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Purpose: The All-on-4 treatment concept has been shown to be an effective clinical procedure; however, to date, no studies have analyzed the subgingival microbiota present in these restorations. The purpose of this study was to evaluate the microbial profile of the subgingival biofilm around dental implants placed in the All-on-4 protocol and compare the microbial profile around axial and tilted implants., Materials and Methods: Fourteen subjects treated by the All-on-4 concept were evaluated clinically and microbiologically. Subgingival biofilm was collected from each patient, and the amount of 40 species of bacteria was assessed using the checkerboard DNA-DNA hybridization technique., Results: The results for the indices of probing depth (PD), bleeding on probing, marginal bleeding, and visible plaque were 2.32 mm, 46%, 60%, and 57%, respectively. Tilted implants presented a significantly higher mean PD and Plaque Index compared with axial implants (P < .05). Fusobacterium nucleatum ssp vincentii, Veillonella parvula, and Fusobacterium nucleatum ssp polymorphum were found in higher levels; however, no difference in the microbial composition was observed between tilted and axial implants (P > .05). Tilted implants presented statistically higher mean levels for the orange complex in relation to the axial implants (P < .05)., Conclusion: Despite the clinical success rate of the All-on-4 protocol, the subgingival biofilm of tilted implants presented a higher proportion for the orange complex pathogens in comparison to axial implants. These data could suggest that subjects with this modality of implant-supported restoration must be aware that they need a more rigorous maintenance protocol.

Objectives: To observe and to compare histologically and histomorphometrically, the combined effect of drilling sequence and implant diameter in vivo., Material and Methods: A total of 72 alumina-blasted and acid-etched Ti-6Al-4V implants with three different diameters (3.75, 4.2, and 5 mm, n = 24 for each group) were placed in the right and left tibiae of 12 beagle dogs. Within the same diameter group, half of the implants were inserted after a simplified drilling procedure (pilot drill + final diameter drill) on one tibia and the other half were placed using the conventional drilling procedure on the other tibia. After 1 week, half of the animals (n = 6) were sacrificed, and the other half was sacrificed after 5 weeks (n = 6). The retrieved bone-implant samples were subjected to non-decalcified histologic sectioning, and the bone-to-implant contact (BIC) and the bone area fraction occupancy (BAFO) were analyzed. Primary statistical analysis used a mixed model analysis of variance with significance level set at P < 0.05., Results: Histologic observation showed that at 1 week, immature woven bone formed in vicinity of the implant, whereas at 5 weeks, the woven bone was replaced by lamellar bone, which formed in proximity with the implant. Histomorphometrically, the simplified technique was associated with significantly greater BIC and BAFO after 1 week. Differences between techniques were not longer apparent after 5 weeks, but BAFO was inversely and significantly associated with implant diameter at that time., Conclusions: The simplified technique did not impair either early or late bone formation for any tested implant diameter; however, wider diameters were associated with less bone formation at longer healing times for both techniques., (© 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background: To date, some experimental studies have addressed the effect of bone drilling technique and sequence on dental implant osseointegration. In the present study, the authors hypothesize that there would be no differences in osseointegration when reducing the number of drills for osteotomy compared to the conventional drilling protocols., Methods: Seventy-two implants (diameters 3.75 mm and 4.2 mm; n = 36 for each diameter) were bilaterally placed in the tibia of 18 beagles for 1, 3, and 5 weeks. Half of the implants of each diameter were placed using a simplified drilling procedure (pilot and final drill), and the other half were placed using a conventional drilling procedure (all drills in sequence). The retrieved samples were subjected to histologic and histomorphometric evaluation., Results: Histology showed that new bone formed around the implant, and inflammation or bone resorption was not evident for both groups. Histomorphometrically, the simplified group presented significantly higher bone-to-implant contact and bone area fraction occupancy compared to the conventional group after 1 week; however, no differences were detected at 3 and 5 weeks., Conclusion: Bone responses to the implant with the simplified protocol can be comparable to the conventional protocol.

Objectives: To compare the biomechanical fixation and histomorphometric parameters between two implant surfaces: non-washed resorbable blasting media (NWRBM) and alumina-blasted/acid-etched (AB/AE), in a dog model., Material and Methods: The surface topography was assessed by scanning electron microscopy, optical interferometry and chemistry by X-ray photoelectron spectroscopy (XPS). Six beagle dogs of ∼1.5 years of age were utilized and each animal received one implant of each surface per limb (distal radii sites). After a healing period of 3 weeks, the animals were euthanized and half of the implants were biomechanically tested (removal torque) and the other half was referred to nondecalcified histology processing. Histomorphometric analysis considered bone-to-implant contact (BIC) and bone area fraction occupancy (BAFO). Following data normality check with the Kolmogorov-Smirnov test, statistical analysis was performed by paired t-tests at 95% level of significance., Results: Surface roughness parameters S(a) (average surface roughness) and S(q) (mean root square of the surface) were significantly lower for the NWRBM compared with AB/AE. The XPS spectra revealed the presence of Ca and P in the NWRBM. While no significant differences were observed for both BIC and BAFO parameters (P>0.35 and P>0.11, respectively), a significantly higher level of torque was observed for the NWRBM group (P=0.01). Bone morphology was similar between groups, which presented newly formed woven bone in proximity with the implant surfaces., Conclusion: A significant increase in early biomechanical fixation was observed for implants presenting the NWRBM surface., (© 2011 John Wiley & Sons A/S.)

Objectives: To evaluate the effect of insertion torque on micromotion to a lateral force in three different implant designs., Material and Methods: Thirty-six implants with identical thread design, but different cutting groove design were divided in three groups: (1) non-fluted (no cutting groove, solid screw-form); (2) fluted (90° cut at the apex, tap design); and (3) Blossom(™) (Patent pending) (non-fluted with engineered trimmed thread design). The implants were screwed into polyurethane foam blocks and the insertion torque was recorded after each turn of 90° by a digital torque gauge. Controlled lateral loads of 10 N followed by increments of 5 up to 100 N were sequentially applied by a digital force gauge on a titanium abutment. Statistical comparison was performed with two-way mixed model ANOVA that evaluated implant design group, linear effects of turns and displacement loads, and their interaction., Results: While insertion torque increased as a function of number of turns for each design, the slope and final values increased (P<0.001) progressively from the Blossom to the fluted to the non-fluted design (M ± standard deviation [SD]=64.1 ± 26.8, 139.4 ± 17.2, and 205.23 ± 24.3 Ncm, respectively). While a linear relationship between horizontal displacement and lateral force was observed for each design, the slope and maximal displacement increased (P<0.001) progressively from the Blossom to the fluted to the non-fluted design (M ± SD=530 ± 57.7, 585.9 ± 82.4, and 782.33 ± 269.4 μm, respectively). There was negligible to moderate levels of association between insertion torque and lateral displacement in the Blossom, fluted and non-fluted design groups, respectively., Conclusion: Insertion torque was reduced in implant macrodesigns that incorporated cutting edges, and lesser insertion torque was generally associated with decreased micromovement. However, insertion torque and micromotion were unrelated within implant designs, particularly for those designs showing the least insertion torque., (© 2011 John Wiley & Sons A/S.)

Purpose: This study tested the hypothesis that early integration of plateau root form endosseous implants is significantly affected by surgical drilling technique., Materials and Methods: Sixty-four implants were bilaterally placed in the diaphysial radius of 8 beagles and remained 2 and 4 weeks in vivo. Half the implants had an alumina-blasted/acid-etched surface and the other half a surface coated with calcium phosphate. Half the implants with the 2 surface types were drilled at 50 rpm without saline irrigation and the other half were drilled at 900 rpm under abundant irrigation. After euthanasia, the implants in bone were nondecalcified and referred for histologic analysis. Bone-to-implant contact, bone area fraction occupancy, and the distance from the tip of the plateau to pristine cortical bone were measured. Statistical analyses were performed by analysis of variance at a 95% level of significance considering implant surface, time in vivo, and drilling speed as independent variables and bone-to-implant contact, bone area fraction occupancy, and distance from the tip of the plateau to pristine cortical bone as dependent variables., Results: The results showed that both techniques led to implant integration and intimate contact between bone and the 2 implant surfaces. A significant increase in bone-to-implant contact and bone area fraction occupancy was observed as time elapsed at 2 and 4 weeks and for the calcium phosphate-coated implant surface compared with the alumina-blasted/acid-etched surface., Conclusions: Because the surgical drilling technique did not affect the early integration of plateau root form implants, the hypothesis was refuted., (Copyright © 2011 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.)

Objectives: This study evaluated the effect of magnesium dietary deficiency on bone metabolism and bone tissue around implants with established osseointegration., Materials and Methods: For this, 30 rats received an implant in the right tibial metaphysis. After 60 days for healing of the implants, the animals were divided into groups according to the diet received. Control group (CTL) received a standard diet with adequate magnesium content, while test group (Mg) received the same diet except for a 90% reduction of magnesium. The animals were sacrificed after 90 days for evaluation of calcium, magnesium, osteocalcin and parathyroid hormone (PTH) serum levels and the deoxypyridinoline (DPD) level in the urine. The effect of magnesium deficiency on skeletal bone tissue was evaluated by densitometry of the lumbar vertebrae, while the effect of bone tissue around titanium implants was evaluated by radiographic measurement of cortical bone thickness and bone density. The effect on biomechanical characteristics was verified by implant removal torque testing., Results: Magnesium dietary deficiency resulted in a decrease of the magnesium serum level and an increase of PTH and DPD levels (P ≤ 0.05). The Mg group also presented a loss of systemic bone mass, decreased cortical bone thickness and lower values of removal torque of the implants (P ≤ 0.01)., Conclusions: The present study concluded that magnesium-deficient diet had a negative influence on bone metabolism as well as on the bone tissue around the implants., (© 2010 John Wiley & Sons A/S.)

Calcium phosphate-based bioactive ceramics in various physical and chemical formulations have been extensively utilized as biomaterials for bone regeneration/conduction. However, the determination of their in vivo temporal behavior from the short to long term in humans has been a challenge due to the lack of physical reference for morphologic and morphometric evaluation. The present study evaluated bone morphology and morphometry (bone-to-implant contact [BIC]) around plasma-sprayed hydroxyapatite (PSHA)-coated endosseous implants that were retrieved due to prosthetic reasons while successfully in function at the posterior region of the jaws from as early as 2 months to ∼13 years after a 6-month healing period after placement. Bone morphology was evaluated by light microscopy, and BIC was determined using computer software. Irrespective of the time in vivo, lamellar bone was observed in close contact with the implant PSHA-coated surface and between plateaus. BIC ranged from ∼35-95%, was highly directional, and Haversian-like osteonic morphology between plateaus was observed for most implants. The PSHA coating was present with little variation in thickness between the samples retrieved regardless of time in vivo.