Assisted removal of metal housings from overdentures with a 445-nm diode laser: A dental technique.

A straightforward, laser-assisted method of extracting the metal housings from an overdenture by using the visible (blue) light of a high-power dental diode laser is presented. This approach produced localized softening of the acrylic resin, allowing the metal housing to be dislodged without damage. This technique minimizes damage to the metal housings during removal, is rapid and conservative, and may help reduce patient costs.

Implant and prosthetic rehabilitation of a patient with mucous membrane pemphigoid.

Mucous membrane pemphigoid (MMP) is an autoimmune condition characterized by subepithelial separation and deposition of autoantibodies and complement along the basement membrane zone. The disease results in the development of vesiculobullous lesions of the mucous membranes and skin. This report discusses the surgical treatment and management and the prosthetic implant rehabilitation of a patient with mucous membrane pemphigoid. The rationale for this treatment was to fabricate a prosthesis that was stable and did not rub against the gingival tissues and that was easily cleaned. The overdenture attachment system used provides more stability than other attachment systems while allowing the prosthesis and abutments to be easily cleaned.

Role of mechanical compression on bone regeneration around a particulate bone graft material: an experimental study in rabbit calvaria.

PURPOSE: This experimental study was designed to analyze the effect of different compressive forces on the bone regeneration around a particulate bone graft material. MATERIAL AND METHODS: Eighty 6-mm-diameter defects were created in the calvaria of 20 New Zealand rabbits (4 defects per rabbit calvaria). All the defects were filled with particles of synthetic bone. Two standardized compressive forces were then applied, 4.1 g to half the defects (Test A) and 8.2 g to the other half (Test B), all for 1 min. The graft sites were allowed to heal for 6 weeks, after which the rabbits were euthanized. The calvarium vault of each animal was extracted, radiographed, and prepared for histomorphometric analysis. The percentage of defect fill, bone density, new bone formation, and residual bone graft material were recorded, and the results were subjected to statistical analysis. RESULTS: Histological evaluation found that defect closure among the Test A (lower compression) group ranged from 38.34 (95% lower CI) to 55.8 (95% upper CI) (mean 47 ± 8.5%), while among the Test B group (higher compression), it ranged from 81.26 (95% lower CI) to 95.32 (mean 88 ± 7.3%). Significantly more closure was achieved for the Test B group (P < 0.05). Histomorphometric comparison of the two groups found significantly more new bone formation, higher bone density, and a higher percentage of defect fill in the defects subjected to the higher compression level (P < 0.05). CONCLUSIONS: Increasing the compressive force applied to bone graft particulate used to fill small defects created in rabbit calvaria appears to be beneficial.

Marginal bone loss evaluation around immediate non-occlusal microthreaded implants placed in fresh extraction sockets in the maxilla: a 3-year study.

OBJECTIVE: To evaluate marginal bone loss over 3 years around immediate microthreaded implants placed in the maxillary anterior/esthetic zone and immediately restored with single crowns. MATERIAL AND METHODS: Seventy-one implants (with microthreads up to the platform--rough surface body and neck, internal connection and platform switching) were placed in fresh extraction sockets in the maxillary arches of 30 men and 23 women (mean age 37.85 ± 7.09 years, range 27-60). All subjects had at least 3 mm of soft tissue to allow the establishment of adequate biologic width and to reduce bone resorption. Each patient received a provisional restoration immediately after implant placement with slight occlusal contact. Mesial and distal bone height was evaluated using digital radiography on the day following implant placement (baseline) and after 1, 2, and 3 years. Primary stability was measured with resonance frequency analysis. RESULTS: No implants failed, resulting in a cumulative survival rate of 100% after 3 years. Marginal bone loss from implant collar to bone crest measured at baseline (peri-implant bone defect at the fresh extraction socket) and after 3 years was 0.86 mm ± 0.29 mm. Mesial and distal site crestal bone loss ranged from 3.42 mm ± 1.2 mm at baseline to 3.51 mm ± 1.5 mm after 3 years (P = 0.063) and from 3.38 mm ± 0.9 mm at baseline to 3.49 mm ± 0.9 mm after 3 years, respectively (P = 0.086). CONCLUSIONS: This prospective study found minimal marginal bone loss and a 100% implant survival rate over the 3-year follow-up for microthreaded immediate implants subjected to immediate non-occlusal loading.

Influence of the implant design on osseointegration and crestal bone resorption of immediate implants: a histomorphometric study in dogs.

PURPOSE: The aim of this study was to evaluate bone-to-implant contact after immediate implant placement at different levels in relation to crestal bone in American foxhound dogs. MATERIALS AND METHODS: The mandibular second, third, and fourth premolars of six American foxhound dogs were extracted bilaterally. Randomly, three immediate implants were placed in the hemimandible of each dog at the bone crest (control group) or 2 mm subcrestally (test group). Three dogs were allowed an 8-week healing period; the other three were left a 12-week healing period. After healing periods, histomorphometric analyses of the specimens were carried out to measure BIC values and bone remodeling. RESULTS: All implants healed uneventfully and were available for histological analysis. The total BIC mean values were 44.52% (± 8.67) and 39.50% (± 9.25) at 8 and 12 weeks, respectively, for the control group, and 47.33% (± 5.23) and 53.85% (± 4.21) at 8 and 12 weeks after healing for the test group, respectively. There was observed less bone resorption in the group of implants placed subcrestally. CONCLUSION: Our findings suggest that less resorption may be expected when implants are inserted 2 mm subcrestally. Moreover, higher BIC values in the group of subcrestal implants were found.

Bone neo-formation and mineral degradation of 4Bone.(®) Part II: histological and histomorphometric analysis in critical size defects in rabbits.

OBJECTIVE: To carry out the histological and histomorphometric plus radiological analysis of biphasic ceramic. MATERIALS AND METHOD: In this study, porous HA/ßTCP (4Bone(®) ) ceramic material was tested for the bone repairing capacity and osteoinductive potential in a New Zealand rabbit model. The ratio of the ceramic's components HA/ßTCP was 60/40 (in wt%). RESULTS: The 4Bone(®) showed significantly more bone formation in the pores and in the periphery of the graft than the control group. Histomorphometric analysis revealed that the ceramic material (66.43% ± 0.29) produced higher values of bone-to-implant contact (BIC) percentages (higher quality, closer contact); moreover, defect closure was significative higher in relation with control group (64.15% ± 3.52). CONCLUSIONS: 4Bone(®) is a biocompatible, partially resorbable and osteoconductive grafting material. Biphasic graft material of HA/ßTCP with a porosity of 95% without loading favors new bone formation.

Bone neo-formation and mineral degradation of 4Bone.(®) Part I: material characterization and SEM study in critical size defects in rabbits.

OBJECTIVE: This study reports the characterization process and in vivo application of a new high-porosity biphasic calcium phosphate (4Bone(®) - HA 60%/ß-TCP 40%) inserted into the critical size defect of a rabbit tibiae. MATERIAL AND METHODS: Two critical size defects of 6 mm diameter were created in each tibia of 15 New Zealand rabbits, and a total of 60 defects were divided into a test group filled with 4Bone(®) (n = 30) and a control group (n = 30). The material and the implants were characterized by scanning electron microscope (SEM) fitted with energy-dispersive X-ray spectroscopy (EDX). RESULTS: The biomaterial's grain size decreased progressively with the graft integration process over the 60-day study period. Element analysis revealed increased percentages of Ca/P (2.86 ± 0.32 vs. 1.97 ± 0.59) in new bone and at the interface (P < 0.05). Element mapping showed that Ca and P were concentrated in the medullary and cortical zones in the test group but were concentrated only in cortical zones in the control group. CONCLUSIONS: Critical size defects in a rabbit tibia model can be sealed using this highly porous biphasic calcium phosphate; it supports new bone formation, creates a bridge between defect borders, and facilitates bone in growth.

Narrow- versus mini-implants at crestal and subcrestal bone levels. Experimental study in beagle dogs at three months.

OBJECTIVE: The objective of this study was to evaluate the osseointegration and crestal bone loss (CBL) in two implant designs with different diameters (Mini Sky® and Narrow Sky®) implants, placed at different vertical levels at healed canine ridges. MATERIAL AND METHODS: The second, third, and fourth mandibular premolars of six Beagle dogs were extracted bilaterally. After 2 months healing, four implants divided into two groups according to their diameters (i.e., Narrow Sky® and Mini Sky®) were placed in each hemi-mandible at the level of the bone crest or 2 mm subcrestally. The animals were euthanized at 12 weeks and undecalcified samples were processed for histology. Histomorphometric analysis was carried out to compare bone-to-implant contacts (BIC) and crestal bone loss (CBL). RESULTS: There were not significant differences in CBL between groups when the implants were placed at subcrestal bone level (p > 0.05), meanwhile the CBL was significantly higher for both groups when the implants were inserted at crestal level (p < 0.05). All implants were osseointegrated presenting a minimum BIC percentage of 56%. The major percentages of BIC were found for both groups at subcrestal level (p < 0.05). CONCLUSIONS: Within the limitations of this experimental study may be concluded that the implant diameter does not affect the CBL. BIC values are affected by implant diameter and design been higher for narrow implants compared to mini-implants. Subcrestal insertion of both implants favors crestal bone preservation but crestal insertion of both designs is associated with crestal bone loss CLINICAL RELEVANCE: The study shows that narrow implants protect peri-implant crestal bone.

Clinical and radiographic evaluation of osseotite-expanded platform implants related to crestal bone loss: a 10-year study.

OBJECTIVE: The aim of this prospective clinical study was to evaluate the survival rates at 10 years of expanded platform implants placed in the anterior zone of the maxilla and immediately restored with single crowns. MATERIALS AND METHODS: Implants incorporating the platform-switching concept were placed in fresh extraction sockets in the maxillary arch, with each patient receiving a provisional restoration immediately after implant placement. After 15 days, final screwed restorations were inserted. Mesial and distal bone heights were evaluated using digital radiography on the day following implant placement and at 1, 5, 7, and 10 years. Primary stability was measured with resonance frequency analysis (RFA) using the Osstell Mentor device. Eighty-six implants were placed in 32 men and 32 women ranging in age between 29 and 60 (mean, 39.64 ± 5.16 years). RESULTS: Marginal bone loss from implant collar to bone crest between baseline and 10 years follow-up was 1.01 mm ± 0.22. Mesial site crestal bone loss ranged from 3.57 mm ± 1.1 at baseline to 3.77 mm ± 0.7 at 10-year. Distal site crestal bone loss ranged from 3.49 mm ± 0.8 at baseline to 3.73 mm ± 0.7 at 10 year. CONCLUSION: The platform-switched implants remained stable over the course of 10 years and had an overall survival rate of 97.1%.

Influence of biphasic ß-TCP with and without the use of collagen membranes on bone healing of surgically critical size defects. A radiological, histological, and histomorphometric study.

OBJECTIVES: The aim of this study was to investigate, by means of radiological and histomorphometric analysis, the effect of resorbable collagen membranes on critical size defects (CSD) in rabbit tibiae filled with biphasic calcium phosphate. MATERIALS AND METHODS: Three CSD of 6 mm diameter were created in both tibiae of 20 New Zealand rabbits and divided into three groups according to the filling material: Group A (Ossceram), Group B (Ossceram plus Alveoprotect membrane), and Group C (unfilled control group). Five animals from each group were sacrificed after 15, 30, 45, and 60 days. Anteroposterior and lateral radiographs were taken. Samples were processed for observation under light microscopy. RESULTS: At the end of treatment, radiological analysis found that cortical defect closure was greater in Group B than Group A, and radiopacity was clearly lower and more heterogeneous in the Group A cortical defects than in Group B. There was no cortical defect closure in Group C. Histomorphometric evaluation showed significant differences in newly formed bone and cortical closure in Group B compared with Groups A and C, with the presence of higher density newly formed bone in cortical and medullar zones. There was no cortical defect closure or medullar bone formation in Group C. CONCLUSIONS: Biphasic calcium phosphate functioned well as a scaffolding material allowing mineralized tissue formation. Furthermore, the addiction of absorbable collagen membranes enhanced bone gain compared with non-membrane-treated sites.

Histological, radiological and histomorphometric evaluation of immediate vs. non-immediate loading of a zirconia implant with surface treatment in a dog model.

OBJECTIVE: The aim of this study was to assess the performance of zirconia implants under immediate loading compared with delayed loading in dogs over 30-90 days. MATERIALS AND METHODS: Tooth extractions were made for the subsequent placement of dental implants at premolars P2, P3, P4 and molars M1 bilaterally in the dog mandible. Forty eight zirconia implants, 4 mm in diameter and 10 mm in length, were inserted, whose neck and body surfaces had been treated with femtosecond laser texturing; 24 implants were loaded immediately and 24 remained unloaded during the osseointegration period. Final radiographs were taken recording stability values before sacrifice at 30 or 90 days when sample removal for histological and histomorphometric analysis was performed. Bone-to-implant contact, crestal bone loss and implant stability were evaluated at these two study times. RESULTS: Bone-to-implant contact values after 30 days were 38.9% for immediately loaded implants and 32% for non-loaded implants. After 90 days, values increased to 65% for immediately loaded and 57.6% for non-loaded implants. After 30 days, there was more crestal bone lost in the non-loaded group (0.58 ± 0.28 mm) compared with the immediately loaded group (0.5 ± 0.3 mm). After 90 days, there was improved stability in both groups, but was lower in the immediately loaded group (0.5 ± 0.23 mm) compared with the non-loaded group (0.56 ± 0.28 mm). Initial implant stability values were -3.5 PTV at the moment of implant placement. Stability values after the first 30 days were -4 for immediately loaded implants and -3 for non-loaded. At 90 days, non-loaded implants showed -4.9, whereas immediately loaded showed -7.1. CONCLUSIONS: For the different parameters studied, zirconia implants treated with femtosecond laser and subjected to immediate loading showed better results compared with non-loaded implants in terms of BIC, crestal bone loss and implant stability.

Peri-implant tissue reactions to immediate nonocclusal loaded implants with different collar design: an experimental study in dogs.

PURPOSE: The aim of this study was to evaluate bone remodelling and soft tissue reactions around immediate nonocclusal loaded implants with different collar configuration in beagle dogs. MATERIAL AND METHODS: The mandibular bilateral second, third and fourth premolars of six beagle dogs were extracted. After 3 months of healing, four implants were placed in the mandibles of each dog. Randomly, two implants with a 1.5 mm polished surface collar (TSA, control group) and two implants with a 0.7 mm polished surface collar and 2.5 mm microthreaded area (TSAA, test group) were inserted. Both groups were treated with a minimal mucoperiosteal flap elevation approach. Impressions were taken and two single screw-retained restorations were inserted in each hemi-mandible 2 days after the implant placement. The animals were sacrificed at 1, 2 and 3 months (two specimens each), and biopsies were obtained. Samples were processed for ground sectioning. Histomorphometric analysis was carried out to compare buccal and lingual bone height loss and soft tissue behaviour between the two groups. RESULTS: Crestal bone resorption was significantly higher in the control group (P > 0.05). The establishment of the biological width showed similar outcomes for both groups. Only the distance from the top of the peri-implant mucosa to the apical portion of the barrier epithelium at lingual aspect was significantly more pronounced in the control group (P > 0.05). CONCLUSIONS: The alterations that occurred in the peri-implant tissues were related to the adaptation that occurred after the loading conditions in both groups. The microthread design might have an effect in maintaining the marginal bone loss against loading.

In vitro comparison of resonance frequency analysis devices to evaluate implant stability of narrow diameter implants at varying drilling speeds in dense artificial bone blocks.

BACKGROUND: There are no studies that have assessed the implant stability quotient (ISQ) values of narrow diameter implants placed in artificial dense bone blocks at varying drilling speeds (DSs). PURPOSE: The aim of the present in vitro experiment was to compare the performance of OSSTELL and Penguin devices to evaluate implant stability at DSs of 800 and 2000 rpm. MATERIALS AND METHODS: A total of 360 osteotomies were created in dense artificial bone blocks at DSs of 800 and 2000 rpm. Dental implants from three manufacturers (group-1: NobelActive implants, Nobel Biocare, Yorba Linda, California; group-2: Zimmer, Eztetic-Zimmer implants, Zimmer Biomet Dental, Palm Beach Gardens, Florida; and group-3: Astra Tech implant system, Dentsply Sirona, York, Pennsylvania) were randomly placed in these osteotomies using an insertion torque of 15 Ncm (60 implants/group). Implant stability in all bone blocks immediately following implant placement was evaluated using the OSSTELL and Penguin devices. ISQ values were presented as means ± SD. Statistical significance was set at P < .05. RESULTS: There was no significant difference in the ISQ values obtained from the OSSTELL and Penguin devices for implants in groups 1, 2, and 3. There was no significant difference when ISQ values obtained from the OSSTELL device were compared with the Penguin device for narrow diameter dental implants placed in dense bone blocks with osteotomies performed at 800 and 2000 rpm. ISQ values showed statistically significant higher values for OSSTELL compared to Penguin device. CONCLUSION: The OSSTELL and Penguin devices are reliable for the assessment of implant stability in dense artificial bone. Implant design and site-DS does not seem to have a significant impact of implant stability in artificial dense bone blocks.

In Vitro Effect of Drilling Speed on the Primary Stability of Narrow Diameter Implants with Varying Thread Designs Placed in Different Qualities of Simulated Bone.

It is hypothesized that there is no statistically significant impact of drilling speed (DS) on the primary stability (PS) of narrow-diameter implants (NDIs) with varying thread designs placed in dense and soft simulated bone. The aim of this in vitro study was to evaluate the impact of DS on the PS of NDIs with varying thread designs placed in dense and soft simulated bone. Two hundred and forty osteotomies for placement of various implant macro-designs were divided into three groups (80 implants per group): Group A (NobelActive, 3.0/11.5 mm); Group B (Astra OsseoSpeed-EV, 3.0/11 mm); and Group C (Eztetic-Zimmer, 3.1/11.5 mm) implants. These implants were placed in artificial dense and soft simulated bone using DSs of 800 and 2000 revolutions per minute (RPM). Resonance frequency analysis (RFA) and implant stability quotient (ISQ) were assessed. Group comparisons were performed using the one-way analysis of variance with Tukey's post hoc tests. Level of significance was set at P < 0.05. In groups A and B, there was no difference in the ISQ for NDIs inserted in dense bone at 800 and 2000 RPM. In Group C, ISQ was significantly higher for NDIs placed in dense bone at 800 PRM compared to 2000 RPM (P < 0.05). In Group A, ISQ values were significantly higher for NDIs inserted in soft bone at 2000 RPM as compared to those inserted at 800 RPM (P < 0.05). For NDIs, a lower drilling speed in dense artificial simulated bone and a higher drilling speed in soft artificial simulated bone is associated with high primary stability.

Various Tip Applications and Temperature Changes of Er,Cr:YSGG-Laser Irradiated Implants In Vitro.

The impact of the laser tip on implant temperature when irradiating implants with lasers to treat peri-implantitis has received little attention. The present study was designed to assess the influence of two laser tips (sapphire chisel [MC3] and radial firing perio [RFP]) on temperature change of an implant irradiated with an Er,Cr:YSGG laser in vitro under various operational conditions. The results suggest that Er,Cr:YSGG irradiation using either tip with supplemental cooling can be a thermally safe approach to implant decontamination. However, use of the RFP tip consistently resulted in a greater temperature rise. The MC3 tip thus may be preferable to the RFP tip for open-flap implant debridement.

αTCP ceramic doped with dicalcium silicate for bone regeneration applications prepared by powder metallurgy method: in vitro and in vivo studies.

This study reports on the in vitro and in vivo behavior of α-tricalcium phosphate (αTCP) and also αTCP doped with either 1.5 or 3.0 wt % of dicalcium silicate (C2 S). The ceramics were successfully prepared by powder metallurgy method combined with homogenization and heat treatment procedures. All materials were composed of a single-phase, αTCP in the case of a pure material, or solid solution of C2 S in αTCP for the doped αTCP, which were stable at room temperature. The ceramics were tested for bioactivity in simulated body fluid, cell culture medium containing adult mesenchymal stem cells of human origin, and in animals. Analytical scanning electron microscopy combined with chemical elemental analysis was used and Fourier transform infrared and conventional histology methods. The in vivo behavior of the ceramics matched the in vitro results, independently of the C2 S content in αTCP. Carbonated hydroxyapatite (CHA) layer was formed on the surface and within the inner parts of the specimens in all cases. A fully mineralized new bone growing in direct contact with the implants was found under the in vivo conditions. The bioactivity and biocompatibility of the implants increased with the C2 S content in αTCP. The C2 S doped ceramics also favoured a phase transformation of αTCP into CHA, important for full implant integration during the natural bone healing processes. αTCP ceramic doped with 3.0 wt % C2 S showed the best bioactive in vitro and in vivo properties of all the compositions and hence could be of interest in specific applications for bone restorative purposes.

Physical properties, mechanical behavior, and electron microscopy study of a new α-TCP block graft with silicon in an animal model.

This study reports the characterization process and in vivo application of a new block bone graft of α-TCP with silicate in three different percentages in the aim of determining the influence of the silicate. Three groups of cylindrical implants (6 ± 0.01 mm diameter, 8 ± 0.01 mm length) with varying Si composition were studied: A: 3 wt % C(2) S; B: 1.5 wt % C(2) S; C: 100 wt % TCP-0 wt % C(2) S. These were implanted randomly in critical size defects in New Zealand rabbits. X-ray diffraction analysis was performed to determine the crystalline phases of the different compositions. Histomorphometric analysis produced one measurement of bone-to-implant contact. Comparing the α-TCPss ceramics, the trial found improved mechanical properties due to the silicon content in solid solution as well as densification. Previous studies have shown that the mechanical strengths of sintered ceramics correlate to densification as well as grain size and mechanical properties. Because of its mechanical and biological behavior, the study has shown α-TCP with C(2) S to be an alternative to other bone graft substitutes for use in bone reconstructive surgery in the fields of veterinary, medicine, and oral and maxillofacial surgery.