Effect of acidic pH on surface roughness of esthetic dental materials.

STATEMENT OF PROBLEM: Exposure to gastric acid in patients with bulimia nervosa and gastroesophageal reflux disease (GERD) causes demineralization of hard tooth structures. This chemical attack also causes the degradation of dental ceramics, which results in increased surface roughness and reduced strength. However, studies comparing the effect of acidic pH on resin matrix ceramic with other computer-aided design and computer-aided manufacturing (CAD-CAM) esthetic materials are lacking. PURPOSE: The purpose of this in vitro study was to compare the surface roughness changes of different CAD-CAM restorative dental materials after exposure to acidic pH by using a 3D optical interferometer. MATERIAL AND METHODS: Five esthetic CAD-CAM block materials, a leucite glass-ceramic (IPS Empress CAD), a zirconia (BruxZir Solid Zirconia), a resin matrix ceramic (VITA Enamic), a lithium disilicate glass-ceramic (IPS e.max CAD), and a feldspathic porcelain (VITABLOCS Mark II CAD) were tested. Eighteen specimens were sectioned from CAD-CAM blocks into 2-mm-thick rectangular plates and immersed in 10 mL of 5% hydrochloric acid (HCl) with (pH=2) at 37 °C for 45 and 91 hours. The surface roughness average (Ra) of the specimens was measured by using a 3D optical interferometer before the storage period (baseline), after 45 hours, and after 91 hours of exposure to HCl. Statistical analyses were performed with the Kruskal-Wallis test and the post hoc Dunn test with Bonferroni correction (α=.05). RESULTS: Regarding the comparison of surface roughness changes at different periods of evaluation (baseline, 45 hours, 91 hours), there were no statistically significant differences for lithium disilicate (P=.063) or zirconia (P=.513). Leucite glass-ceramic, feldspathic porcelain, and the resin matrix ceramic demonstrated statistically significant differences (P<.001). For all tests that were statistically significant, greater surface roughness was found at the time point with the longer HCl exposure. Regarding the comparison of materials in terms of change in surface roughness between baseline to 45 hours and baseline to 91 hours, the Kruskal-Wallis test indicated a statistically significant difference among the materials in both cases (P<.001). Lithium disilicate and zirconia exhibited the least change in surface roughness among the 5 materials. CONCLUSIONS: Leucite glass-ceramic, feldspathic porcelain, and resin matrix ceramic showed statistically significant increases in surface roughness when they were exposed to simulated gastric acid for 45 and 91 hours. Lithium disilicate and zirconia showed no statistically significant change in surface roughness after exposure to HCl for 45 and 91 hours.

Ions release Evaluation and Changes in Mini-implant Orthodontic Surface.

AIM: To evaluate, in vitro, the mini-implant surface changes and the release of ions after immersion in artificial saliva during follow-up of 60 and 120 days. MATERIALS AND METHODS: As for the surface features, examined in a scanning electron microscope (SEM), before and after immersion in artificial saliva, there was a rough and uneven surface, suggestive of corrosion areas for the two trademarks evaluated after 120 days of immersion. The extracts generated in artificial saliva analysis were submitted to energy dispersive spectroscopy to identify the solid corrosion products produced on the surfaces of miniscrews. RESULTS: Both SIN miniscrews and Neodent brands were observed to release minimal quantities of silver ions, chromium, iron, nickel, titanium, and vanadium. Regarding titanium, this index varied from 88.84% in the control group of Neodent brand, and 91.29% in the control group of SIN brand. For the aluminum content, the quantities ranged from 4.91% in group immersed for 60 days in Neodent brand to 8.71% for the SIN control group. Considering vanadium, the index ranged from 2.65% in the group immersed for 120 days to 4.53% in the control group, both for Neodent brand. Statistically significant differences in iron ion were observed between the control group and the miniscrews brand SIN after 60 and 120 days and for Neodent after 60 days of immersion. The titanium ions suffered statistically significant decrease for both brands after 120 days of storage when compared with the control group. CONCLUSION: The studied miniscrews showed results consistent with the biosafety of alloys for use, in vivo. CLINICAL SIGNIFICANCE: The knowledge of the physical/chemical state of corrosion products released in the oral cavity is very important for the toxicological assessment of metal alloys used in dental miniscrews.

Nanomechanical Assessment of Bone Surrounding Implants Loaded for 3 Years in a Canine Experimental Model.

PURPOSE: This work evaluated the nanomechanical properties of bone surrounding submerged and immediately loaded implants after 3 years in vivo. It was hypothesized that the nanomechanical properties of bone would markedly increase in immediately and functionally loaded implants compared with submerged implants. MATERIALS AND METHODS: The second, third, and fourth right premolars and the first molar of 10 adult Doberman dogs were extracted. After 6 months, 4 implants were placed in 1 side of the mandible. The mesial implant received a cover screw and remained unloaded. The remaining 3 implants received fixed dental prostheses within 48 hours after surgery that remained in occlusal function for 3 years. After sacrifice, the bone was prepared for histologic and nanoindentation analysis. Nanoindentation was carried out under wet conditions on bone areas within the plateaus. Indentations (n = 30 per histologic section) were performed with a maximum load of 300 µN (loading rate, 60 µN per second) followed by a holding and unloading time of 10 and 2 seconds, respectively. Elastic modulus (E) and hardness (H) were computed in giga-pascals. The amount of bone-to-implant contact (BIC) also was evaluated. RESULTS: The E and H values for cortical bone regions were higher than those for trabecular bone regardless of load condition, but this difference was not statistically significant (P > .05). The E and H values were higher for loaded implants than for submerged implants (P < .05) for cortical and trabecular bone. For the same load condition, the E and H values for cortical and trabecular bone were not statistically different (P > .05). The loaded and submerged implants presented BIC values (mean ± standard deviation) of 57.4 ± 12.1% and 62 ± 7.5%, respectively (P > .05). CONCLUSION: The E and H values of bone surrounding dental implants, measured by nanoindentation, were higher for immediately loaded than for submerged implants.

Resin composite repair for implant-supported crowns.

This study evaluated the reliability of implant-supported crowns repaired with resin composites. Fifty-four titanium abutments were divided in three groups (n = 18 each) to support resin nanoceramic molar crowns, as follows: (LU) (Lava Ultimate, 3M ESPE); LU repaired with either a direct or an indirect resin composite. Samples were subjected to mouth-motion accelerated-life testing in water (n = 18). Cumulative damage with a use stress of 300 N was used to plot Weibull curves for group comparison. Reliability was calculated for a mission of 100,000 cycles at 400 N load. Beta values were 0.83 for LU, 0.31 and 0.27 for LU repaired with Filtek and Ceramage, respectively. Weibull modulus for LU was 9.5 and η = 1047 N, m = 6.85, and η = 1002 N for LU repaired with Ceramage, and m = 4.65 and η = 766 N for LU repaired with Filtek (p < 0.10 between LU and LU repaired with Filtek). Reliability at 400 N was 100% for both LU and LU repaired with Ceramage which were significantly higher than LU Filtek repair (32%). LU restored crowns failed cohesively. Fractures were confined within the restored material, and detailed fractography is presented. The performance of resin nanoceramic material repaired with an indirect composite was maintained after accelerated-life testing compared to unrepaired controls. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1481-1489, 2017.

The Effect of Osteotomy Dimension on Implant Insertion Torque, Healing Mode, and Osseointegration Indicators: A Study in Dogs.

PURPOSE: This study investigated the effect of the osteotomy diameter for implant placement torque and its effect on the osseointegration. MATERIALS AND METHODS: Eight male beagle dogs received 48 implants (3.75 mm × 10 mm) in their right and left radius, 3 implants per side and allowed to heal for 3 weeks. Three experimental groups were evaluated. Group 1: implant with an undersized osteotomy of 3.0 mm; group 2: osteotomy of 3.25 mm, and group 3: osteotomy of 3.5 mm. The insertion torque was recorded for all implants. Histological sectioning and histometric analysis were performed evaluating bone-to-implant contact (BIC) and bone area fraction occupancy (BAFO). RESULTS: Implants of group 1 presented statistically higher insertion torque than those of groups 2 and 3 (P < 0.01). No differences in BIC or BAFO were observed between the groups. From a morphologic standpoint, substantial deviations in healing mode were observed between groups. CONCLUSION: Based on the present methodology, the experimental alterations of surgical technic can be clinically used with no detrimental effect over the osseointegration process.

Implant design and its effects on osseointegration over time within cortical and trabecular bone.

Healing chambers present at the interface between implant and bone have become a target for improving osseointegration. The objective of the present study was to compare osseointegration of several implant healing chamber configurations at early time points and regions of interest within bone using an in vivo animal femur model. Six implants, each with a different healing chamber configuration, were surgically implanted into each femur of six skeletally mature beagle dogs (n = 12 implants per dog, total n = 72). The implants were harvested at 3 and 5 weeks post-implantation, non-decalcified processed to slides, and underwent histomorphometry with measurement of bone-to-implant contact (BIC) and bone area fraction occupied (BAFO) within healing chambers at both cortical and trabecular bone sites. Microscopy demonstrated predominantly woven bone at 3 weeks and initial replacement of woven bone by lamellar bone by 5 weeks. BIC and BAFO were both significantly increased by 5 weeks (p < 0.001), and significantly higher in cortical than trabecular bone (p < 0.001). The trapezoidal healing chamber design demonstrated a higher BIC than other configurations. Overall, a strong temporal and region-specific dependence of implant osseointegration in femurs was noted. Moreover, the findings suggest that a trapezoidal healing chamber configuration may facilitate the best osseointegration. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 1091-1097, 2016.

Osseointegration of Plateau Root Form Implants: Unique Healing Pathway Leading to Haversian-Like Long-Term Morphology.

Endosteal dental implants have been utilized as anchors for dental and orthopedic rehabilitations for decades with one of the highest treatment success rates in medicine. Such success is due to the phenomenon of osseointegration where after the implant surgical placement, bone healing results into an intimate contact between bone and implant surface. While osseointegration is an established phenomenon, the route which osseointegration occurs around endosteal implants is related to various implant design factors including surgical instrumentation and implant macro, micro, and nanometer scale geometry. In an implant system where void spaces (healing chambers) are present between the implant and bone immediately after placement, its inherent bone healing pathway results in unique opportunities to accelerate the osseointegration phenomenon at the short-term and its maintenance on the long-term through a haversian-like bone morphology and mechanical properties.

Probability of survival of implant-supported metal ceramic and CAD/CAM resin nanoceramic crowns.

OBJECTIVES: To evaluate the probability of survival and failure modes of implant-supported resin nanoceramic relative to metal-ceramic crowns. METHODS: Resin nanoceramic molar crowns (LU) (Lava Ultimate, 3M ESPE, USA) were milled and metal-ceramic (MC) (Co-Cr alloy, Wirobond C+, Bego, USA) with identical anatomy were fabricated (n=21). The metal coping and a burnout-resin veneer were created by CAD/CAM, using an abutment (Stealth-abutment, Bicon LLC, USA) and a milled crown from the LU group as models for porcelain hot-pressing (GC-Initial IQ-Press, GC, USA). Crowns were cemented, the implants (n=42, Bicon) embedded in acrylic-resin for mechanical testing, and subjected to single-load to fracture (SLF, n=3 each) for determination of step-stress profiles for accelerated-life testing in water (n=18 each). Weibull curves (50,000 cycles at 200N, 90% CI) were plotted. Weibull modulus (m) and characteristic strength (η) were calculated and a contour plot used (m versus η) for determining differences between groups. Fractography was performed in SEM and polarized-light microscopy. RESULTS: SLF mean values were 1871N (±54.03) for MC and 1748N (±50.71) for LU. Beta values were 0.11 for MC and 0.49 for LU. Weibull modulus was 9.56 and η=1038.8N for LU, and m=4.57 and η=945.42N for MC (p>0.10). Probability of survival (50,000 and 100,000 cycles at 200 and 300N) was 100% for LU and 99% for MC. Failures were cohesive within LU. In MC crowns, porcelain veneer fractures frequently extended to the supporting metal coping. CONCLUSION: Probability of survival was not different between crown materials, but failure modes differed. SIGNIFICANCE: In load bearing regions, similar reliability should be expected for metal ceramics, known as the gold standard, and resin nanoceramic crowns over implants. Failure modes involving porcelain veneer fracture and delamination in MC crowns are less likely to be successfully repaired compared to cohesive failures in resin nanoceramic material.

Assessment of Atmospheric Pressure Plasma Treatment for Implant Osseointegration.

This study assessed the osseointegrative effects of atmospheric pressure plasma (APP) surface treatment for implants in a canine model. Control surfaces were untreated textured titanium (Ti) and calcium phosphate (CaP). Experimental surfaces were their 80-second air-based APP-treated counterparts. Physicochemical characterization was performed to assess topography, surface energy, and chemical composition. One implant from each control and experimental group (four in total) was placed in one radius of each of the seven male beagles for three weeks, and one implant from each group was placed in the contralateral radius for six weeks. After sacrifice, bone-to-implant contact (BIC) and bone area fraction occupancy (BAFO) were assessed. X-ray photoelectron spectroscopy showed decreased surface levels of carbon and increased Ti and oxygen, and calcium and oxygen, posttreatment for Ti and CaP surfaces, respectively. There was a significant (P < 0.001) increase in BIC for APP-treated textured Ti surfaces at six weeks but not at three weeks or for CaP surfaces. There were no significant (P = 0.57) differences for BAFO between treated and untreated surfaces for either material at either time point. This suggests that air-based APP surface treatment may improve osseointegration of textured Ti surfaces but not CaP surfaces. Studies optimizing APP parameters and applications are warranted.

Digitally produced fiber-reinforced composite substructures for three-unit implant-supported fixed dental prostheses.

PURPOSE: This study aimed to evaluate the probability of survival, Weibull modulus, characteristic strength, and failure modes of computer-aided design/computer-assisted manufacture (CAD/CAM) fiber-reinforced composite (FRC) substructures used for implant-supported fixed dental prostheses (ISFDPs). MATERIALS AND METHODS: Three-unit ISFDPs (first molar pontic) fabricated as a monolithic composite piece or as composite veneered on a CAD/CAM FRC substructure with either a 12-mm² or 3-mm² connector area (n = 18 each) were subjected to step-stress accelerated life testing in water. Use-level probability Weibull curves and the probability of survival were calculated. Fractographic analysis was performed under polarized light and scanning electron microscopy. RESULTS: Fatigue did not accelerate the failure of any group, whereas prosthesis strength was the main factor in increased failure (ß < 1). The probability Weibull contour plot showed no differences between the ISFDPs with 12 mm² and the monolithic composite ISFDP in characteristic strength (η = 643.5 N and 742.7 N, respectively) or Weibull modulus (6.7 and 5.8, respectively), whereas both were significantly higher than 3 mm² (444.91 N and 9.57). The probability of survival was not statistically different between groups at 100,000 mission cycles at 300 N. Differences were observed in fatigue failures above 800 N; monolithic composite ISFDPs failed catastrophically, whereas those with CAD/CAM FRC substructures presented veneer/composite cohesive or adhesive failures. Cracks evolved from the occlusal contact toward the margins of the cohesively failed composite, and in CAD/CAM FRC prostheses, competing failure modes of cracks developing at the connector area with those at the indentation contact were observed. CONCLUSION: The probability of survival did not differ between CAD/CAM FRC with either 3-mm² or 12-mm² connector areas, monolithic composite, or metal-ceramic ISFDPs previously tested under the same methodology. However, differences in failure modes were detected between groups.

Progressive plateau root form dental implant osseointegration: A human retrieval study.

Although preclinical and sparse human histology retrieval studies have shown that the interface between implant and bone is constantly remodeling, no human retrieval database has been developed to determine the effect of functional loading time and other clinical/implant design variables on osseointegration. The present study tested the hypothesis that bone-to-implant contact (BIC) and bone area fraction occupancy (BAFO) increase over functional loading time around dental implants. Due to prosthetic retreatment reasons, 93 human implant retrievals from the same manufacturer (Bicon LLC, Boston, MA, USA) were obtained over a period of approximately 15 years. The retrieved implants were under functional loading from 120 days to ∼18 years and were histomorphologic/metrically evaluated. BIC/BAFO were assessed as a function of multiple independent variables: implant surface type, diameter, length, jaw (maxilla/mandible), region (anterior/posterior), and time of functional loading. The results showed that both BIC and BAFO increased over time independently of implant design/clinical variables, supporting the postulated hypothesis.

Bone regeneration around implants placed in fresh extraction sockets covered with a dual-layer PTFE/collagen membrane: an experimental study in dogs.

This study investigated whether the use of a dual-layer polytetrafluoroethylene (PTFE)/porcine-derived bioresorbable pericardium membrane enhances the osseointegration around implants compared to a single-layer porcine-derived bioresorbable pericardium membrane and a no-membrane control group. Endosseous implants were placed in the fresh extraction sockets of beagles. At 6 weeks, bone loss and apical soft tissue migration occurred in the control group, whereas bone successfully formed to the neck of the implant for the single-layer porcine-derived bioresorbable pericardium membrane group. The dual-layer PTFE/ porcine-derived bioresorbable pericardium membrane showed bone growth coronal to the neck of the implant. Bone-to-implant contact and buccal bone loss were respectively higher and lower relative to the single-layer but not statistically different.

Novel implant design improves implant survival in multirooted extraction sites: a preclinical pilot study.

BACKGROUND: The primary aim is to evaluate clinical, radiographic, and histologic parameters of novel implants with "three roots" design that were inserted into fresh multirooted extraction sockets. A secondary aim is to compare this new implant to standard root-form dental implants. METHODS: Immediate implantation of novel or standard design 6 × 6-mm implants was performed bilaterally into multirooted sockets in mandibles of mini-pigs. Twelve weeks later, clinical, radiographic, stability, histomorphometric, and microcomputed tomography (micro-CT) analyses were performed. RESULTS: Survival rates were significantly higher in the test implants compared with control (92.8% versus 33.3%, respectively; P <0.001). Bone loss was greater in the control compared with the test by sounding (mean 3.42 ± 0.68 versus 1.96 ± 0.34 mm) and radiography (mean 3.35 ± 0.62 versus 2.27 ± 0.33 mm). Histologic and micro-CT analyses demonstrated bone fill in the inner part of the test implants. Moreover, bone-to-implant contact was higher in the test implants (55.50% ± 3.68% versus 42.47% ± 9.89%). Contrary to the clinical, radiographic, and histomorphometric results, resonance frequency analysis measurements were greater in the control group (77.74 ± 3.21 implant stability quotient [ISQ]) compared with the test group (31.09 ± 0.28 ISQ), P = 0.008. CONCLUSIONS: The novel design implants resulted in significantly greater survival rate in multirooted extraction sites. Further studies will be required to validate these findings.

Histologic and biomechanical evaluation of 2 resorbable-blasting media implant surfaces at early implantation times.

This study evaluated 3 implant surfaces in a dog model: (1) resorbable-blasting media + acid-etched (RBMa), alumina-blasting + acid-etching (AB/AE), and AB/AE + RBMa (hybrid). All of the surfaces were minimally rough, and Ca and P were present for the RBMa and hybrid surfaces. Following 2 weeks in vivo, no significant differences were observed for torque, bone-to-implant contact, and bone-area fraction occupied measurements. Newly formed woven bone was observed in proximity with all surfaces.

Surface characterization, biomechanical, and histologic evaluation of alumina and bioactive resorbable blasting textured surfaces in titanium implant healing chambers: an experimental study in dogs.

PURPOSE: The present study was conducted to determine whether biomechanical and histologic parameters would differ between implant surfaces blasted with bioactive ceramic resorbable media (biologic blasting) and blasted with alumina and acid-etched. MATERIALS AND METHODS: Fourteen beagle dogs were used. Eight animals received two implants of each surface per limb, and each limb provided samples that remained in vivo for 3 and 6 weeks. The other six animals received two implants of each surface in one limb, which remained in vivo for 1 week. After euthanization, half of the implants were subjected to torque-to-interface fracture; the other half of the implants were processed for nondecalcified histology to calculate bone-to-implant contact (BIC) and bone area fraction occupancy (BAFO). Statistical analysis was performed with the Kruskal-Wallis test (95% level of significance). RESULTS: While no significant differences were observed for BIC and BAFO between surfaces at all three times in vivo and for torque levels at 1 and 3 weeks, a significantly higher torque was observed for the biologic blasting group after 6 weeks in vivo. Bone morphology was similar between groups at all times. CONCLUSION: A significant increase in early biomechanical fixation was observed for implants with the biologic blasting surface. However, no significant differences were observed for BIC and BAFO at any observation point.

Implant biomechanical stability variation at early implantation times in vivo: an experimental study in dogs.

PURPOSE: To demonstrate the degree of stability decrease and subsequent increase of dental implants at early implantation times in a beagle model. MATERIALS AND METHODS: The mandibular premolars and first molars of eight beagle dogs were extracted and the ridges allowed to heal for 8 weeks. Thirty-two (n = 16 each group) implants were placed bilaterally, and remained in vivo for 1 and 3 weeks. The implants with comparable dimensions were divided as follows: group 1, Straumann Bone Level with SLActive surface; group 2, Nobel Speedy Replace RP with TiUnite surface. During insertion and following sacrifice, the implants were torqued to determine insertion and interface failure values. Histologic sections were prepared for microscopy. Statistical analysis was performed using Kruskal-Wallis and multiple paired and non-paired t tests considering unequal variances at a 95% level of significance. RESULTS: High insertion torque values were observed along with a significant decrease at 1 week in vivo (P = .003). At 3 weeks, the biomechanical fixation levels increased and were comparable to the insertion torque value. Histology showed that interfacial bone remodeling and initial woven bone formation was observed around both implant groups at 1 and 3 weeks. CONCLUSIONS: As time elapsed early after implantation, the biomechanical stability of dental implants initially decreased and subsequently increased.

The effect of simplifying dental implant drilling sequence on osseointegration: an experimental study in dogs.

Objectives. To test the hypothesis that there would be no differences in osseointegration by reducing the number of drills for site preparation relative to conventional drilling sequence. Methods. Seventy-two implants were bilaterally placed in the tibia of 18 beagle dogs and remained for 1, 3, and 5 weeks. Thirty-six implants were 3.75 mm in diameter and the other 36 were 4.2 mm. Half of the implants of each diameter were placed under a simplified technique (pilot drill + final diameter drill) and the other half were placed under conventional drilling where multiple drills of increasing diameter were utilized. After euthanisation, the bone-implant samples were processed and referred to histological analysis. Bone-to-implant contact (BIC) and bone-area-fraction occupancy (BAFO) were assessed. Statistical analyses were performed by GLM ANOVA at 95% level of significance considering implant diameter, time in vivo, and drilling procedure as independent variables and BIC and BAFO as the dependent variables. Results. Both techniques led to implant integration. No differences in BIC and BAFO were observed between drilling procedures as time elapsed in vivo. Conclusions. The simplified drilling protocol presented comparable osseointegration outcomes to the conventional protocol, which proved the initial hypothesis.

Biomechanical testing of microblasted, acid-etched/microblasted, anodized, and discrete crystalline deposition surfaces: an experimental study in beagle dogs.

PURPOSE: Modifications in implant surface topography and chemistry may alter the early bone response at different levels. This study characterized four implant surfaces and evaluated the biomechanical fixation and histologic response at early implantation times in a canine radius model. MATERIALS AND METHODS: External-hexagon Branemark-type implants were used with four experimental surfaces: microblasted (MI), acid-etched and microblasted (AAM), anodized (A), and discrete crystalline deposition (DCD). Surface topography was assessed by scanning electron microscopy, interferometry, and x-ray photoelectron spectroscopy. The implants were placed in the central region of the radii of eight beagle dogs and remained in vivo for 10 or 30 days. The implants were torqued to interface failure, and a general linear statistical model with torque as the dependent variable and implant surface and time in vivo as independent variables was used. RESULTS: All surfaces presented were textured, and different surface chemistries were observed. No significant differences between implant surfaces were observed for torque at 10 days. However, at 30 days, the AAM surface presented significantly higher torque values compared to the DCD and A surfaces. Significantly higher torque values were observed at 30 days compared to 10 days (P < .001). CONCLUSIONS: Significantly different biomechanical fixation dependent on surface preparation was observed after 30 days, and all surfaces were biocompatible and osteoconductive.

Reimplantation of dental implants following ligature-induced peri-implantitis: a pilot study in dogs.

OBJECTIVES: This preliminary investigation aimed to evaluate the potential of contaminated implants to reosseointegrate into pristine sites and, in addition, to assess the potential of osseointegration of new implants in peri-implantitis sockets in a canine model. METHODS: All mandibular premolars were bilaterally extracted from two mongrel dogs. Following 12 weeks of healing, two dental implants were inserted on each hemiarch. Forty-five days following implant placement, a silk ligature secured with cyanoacrylate was placed around the implants' cervical region in order to induce peri-implantitis. After another 45 days from ligature placement, the implants were mechanically removed using counter rotation with a ratchet and were reimplanted without any decontamination (neither rinsing nor chemical or mechanical cleaning) in adjacent pristine zones. In sites where implants were removed, new, wider-diameter implants were placed in the infected sockets. Forty-five days following reimplantation surgery, the dogs were sacrificed; nondecalcified specimens were processed and toluidine blue stained for morphologic and morphometric (bone-to-implant contact [BIC]) assessment under an optical microscope. RESULTS: In dog 1 all the implants (both in the pristine and in the infected sites) survived and osseointegrated while in dog 2, six out of eight implants failed to osseointegrate and exfoliated. Overall, the mean BIC of all implants was 51.08% (SD 20.54). The mean BIC for the infected implants placed into pristine sites was 51.48% ± 26.29% (SD) and the mean BIC for the new implants in peri-implantitis socket was 50.58% ± 14.27% (SD). CONCLUSIONS: Within the limitations of this preliminary investigation, especially the small number of animals, osseointegration seems to be achievable both in infected sites and around contaminated implant surfaces.

Buccal and lingual bone level alterations after immediate implantation of four implant surfaces: a study in dogs.

OBJECTIVES: Bone formation and maintenance around implants placed immediately after tooth extraction may be affected by implant surface treatment and compromise long-term esthetic results. This study morphometrically evaluated buccal bone loss and bone-to-implant contact (BIC) of four implant systems placed immediately after tooth extraction in a dog model. MATERIAL AND METHODS: The premolars of eight beagle dogs were bilaterally extracted with a full-thickness flap, and root-form dental implants were placed on the root extraction socket. Implants (n = 16 each) with different surface treatments were placed from sites 1 to 4 and alternated between animals to allow evaluation of the same number of implants at sites and evaluation time points. Implant surface treatments were as follows: anodized, discrete crystalline deposition, SLActive, and microblasted. The left and right side provided implants that stayed for 2 and 4 weeks, respectively. Submerged healing was allowed and bone-to-implant contact (BIC) and buccal bone loss were morphometrically measured. Linear mixed models (P < 0.05) were used to assess differences between groups, across time, and their interaction. RESULTS: Buccal bone loss was observed to approximately double between 2 and 4 weeks (P = 0.01). BIC also increased between 2 and 4 weeks, by 20-25% (P = 0.01). These changes were statistically similar for each surface. CONCLUSION: When placed immediately after tooth extraction, the evaluated histomorphometric parameters vary only with time.