The International Journal of Oral & Maxillofacial Implants, 02/2015

Purpose: Immediate implantation has become one of the therapeutic options for replacement of a hopeless tooth. In the case of a tooth with a periapical lesion, this approach remains controversial. The aims of this article were to systematically review the evidence on immediate implants in sites with periapical lesions with reference to: (1) survival rates, (2) changes in crestal bone levels and marginal tissues, (3) complication rates, and (4) comparison of clinical outcomes with other implant treatments. Materials and Methods: An electronic search was conducted in MEDLINE (PubMed), Cochrane Central Register of Controlled Trials (CENTRAL), and EMBASE for articles published between January 1990 and August 2013. Publications were screened, and data extraction and quality assessment were performed. Implant survival rates were calculated using predicted Kaplan-Meier survival analysis. Crestal bone level changes, soft tissue outcomes, complications, and procedure characteristics were analyzed descriptively. Results: Initially, 301 articles were identified. Three prospective controlled trials of immediate implant placement in sites with periapical lesions with a follow-up period of at least 1 year were selected for the survival analysis. The predicted cumulative 5-year survival rate of immediate implants in sites with periapical lesions was 96.23%. Bone and gingival level changes were comparable to those of implants placed in sites without periapical pathology. The complication rates, reported in only one study, were 15.4% (2/13) in sites with periapical lesions and 6.7% (1/15) in healthy sites. Conclusion: Limited evidence suggests that immediate implant placement in sites with periapical lesions leads to clinical outcomes comparable to those of immediate implants in healthy sites. Additional prospective controlled trials with large sample sizes and long-term follow-up are needed to further investigate these results. Keywords: dental implants, evidence-based dentistry, oral pathology

Purpose: The aim of this study was to evaluate the effect of collagenated heterologous bone graft (CHBG) and Ankaferd Blood Stopper (ABS), a plant extract, on bone healing after sinus floor augmentation. Materials and Methods: Thirty-six New Zealand rabbits were used. Bilateral sinus augmentation was performed, and 72 bone defects were created. The maxillary sinuses were grafted with four different biomaterials: blood clot (control group), CHBG (Apatos Mix, OsteoBiol, Tecnoss) (graft group), ABS (ABS group), and ABS + CHBG (ABS+graft group). The rabbits were sacrificed at 1, 4, and 8 weeks after surgery. Histochemical and immunohistochemical examinations were performed on all samples. Staining with hematoxylin-eosin and Masson trichrome was performed, and bone marker activity was evaluated. Results: Lymphocyte infiltration was high at the first week in all groups and decreased from 1 to 8 weeks. All materials were biocompatible. Osteoclast numbers increased in the control group from 1 to 8 weeks and decreased in the other groups. There was no new bone formation in week 1 in all groups. New bone formation increased in all groups from 1 to 8 weeks, and at the fourth week, new bone formation was greater in the ABS and ABS+graft groups than in the other groups. There were osteoclasts around the bone graft materials, but degeneration of the graft was seen only in the ABS+graft group at week 8. Conclusion: ABS accelerates bone healing in sinus augmentation procedures and can be used alone or with CHBG. CHBG has osteoconductive properties, and ABS can accelerate bone graft degeneration. Keywords: Ankaferd Blood Stopper, bone healing, collagenated heterologous bone graft, sinus augmentation, tartrate-resistant acid phosphatase

Purpose: This study was performed to determine the accuracy of measurements of bone mineral density (BMD) and cortical bone thickness (CBT) at miniscrew implantation sites in small animals and to verify the usefulness of in vivo microcomputed tomography (micro-CT). Materials and Methods: Rat femurs were scanned before and after placing miniscrews using in vivo micro-CT. The images were superimposed using a subtraction method with bone volume measurement software. At each screw site, the total BMD was calculated as the average BMD of a cylinder 1.6 mm in diameter and 2.0 mm in depth, while the cortical BMD was the average BMD of a cylinder 1.6 mm in diameter and 1.0 mm in depth. CBT was measured three times on transaxial images of the rat femurs, and the average value was used. All miniscrews were placed using the maximum torque, verified with a digital torque tester. To verify the usefulness and accuracy of in vivo micro-CT, CBT on micro-CT images was compared with that measured on histologic sections. Results: Significant correlations were observed between placement torque and cortical BMD (R = 0.572), total BMD (R = 0.732), and CBT (R = 0.788). There was a significant correlation between CBT measured via field-emission scanning electron microscopy images and CBT measured with in vivo micro-CT (R = 0.974). Conclusions: The BMD over a narrow range can be measured accurately in small animals with high reproducibility of the trabecular structure using a combination of high-resolution in vivo micro-CT and image superimposition using a threedimensional subtraction method. Keywords: bone mineral density, microcomputed tomography, miniscrew, orthodontic anchorage

Purpose: The reliability of oral rehabilitation by four zygomatic implants with no anterior support remains to be determined. The aim of this systematic review was to assess the predictability of this approach in regard to implant survival, technical and biologic complications, and quality of life. Materials and Methods: An electronic literature search was conducted from September 2000 to November 2013. Human clinical trials in which oral rehabilitation was achieved by the use of four zygomatic implants with no additional placement of standard implants were included. The primary outcome was the survival rate of the zygomatic implants. In addition, random effects meta-analyses of the selected studies were applied to avoid potential bias caused by methodologic differences among studies. Results: Zygomatic implant survival rate weighted mean (WM) was 96.7% (range, 95.8% to 99.9%), with a 95% confidence interval (CI) of 92.5% to 98.5%. Only a limited number of surgical complications were reported, with orbital perforation the most significant. Similar results were obtained for prosthetic complications (few occurrences). Additionally, patient satisfaction levels were shown to be high, approaching that of the general population. Conclusion: Data from the present systematic review suggest that maxillary rehabilitation by four zygomatic implants with no anterior support is a reliable approach. Keywords: Zygomatic implant, dental implant, endosseous implant, oral rehabilitation, evidence-based dentistry

Purpose: The aim of this study was to evaluate the capability of chemicals to decontaminate Escherichia coli (E coli) or Porphyromonas gingivalis (P gingivalis) from sandblasted acid-etched (SAE) titanium dental implants. Materials and Methods: SAE titanium dental implants were contaminated with E coli or P gingivalis and incubated in a sterile bacterial culture media under aerobic and anaerobic conditions, respectively. The implants were treated with 10 different conditions: calcium hydroxide [Ca(OH)2] paste for 1 minute and saline irrigation for 1 minute; Ca(OH)2 paste for 1 minute and 0.2% chlorhexidine digluconate (CHXD) irrigation for 1 minute; 0.2% CHXD for 1 minute; Dakin's solution for 1 minute; tetracycline hydrochloride (T-HCl) as a 1 g per 20 mL solution for 1, 2, and 3 minutes; and T-HCl paste for 1, 2, and 3 minutes. All implants were irrigated with 1 mL of saline solution and incubated under aerobic and anerobic conditions for 24 hours or 48 hours for E coli- and P gingivalis-contaminated implants, respectively. The control group was submitted to all procedures except for the chemical treatments. Aliquots were removed, and turbidity was measured by spectrophotometry. The level of bacterial growth in control cultures was considered to have a decontamination percentage (DC%) of 0. Results: Spectrophotometric analysis showed that all chemical treatments resulted in significantly higher DC% compared to controls for SAE implants contaminated with E coli (P .05) or P gingivalis (P .05). For the P gingivalis experiments, SAE implants treated with Ca(OH)2 paste and saline solution had a lower DC% (39.3%) than those in the other treatment groups. In the E coli experiments, DC% was significantly lower for SAE implants treated with Ca(HO)2 paste and saline solution (48.7%), Dakin's solution (92.7%), or T-HCl paste for 1 minute (96.6%) than those in the other groups. Conclusion: The DC% of SAE implants contaminated with E coli or P gingivalis by means of chemicals commonly used in dentistry is high, with the exception of Ca(OH)2 paste burnished for 1 minute and then irrigated with saline solution for 1 minute. Keywords: calcium hydroxide, Dakin's solution, dental implants, Porphyromonas gingivalis, sandblasted acid-etched, tetracycline hydrochloride

Purpose: The aim of this study was to demonstrate the potential of microcomputed tomography (micro- CT) technology in the assessment of retrieved dental implants. Cases are presented to illustrate the value of micro-CT imaging techniques in determining possible mechanical causes for dental implant failures. Materials and Methods: Eight retrieved dental implants were randomly selected from a pool and imaged using a micro-CT device. Source voltages (80 to 100 kV) and source-to-detector distances (65 to 70 mm) were based on signal quality requirements with an additional criterion of achieving the highest resolution with the sample entirely in the field of view in the projection plane. One additional sample was chosen for histology and tomographic imaging so that the information contained therein could be compared. Results: The micro-CT images displayed high contrast between the implant, bone, and background, with negligible metal artifacts. The micro-CT technology used in this study delivered excellent images of the retrieved implants. As a result of the quality and resolution (pixel size: 5.52 to 6.15 μm) of the images, surface morphology as well as internal structures of the retrieved implants could be observed in great detail. The majority of the retrieved implants had increased wear, dents, pits, regular shallow scratches, and deep scratches in the implant-toabutment engagement area. Furthermore, plastic deformations, microcracks, and brittle implant fractures were observed in two implants. Conclusion: The mechanical competence of dental implant components plays a major role in the success of implant treatment. When failures do occur, a nondestructive three-dimensional assessment of such failed implants and their components is helpful in understanding the underlying factors. Micro-CT was found to be a useful tool for the morphologic assessment of retrieved dental implants. Keywords: dental implants, mechanical damage, microcomputed tomography, nondestructive imaging, retrieved implants

Purpose: The aim of this study was to determine, before implant placement, the outcome of ridge preservation surgery after extractions of one or more adjacent teeth on the dimensions of the edentulous ridge. Materials and Methods: Nineteen extraction sites in four dogs were randomly divided into three groups: group 1 = single premolars (n = 7 sites); group 2 = two adjacent premolars (n = 6 sites); group 3 = three adjacent premolars (n = 6 sites). Extraction was followed by ridge preservation surgery using a combination of xenograft and collagen membrane after full-thickness flap reflection. All animals were sacrificed 4 months later, and each extraction site was sectioned in the sagittal plane so that alveolar bone measurements could be made in both the buccolingual and apicocoronal directions using microcomputed tomography. Results: Mean buccolingual width of the ridges postsurgery was 4.80 ± 2.78 mm, 4.98 ± 2.65 mm, and 4.79 ± 2.79 mm in groups 1, 2, and 3, respectively. The mean vertical distance from the cementoenamel junction to the crest of the ridge was 1.94 ± 0.42 mm, 2.05 ± 0.48 mm, and 2.60 ± 0.67 mm in groups 1, 2, and 3, respectively. No statistically significant difference was seen between single and multiple extraction sites. Conclusion: Ridge preservation surgery results in a similar pattern of bone remodeling in the horizontal and vertical dimensions of the edentulous ridge after single and multiple adjacent tooth extractions. Keywords: ridge dimensions, ridge preservation surgery, tooth extractions

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 (β 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. Keywords: computer-aided design/computer-assisted manufacture, fiber-reinforced composite, fixed dental prostheses, fatigue, Weibull

Purpose: Digital developments have led to the opportunity to compose simulated patient models based on three-dimensional (3D) skeletal, facial, and dental imaging. The aim of this systematic review is to provide an update on the current knowledge, to report on the technical progress in the field of 3D virtual patient science, and to identify further research needs to accomplish clinical translation. Materials and Methods: Searches were performed electronically (MEDLINE and OVID) and manually up to March 2014 for studies of 3D fusion imaging to create a virtual dental patient. Inclusion criteria were limited to human studies reporting on the technical protocol for superimposition of at least two different 3D data sets and medical field of interest. Results: Of the 403 titles originally retrieved, 51 abstracts and, subsequently, 21 full texts were selected for review. Of the 21 full texts, 18 studies were included in the systematic review. Most of the investigations were designed as feasibility studies. Three different types of 3D data were identified for simulation: facial skeleton, extraoral soft tissue, and dentition. A total of 112 patients were investigated in the development of 3D virtual models. Conclusion: Superimposition of data on the facial skeleton, soft tissue, and/or dentition is a feasible technique to create a virtual patient under static conditions. Three-dimensional image fusion is of interest and importance in all fields of dental medicine. Future research should focus on the real-time replication of a human head, including dynamic movements, capturing data in a single step. Keywords: computer-assisted image processing, digital dental medicine, image fusion, patient simulation, superimposition

Purpose: To evaluate the efficacy of various types of lasers (neodymium-doped yttrium-aluminum-garnet [Nd:YAG], carbon dioxide [CO2], diode, erbium/chromium-doped yttrium-scandium-gallium-garnet [Er,Cr:YSGG], and erbium-doped yttrium-aluminum-garnet [Er:YAG]) in the treatment of peri-implantitis and their use in surgical and nonsurgical procedures. Materials and Methods: Human studies for the treatment of peri-implantitis with laser therapy, published between 2002 and January 2014, were collected utilizing the electronic databases PubMed, Ovid, MEDLINE, Cochrane, and Google Scholar. Two reviewers conducted the study selection, data collection, and validity assessment. Results: Eight hundred twelve studies were selected in the initial title search; 13 studies were then chosen for this review. No human studies evaluated the effect of the Nd:YAG laser on peri-implantitis. The CO2 laser is reported to be safe and able to enhance bone regeneration. The diode laser (980 nm) seems to be effective in its bactericidal effect without changing the implant surface pattern. The Er,Cr:YSGG laser was reported to obtain bone regeneration around a failing implant in one case, while the Er:YAG laser exhibits a strong bactericidal effect against periodontopathic bacteria at a low energy level. Conclusion: Although lasers have shown promising results in reducing clinical signs of peri-implantitis, because of the limited sample sizes and short follow-up periods, no firm conclusion can be drawn at this moment. Hence, there is a need for more well-designed, longitudinal, randomized controlled clinical trials. Keywords: carbon dioxide laser, diode laser, erbium/chromium-doped yttrium-scandium-gallium-garnet laser, erbium-doped yttrium-aluminum-garnet laser, neodymium-doped yttrium-aluminum-garnet laser, peri-implantitis

Purpose: The implant-abutment connection area is known to be the weakest part of an internal-connection zirconia abutment and therefore the most likely to fracture. The aim of this study was to evaluate the complementary effect of a titanium insert on the fracture strength of a zirconia abutment. Materials and Methods: Three types of abutments with internal connection structures were selected and assembled: titanium abutment-titanium abutment screw (Ti-Ti), zirconia abutment-titanium abutment screw (Zr-Ti), and zirconia abutment-titanium insert-titanium abutment screw (Zr+Ti-Ti). Fifteen abutments and 15 implants were used and divided into three groups of five specimens each. Compressive loading was applied to the specimens at 30 degrees off-axis with dislocation speed of 1 mm/min and was increased until deformation occurred. Results: The Ti-Ti specimens showed the highest maximum fracture load, followed by the Zr+Ti-Ti specimens; the Zr-Ti assemblies were the weakest. Significant differences in fracture strength were found between the groups. All of the investigated Zr abutments fractured. However, in the Zr+Ti-Ti specimens, 60% of the Ti abutment screws fractured and 40% bent, whereas all of the abutment screws in the Zr-Ti group were only bent. Conclusion: The Ti insert, as a substitute for the weakest part of a Zr abutment in an implant with an internal friction connection, can reinforce the fracture strength of a Zr abutment. Keywords: dental implant abutment, fracture strength, internal connection, titanium insert, zirconia

Purpose: The purpose of this study was to compare bone temperature changes during implant drilling with two drill designs employed in three different drilling sequences. Materials and Methods: Two implant drill designs and three drilling sequences were evaluated in vitro using artificial bone cylinders. The evaluated drills were different only in the cutting-surface length (control, 16 mm; test, 4 mm). Three drilling sequences (control A, test B1, and test B2) were evaluated with and without irrigation. Temperatures were measured with thermocouple technology. The temperature changes generated by the final drill of each sequence were recorded as the experimental results and were subjected to the Student t test. Results: There were statistically significant differences in temperature changes when comparing the control group A with the test groups B1 (P = .001) and B2 (P = .01) during drilling without coolant. The mean temperature changes were 12.4°C, 6.5°C, and 13.7°C for groups A, B1, and B2, respectively. The Student t test showed statistically significant differences between temperature changes of the control group A and the test groups B1 (P .01) and B2 (P .05) during drilling with coolant. The mean temperature changes were 0.9°C, 0.7°C, and 1.9°C for groups A, B1, and B2, respectively. Conclusion: Reduction in length of the cutting surface of the drill may limit frictional heat. Drills with the same length of cutting surface may induce lower bone temperature changes, when considering a preliminary drilling step with a pilot drill. Keywords: bone, dental implant, drill sequence, heat induction, implant drill, temperature changes

Purpose: This retrospective study was set to explore the influence of local bone density (BD) on implant cumulative survival rates (ICSRs) and to assess prognostic factors associated with implant failure at sites with different BD. Materials and Methods: Between January 2005 and December 2011, 2,684 implants were placed in 1,377 patients and included in the study. Implants at sites with different BD were divided into four groups (G1 to G4) according to the Lekholm and Zarb classification, corresponding to bone types 1 to 4. ICSRs and the reasons for failure in each group were evaluated. Factors related to the local distribution of BD were also analyzed. A number of predictive variables were examined by univariate and multivariate analyses to evaluate prognostic factors and their influence on implant failure rates. Results: In total, 45 implants were lost, resulting in ICSRs for G1 to G4 of 100%, 98.18%, 96.83%, and 92.25%, respectively. The main reasons for failure in each group were failed osseointegration and occlusal overloading. Low BD was associated with advanced age (> 50 years) and the posterior maxilla. Based on multivariate analysis, diabetes mellitus and nonthreaded implants were significant factors in the high-BD group (G2), while advanced age, smoking, nonthreaded implants, and immediate loading were risk factors for the low-BD group (G3 and G4). Conclusion: BD is one of the most important factors influencing the long-term ICSR, which decreases with decreasing BD values. Accurate risk evaluation for sites with different BD before implantation will be beneficial to implant survival. Keywords: bone density, dental implants, implant cumulative survival rate, prognostic factors

Purpose: One of the major factors governing implant success is the quantity and density of the host bone. The aim of this work was to determine whether mandibular bone texture and cortical width measurements on plain radiographs could be associated with implant failure and/or marginal bone loss. Materials and Methods: A statistical model was built to predict implant failure; it incorporated several radiographic features of cortical and cancellous bone texture, cortical width, and patient smoking habits. Cortical width measurements and texture measurements of cortical and cancellous bone were made on the panoramic radiographs of 460 subjects. These were used to predict implant failure and marginal bone loss after 5 years. Receiver operating characteristic (ROC) curve analysis and area under the curve (AUC) were used to determine the diagnostic accuracy of the variables in predicting implant failure and marginal bone loss. Additionally, for 91 of 460 subjects with periapical radiographs, marginal bone levels around implants were measured over a 5-year period. Results: Of the 460 patients assessed for implant failure, 29 had failed implants (93.7% success rate). The ROC curve built from this model had a sensitivity of 62.1% and specificity of 67.5%. The AUC from the model was 0.690 (95% confidence interval [CI] 0.597 to 0.783). A model was also built to predict marginal bone loss. The ROC curve had 78.6% sensitivity and 74.6% specificity (AUC = 0.880, 95% CI = 0.810 to 0.953). Mandibular cortical width was not a significant predictor of either implant failure or bone loss. Conclusion: In a retrospective analysis 5 years after implant placement, features of cancellous and cortical bone of the mandible were significant in predicting implant failure and marginal bone loss in a sample of 460 patients. Keywords: bone density, bone loss, cancellous bone, cortical bone, dental implants, failure, mandible

Purpose: Few reports have evaluated cumulative survival rates of implants placed in the pterygoid region in the medium term. The objective of this study was to evaluate success rates of pterygoid implants and prostheses in patients treated in the atrophic posterior maxilla. Materials and Methods: A retrospective study was performed of patients with an atrophic posterior maxilla rehabilitated with pterygoid implants between 1999 and 2010 and followed for at least 36 months after implant loading. Two outcome variables were considered: implant success and prosthesis success. The following predictor variables were recorded: sex, age, implant placement angulation, number and size of implants, prosthetic rehabilitation, bone loss, date of prosthesis delivery, and date of last follow-up. A statistical model was used to estimate the survival rates and associated confidence intervals. Data were analyzed using the Kaplan-Meier method and log-rank test to compare survival curves. Results: A total of 238 titanium implants (172 anterior and 66 pterygoid) were placed in 56 patients. The 3-year overall pterygoid implant survival rate was 99%. The 3-year overall prosthesis survival rate was 97.7%. The mean bone loss around pterygoid implants after 3 years of loading was 1.21 mm (range, 0.31 to 1.75). All patients were wearing the prostheses at the most recent follow-up examination. Conclusion: Placement of implants in the pterygoid region is a viable alternative treatment modality for rehabilitation of patients with an atrophic posterior maxilla. Keywords: atrophic maxilla, pterygoid, pterygoid implants, pterygomaxillary implants

Purpose: Control over marginal bone loss (MBL) and its progression is critical for preserving peri-implant tissue health. A moderate MBL over the first year has conventionally been associated with clinical success. However, different implants are associated with distinct amounts of MBL during their first functional year. Therefore, this study evaluated the MBL in pristine maxillary bone around implants with different types of implant-abutment connections and sought to determine the effect of other clinical factors on this tissue response. Materials and Methods: Two hundred forty-six implants were placed in 101 patients with a mean age of 54.43 years. The MBL around two different types of implants (internal versus external prosthetic connection) was evaluated at 6 and 18 months after loading. Different variables were recorded to analyze their influence on radiographic parameters using a complex samples general linear model. Results: At 18 months, MBL ranged from 0 to 3.56 mm; less than 1 mm was lost around 46.3% (mesial) and 40.2% (distal) of the implants, while no bone was lost around 19.5% (mesial) and 19.9% (distal). The MBL was significantly higher around external than internal connections (0.714 vs 0.516 mm/year, respectively). Age, smoking habit, and connection type were directly related to mesial and distal MBL at 6 and 18 months postloading. Conclusion: Implant design is a key factor in peri-implant MBL. Age and smoking also play major roles in maintaining the stability of peri-implant bone. Keywords: dental implant, dental implant design, dental prosthesis, implant-abutment connection, implant-abutment interface, marginal bone

Purpose: This study evaluated the effects of different implant-based prostheses on swallowing threshold, dietary intake, and oral health-related quality of life (OHRQoL). Materials and Methods: This prospective paired controlled clinical trial followed partially edentulous subjects, who sequentially used implant-supported removable partial dentures and implant-supported fixed partial dentures (IFPDs). Swallowing threshold was assessed by counting the masticatory cycles and median particle size (X50) calculation. Nutritional intake was verified by a 3-day food record. OHRQoL was measured with the Oral Health Impact Profile (OHIP-49). Data were evaluated with repeated-measures analysis of variance. Results: Twelve subjects (mean age 62.6 ± 7.8 years; range, 55 to 87) took part in the study. IFPD treatment significantly reduced X50 values and the number of chewing cycles. Higher intake of fiber, calcium, and iron and lower consumption of cholesterolrich food were observed after IFPD use. OHIP summary score and OHIP physical pain domain were lower with the IFPD. Conclusion: IFPD use leads to more efficient mastication and improves dietary intake and OHRQoL. This information will guide dentists to better clinical management of partially edentulous patients. Keywords: dental implants, nutrition status, partial edentulism, quality of life

Purpose: The purpose of this study was to assess the influence of momentary retention forces on patient satisfaction and quality of life of two-implant-retained mandibular overdenture wearers. Materials and Methods: Edentulous patients who had been rehabilitated with two-implant-supported mandibular overdentures with single attachments and maxillary complete dentures at a university clinic were included in this study. The overdenture attachments were either ball or locator attachments. All the patients completed the Turkish version of the Oral Health Impact Profile-14 (OHIP-14) and the visual analog scale (VAS) satisfaction questionnaires. Momentary retention forces of the overdentures were measured using a custom-made dynamic testing machine. Results: Fifty-five patients were included in this study. No statistically significant association was detected between momentary retention forces and VAS scores (P > .05), but higher retention forces presented significantly better quality of life scores in the social disability and handicap domains of OHIP- 14 (P .05). Conclusion: Within the limitations of this clinical study, it may be presumed that although higher instant retention force of an implant-retained overdenture provides better quality of life, it does not affect patient satisfaction. Keywords: interforaminal implants, mandibular overdenture, momentary retention forces, patient satisfaction, quality of life

Purpose: The objectives of this case series are to describe a novel clinical approach to treat completely edentulous patients and determine its viability. Computer-guided implant planning was used to create a screwretained surgical template (ST) supported by transitional implants and a fixed screw-retained provisional prosthesis supported by the transitional implants at the time of definitive implant placement. Materials and Methods: Five patients with at least one edentulous arch were treated. After the diagnostic tooth setup was performed, a duplicate with radiopaque acrylic resin was fabricated to serve as a surgical template (ST) for the placement of screw-form transitional implants and a radiographic guide (RG). Four transitional implants were strategically placed through the guide where they would not interfere with the future definitive implants. The transitional implants were used to support the RG during computed tomographic scanning. Subsequently, the RG was converted into a second ST based on three-dimensional virtual planning. Eight implants were placed by the computer-guided system, and an immediate prefabricated fixed provisional was connected to the transitional implants. Results: All the implants included in the study achieved primary stability and osseointegrated successfully. For 4 months, the transitional implants served successfully as abutments for the provisional prosthesis. Conclusion: This innovative clinical approach overcomes the limitations of a mucosa/ bone-supported ST by offering fixed, reproducible support for the RG and ST by means of transitional implants. The delivery of a prefabricated screw-retained provisional on transitional implants allows for passive healing and minimum chairside adjustments. Keywords: computer-guided surgery, dental implants, full-arch implant rehabilitation, full-arch fixed provisionalization, transitional implant

Purpose: The management of occlusal forces on implant restorations may influence their long-term prosthetic success. The purpose of this randomized controlled trial was to compare marginal bone level changes around adjacent splinted and nonsplinted implants, functionally loaded with cemented restorations, up to 10 years in maxillae. Materials and Methods: During 2002 and 2003, all patients who received three adjacent implants in a private office and a university setting were included in this study. All implants featured an external-hexagon design and were placed in the posterior maxilla. Implants in the left maxilla were randomly selected to be restored with splinted cemented restorations; maxillary right implants were restored with nonsplinted cemented restorations. Marginal bone resorption was measured with intraoral radiographs yearly over a period of at least 10 years after placement of abutments and restorations. The amount of bone loss in each group was analyzed with the two-sample Wilcoxon rank-sum (Mann-Whitney) test because variable bone loss was normally distributed at the fifth year only. Results: One hundred thirty-two implants were placed in 44 patients. Three implants failed at stage-two surgery. Five years after initial loading, two patients moved away and were lost to follow-up (6 implants in total); three additional patients did not complete the study (9 implants in total). Of the remaining 114 implants, 60 left implants were restored with splinted cemented restorations and 54 right implants were restored with nonsplinted cemented restorations. At 10 years, the splinted group showed a mean of 1.2 mm (interquartile range: 0.2 mm) of bone loss; the nonsplinted group showed 1.3 mm (interquartile range: 0.2 mm). Conclusion: A significant difference in bone loss was seen between the two groups. However, the difference of 0.1 mm was not considered clinically meaningful. Keywords: bone level change, dental implants, implant-supported partial prostheses, multiple nonsplinted implants, multiple splinted implants

Purpose: The aim of this in vitro study was to evaluate the stress pattern on the abutments in two different full-arch implant-supported clinically equivalent prosthetic rehabilitations. Materials and Methods: Two steel master casts were created and titanium implants were inserted in two different configurations. One configuration used four implants, with the distal implants tilted 30 degrees (4IMP configuration), and the other used five axially inclined implants (5IMP configuration). A straight multiunit abutment (MUA) was connected to every axial implant and a 30-degree angulated MUA was connected to each tilted implant. One titanium framework was fabricated for each configuration, with a 5-mm (4IMP configuration) or a 15-mm (5IMP configuration) distal cantilever length. Six cycles of vertical loading between 20 and 200 N were applied unilaterally at the most distal point of the frameworks on both sides. Readings of the deformations at the abutment level were obtained with the use of linear strain gauges. Results: A similar pattern of deformation was seen in both configurations. The greatest compressive stress was measured by the strain gauge on the abutment closest to load application and was similar for the 4IMP and 5IMP configurations. The tensile stress measured on the same abutment was higher in the 5IMP configuration than in the 4IMP configuration. In terms of the distribution of stresses, the deformation measured on the central abutment in the 5IMP configuration was less than 10% of the overall stress in all the tested conditions. Conclusion: There was no difference in strain between the two different designs, so the use of tilted implants with angulated abutments to reduce cantilever length could be considered a viable clinical option. Keywords: dental implants, dental materials, dental prosthesis design, implant abutment, stress analysis

Purpose: To compare immediate and conventional loading protocols for fixed full-arch mandibular prostheses supported by immediate and nonimmediate implants. Materials and Methods: A prospective controlled nonrandomized study with 12 months of follow-up included patients requiring fixed full-arch rehabilitations supported by immediate and nonimmediate implants. Eighteen patients were treated with conventional loading (control group), and 18 were treated with immediate loading (test group). Each patient received four to six implants; implants with insertion torque 35 Ncm were excluded from the study and loaded conventionally. The following variables were assessed: implant success, biologic and prosthetic complications, success of the immediately loaded provisional prostheses, and marginal bone loss. Statistical analysis was performed with nonparametric tests (chi-square, Mann-Whitney, Kruskal-Wallis) with an alpha value of .05. Results: Thirtysix patients consecutively enrolled in the study. Two control group patients failing to attend control visits and 12 implants that did not achieve an insertion torque of 35 Ncm were excluded. The final sample consisted of 34 patients and 183 implants (98 test and 85 control implants). Implant success rates were 99.0% (test) and 97.6% (control). Within the test group, success rates for immediate and nonimmediate implants were 100% and 97.6%, respectively. Differences were not statistically significant. All immediately loaded prostheses were successful. Five provisional fixed prostheses presented with loosened screws; all control group patients reported discomfort with the provisional denture. Average bone loss was 0.71 mm (standard deviation 0.25 mm) in the test group and 0.60 mm (standard deviation 0.28 mm) in the control group. Conclusion: No significant differences were seen in implant success and peri-implant marginal bone loss between immediate and conventional loading of mandibular fixed full-arch prostheses supported by immediate and nonimmediate implants. Biologic and prosthetic complications were rare, and all immediately loaded provisional fixed prostheses performed successfully. Keywords: controlled clinical trial, full-arch prosthesis, immediate loading, immediate implants, loading protocols

Purpose: The aim of the study was to examine the influence of a short drilling protocol on peri-implant crestal bone levels. Materials and Methods: Forty implants were placed in the posterior mandibles of 20 patients. The implants (diameter, 4.2 mm; length, 10 to 11.5 mm) were inserted in pairs: one implant was inserted using the standard drilling protocol (five drills in sequence), while the other was inserted using the short drilling protocol sequence (three drills). All implants received healing abutments and were restored with single-unit restorations after 3 months of healing. Analysis of crestal bone level was based on radiographs taken at insertion and at 3, 6, and 12 months after insertion. The results were analyzed using software Image J 1.46r (National Institutes of Health). Crestal bone level was measured in millimeters at the distal aspect of each implant. Results: None of the implants in either group was lost during the 12-month followup period, and all patients completed the follow-up examination. The drilling time for the insertion of one implant with the short drilling protocol was 1.03 ± 3.63 minutes compared to 1.57 ± 2.88 minutes for the standard protocol. The mean values of crestal bone loss at 12 months were 0.94 ± 0.43 mm for implants placed using the standard protocol and 0.90 ± 0.33 mm for implants placed using the short drilling protocol. No statistically significant differences were noted. Conclusion: Using the short drilling protocol reduced the surgery time by approximately 50% and did not affect crestal bone remodeling during the first year postinsertion. Keywords: bone remodeling, conical connection, final single-use drill, short drilling protocol, peri-implant bone level

Purpose: The aim of this study was to evaluate the behavior of a demineralized bone matrix membrane and a polytetrafluoroethylene (PTFE) membrane in the process of bone repair of surgical defects filled with autogenous bone in rats. Materials and Methods: Sixty rats weighing approximately 250 g each were selected and separated into three groups: control group without membrane, demineralized bone matrix membrane group, and PTFE membrane group. Bilaterally, surgical defects of 2 mm in diameter were prepared in the tibiae. The defect in the left tibia was filled with particulate autogenous bone collected during the creation of the two defects and was left uncovered (control) or was covered with the membranes investigated by the present study. At 10 or 60 days postoperatively, the rats were euthanized and the left tibiae were submitted to routine laboratory processing for histomorphometric analysis. All groups were evaluated separately on the 10th and 60th days after surgery. The Kruskal-Wallis test was used for group comparison. Results: The membrane-treated defects showed a delay in healing. Sites treated with demineralized bone matrix membrane showed, as early as day 10, more newly formed bone and slow replacement until day 60. At day 60, the sites covered with demineralized bone matrix membrane and with synthetic membrane showed statistically significant results. Conclusion: The demineralized bone matrix membrane proved to be biocompatible. In terms of newly formed bone area, both membranes showed similar performance. Keywords: autologous transplantation, guided tissue regeneration, homologous transplantation

Purpose: The objectives of this study were to evaluate: (1) the clinical outcome of fresh frozen human allogeneic bone grafts (FFB) used for the reconstruction of severely atrophied edentulous ridges; (2) the survival rate of implants placed in the reconstructed areas; and (3) bone resorption. Materials and Methods: During a 2-year period, 19 patients with severely atrophied partially or totally edentulous ridges who were candidates for an implant-supported prosthesis were consecutively enrolled and reconstructed with FFB iliac blocks. Five to 7 months later, 117 implants were placed in the reconstructed areas, and prosthetic rehabilitation was started 5 to 6 months afterward. Results: The mean follow-up of patients after prosthetic loading was 27 months (range, 20 to 32 months). Prior to implant placement, graft exposure with partial or total loss of the graft occurred in four patients. After implant placement, bone graft exposures with partial loss of the grafts occurred in nine patients; in two patients, both grafts and implants were removed. The cumulative survival rate of implants was 90.2%. The mean (± standard deviation) graft resorption before implant placement was 0.98 ± 0.77 mm (range, 0 to 4 mm), while these values were 1.21 ± 1.05 mm (range, 0 to 6 mm) at loading, 1.55 ± 1.57 mm (range, 0 to 8 mm) at 12 months, and 1.93 ± 1.38 mm (range, 1 to 9 mm) at 24 months. Conclusion: Within the limits of this study (limited sample of patients and short follow-up), the reconstruction of severely atrophic edentulous ridges with FFB is associated with a relevant incidence of bone exposures and partial or total loss of the grafts, which may compromise the long-term survival of implants placed in the reconstructed areas. Keywords: allogeneic grafts, atrophy, bone graft, dental implant, fresh frozen allogeneic bone, reconstruction

Purpose: The aim of this study was to compare the promotion of osteogenesis in vitro on three types of titanium surfaces: a strontium-hydroxyapatite (Sr-HA)-coated surface, a nano-HA-coated surface, and an uncoated roughened surface. Materials and Methods: Sr-HA and HA were placed on disks with a roughened titanium surface by electrochemical deposition. MC3T3-E1 preosteoblast cells and rat bone mesenchymal stem cells were cultured on the Sr-HA, HA-coated, and uncoated roughened disks, and cell adhesion, proliferation, viability, osteogenic differentiation, and formation of mineralized nodules were measured at various time points. Results: The Sr-HA coating produced by a simple electrochemical deposition treatment evidently enhanced the attachment, spreading, alkaline phosphatase activity, and extracellular matrix calcium mineralization of mouse bone mesenchymal stem cells and MC3T3-E1 cells compared with an untreated roughened titanium surface and a nano-HA-coated surface. Conclusion: This study suggests that a Sr-doped nano-HA coating produced through electrochemical deposition improves the osteoconductivity of a microrough titanium surface. Keywords: dental implants, electrochemical deposition, osseointegration, strontium hydroxyapatite, titanium

The aim of this study is to compare magnetic resonance imaging (MRI) with computed tomography (CT) for visualization of an orbital alloplastic prosthesis made of ultra-high-molecular-weight polyethylene (UHMW-PE) both in vitro and in vivo. A study of 15 test implants from UHMW-PE visualized in vitro in CT and MRI and an in vivo visualization in a patient who suffered from orbital injury and underwent reconstructive surgery is presented. The postsurgery MRI showed the UHMW-PE material clearly, with no significant artifacts. The surrounding tissues could be satisfactorily evaluated. The CT scans did not present the graft material. Both techniques were sufficient tools for in vitro evaluation of the shape and measurement of the prosthesis. Keywords: alloplastic prosthesis, computed tomography, magnetic resonance imaging, orbital injury, ultra-high-molecular-weight polyethylene