A longitudinal study of quality of life of elderly with mandibular implant-supported fixed prostheses

Objectives: To verify the consequences of implant-supported fixed oral rehabilitation on the quality of life (QL) of elderly individuals.Material and methods: Fifteen patients were studied, being 10 females and five males; all were aged > 60 years, were completely edentulous, wore removable dentures on both arches, and were treated with implant-supported fixed dentures. Three QL questionnaires were applied, two related to the oral conditions (Oral Impact on Daily Performance - OIDP - and Oral Health Impact Profile, short version - OHIP-14) and one dealing with global aspects (World Health Organization Quality of Life - WHOQOL-BREF), before 3, 6, and 18 months after surgical placement of implants.Results: Scores in the OIDP and OHIP-14 questionnaires were better after dental treatment. The WHOQOL-BREF was less sensitive, confirming the higher reliability of specific questionnaires (focal) compared with general questions in such situations.Conclusion: Treatment with implant-supported fixed prostheses improved QL in the elderly; these effects are better detected by specific instruments focused on the subject.

Influence of lateral pressure to the implant bed on osseointegration: an experimental study in dogs

AimTo study osseointegration and bone-level changes at implants installed using either a standard or a reduced diameter bur for implant bed preparation.Material and methodsIn six Labrador dogs, the first and second premolars were extracted bilaterally. Subsequently, mesial roots of the first molars were endodontically treated and distal roots, including the corresponding part of the crown, were extracted. After 3 months of healing, flaps were elevated and recipient sites were prepared in all experimental sites. The control site was prepared using a standard procedure, while the test site was prepared using a drill with a 0.2 mm reduced diameter than the standard one used in the contra-lateral side. After 4 months of healing, the animals were euthanized and biopsies were obtained for histological processing and evaluation.ResultsWith the exception of one implant that was lost, all implants were integrated in mineralized bone. The alveolar crest underwent resorption at control as well as at test sites (buccal aspect similar to 1 mm). The most coronal contact of bone-to-implant was located between 1.2 and 1.6 mm at the test and between 1.3 and 1.7 mm at the control sites. Bone-to-implant contact percentage was between 49% and 67%. No statistically significant differences were found for any of the outcome variables.ConclusionsAfter 4 months of healing, lateral pressure to the implant bed as reflected by higher insertion torques (36 vs. 15 N cm in the premolar and 19 vs. 7 N cm in the molar regions) did not affect the bone-to-implant contact.To cite this article:Pantani F, Botticelli D, Garcia IR Jr., Salata LA, Borges GJ, Lang NP. Influence of lateral pressure to the implant bed on osseointegration: an experimental study in dogs.Clin. Oral Impl. Res. 21, 2010; 1264-1270.doi: 10.1111/j.1600-0501.2009.01941.x.

Influence of various implant platform configurations on peri-implant tissue dimensions: an experimental study in dog

AimTo evaluate the influence (i) of various implant platform configurations and (ii) of implant surface characteristics on peri-implant tissue dimensions in a dog model.Material and methodsMandibular premolars and first molars were extracted bilaterally in six Labrador dogs. After 3 months of healing, two implants, one with a turned and a second with a moderately rough surface, were installed on each side of the mandible in the premolar region. on the right side of the mandible, implants with a tapered and enlarged platform were used, while standard cylindrical implants were installed in the left side of the mandible. Abutments with the diameter of the cylindrical implants were used resulting in a mismatch of 0.25 mm at the tapered implant sites. The flaps were sutured to allow a non-submerged healing. After 4 months, the animals were sacrificed and ground sections were obtained for histometric assessment.ResultsAll implants were completely osseointegrated. A minimal buccal bone resorption was observed for both implant configurations and surface topographies. Considering the animals as the statistical unit, no significant differences were found at the buccal aspect in relation to bone levels and soft tissue dimensions. The surface topographies did not influence the outcomes either.ConclusionsThe present study failed to show differences in peri-implant tissue dimensions when a mismatch of 0.25 mm from a tapered platform to an abutment was applied. The surface topographies influence a neither marginal bone resorption or peri-implant soft tissue dimension.To cite this article:Baffone GM, Botticelli D, Pantani F, Cardoso LC, Schweikert MT, Lang NP. Influence of various implant platform configurations on peri-implant tissue dimensions: an experimental study in dog.Clin. Oral Impl. Res. 22, 2011; 438-444.

Bone healing in surgically created defects treated with either bioactive glass particles, a calcium sulfate barrier, or a combination of both materials: A histological and histometric study in rat tibias

Objective: The purpose of this study was to histologically analyze the influence of bioactive glass and/or a calcium sulfate barrier on bone healing in surgically created defects in rat tibias. Material and methods: Sixty-four rats were divided into 4 groups: C (control), CS (calcium sulfate), BG (bioactive glass), and BG/CS (bioactive glass/calcium sulfate). A surgical defect was created in the tibia of each animal. In Group CS, a calcium sulfate barrier was placed to cover the defect. In Group BG the defect was filled with bioactive glass. In Group BG/CS, it was filled with bioactive glass and protected by a barrier of calcium sulfate. Animals were sacrificed at 10 or 30 days post-operative. The formation of new bone in the cortical area of the defect was evaluated histomorphometrically. Results: At 10 days post-operative, Group C presented significantly more bone formation than Groups CS, BG, or BG/CS. No statistically significant differences were found between the experimental groups. At 30 days post-operative, Group C demonstrated significantly more bone formation than the experimental groups. Groups CS and BG/CS showed significantly more bone formation than Group BG. No statistically significant differences were found between Group CS and BG/CS. Conclusions: (a) the control groups had significantly more bone formation than the experimental groups; (b) at 10 days post-operative, no significant differences were found between any of the experimental groups; and (c) at 30 days post-operative, the groups with a calcium sulfate barrier had significantly more bone formation than the group that used bioactive glass only. Copyright © Blackwell Munksgaard 2005.

Bone healing in critical-size defects treated with bioactive glass/calcium sulfate: A histologic and histometric study in rat calvaria

Objective: The purpose of this study was to analyze histologically the influence of bioactive glass (BG) with or without a calcium sulfate (CS) barrier on bone healing in surgically created critical-size defects (CSD) in rat calvaria. Material and methods: A CSD was made in each calvarium of 48 rats. They were divided into three groups: C (control): blood clot only; BG: defect filled with BG; and BG/CS: defect filled with BG covered by a CS barrier. Animals were euthanized at 4 or 12 weeks. Formation of new bone was evaluated histomorphometrically. Results: No defect completely regenerated with bone. BG particles were observed in Groups BG and BG/CS at both periods of analysis. The thickness throughout the healing area in Groups BG and BG/CS was similar to the original calvarium, while Group C presented a thin connective tissue in the center of the defect in both periods of analysis. At 4 weeks, Groups C and BG/CS presented significantly more bone formation than Group BG. No significant differences were found between Groups C and BG/CS. At 12 weeks, no significant differences in the amount of bone formation were observed among the three groups. When comparing 4 and 12 weeks, there was a significant increase in new bone formation within groups BG and BG/CS, but not C. Conclusion: BG particles, used with or without a CS barrier, maintained the volume and contour of the area grafted in CSD. However, they did not lead to a significant difference in bone formation when compared with control at 12 weeks post-operative. © 2007 Blackwell Munksgaard.

Immunohistochemical, tomographic and histological study on onlay iliac grafts remodeling

The information concerning the molecular events taking place in onlay bone grafts are still incipient. The objective of the present study is to correlate the effects of perforation of resident bone bed on (1) the timing of onlay autogenous graft revascularization; (2) the maintenance of volume/density of the graft (assessed through tomography); and (3) the occurrence of bone remodeling proteins (using immunohistochemistry technique) delivered in the graft. Thirty-six New Zealand White rabbits were subjected to iliac crest onlay bone grafting on both sides of the mandible. The bone bed was drill-perforated on one side aiming at accelerating revascularization, whereas on the other side it was kept intact. After grafts fixation and flaps suture all animals were submitted to tomography on both mandible sites. Six animals were sacrificed, respectively, at 3, 5, 7, 10, 20 and 60 days after surgery. A second tomography was taken just before sacrifice. Histological slides were prepared from each grafted site for both immunohistochemistry analysis [osteopontin, osteocalcin, type I collagen and vascular endothelial growth factor (VEGF) anti-bodies] and histometric analysis. The values on bone volume measured on tomography showed no statistic significance (P≥0.05) between perforated and intact sites. Grafts placed on perforated beds showed higher bone density values compared with non-perforated ones at 3 days (P≤0.05). This correlation was inverted at 60 days postoperatively. The findings from VEGF labeling revealed a tendency for earlier revascularization in the perforated group. The early revascularization of bone grafts accelerated the bone remodeling process (osteocalcin, type I collagen and osteopontin) that led to an increased bone deposition at 10 days. The extended osteoblast differentiation process at intermediate stages in the perforated group cooperated for a denser bone at 60 days. © 2008 Blackwell Munksgaard.

Immunohistochemical, tomographic and histological study on onlay bone graft remodeling. Part II: Calvarial bone

Objectives: Little information is available on the molecular events that occur during graft incorporation over time. The calvarial bone (Cb) grafts have been reported to produce greater responses compared with other donor regions in maxillofacial reconstructions, but the scientific evidences for this are still lacking. The objectives of this study are (1) to study the morphological pattern of Cb onlay bone grafts and compare them with the biological events through immunohistochemical responses and (2) to establish the effects of perforations in maintaining the volume and bone density of the receptor bed. Material and methods: Sixty New Zealand White rabbits were submitted to Cb onlay bone grafts on the mandible. In 30 rabbits, the receptor bed was perforated (perforated group), while for the remaining animals the bed was kept intact (non-perforated group). Six animals from each group were sacrificed at 5, 7, 10, 20 and 60 days after surgery. Histological sections from the grafted area were prepared for immunohistochemical and histological analyses. Immuno-labeling was found for proteins Osteoprotegerin (OPG), receptor activator of nuclear factor-κβ ligand (RANKL), alkaline phosphatase (ALP), osteopontin (OPN), vascular endothelial growth factor (VEGF), tartrate-resistant acid phosphatase (TRAP), Type I collagen (COL I) and osteocalcin (OC). The tomography examination [computerized tomography (CT) scan] was conducted just after surgery and at the sacrifice. Results: The histological findings revealed that the perforations contributed to higher bone deposition during the initial stages at the graft-receptor bed interface, accelerating the graft incorporation process. The results of the CT scan showed lower resorption for the perforated group (P≤0.05), and both groups showed high bone density rates at 60 days. This set of evidences is corroborated by the immunohistochemical outcomes indicating that proteins associated with revascularization and osteogenesis (VEGF, OPN, TRAP and ALP) were found in higher levels in the perforated group. Conclusions: These findings indicate that the bone volume of calvarial grafts is better maintained when the receptor bed is perforated, probably resulting from more effective graft revascularization and greater bone deposition. The process of bone resorption peaked between 20 and 60 days post-operatively in both groups although significantly less in the perforated group. © 2009 John Wiley & Sons A/S.

Influence of implant positioning in extraction sockets on osseointegration: Histomorphometric analyses in dogs

Aim: To evaluate the influence of implant positioning into extraction sockets on osseointegration. Material and methods: Implants were installed immediately into extraction sockets in the mandibles of six Labrador dogs. In the control sites, the implants were positioned in the center of the alveolus, while in the test sites, the implants were positioned 0.8 mm deeper and more lingually. After 4 months of healing, the resorptive patterns of the alveolar crest were evaluated histomorphometrically. Results: All implants were integrated in mineralized bone, mainly composed of mature lamellar bone. The alveolar crest underwent resorption at the control as well as at the test sites. After 4 months of healing, at the buccal aspects of the control and test sites, the location of the implant rough/smooth limit to the alveolar crest was 2±0.9 mm and 0.6±0.9 mm, respectively (P<0.05). At the lingual aspect, the bony crest was located 0.4 mm apically and 0.2 mm coronally to the implant rough/smooth limit at the control and test sites, respectively (NS). Conclusions: From a clinical point of view, implants installed into extraction sockets should be positioned approximately 1 mm deeper than the level of the buccal alveolar crest and in a lingual position in relation to the center of the alveolus in order to reduce or eliminate the exposure above the alveolar crest of the endosseous (rough) portion of the implant. © 2009 John Wiley & Sons A/S.

Autogenous bone combined with anorganic bovine bone for maxillary sinus augmentation: Analysis of the osteogenic potential of cells derived from the donor and the grafted sites

Objectives: This study aimed to comparatively evaluate the in vitro osteogenic potential of cells obtained from the mandibular ramus (MR, autogenous bone donor site) and from the maxillary sinus (MS) bone grafted with a mixture of anorganic bovine bone (ABB) and MR prior to titanium implant placement (MS, grafted implant site). Material and methods: Cells were obtained from three patients subjected to MS floor augmentation with a 1: 1 mixture of ABB (GenOx Inorg®) and MR. At the time of the sinus lift procedure and after 8 months, prior to implant placement, bone fragments were taken from MR and MS, respectively, and subjected to trypsin-collagenase digestion for primary cell culturing. Subcultured cells were grown under osteogenic condition for up to 21 days and assayed for proliferation/viability, osteoblast marker mRNA levels, alkaline phosphatase (ALP) activity and calcium content/Alizarin red staining. ALP activity was also determined in primary explant cultures exposed to GenOx Inorg® (1: 1 with MR) for 7 days. Data were compared using either the Mann-Whitney U-test or the Kruskal-Wallis test. Results: MS cultures exhibited a significantly lower osteogenic potential compared with MR cultures, with a progressive increase in cell proliferation together with a decrease in osteoblast markers, reduced ALP activity and calcium content. Exposure of MR-derived primary cultures to GenOx Inorg® inhibited ALP activity. Conclusion: These results suggest that the use of GenOx Inorg® in combination with MR fragments for MS floor augmentation inhibits the osteoblast cell differentiation at the implant site in the long term. © 2013 John Wiley & Sons A/S.

Graft incorporation and implant osseointegration following the use of autologous and fresh-frozen allogeneic block bone grafts for lateral ridge augmentation

Objectives: To compare autogenous bone (AT) and fresh-frozen allogeneic bone (AL) in terms of histomorphometrical graft incorporation and implant osseointegration after grafting for lateral ridge augmentation in humans. Materials and methods: Thirty-four patients were treated with either AL (20 patients) or AT (14 patients) onlay grafts. During implant installation surgery 6 months after grafting, cylindrical biopsies were harvested perpendicularly to the lateral aspect of the augmented alveolar ridge. Additionally, titanium mini-implants were installed in the grafted regions, also perpendicularly to the ridge; these were biopsied during second-stage surgery. Histological/histomorphometric analysis was performed using decalcified and non-decalcified sections. Results: Histological analysis revealed areas of necrotic bone (NcB) occasionally in contact with or completely engulfed by newly formed vital bone (VB) in both AT and AL groups (55.9 ± 27.6 vs. 43.1 ± 20.3, respectively; P = 0.19). Statistically significant larger amounts of VB (27.6 ± 17.5 vs. 8.4 ± 4.9, respectively; P = 0.0002) and less soft connective tissue (ST) (16.4 ± 15.6 vs. 48.4 ± 18.1, respectively; P ≤ 0.0001) were seen for AT compared with AL. No significant differences were observed between the groups regarding both bone-to-implant contact (BIC) and the bone area between implant threads (BA) on the mini-implant biopsies. Conclusion: Allogeneic bone block grafts may be an option in cases where a limited amount of augmentation is needed, and the future implant can be expected confined within the inner aspect of the bone block. However, the clinical impact of the relatively poor graft incorporation on the long-term performance of oral implants placed in AL grafts remains obscure. © 2013 John Wiley & Sons A/S.

Fate of autologous and fresh-frozen allogeneic block bone grafts used for ridge augmentation. A CBCT-based analysis

Objectives: To evaluate dimensional changes in autologous (AT) and fresh-frozen allogeneic (AL) block bone grafts 6 months after alveolar ridge augmentation. Material and methods: Twenty-six partially or totally edentulous patients treated either with fresh-frozen AL bone or AT bone onlay block grafts prior to implant placement (13 patients in each group), were included in this analysis. Patients received CBCT (i-CAT Classic) examinations prior to surgery and 14 days and 6 months after grafting. Differences in alveolar ridge area among the various observation times were evaluated by planimetric measurements on two-dimensional CBCT images of the grafted regions. Nineteen grafted blocks from each group were evaluated. Results: Significant increase in alveolar ridge dimensions, allowing implant placement, was obtained with both types of grafts 6 months after grafting; no significant differences in alveolar ridge area were observed between the groups at the various observation times. However, graft resorption in the AL group was significantly larger compared to that in the AT group at 6 months. Conclusions: Larger bone graft resorption was seen in patients treated with fresh-frozen AL bone than in those treated with AT bone 6 months following alveolar ridge augmentation. © 2011 John Wiley & Sons A/S.

Comparisons between Bio-Oss® and Straumann® Bone Ceramic in immediate and staged implant placement in dogs mandible bone defects

Objective: To compare immediate and staged approach implant placement in circumferential defects treated with deproteinized bovine bone mineral (DBBM); hidroxyapatite/tricalcium phosphate (HA/TP); autogenous bone (Ab); and coagulum (Cg); upon implant stability, osseointegration and alveolar crest maintenance. Materials and methods: Six dogs underwent extractions of lower premolars, bilaterally. Twelve weeks later four bone defects (6 mm wide/4 mm long) were drilled at one side and randomly filled with DBBM; HA/TP; Ab; and Cg, respectively, and left to heal (staged approach). Eight weeks later one implant (Osseospeed™, AstraTech) was placed in experimental sites. At the same session four defects were drilled on contra-lateral side and implants were inserted immediately after biomaterials grafting (immediate approach). Animals were euthanized 8 weeks later. Implant stability was measured by resonance frequency analysis (RFA) at installation and after sacrifice. Ground sections were prepared for bone contact (BIC); bone area (BA); distance implant shoulder-bone crest (IS-C); distance implant shoulder first bone contact (IS-B); and areas occupied by soft tissue. Results: The BA and BIC were superior in the staged approach. The Cg exhibited higher BIC and BA as compared with other materials at the total implant body (P = 0.004 and 0.012, respectively). The DBBM, HA/TP and Ab groups rendered similar BA and BIC. The immediate approach resulted in less crest resorption compared to staged approach. The biomaterials did not affect the IS-C and IS-B measurements. Particles area tended to be higher in DBBM group than HA/TP (P = 0.15), while soft tissue infiltrate was higher in DBBM group when used in the immediate approach (P = 0.04). The RFA indicated gain in stability in the staged approach (P = 0.002). The correlation test between RFA vs. BIC and BA demonstrated inferior stability for DBBM group in immediate approach (P = 0.01). Conclusions: Implants placed in healed defects resulted in better stability as a consequence of higher BIC and BA. The Cg alone rendered increased BIC compared to other materials in both approaches. Immediate approach should be preferable to staged approach in terms of alveolar crest maintenance. The BIC and BA values did not vary between micro and macro-threads in this experimental model. Implants installed in sites filled with DBBM in immediate approach were less stable. © 2011 John Wiley & Sons A/S.

Effect of microthread presence and restoration design (screw versus cemented) in dental implant reliability and failure modes

Objectives: This study evaluated the reliability and failure modes of implants with a microthreaded or smooth design at the crestal region, restored with screwed or cemented crowns. The postulated null hypothesis was that the presence of microthreads in the implant cervical region would not result in different reliability and strength to failure than smooth design, regardless of fixation method, when subjected to step-stress accelerated life-testing (SSALT) in water. Materials and methods: Eighty four dental implants (3.3 × 10 mm) were divided into four groups (n = 21) according to implant macrogeometric design at the crestal region and crown fixation method: Microthreads Screwed (MS); Smooth Screwed (SS); Microthreads Cemented (MC), and Smooth Cemented (SC). The abutments were torqued to the implants and standardized maxillary central incisor metallic crowns were cemented (MC, SC) or screwed (MS, SS) and subjected to SSALT in water. The probability of failure versus cycles (90% two-sided confidence intervals) was calculated and plotted using a power law relationship for damage accumulation. Reliability for a mission of 50,000 cycles at 150 N (90% 2-sided confidence intervals) was calculated. Differences between final failure loads during fatigue for each group were assessed by Kruskal-Wallis along with Benferroni's post hoc tests. Polarized-light and scanning electron microscopes were used for failure analyses. Results: The Beta (β) value (confidence interval range) derived from use level probability Weibull calculation of 1.30 (0.76-2.22), 1.17 (0.70-1.96), 1.12 (0.71-1.76), and 0.52 (0.30-0.89) for groups MC, SC, MS, and SS respectively, indicated that fatigue was an accelerating factor for all groups, except for SS. The calculated reliability was higher for SC (99%) compared to MC (87%). No difference was observed between screwed restorations (MS - 29%, SS - 43%). Failure involved abutment screw fracture for all groups. The cemented groups (MC, SC) presented more abutment and implant fractures. Significantly higher load to fracture values were observed for SC and MC relative to MS and SS (P < 0.001). Conclusion: Since reliability and strength to failure was higher for SC than for MC, our postulated null hypothesis was rejected. © 2012 John Wiley & Sons A/S.

Reliability and failure modes of internal conical dental implant connections

Objective: Biological and mechanical implant-abutment connection complications and failures are still present in clinical practice, frequently compromising oral function. The purpose of this study was to evaluate the reliability and failure modes of anterior single-unit restorations in internal conical interface (ICI) implants using step-stress accelerated life testing (SSALT). Materials and methods: Forty-two ICI implants were distributed in two groups (n = 21 each): group AT-OsseoSpeed™ TX (Astra Tech, Waltham, MA, USA); group SV-Duocon System Line, Morse Taper (Signo Vinces Ltda., Campo Largo, PR, Brazil). The corresponding abutments were screwed to the implants and standardized maxillary central incisor metal crowns were cemented and subjected to SSALT in water. Use-level probability Weibull curves and reliability for a mission of 50,000 cycles at 200 N were calculated. Differences between groups were assessed by Kruskal-Wallis along with Bonferroni's post-hoc tests. Polarized-light and scanning electron microscopes were used for failure analyses. Results: The Beta (β) value derived from use level probability Weibull calculation was 1.62 (1.01-2.58) for group AT and 2.56 (1.76-3.74) for group SV, indicating that fatigue was an accelerating factor for failure of both groups. The reliability for group AT was 0.95 and for group SV was 0.88. Kruskal-Wallis along with Bonferroni's post-hoc tests showed no significant difference between the groups tested (P > 0.27). In all specimens of both groups, the chief failure mode was abutment fracture at the conical joint region and screw fracture at neck's region. Conclusions: Reliability was not different between investigated ICI connections supporting maxillary incisor crowns. Failure modes were similar. © 2012 John Wiley & Sons A/S.