Sinus Floor Augmentation Comparing an In Situ Hardening Biphasic Calcium Phosphate (Hydroxyapatite/ß-Tricalcium Phosphate) Bone Graft Substitute with a Particulate Biphasic Calcium Phosphate (Hydroxyapatite/ß-Tricalcium Phosphate) Bone Graft Substitute: An Experimental Study in Sheep.

OBJECTIVE: The aim of the present split-mouth study in sheep was to assess the influence of in situ hardening properties of a biphasic calcium phosphate (BCP) bone graft substitute (BGS) (ratio hydroxyapatite/ß-tricalcium phosphate = 60/40) compared with a particulate BGS with the same biphasic core-granule composition without in situ hardening properties on sinus floor augmentation. MATERIALS AND METHODS: Therefore, bilateral sinus floor augmentation was performed in eight sheep. Poly(lactide-co-glycolide) (PLGA)-coated, in situ hardening biphasic BGS (PLGA-NMP [N-Methyl-2-pyrrolidone]-BCP) was placed at the test site, and a particulate biphasic BGS without PLGA coating (BCP) was used for the contralateral site as a control. Animals were sacrificed after 21 weeks. Sinus augmentation sites were analyzed histologically. The volume was analyzed by computed tomography. Histomorphometric parameters were assessed for the 12 and 21 weeks' time points. Slopes of new bone formation over time were compared with a linear growth regression model. RESULTS: Bone formation after 12 and 21 weeks of healing was 8.94% (±3.74) and 19.82% (±6.29) for PLGA-NMP-BCP and 7.00% (±2.58) and 14.38% (±4.51) for BCP, respectively. The bone growth rate for PLGA-NMP-BCP was higher than the growth rate for BCP (probability 97.5%). The total fraction of calcified hard tissue (% bone fraction + % biomaterial) was around 46% for both tested biomaterials, 21 weeks after sinus floor augmentation. CONCLUSION: The in situ hardening BGS (PLGA-NMP-BCP) performed better than the particulate material (BCP) in terms of bone formation rate. The in situ hardening properties of the PLGA-NMP-BCP material mediated by the PLGA coating and NMP solution as plasticizer had no negative influence on the bone formation.

Immediate loading of four interforaminal implants supporting a locator-retained mandibular overdenture in the elderly. Results of a 3-year randomized, controlled, prospective clinical study.

BACKGROUND: Implant-retained overdentures have become a standard option for the prosthetic treatment of the edentulous mandible in the elderly. PURPOSE: This prospective study aimed to compare immediate and conventional loading of four interforaminal implants supporting a Locator-retained mandibular overdenture in elderly patients regarding implant survival, implant stability, and implant-related complications. MATERIAL AND METHODS: The study population comprised 20 completely edentulous patients (11 males) aged 60 years and older with severe mandible resorption. Each patient received four interforaminal implants (Neoss Ltd., Harrogate, UK). Following randomization, implants were loaded either immediately after dental implant surgery or 3 months after implant placement with the Locator-abutment system. At follow-up visits 3, 6 12, 24, and 36 months after loading, implant stability was evaluated with Periotest and Ostell. RESULTS: Twenty patients received 80 implants. In eight patients, 32 implants were loaded immediately. Two patients had to be switched from the immediate to the conventional loading group due to insufficient primary stability (≤30 Ncm). Implant survival was similar in both groups after 36 months. No implant was lost. Decreasing Periotest, and accordingly, increasing Ostell measurements indicated adequate osseointegration in both groups. The course of treatment was not significantly different in the two groups. There were comparable incidences of postoperative complaints like swelling, hematoma, or wound dehiscence, as well as need for prosthetic treatment due to abutment loosening or occlusal discrepancies. Incidence of pressure marks and number of patient visits were significantly higher in the conventional loading group. CONCLUSION: With sufficient primary stability, immediate loading of four interforaminal implants in the edentulous mandible might be the preferential choice in the elderly, reducing total treatment time, and number of patient visits.

The influence of particulated autogenous bone on the early volume stability of maxillary sinus grafts with biphasic calcium phosphate: a randomized clinical trial.

BACKGROUND: It is unknown whether autogenous bone impacts the grafts' stability when added to biphasic calcium phosphate (BCP) within the first six months of maxillary sinus augmentation (MSA). PURPOSE: To investigate the volume stability of BCP alone and in mixtures with autogenous bone for MSA. MATERIALS AND METHODS: Bilateral maxillary sinus augmentation was performed in eight patients in a split-mouth design using BCP at the control site and adding particulated autologous bone at the test site (BCPAB). Based on 16 computed tomography (CT) the volumetric changes were evaluated using the Voxim® software (version 6.3, IVS Technology GmbH, Chemnitz, Germany) by comparing the graft volumes within two weeks of the sinus lift procedure with CT data obtained six months later. Changes of the graft volumes were calculated and statistically significant differences between the two groups were evaluated. RESULTS: Overall, the volumes decreased by 15% for BCP and 18% for BCPAB. The time-dependent decreases were statistically significant in both groups. Differences between the two groups were not statistically significant (p = .065). CONCLUSIONS: An evident decrease of graft volume over the first 6 months of healing has to be expected irrespective of bone graft composite. Autogenous bone seems to have no evident impact on the volume decrease when added to BCP.

Influence of different conditioning methods on immediate and delayed dentin sealing.

STATEMENT OF PROBLEM: Data are needed to evaluate the effect of various conditioning methods on immediate and delayed dentin sealing. PURPOSE: The purpose of this study was to test bond strength and surface configuration of immediate and delayed dentin sealing surfaces after applying different surface conditioning methods. MATERIAL AND METHODS: A total of 96 premolars were allocated to the immediate and delayed groups. The groups differed in the timing of dentin sealing. The immediate-group specimens were sealed with a self-etching adhesive immediately after preparation. The delayed-group specimens were sealed before the final ceramic restoration bonding. Provisional restorations were cemented on immediate-group and delayed-group specimens for 1 week. Four conditioning methods were used: polishing with fluoride-free pumice paste, airborne-particle abrasion with silicoated aluminum oxide, glycin, or calcium carbonate. After 24-hour storage, the shear bond strength was tested. The fractured specimens were optically inspected with a stereomicroscope. An optical 3-dimensional surface analysis was performed for quantitative and qualitative evaluation. A 2-way ANOVA with post hoc Tukey honestly significant difference tests for significant effects was performed to investigate effects of the 2 factors, sealing and conditioning, and their interaction (α=.05). RESULTS: Two-way ANOVA found significant differences between the sealing and conditioning groups. The immediate group had significantly lower bond strengths than the delayed group. In all groups, surface polishing produced the highest bond strengths, and airborne-particle abrasion with calcium carbonate produced the lowest. Fracture analysis found more failures in the adhesive layers in the immediate groups and a prevalence of mixed failures in the delayed groups. The surface analysis found significant abrasion and roughness when airborne-particle abrasion with silicoated aluminum oxide was used for immediate and delayed dentin sealing surfaces. CONCLUSIONS: Polishing and airborne-particle abrasion with silicoated aluminum oxide or glycin are efficient methods in conditioning immediate and delayed dentin sealing surfaces. Airborne-particle abrasion with silicoated aluminum oxide leaves significant surface alterations on both types of surfaces.

Human cadaver study evaluating a new measurement technique for graft volumes after sinus floor elevation.

PURPOSE: Volumetric data can be used as complementary information to characterize grafting materials. The aim of this cadaveric study was to analyze a noncommercial measurement technique based on the novel concept of an "interactive rigid registration algorithm" (IRRA). Parameters analyzed included the reproducibility of IRRA measurements and their reliability in comparison with the established measurement technique of "region growing segmentation thresholding" (RGST). MATERIALS AND METHODS: Three human skulls were used to simulate a total of 18 sinus grafts, using three incremental grafting procedures in each sinus (three skulls ×t wo sinuses × three grafting increments). Radiopaque impression material was used for the simulated grafts, whose volumes were recorded by computed tomography from three different tilt angles. The reproducibility of IRRA measurements and the reliability of volumetric results obtained with both the IRRA and RGST techniques were evaluated by appropriate intraclass correlation coefficient (ICC) and Bland-Altman analysis. RESULTS: ICC greater than 0.9 indicated close to perfect agreement of the results obtained with both methods and good reproducibility of the IRRA measurements. Bland-Altman analysis demonstrated good inter-method and intramethod agreement. CONCLUSIONS: The IRRA measurement technique can be recommended as a noninvasive tool to evaluate graft volumes in human maxillary sinuses.

Impact of autogenous concentrated bone marrow aspirate on bone regeneration after sinus floor augmentation with a bovine bone substitute--a split-mouth pilot study.

PURPOSE: Mesenchymal stem cells (MSC) with biomaterials have osteoinductive potential. The aim of this study was to evaluate early bone formation in xenogenic sinus grafts in a direct comparison with and without MSCs after 3 and 6 months. Literature on bone formation in pure xenogenic graft materials after 3 months in a human model is still lacking. MATERIALS AND METHODS: In a split-mouth design, seven patients with a bilateral highly atrophic posterior maxilla were included. The test side was grafted with MSCs from concentrated bone marrow aspirate admixed to the bone graft material. On the control side, pure bovine bone material was applied. Biopsies were taken navigated after 3 and 6 months. RESULTS: After 3 months, new bone formation in the control group was 11.8% (SD 6.2%) and in the test group 7.4% (SD 4.1%). After 6 months, the control group showed 13.9% (SD 8.5%) of new bone and the test group 13.5% NB (SD 5.4%). The fraction of bovine bone material after 3 months was 42.6% (SD 3.5%) in the test group and 34.9% (SD 11.8%) in the control group. After 6 months, the biomaterial content was comparable at both sides (test 36.2%, SD 7.8%; control 39.5%, SD 9.3%). CONCLUSIONS: There was no significant difference in new bone formation between the test and control group with n = 7. The results may be dominated by the high mineral content of the biomaterial but could nevertheless be valuable for meta-analysis in the future.

Color stability of different composite resin materials.

STATEMENT OF PROBLEM: Data are needed to better predict the color stability of current composite resin materials. PURPOSE: The purpose of this study was to evaluate the impact of different storage solutions on the color stability of different composite resin materials. MATERIAL AND METHODS: Different restorative and adhesive composite resin specimens (dual-polymerizing self-adhesive resin cement, autopolymerizing resin-based composite resin, dual-polymerizing resin-based composite resin, nanohybrid composite resin, and microhybrid composite resin) were fabricated and stored in red wine, black tea, chlorhexidine, sodium fluoride, tea tree oil, or distilled water for 4 weeks at 37°C. Color parameters were measured with a colorimeter before and after storage. Total color differences and specific coordinate differences were expressed as ΔE, ΔL, Δa, and Δb. A 2-way and 1-way analysis of variance (ANOVA) with Bonferroni adjustment for multiple comparisons were applied for statistical calculations (α=.05). RESULTS: Red wine caused the most severe discoloration (ΔE >10), followed by black tea with perceptible (ΔE >2.6) to clinically unacceptable discoloration (ΔE >5.5). Colored mouth rinses discolored the materials to a lesser extent with clinically acceptable values. Dual-polymerizing resin adhesives showed a higher amount of discoloration. CONCLUSIONS: Current restorative and adhesive composite resin materials discolor over time under the influence of different storage solutions. The composition related to the polymerizing mode seemed to be a causative factor.

Tri-lineage potential of intraoral tissue-derived mesenchymal stromal cells.

The purpose of this study was to analyse the potential of intraoral tissues as a source of mesenchymal stromal and progenitor cells (MSPCs) for usage in future cell-based therapy models. Cells were isolated from four different tissues harvested during oral surgery intervention: (1) bone explants from the posterior maxilla, (2) bone explants from the oblique line, (3) from the mandibular periosteum, and (4) from the dental pulp. Donor sites and tissues were evaluated in terms of their accessibility, donor-site morbidity and average time period until appearance of MSPC colonies. Cell characterization was performed by flow cytometry and evaluation of in vitro osteogenic, adipogenic and chondrogenic differentiation potential. Adherent cell colonies were isolated from tissues from all sites after 4-8 days. The cells showed characteristics of MSPCs, so they were expanded up to clinical scales and demonstrated multipotency. The lowest donor-site morbidity was observed in the posterior maxilla harvests, while the highest donor-site morbidity was associated with harvests from mandibular sites. All sites seem to be potential sources of mesenchymal stromal and progenitor cells for tissue engineering approaches. Therefore, harvest morbidity and patient acceptance should affect the choice of the appropriate site.

Evaluation of graft cell viability-efficacy of piezoelectric versus manual bone scraper technique.

PURPOSE: The aim of the present study was to compare the influence of 2 different bone scrapers with respect to graft quality. MATERIALS AND METHODS: The study was conducted as a prospective, controlled experimental study of patients selected from the outpatient unit of the Department of Oral Surgery and Radiology (Dental Clinic, Medical University, Graz, Austria). Bone samples were obtained during routine lower third molar removal. Both a manual bone scraper (MS) and a piezoelectric device (PD) were used in directly adjacent regions in each case. As variables, the chip morphology, cell viability, and osteogenic differentiation were investigated. For statistical analysis, the Student t test and Fisher's exact test (P < .05) were applied. RESULTS: A total of 20 patients (12 women and 8 men, mean age 28.15 ± 5.8 years) were included in the study. A series of 40 bone samples was obtained during lower third molar removal. MS and PD enabled similar intraoral harvest of bone chips. In vitro outgrowth of adherent cells was found in 90% of the MS and 80% of the PD samples after 7 to 18 days, without statistical significance (P = .67). Similar cell viability of outgrowing cells in both groups was observed (94.7% ± 2.2% in the MS group and 94.1% ± 1.6% in the PD group). Reverse transcriptase-polymerase chain reaction analysis and the staining pattern verified osteopotent cells in both groups. CONCLUSIONS: Both manual and piezoelectric techniques are adequate harvesting technologies for limited intraoral augmentations. Our results did not show an advantage for the piezoelectric device.

Modified iliac bone harvesting--morbidity and patients' experience.

PURPOSE: The aim of the present retrospective study was to evaluate the postoperative morbidity and patients' satisfaction after harvesting a bicortical bone graft from the anterior iliac wing using a modified surgical technique. MATERIALS AND METHODS: Between 1996 and 2006, 36 patients underwent bicortical bone block harvesting procedures from the ilium with subsequent bone augmentation of the jaws under general anesthesia at the Department of Oral Surgery, Medical University Graz. A modification of the harvesting technique proposed by Tayapongsak et al was used. Of the 36 patients, 32 participated in the present retrospective study. The clinical trial was based on the evaluation of the clinical records, a follow-up examination of the donor site, and the patient's personal assessment of the course of therapy. RESULTS: Apart from 1 postoperative hematoma, 1 infected wound, and 1 postoperative seroma that had to be treated, no intra- or postoperative complications developed. At 3 to 14 days (mean 11.06) after the surgical procedure, the patients were free of pain. Gait disturbance was present for an average of 14 days. The clinical follow-up examination at the donor region was without any pathologic findings. The patients' personal assessment of the therapy course revealed high acceptance: 84% would agree to the same treatment if they had to choose, and 87% would recommend this treatment to other patients. On a pain scale of 1 to 10, the overall therapy course was assessed at an average of 1.77. CONCLUSIONS: Iliac bone grafts are the treatment of choice to reconstruct extensive maxillary defects. This retrospective evaluation revealed minor complications and morbidity and high patient acceptance, supporting its use.