of 0.40 mm2 (±0.377), 0.41 mm2 (±0.39) and 0.485 mm2 (±0.47) and 0.477 mm2 (±0.43) described cement voids at the abutment/crown interface; a mean value of 0.062 mm (±0.03), 0.064 mm (±0.35), 0.055 mm (±0.016) and 0.054 mm (±0.024) described marginal gaps. Statistics showed tendency of intraoral cementation to have significantly higher cement remnants compared with abutments with extraoral cementation groups. At the same time, the presence of voids was significantly higher in case of extraoral cementation. No significant differences between groups for the variable "gap". CONCLUSIONS: Despite the presence of more voids, extraoral cementation reduces cement excess. However, using low adhesivity cement and careful cement removal, a very limited quantity of cement remnants was observed also in the intraoral cementation.

Ultrastructural study by backscattered electron imaging and elemental microanalysis of biomaterial-to-bone interface and mineral degradation of bovine xenografts in maxillary sinus floor elevation.

OBJECTIVES: The aim of this study was to perform an ultrastructural study of the bone-to-biomaterial interface and biomaterial mineral degradation in retrieved bone biopsies following maxillary sinus augmentation using bovine xenografts (Endobon(®)) in 15 clinical cases. MATERIALS AND METHODS: Nine months after sinus lifting, bone cores were harvested from the maxillary sinus. The specimens were processed for observation under a scanning electron microscope with backscattered electron imaging (SEM-BSE). In addition, chemical analysis and elemental mapping of the mineral composition were generated using a microanalytical system based on energy-dispersive X-ray spectrometry (EDX). RESULTS: No clinical complications occurred during surgery. Scanning electron microscopy revealed that newly formed bone was closely attached to the xenograft. Elemental analysis showed a significantly high Ca/P ratio in the residual biomaterials (3.031 ± 0.104) compared with the interface (2.908 ± 0.115) and new bone (2.889 ± 0.113), which suggests that there may be a gradual diffusion of Ca ions from the biomaterial into the newly forming bone at the interface as part of the biomaterial's resorption process. EDX analysis of the residual bovine biomaterial showed particle categories with different mean Ca/P ratios according to size, pointing to different stages of the resorption process. CONCLUSIONS: The biomaterial proved to be biocompatible and osteoconductive when used as a bone substitute for maxillary sinus elevation. The grafting material used is not a completely resorbable material over the time period covered by this study.

Regenerated Traumatic Bone Cyst With Platelet-Rich Fibrin in the Mandible: A Case Report.

INTRODUCTION: Traumatic bone cyst is a pseudocyst which is characterized as an asymptomatic unilocular single lesion with an empty cavity without epithelial lining. Its etiology is still debated, it is more frequent among young people and it is often localized in the posterior mandible zone. A case report is described about diagnosis and conservative treatment of a traumatic bone cyst in anterior zone of lower mandible. CASE PRESENTATION: The report describes a 22-year-old female with a traumatic bone cyst in anterior mandible as accidental discovery from a routine orthopantomography. A conservative approach was conducted to treat the lesion through a submarginal incision, an osteotomy with ultrasound, a filling of the cavity with advanced platelet-rich fibrin membranes, and repositioning of the cortical bone. The radiological follow-up to 6 months confirmed the healing of the lesion. CONCLUSION: The conservative approach through submarginal incision, osteotomy with ultrasound, filling with A-PRF+ membranes and repositioning of cortical bone ensures optimal bone healing and avoids gingival recessions at six months follow-up, showing to be a good alternative for satisfactory defect resolution in similar clinical cases.