A Systematic Review on Organ-on-a-Chip in PDMS or Hydrogel in Dentistry: An Update of the Literature.

Organs-on-a-chip (OoCs) are microfluidic devices constituted by PDMS or hydrogel in which different layers of cells are separated by a semipermeable membrane. This technology can set many parameters, like fluid shear stress, chemical concentration gradient, tissue-organ interface, and cell interaction. The use of these devices in medical research permits the investigation of cell patterning, tissue-material interface, and organ-organ interaction, mimicking the complex structures and microenvironment of human and animal bodies. This technology allows us to reconstitute in vitro complex conditions that recapitulate in vivo environments. One of the main advantages of these systems is that they represent a very realistic model that, in many cases, can replace animal experimentation, eliminating costs and related ethical issues. Organ-on-a-chip can also contain bacteria or cancer cells. This technology could be beneficial in dentistry for testing novel antibacterial substances and biomaterials, performing studies on inflammatory disease, or planning preclinical studies. A significant number of publications and reviews have been published on this topic. Still, to our knowledge, they mainly focus on the materials used for fabrication and the different patterns of the chip applied to the experimentations. This review presents the most recent applications of organ-on-a-chip models in dentistry, starting from the reconstituted dental tissues to their clinical applications and future perspectives.

The Influence on Osseointegration of Immediate Functional Loading on Single Crowns: A Randomized, Double-Blind, Split Mouth Controlled Clinical Trial with Histomorphometric Evaluation.

PURPOSE: To evaluate the influence of immediate loading on osseointegration and bone density of implants installed in a healed alveolar bone crest and supporting single crowns. MATERIALS AND METHODS: Two solid titanium transmucosal mini-screws were inserted in the distal regions of the mandible in 14 patients. One mini-implant was immediately functionally loaded, whereas the other was left unloaded. After two months of healing, biopsies were retrieved and new bone, old bone, and total bone (new and old bone) were assessed. RESULTS: Histological examination was performed on biopsies This peer-reviewed, accepted manuscript will undergo final editing and production prior to print publication. from 12 patients (n=12). New bone-to-implant contact percentage (BIC%) was 40.3 ± 16.8 % and 55.1 ± 19.1 % (p=0.043) at the unloaded and loaded sites, respectively, while the total BIC% was 44.9 ± 17.0 % and 59.5 ± 18.8 %, respectively (p=0.034). The new bone density was 45.9 ± 11.6 % and 45.9 ± 16.7 % in the unloaded and loaded implants, respectively (p=0.622). CONCLUSIONS: Immediate loading positively affected bone apposition on the implant surface, while no effect on bone density was observed after 2 months of healing.

3D printed dental implants with a porous structure: The in vitro response of osteoblasts, fibroblasts, mesenchymal stem cells, and monocytes.

AIMS: The first aim of this study was to characterize the surface topography of a novel 3D-printed dental implant at the micro- and macro-level. Its second aim was to evaluate the osteogenic, angiogenic, and immunogenic responses of human oral osteoblasts (hOBs), gingival fibroblasts (hGFs), mesenchymal stem cells (hAD-MSCs), and monocytes to this novel implant surface. METHODS: A 3D-printed Ti-6Al-4 V implant was produced by selective laser melting and subjected to organic acid etching (TEST). It was then compared to a machined surface (CTRL). Its biological properties were evaluated via cell proliferation assays, morphological observations, gene expression analyses, mineralization assessments, and collagen quantifications. RESULTS: Scanning electron microscopy analysis showed that the TEST group was characterized by a highly interconnected porous architecture and a roughed surface. The morphological observations showed good adhesion of cells cultured on the TEST surface, with a significant increase in hOB growth. Similarly, the gene expression analysis showed significantly higher levels of osseointegration biomarkers. Picrosirius staining showed a slight increase in collagen production in the TEST group compared to the CTRL group. hAD-MSCs showed an increase in endothelial and osteogenic commitment-related markers. Monocytes showed increased mRNA synthesis related to the M2 (anti-inflammatory) macrophagic phenotype. CONCLUSIONS: Considering the higher interaction with hOBs, hGFs, hAD-MSCs, and monocytes, the prepared 3D-printed implant could be used for future clinical applications. CLINICAL RELEVANCE: This study demonstrated the excellent biological response of various cells to the porous surface of the novel 3D-printed implant.

Mineralization and morphology of peri-implant bone around loaded and unloaded dental implants retrieved from the human mandible.

PURPOSE: Limited data is reported regarding the bone mineralization around dental implants in the first months from insertion. The study analyzed the peri-implant bone around loaded and unloaded implants retrieved from human mandible after 4 months from placement. METHOD: The composition and mineralization of human bone were analyzed through an innovative protocol technique using Environmental-Scanning-Electron-Microscopy connected with Energy-Dispersive-X-Ray-Spectroscopy (ESEM/EDX). Two regions of interest (ROIs, approximately 750×500 µm) for each bone implant sample were analyzed at the cortical (Cortical ROI) and apical (Apical ROI) implant threads. Calcium, phosphorus, and nitrogen (atomic%) were determined using EDX, and the specific ratios (Ca/N, P/N, and Ca/P) were calculated as mineralization indices. RESULTS: Eighteen implant biopsies from ten patients were analyzed (unloaded implants, n=10; loaded implants, n=8). For each ROI, four bone areas (defined bones 1-4) were detected. These areas were characterized by different mineralization degree, varied Ca, P and N content, and different ratios, and by specific grayscale intensity detectable by ESEM images. Bony tissue in contact with loaded implants at the cortical ROI showed a higher percentage of low mineralized bone (bone 1) and a lower percentage of remodeling bone (bone 2) when compared to unloaded implants. The percentage of highly mineralized bone (bone 3) was similar in all groups. CONCLUSION: Cortical and apical ROIs resulted in a puzzle of different bone "islands" characterized by various rates of mineralization. Only the loaded implants showed a high rate of mineralization in the cortical ROI.

Red Light and 5% Aminolaevulinic Acid (5%) Inhibit Proliferation and Migration of Dysplastic Oral Keratinocytes via ROS Production: An In Vitro Study.

Undiagnosed and untreated oral precancerous lesions often progress into malignancies. Photodynamic therapy (PDT) might be a minimally invasive alternative to conventional treatments. 5-aminolevulinic acid (5-ALA) is one of the most commonly used photosensitizers in PDT, and it is effective on many cancer types. However, its hydrophilic characteristic limits cell membrane crossing. In the present study, the effect of a newly formulated gel containing 5% 5-ALA in combination with red light (ALAD-PDT) on a premalignant oral mucosa cell line was investigated. The dysplastic oral keratinocyte (DOK) cells were incubated with ALAD at different concentrations (0.1, 0.5, 1, and 2 mM) at two different times, 45 min or 4 h, and then irradiated for 7 min with a 630 nm LED (25 J/cm2). MTT assay, flow cytometry, wound healing assay, and quantitative PCR (qPCR) were performed. ALAD-PDT exerted inhibitory effects on the proliferation and migration of DOK cells by inducing ROS and necrosis. mRNA analysis showed modulation of apoptosis-related genes' expression (TP53, Bcl-2, survivin, caspase-3, and caspase-9). Furthermore, there was no difference between the shorter and longer incubation times. In conclusion, the inhibitory effect of the ALAD-PDT protocol observed in this study suggests that ALAD-PDT could be a promising novel treatment for oral precancerous lesions.

Photodynamic Therapy with Aminolevulinic Acid Enhances the Cellular Activity of Cells Cultured on Porcine Acellular Dermal Matrix Membranes Used in Periodontology.

This study aims to test a photodynamic protocol based on a gel containing aminolevulinic acid followed by red-LED (ALAD-PDT) irradiation on human gingival fibroblasts (hGFs) and osteoblasts (hOBs) cultured on a porcine acellular dermal matrix membrane (PADMM). In the previous literature, ALAD-PDT showed solid antibacterial activity and proliferative induction on HGFs cultured on plates and HOBs cultured on a cortical lamina. PADMMs are used in dentistry and periodontology to treat gingival recessions and to increase the tissue thickness in the case of a thin biotype without the risks or postoperative discomfort associated with connective tissue grafts. However, one of the possible complications in this type of surgery is represented by bacterial invasion and membrane exposition during the healing period. We hypothesized that the addition of ALAD-PDT to PADMMs could enhance more rapid healing and decrease the risks connected with bacterial invasion. In periodontal surgery, PADMMs are inserted after a full-thickness flap elevation between the bone and the flap. Consequently, all procedures were performed in parallel on hOBs and hGFs obtained by dental patients. The group control (CTRL) was represented by the unexposed cells cultured on the membranes, group LED (PDT) were the cells subjected to 7 min of red LED irradiation, and ALAD-PDT were the cells subjected to 45 min of ALAD incubation and then to 7 min of red LED irradiation. After treatments, all groups were analyzed for MTT assay and subjected to histological examination at 3 and 7 days and to the SEM observations at 3, 7, and 14 days. Different bone mineralization assays were performed to quantify the effects of ALAD-PDT on hOBs: ALP activity, ALP gene expression, osteocalcin, and alizarin red. The effects of ALAD-PDT on hGFs were evaluated by quantifying collagen 1, fibronectin, and MMP-8. Results showed that ALAD-PDT promoted cellular induction, forming a dense cellular network on hOBs and hGFs, and the assays performed showed statistically significantly higher values for ALAD-PDT with respect to LED alone and CTRLs. In conclusion, ALAD-PDT could represent a promising aid for enhancing the healing of gingival tissues after PADMM applications.

Alveolar Ridge Preservation Procedures Performed with a Freeze-Dried Bone Allograft: Histologic Outcomes in a Cohort Study.

The primary aim of this study was to assess the histomorphometric outcomes of extraction sockets grafted with freeze-dried bone allograft (FDBA) and sealed with a collagen membrane after 3 months of healing in specific region of interest (ROI) areas. The secondary aims were to analyze the biomaterial resorption rate, the bone-to-biomaterial contact (BBC), and the area and perimeter of grafted particles compared with commercially available FDBA particles. Fifteen patients underwent tooth extractions and ridge preservation procedures performed with FDBA and a collagen membrane. Bone biopsy samples were harvested after 3 months at the time of implant placement for histologic and histomorphometric analysis. Two areas of concern (ROI1 and ROI2) with different histologic features were identified within the biopsy samples; ROI1, ROI2, and commercially available particles were analyzed and compared. The following parameters were analyzed: newly formed bone, marrow space, residual graft particles, perimeter and area of FDBA particles, and BBC. The histomorphometric analysis showed 35.22% ± 10.79% newly formed bone, 52.55% ± 16.06% marrow spaces, and 12.41% ± 7.87% residual graft particles. Moreover, the histologic data from ROI1 and ROI2 showed that (1) the mean percentage of BBC was 64.61% ± 27.14%; (2) the newly formed bone was significantly higher in ROI1 than in ROI2; (3) the marrow space was significantly lower in ROI1 than in ROI2; and (4) the FDBA particles in ROI1 sites showed significantly lower area and perimeter when compared to commercially available FDBA particles. This latter data led to the hypothesis that FDBA particles embedded in newly formed bone undergo a resorption/remodeling process.

Effect of alveolar ridge preservation on peri-implant mucositis and peri-implantitis prevalence: A multicenter, cross-sectional study.

OBJECTIVES: Alveolar ridge preservation (ARP) is a procedure with the aim to reduce bone resorption that occurs after tooth extraction, facilitating the following implant placement. The aim of this cross-sectional study was to evaluate the prevalence of mucositis and peri-implantitis around implants inserted in sites treated with ARP and to investigate possible risk factors. MATERIALS AND METHODS: Patients who received at least one dental implant inserted in a grafted socket were considered eligible for this study. Patients were recalled for a follow-up visit; medical history, clinical and demographic data were collected. Univariate logistic regression analyses have been performed for both implant-level and patient-level variables. Indeed, moderation analysis was used to investigate the indirect relationship between age and marginal bone level. RESULTS: Fifty-one patients who received 61 implants were enrolled in this cross-sectional study. Thirty-three implants were classified as "healthy" (54.1%), 23 implants showed signs of peri-implant mucositis (37.7%), and 5 implants were diagnosed with peri-implantitis (8.2%). Data analyzed at the patient level showed that 49% of the patients were healthy, 45.1% of the patients had mucositis and 5.9% of the patients were affected by peri-implantitis. Mandibular sites and type III grafted sockets showed a significant association with peri-implantitis; in addition, a history of periodontitis and an increase in age showed higher risks of developing mucositis or peri-implantitis. CONCLUSIONS: Implants inserted in grafted sockets showed favorable rates of healthy implants in the long term. CLINICAL RELEVANCE: The ridge preservation procedures do not seem to increase the risk of developing mucositis or peri-implantitis.

Osteoblasts and Fibroblasts Interaction with a Porcine Acellular Dermal Matrix Membrane.

The use of collagen membranes has remained the gold standard in GTR/GBR. In this study, the features and the biological activities of an acellular porcine dermis collagen matrix membrane applicable during dental surgery were investigated, and also by applying hydration with NaCl. Thus, two tested membranes were distinguished, the H-Membrane and Membrane, compared to the control cell culture plastic. The characterization was performed by SEM and histological analyses. In contrast, the biocompatibility was investigated on HGF and HOB cells at 3, 7, and 14 days by MTT for proliferation study; by SEM and histology for cell interaction study; and by RT-PCR for function-related genes study. In HOBs seeded on membranes, mineralization functions by ALP assay and Alizarin Red staining were also investigated. Results indicated that the tested membranes, especially when hydrated, can promote the proliferation and attachment of cells at each time. Furthermore, membranes significantly increased ALP and mineralization activities in HOBs as well as the osteoblastic-related genes ALP and OCN. Similarly, membranes significantly increased ECM-related and MMP8 gene expression in HGFs. In conclusion, the tested acellular porcine dermis collagen matrix membrane, mainly when it is hydrated, behaved as a suitable microenvironment for oral cells.

A Narrative Review on the Effectiveness of Bone Regeneration Procedures with OsteoBiol® Collagenated Porcine Grafts: The Translational Research Experience over 20 Years.

Over the years, several bone regeneration procedures have been proposed using natural (autografts, allografts, and xenografts) and synthetic (i.e., metals, ceramics, and polymers) bone grafts. In particular, numerous in vitro and human and animal in vivo studies have been focused on the discovery of innovative and suitable biomaterials for oral and maxillofacial applications in the treatment of severely atrophied jaws. On this basis, the main objective of the present narrative review was to investigate the efficacy of innovative collagenated porcine bone grafts (OsteoBiol®, Tecnoss®, Giaveno, Italy), designed to be as similar as possible to the autologous bone, in several bone regeneration procedures. The scientific publications were screened by means of electronic databases, such as PubMed, Scopus, and Embase, finally selecting only papers that dealt with bone substitutes and scaffolds for bone and soft tissue regeneration. A total of 201 papers have been detected, including in vitro, in vivo, and clinical studies. The effectiveness of over 20 years of translational research demonstrated that these specific porcine bone substitutes are safe and able to improve the biological response and the predictability of the regenerative protocols for the treatment of alveolar and maxillofacial defects.

Computer-Guided Bone Biopsy: A Technical Note with the Description of a Clinical Case.

AIM: The aim of this technical note is to present a computer-aided design-computer-aided manufacturing (CAD-CAM) surgical guide to perform a computer-guided bone biopsy. Traditionally, to diagnose abnormal conditions affecting jawbone, a bone biopsy is performed with the use of a trephine bur. The positioning of the bur, during the biopsy, is based on the skill of the surgeon; therefore, an inaccurate placement of a trephine bur may occur. The use of a guide, however, can minimize this risk and achieve a better result. MATERIALS AND METHODS: To determine the site and the extension of bone sampling, the stereolithography file (STL) file of cone-beam computed tomography (CBCT) images is acquired using a specific planning software and superimposed with the STL file of a dental cast; a virtual surgical guide is designed, using the same software that allows a 3D (three-dimensional) view of the guide from different perspectives and planes. The number and site of guide tubes are determined on the basis of the width and the extension of the sampling; thanks to a 3D printer, the surgical guide is manufactured. RESULTS: The use of a customized surgical guide realized with CAD-CAM technology allows a precise and minimally invasive approach, with an accurate three-dimensional localization of the biopsy site. CONCLUSIONS: The high precision, great predictability, time-effectiveness and versatility of the present guide should encourage the clinician to use this minimally invasive surgical approach, but controlled clinical trials should be conducted to evaluate the advantages as well as any possible complications.

Complex Electromagnetic Fields Reduce Candida albicans Planktonic Growth and Its Adhesion to Titanium Surfaces.

This study evaluates the effects of different programs of complex electromagnetic fields (C.M.F.s) on Candida albicans, in planktonic and sessile phase and on human gingival fibroblasts (HGF cells). In vitro cultures of C. albicans ATCC 10231 and HGF cells were exposed to different cycles of C.M.F.s defined as: oxidative stress, oxidative stress/antibacterial, antibacterial, antibacterial/oxidative stress. Colony forming units (CFUs), metabolic activity, cells viability (live/dead), cell morphology, filamentation analysis, and cytotoxicity assay were performed. The broth cultures, exposed to the different C.M.F.s, were grown on titanium discs for 48 h. The quantity comparisons of adhered C. albicans on surfaces were determined by CFUs and scanning electron microscopy. The C. albicans growth could be readily controlled with C.M.F.s reducing the number of cultivable planktonic cells vs. controls, independently by the treatment applied. In particular, the antibacterial program was associated with lower levels of CFUs. The quantification of the metabolic activity was significantly lower by using the oxidative stress program. Live/dead images showed that C.M.F.s significantly decreased the viability of C. albicans. C.M.F.s inhibited C. albicans virulence traits reducing hyphal morphogenesis, adhesion, and biofilm formation on titanium discs. The MTS assay showed no negative effects on the viability of HGF. Independent of the adopted protocol, C.M.F.s exert antifungal and anti-virulence action against C. albicans, no cytotoxicity effects on HGF and can be useful in the prevention and treatment of yeast biofilm infections.

Case Report: Histological and Histomorphometrical Results of a 3-D Printed Biphasic Calcium Phosphate Ceramic 7 Years After Insertion in a Human Maxillary Alveolar Ridge.

Introduction: Dental implant placement can be challenging when insufficient bone volume is present and bone augmentation procedures are indicated. The purpose was to assess clinically and histologically a specimen of 30%HA-60%ß-TCP BCP 3D-printed scaffold, after 7-years. Case Description: The patient underwent bone regeneration of maxillary buccal plate with 3D-printed biphasic-HA block in 2013. After 7-years, a specimen of the regenerated bone was harvested and processed to perform microCT and histomorphometrical analyses. Results: The microarchitecture study performed by microCT in the test-biopsy showed that biomaterial volume decreased more than 23% and that newly-formed bone volume represented more than 57% of the overall mineralized tissue. Comparing with unloaded controls or peri-dental bone, Test-sample appeared much more mineralized and bulky. Histological evaluation showed complete integration of the scaffold and signs of particles degradation. The percentage of bone, biomaterials and soft tissues was, respectively, 59.2, 25.6, and 15.2%. Under polarized light microscopy, the biomaterial was surrounded by lamellar bone. These results indicate that, while unloaded jaws mimicked the typical osteoporotic microarchitecture after 1-year without loading, the BCP helped to preserve a correct microarchitecture after 7-years. Conclusions: BCP 3D-printed scaffolds represent a suitable solution for bone regeneration: they can lead to straightforward and less time-consuming surgery, and to bone preservation.

Histological and Histomorphometric Evaluation of New Bone Formation after Maxillary Sinus Augmentation with Two Different Osteoconductive Materials: A Randomized, Parallel, Double-Blind Clinical Trial.

This study aimed to investigate the histological features of deproteinized equine bone mineral (DEBM) and anorganic bovine bone (ABB) after human sinus augmentation with the lateral approach. Twenty-three sinus augmentations were performed in 16 patients (male: 10/female: 6) using DEBM or ABB in a randomized fashion. Healing took place over the next 6 months. Bone core biopsies (N = 23) were obtained for each subject prior to placing the dental implants. The biopsies were processed for both histological descriptions and histomorphometric analysis. Statistical analyses were applied as appropriate, defining statistical significance as p < 0.05. Core bone biopsies revealed no differences in terms of newly formed bone between groups, or differences in terms of tissue inflammation. Both DEBM and ABB appear to be suitable biomaterials for bone augmentation in sinus lift surgery in the short term. However, dedicated studies are required to confirm these results and their stability in the long term.

Human Histologic Evaluations of the Use of Er,Cr:YSGG Laser to Decontaminate an Infected Dental Implant Surface in Preparation for Implant Reosseointegration.

This investigation was designed to evaluate the reestablishment of bone-to-implant contact on infected dental implant surfaces following decontamination with an erbium, chromium:yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser and reconstructive therapy. Three patients presenting with at least one failing implant each were enrolled and consented to treatment with the Er,Cr:YSGG laser surface decontamination and reconstruction with a bone replacement allograft and a collagen membrane. The laser treatment was carried out at a setting of 1.5 W, air/water of 40%/50%, and pulse rate of 30 Hz. At 6 months, all three patients returned for the study. En bloc biopsy samples of four implants were obtained and analyzed. Two patients had excellent clinical outcomes, while one patient with two adjacent failing implants experienced an early implant exposure during the follow-up period. There was histologic evidence of new bone formation with two implant specimens and less bone gain with the others. Despite the small sample size, these were optimistic findings that suggested a positive role of Er,Cr:YSGG laser in debridement of a titanium implant surface to facilitate subsequent regenerative treatment. This investigation provides histologic evidence as well as encouraging clinical results that use of the Er,Cr:YSGG laser can be beneficial for treatment of peri-implantitis, but further long-term clinical studies are needed to investigate the treatment outcome obtained.

Implant and Prosthetic Success Following Peri-implant Guided Bone Regeneration in the Esthetic Zone Using an Equine Cortical Bone Membrane and an Equine Enzyme-Treated Bone Graft: A Retrospective Study with 9-year Follow-Up.

PURPOSE: A barrier membrane consisting of an equine-derived, demineralized cortical bone sheet has been made available, yet evidence of its effectiveness is currently only anecdotal. This study aimed to obtain preliminary evidence concerning the medium-term prosthetic and implant success rates that may be achieved when such a membrane is used in combination with an equine, enzyme-treated bone graft, concomitantly to implant placement in the esthetic zone. MATERIALS AND METHODS: Records of patients who had one or two implants placed in the anterior sectors of the two arches and had peri-implant bone regeneration carried out using the equine-derived membrane and equine-derived collagen-preserving bone granules were retrospectively collected. Peri-implant marginal bone loss (MBL) was used to assess implant survival. When available, histologic data concerning the equine membrane and cone beam computed tomography (CBCT) scans were analyzed as well. RESULTS: Records of 32 patients (ages 36 to 73 years), corresponding to 44 implants placed, were retrieved and analyzed. The mean follow-up was 113.9 ± 10.2 months. Two implants failed. The implant success rate was 90.9%. Twelve membrane samples could be retrieved and analyzed, showing the membrane was still occlusive at 4.2 ± 1.1 months and only beginning to undergo remodeling. Twelve CBCT scans showed that 65.1 ± 9.8 months after surgery, a newly formed cortical layer could be observed in the zone that had undergone grafting. CONCLUSION: The equine cortical bone membrane and the enzyme-treated bone graft used in this case series achieved a medium-term implant and prosthetic success rate that was not dissimilar to that of other resorbable membranes and grafts for peri-implant guided bone regeneration augmentation. Preliminary medium-term histologic and CBCT data suggest that the membrane may be occlusive for a period of at least 4 months and may contribute to preserve the ridge thickness over time.

Influence of the position of the antrostomy in sinus floor elevation on the healing of mini-implants: a randomized clinical trial.

AIM: To evaluate histologically the healing of mini-implants installed after sinus floor elevation using a lateral approach and placing the antrostomy at different level from the sinus floor. MATERIAL AND METHODS: Sinus floor elevation using a lateral approach was performed in 24 healthy volunteers. The antrostomy was randomly placed either close to the base of the sinus floor (group base) or at about 3-4 mm cranially to it (group standard). After 6 months of healing, mini-implants were installed within the grafted region, through the alveolar crest. Three months later, biopsies were collected. RESULTS: Sixteen biopsies from 16 patients were available for histological analyses. The new bone reached fractions of 40.9 ± 11.9% and 48.5 ± 20.1% at the base and standard groups, respectively (p = 0.208). Xenograft particles were found in contact with the implant surface at percentages of 12.1 ± 11.0% in the base group, and 15.9 ± 23.7% in the standard group (p = 0.674). CONCLUSIONS: Based on the present study, the choice of one or the other position of antrostomy did not influence significantly the outcome and, therefore, should be left to the preference of the surgeon.

Influence of the Dimensions of the Antrostomy on Osseointegration of Mini-implants Placed in the Grafted Region After Sinus Floor Elevation: A Randomized Clinical Trial.

PURPOSE: To evaluate the osseointegration of mini-implants placed in grafted sinuses with lateral windows of two different dimensions. MATERIALS AND METHODS: Sinus floor augmentation was performed in volunteers using a lateral window. The antrostomy was systematically prepared with a height of either 8 mm (large group) or 4 mm (small group). After 6 months of healing, mini-implants were placed in the grafted region. Biopsy specimens including the mini-implants were harvested 3 months after placement. RESULTS: Twenty biopsy specimens, 10 from each group, were suitable for the histologic analysis. Similar amounts of new bone-to-implant contact were obtained in both the large (41.1% ± 19.5%) and the small (42.8% ± 13.2%) groups (P = .940). Small percentages of residues of xenograft were found in contact with the implant surface, with 0.6% ± 1.1% in the large group and 5.9% ± 9.5% in the small group (P = .098). The new bone density around the implants was 31.7% ± 8.2% and 34.0% ± 7.9% in the large and small groups, respectively (P = .623). CONCLUSION: The dimensions of the antrostomy did not influence the histologic healing of implants placed 6 months after sinus floor augmentation.

Histological and Histomorphometrical Evaluation of a New Implant Macrogeometry. A Sheep Study.

Decompression or healing chambers between the threads have been proposed to improve and accelerate the osseointegration process of dental implants. The aim of the present work was to test, in an in vivo sheep study, if healing chambers between the threads could produce a better osseointegration process. Thirty titanium implants (15 conventional design (control) and 15 implants with healing chambers (test)) were inserted in a random fashion in the tibia of 3 sheep. The animals were euthanized after 30 days of healing, and the retrieved specimens treated to obtain thin ground sections. Histological observations showed that the quantity of newly formed bone growing in an apical direction was lower in the control group (1095 µm) when compared to the Test group (1658 µm). This difference was statistically significant. Moreover, a layer of osteogenic matrix was present around the portion of implants immersed in the marrow spaces. This osteogenic tissue was thicker in the test group. In conclusion, the present study confirmed the very good results in implants with healing chambers that presented a higher percentage of new bone formation.