Emanuele Clozza

Shrinkage assessment of low shrinkage composites using micro‐computed tomography

OBJECTIVES The aim of this study was to quantify the polymerization volumetric shrinkage of one regular and two low shrinkage bulk fill composites in class I cavities with or without an adhesive layer, using three-dimensional (3D) micro-computed tomography (μCT). METHODS Class I cavity preparations (2.5 mm depth × 4 mm length × 4 mm wide) were standardized in 36 extracted human third molars, which were randomly divided in six groups (n = 6 each) as follows: Group VIT (regular composite without bonding agent); Group SDR (low shrinkage flowable composite without bonding agent); Group TET (low shrinkage composite without bonding agent); Group VIT/P (regular composite with bonding agent); Group SDR/X (low shrinkage flowable composite with bonding agent); TET/T (low shrinkage composite with bonding agent). Each tooth was scanned via µCT at cavity preparation, immediately after cavity filling, and after light-curing. Acquired μCT data were imported into Amira software for analysis and volume values evaluated between steps from cavity preparation until light-curing. RESULTS Both low shrinkage composites showed a significantly less volumetric shrinkage than VIT. The use of dental adhesive significantly decreased the average volumetric contraction similarly for the three composites, by about 20%. CONCLUSION Both low shrinkage composites showed less volumetric polymerization contraction than the regular composite. The use of dental adhesive decreased the total volumetric shrinkage for all evaluated composites.

Healing of Fresh Extraction Sockets Filled with Bioactive Glass Particles: Histological Findings in Humans

PURPOSE The aim of the present study was to histologically evaluate fresh human sockets filled with bioactive glass after 6 months of healing. MATERIALS AND METHODS In 13 patients, 32 single extraction sites in the anterior area underwent socket ridge preservation procedure (RPP) with a bioactive glass (BioRestore™, Inion Oy, Tampere, Finland). At implant installation, 22 bone cores were trephined out and processed for histomorphometric and immunohistochemical analysis. RESULTS Newly formed immature bone around residual particles of bioactive glass was found in all 22 biopsies. The histomorphometry of the amount of bone, provisional matrix, and residual graft returned a mean ± SD value of 54 ± 31%, 37.9 ± 25.6%, and 8.1 ± 7.8, respectively, 6 months after RPP. CONCLUSION The use of this grafting material in fresh extraction sockets appears to delay the healing processes of the alveolar bone; therefore, its indication as a material for RPP when implant placement is considered within 6 months after extraction should be revised.

The Effects of Subcrestal Implant Placement on Crestal Bone Levels and Bone-to-Abutment Contact: A Microcomputed Tomographic and Histologic Study in Dogs.

PURPOSE Implant design and the implant-abutment interface have been regarded as key influences on crestal bone maintenance over time. The aim of the present study was to determine crestal bone changes around implants placed at different depths in a dog model. MATERIALS AND METHODS Thirty-six two-piece dental implants with a medialized implant-abutment interface and Morse taper connection (Ankylos, Dentsply) were placed in edentulous areas bilaterally in six mongrel dogs. On each side of the mandible, three implants were placed randomly at the bone crest, 1.5 mm subcrestally, or 3.0 mm subcrestally. After 3 months, the final abutments were torqued into place. At 6 months, the animals were sacrificed and samples taken for microcomputed tomographic (micro-CT) and histologic evaluations. RESULTS Micro-CT analysis revealed similar crestal or marginal bone loss among groups. Both subcrestal implant groups lost significantly less crestal and marginal bone than the equicrestal implants. Bone loss was greatest on the buccal of the implants, regardless of implant placement depth. Histologically, implants placed subcrestally were found to have bone in contact with the final abutment and on the implant platform. CONCLUSION Implants with a centralized implant-abutment interface and Morse taper connection can be placed subcrestally without significant loss of crestal or marginal bone. Subcrestal placement of this implant system appears to be advantageous in maintaining bone height coronal to the implant platform.

Facial cystic lymphangioma in adults.

Abstract Lymphangiomas are uncommon congenital malformations of the lymphatic system, generally diagnosed during childhood. These malformations are rarely seen in adults, and the literature provides poor guidelines for treatment options that must be carefully applied to the facial region. Diagnosis in adult subjects is difficult to achieve, and also management of these conditions is still challenging because they tend to infiltrate adjacent tissues, causing frequent relapses. Radical surgery is the main form of treatment, avoiding the sacrifice of function or aesthetics of the patient. Two cases of cystic lymphangioma of the facial region found in adults are described from a clinical and pathologic point of view. The aim of this article was to point out that an early recognition of cystic lymphangioma is a crucial goal to initiate a prompt treatment avoiding serious complication.

Microradiography and microcomputed tomography comparative analysis in human bone cores harvested after maxillary sinus augmentation: a pilot study

OBJECTIVES The aim of this study was to compare microradiography (MR) and microcomputed tomography (μCT) analysis of bone samples following maxillary sinus augmentation at different time periods and determine the relationships between measured area and volume fractions. MATERIALS AND METHODS Lateral window sinus grafts were performed on 10 patients using a mineralized human bone allograft (MHBA). At implant placement, 5-13 months after surgery, 10 bone core biopsies were harvested. Prior to histologic sectioning, bone samples were evaluated with μCT. The morphometric parameters computed by MR and μCT were compared using Pearsons correlation and Bland and Altman analysis and included hard tissue fraction (HV/TV:%), soft tissue fraction (SV/TV:%), vital bone fraction (BV/TV:%) and residual graft fraction (GV/TV:%). RESULTS Strong positive correlation between MR and μCT was found for HV/TV and SV/TV and BV/TV [r = 0.84, 0.84 and 0.69, respectively] but weak for GV/TV [r = 0.10]. CONCLUSION μCT technology shows promising potential as an indicator of bone morphology changes; however, caution should be used in interpreting morphometric parameters, as the different methods reveal important biases.