Clinical evaluation of the agreement between virtual and clinical occlusal registrations: A comparative clinical study.

STATEMENT OF PROBLEM: The accuracy of virtual interocclusal records has been evaluated, but clinical studies comparing the clinical output to the virtual design are lacking. PURPOSE: The purpose of this clinical study was to evaluate the agreement between the virtual occlusal scheme designed by a computer-aided design and computer-aided manufacturing software program and the occlusal scheme obtained clinically on the definitive prosthesis assessed with articulating paper. MATERIAL AND METHODS: The virtual occlusal scheme design of 20 single monolithic crowns and their adjacent teeth was obtained by using an intraoral scanning system in 17 participants. These registrations were compared with conventional occlusal records obtained by applying articulating paper in 2 stages: first with 200-µm blue film and the second with 12-µm metallic red articulation tape. The analysis included both the quantity and the quality of the contacts of the conventional occlusal records referred to as the standard method. For accuracy analysis, virtual record sensitivity was calculated per crown as the percentage of true positive virtual contacts of the actual contacts identified by articulating paper. Specificity was also calculated as the percentage of true negative virtual contacts of the actual sites of clearance. RESULTS: The virtual record sensitivity was 98.5 (95% confidence interval [CI] 96-100) for the crowns and 95 (95% CI 85-100) for the adjacent teeth. The virtual record specificity was 88.6 (95% CI 82.4-94.8) for the crowns and 82.6 (95% CI 77.5-87.6) for the adjacent teeth. The agreement between the clinical and virtual contact intensities on the crowns was 83 (95% CI 73-93) and 67.3 (95% CI 56-78.7) for the adjacent teeth. The positive predictive value was 72.83 (95% CI 60-86). The negative predictive value was 100% (95% CI 100-100). CONCLUSIONS: The intraoral scanning system provided clinically sufficient sensitivity and specificity for identifying the occlusal surface contacts of monolithic crowns. A slight decrease was detected in the system's sensitivity and specificity in identifying contacts on adjacent teeth and a larger decrease identifying the intensity of these contacts.

Assessing the Cleanliness of Dental Implants Using Scanning Electron Microscopy and Energy-Dispersive X-ray Spectroscopy Analysis-A SEM and EDS In Vitro Study.

A wide variety of titanium (Ti) alloy dental implant systems are available and as a result, choosing the correct system has become a challenge. Cleanliness of the dental implant surface affects osseointegration but surface cleanliness may be jeopardized during manufacturing. The purpose of this study was to assess the cleanliness of three implant systems. Fifteen implants per system were examined with scanning electron microscopy to identify and count foreign particles. Particle chemical composition analysis was performed with energy-dispersive X-ray spectroscopy. Particles were categorized according to size and location. Particles on the outer and inner threads were quantitatively compared. A second scan was performed after exposing the implants to room air for 10 min. Carbon, among other elements, was found on the surface of all implant groups. Zimmer Biomet dental implants had higher particle numbers than other brands. Cortex and Keystone dental implants showed similar distribution patterns. The outer surface had higher particle numbers. Cortex dental implants were the cleanest. The change in particle numbers after exposure was not significant (p > 0.05). Conclusion: Most of the implants studied were contaminated. Particle distribution patterns vary with the manufacturer. The wider and outer areas of the implant have a higher probability of contamination.

Zirconia CAD/CAM machining vibrations related to zirconia blank shape and initial digital nesting.

AIM: To evaluate CAD/CAM milling vibrations related to zirconia disk design, framework, and location of digital crown nesting during zirconia soft milling. MATERIALS AND METHODS: In the present in vitro study, 25 round zirconia disks of 98 mm (R group) and 15 D-shaped zirconia disks of 71 mm (D group) were placed in a 5-axis CAD/CAM milling unit. The R group had 3 crown milling sites (n = 75) and the D group had 2 crown milling sites (n = 30). In the R group, site A was located 57 mm, site B was 92 mm, and site C was 123 mm from the machine holder attachment. In the D group, site A was 57 mm and site C was 123 mm from the machine holder attachment. A vibration meter (VB-8200; Lutron) was connected to the disk holder, and data (mm/second) were collected during the milling process at the different nesting locations. One-way ANOVA with post-hoc tests and Bonferroni correction for multiple tests were used to compare the groups (α = 0.05). RESULTS: In the R group, site C exhibited the highest mean vibration values compared with site A (P = 0.001). The first and second cutting tools (2.5 and 1 mm) exhibited statistically significant differences between the D and R groups at milling sites A and C (P < 0.001 and P = 0.003, respectively). CONCLUSIONS: Milling vibration increased as the distance between the machine holder arm and a digitally nested site increased. Round zirconia disks induced higher vibration values compared with D-shaped disks.

Effect of Titanium-Base Abutment Height on Optical Properties of Monolithic Anterior Zirconia Crowns.

The effects of different heights of ti-base abutments on the color of anterior screw-retained zirconia restorations fabricated using computer-aided design and computer-aided manufacturing (CAD-CAM) technologies may affect the optical clinical outcome. The purpose of this study was to measure and compare the color parameters of zirconia crowns in different shades on ti-base abutments. Identical specimens (N = 160) were milled to restore the screw-retained central maxillary incisor crown, using 5% mol yttria zirconia (5Y-TZP). The specimens were designed using computer design software to match 3.5 mm and 5.5-mm ti-base abutments and milled using one CAD-CAM technology. Specimens were divided into four main groups depending on zirconia shade (A1/0, A2/3, A3.5/4 and B2/3) and then assigned to two subgroups according to ti-base height. Color measurements in the CIELab coordinates were made using a spectrophotometer under room-light conditions. Color difference (ΔE*) values were calculated using the CIE76 and CIEDE2000 formula. Within the group of A0/1 and A2/3, for 5.5 mm abutment height, a significant difference was found between the means of colors ∆E00 and ∆Eab (p < 0.01). Using a 5.5 mm-height ti-base abutment may produce a clinically unacceptable outcome (ΔEab > 2) in A1/0 and A2/3 color groups.

Marginal Bone Loss and Clinical Complications in Surviving Implants and Recently Placed Implants Splinted Together: A Retrospective Study.

PURPOSE: The objective of this study was to compare marginal bone loss (MBL) and clinical complications between surviving implants (SIs) and recently placed implants (RIs) splinted together to support a fixed partial restoration (FPR). MATERIALS AND METHODS: This retrospective study employed the medical records of patients treated with implant-supported FPRs in the Maccabi-Dent Dental Clinic. Patients were included if they were over the age of 18 years, were treated with RIs adjacent to existing SIs that had previously supported FPRs for more than 1 year, and the RIs and SIs were splinted to support new FPRs. Patients who did not receive annual follow-up or whose records had nondiagnostic radiographs or lacked sufficient restorative data were excluded. MBL was assessed at the last available radiograph and compared to one taken 1 year after loading the splinted RIs and SIs together. Clinical complication data were gathered from patient records. RESULTS: The medical records of 1,907 patients treated with a total of 7,306 implants were examined. Data from 187 implants were extracted from 46 patient records that met the inclusion criteria, with 96 RIs and 91 SIs supporting 56 FPRs. Mean followup was 39 ± 17.5 months. During the follow-up, two implants failed. The overall survival rate was 98.94% (98.96% in RIs and 98.91% in SIs), and the mean MBL in all implants was 0.41 ± 0.58 mm (0.4 ± 0.53 mm in RIs and 0.42 ± 0.45 mm in SIs). Peri-implantitis was reported in eight (4.3%) implants (four RIs and four SIs), screw loosening was reported in nine (4.8%) implants (three RIs and six SIs), ceramic chipping was reported in three (5.3%) restorations supported by four RIs and six SIs, and decementation was reported in one (1.8%) restoration supported by one RI and one SI. There was no statistically significant difference in survival rate, MBL, peri-implantitis, or screw loosening between RIs and SIs. CONCLUSION: There was no statistically significant difference in MBL or clinical complications between RIs and SIs. Splinting RIs and SIs for new prosthetic restoration support is a reasonable treatment choice with a high implant survival rate, low incidence of complications, and acceptable MBL.

A Comparative Evaluation of the Strain Transmitted through Prostheses on Implants with Two Different Macro-Structures and Connection during Insertion and Loading Phase: An In Vitro Study.

Background: The purpose of this study was to measure and compare the strain levels in the peri-implant bone as generated by the blade-like implant (BLI) and the screw-type implant (STI) with two different internal connections (hexagonal and conical) and with a 1:1 and 2:1 crown/implant (C/I) ratio. Methods: The implants (BLI and STI) were placed into sawbones according to the manufacturer's protocol. Two strain gauges, horizontal and vertical to the implant axis, were placed around each implant on the bone surface 1 mm from the cervical part. Each implant was loaded by a material testing machine at a force of 100 N. Micro-strains (µÎµ) generated in the surrounding bone were measured by a strain gauge and recorded. Results: Recorded micro-strains were not significant in both the insertion and loading phases (p < 0.0625). The average recorded micro-strain values were lower in the horizontal dimension of STI with hexagonal connection when the C/I ratio was 2:1 compared with BLI, 210 µÎµ and 443 µÎµ, respectively. Conclusion: Within the limitations of this study, implant design, implant-abutment connection and C/I ratio did not influence strain values in bone and there is no statistically significant effect of these parameters on bone.

Thermal Cycling Effect on Locator System Retention and Metal Surface Roughness.

PURPOSE: To estimate the effects of the thermal cycling (TC) process on the metal surfaces of Locators, as well as retention loss, and the correlation between them. MATERIALS AND METHODS: Twenty-five new Locator R-Tx were included in the study. Four areas were marked on each Locators' patrix metal surface and scanned using a confocal scanner (µsurf explorer; NanoFocus). Three surface roughness parameters were measured in the scans: Sa (average distance of peaks from the central plain of the area), Vmp (volume of the peaks in the area), and Spc (mean curvature of the peaks describing the degree of their sharpness). Retention test was performed using Instron® 4500 compression tension tensile tester at a speed of 10 mm/min. The retention tests were done using a working model made of two acrylic blocks in which the Locator system parts were inserted. The surface parameters measurements and the retention tests were performed 2 times, once before and once after TC. The Locators were subjected to 15,000 TC cycles by investing them into 2 tubs with different water temperatures, 55°C and 5°C. During each 60-second cycle, the Locators were submerged in each tub for 20 seconds, with a 10 second transition time between the tubs. The post-TC retention and surface parameters measurements were compared with those prior to TC and the prior to TC measurements served as controls. Changes in parameters before and after TC were analyzed by a two-way ANOVA nested model with random intercept and slope by restricted maximum likelihood method. Correlation between retention and surface parameters was quantified and examined using Kendall's correlation test. The findings were considered statistically significant if p < 0.05. RESULTS: There was a significant decrease in retention of 16.6N at the second retention test (p < 0.001). A significant statistical decrease in surface parameters were measured after TC process, Sa and Vmp (18 ×10-3 µm, p = 0.041 and 0.94 ×10-3 1/µm, p = 0.001, respectively). A significant statistical increase in Spc of 6.4 ×10-3 µm3 /µm2 (p = 0.023) was noticed. The correlation between retention decreases and surface changes was not statistically significant. CONCLUSION: The TC process causes a substantial reduction in retention to the Locator system over time. In addition, TC causes significant but minor changes to the Locator surface area. Most of the changes are in the horizontal dimension.

Effects of Aging Torque Controllers on Screw Tightening Force and Bacterial Micro-Leakage on the Implant-Abutment Complex.

AIM: We assess the accuracy of torque controllers after several aging processes and the bacterial leakage on implant-abutment complexes (IAC). METHODS: A total of 12 spring-type and 12 friction-type torque controllers and 48 IAC (24 conical and 24 hexagonal connections) were evaluated. Chemical, mechanical, temperature, and pressure-aging methods were applied individually to replicate clinical use. Torque controller accuracy was analyzed before and after aging using a calibrated gauge. To assess bacterial leakage, the IAC were suspended in a bacterial medium for 24 h. Direct Contact Test (DCT) and Polymerase Chain Reaction Test (RT-PCR) analyzed the infiltration of F. nucleatum and P. gingivalis into the IAC micro-gap. RESULTS: A significant decrease in torque after 10 days of aging was found. The spring-type torque controller was affected the most, regardless of the aging method (P < 0.05). PCR results indicated that all groups exhibited significantly more bacterial leakage, regardless of the method used (P < 0.05). The conical IAC demonstrated more bacterial leakage of P. gingivalis compared with the hexagonal IAC (P = 0.07). DCT found bacterial growth in the IAC only before aging and was not identified after aging. CONCLUSION: Aging affects torque accuracy. A reduction in force was noticed after 10 days. The conical IAC exhibits more bacterial leakage, although this was not statistically significant.

Marginal Bone Loss of Dental Implants in Patients with Type 2 Diabetes Mellitus with Poorly Controlled HbA1c Values: A Long-Term Retrospective Study.

PURPOSE: The objective of this study was to report implant survival rates, marginal bone loss, and the impact of prosthesis type among patients with type 2 diabetes mellitus (DMT2), with high hemoglobin A1C (HbA1c) values. MATERIALS AND METHODS: This retrospective study utilized patient medical records from an oral surgeon's office. Patients who had moderately or poorly controlled DMT2 with HbA1c values up to 10% were reviewed. Inclusion criteria were partially or fully edentulous patients diagnosed with DMT2 who were subsequently treated with implant-supported prosthetic restorations. Patients were at least 18 years of age. Exclusion criteria were patients who did not present for annual follow-up visits, patient records with incomplete surgical or restorative data, or nondiagnostic radiographs. All the fixed restorations were cement-retained, and the removable restorations were supported by two to six implants. Marginal bone loss and the consequences of prosthetic type were assessed from the last available radiograph compared with the one taken after the surgical procedure. RESULTS: Data of 357 implants were extracted from the records of 38 patients with HbA1c values (6.9% to 10.0%). The mean follow-up was 7.3 years, with a minimum of 5 years. Six implants failed, yielding a 98.4% overall implant survival rate. The patients were divided into two groups according to the HbA1c values before implant placement. The moderately controlled group included 25 patients with DMT2, with HbA1c values of 6.9% to 8.0%, and the poorly controlled group included 13 patients, with HbA1c values of 8.1% to 10.0%. The overall mean bone loss was 2.02 ± 2.43 mm. In both groups, the maxilla demonstrated more bone loss than the mandible (P < .05). Marginal bone loss in moderately controlled and poorly controlled groups was 1.86 (± 2.21) mm and 2.33 (± 2.85) mm, respectively (P < .05). Removable prostheses also revealed greater bone loss rates compared with fixed prostheses in both groups (P < .05). CONCLUSION: Patients with high HbA1c values (8.1% to 10.0%) had more marginal bone loss than those with lower HbA1c values. Removable dentures should be reconsidered as a standard treatment option in these patients.

Eight-month follow-up of olfactory and gustatory dysfunctions in recovered COVID-19 patients.

PURPOSE: To investigate the recovery of loss of smell and taste among recovered COVID-19 patients. MATERIALS AND METHODS: This cross-sectional follow-up study is a sequel to a study by Biadsee et al. Among the previous study population of 128 non-hospitalized patients, positive for COVID-19 by reverse transcription-polymerase chain reaction (RT-PCR), 97 patients participated in a survey designed for this study. Information and data regarding loss of smell and taste, rate of recovery, xerostomia, and additional symptoms; (Cough, Myalgia, Weakness, Rhinorrhea, Nasal congestion) were collected. RESULTS: A total of 43 men and 54 women were included. Mean age was 37.5 years (range 19-74). Mean follow-up was 229 days (range 191-253). Sixty-five patients reported gustatory dysfunction during the disease of which 61.5% reported full recovery, 38.5% partial recovery. Of 65 patients who reported olfactory impairment during the disease, 52% had full recovery and 48% reported partial recovery of olfactory function. Complete recovery of olfactory function was positively associated with full recovery of gustatory function (p = 0.01). Gender did not significantly affect the recovery of OD and GD (p = 0.45, p = 0.90, respectively). Patients who experienced olfactory dysfunction as an initial symptom had lower rates of olfactory complete recovery (p = 0.043). CONCLUSION: After a mean follow-up of 229 days, complete recovery of smell and taste functions occurred in 52% and 61.5%, respectively. However, dysfunction persisted in 48%-38.5% of patients.

The Effect of Aging on the Roughness and Bacterial Adhesion of Lithium Disilicate and Zirconia Ceramics.

PURPOSE: This in vitro study was designed to compare bacterial adhesion to zirconia versus lithium disilicate crowns after artificial aging. MATERIALS AND METHODS: Seventy-five discs were tested in this study: 25 Cr-Co base metal discs (control), 25 zirconia discs, and 25 lithium disilicate discs. Each sample was polished and glazed appropriately. The discs were subjected to 1000 thermal cycles between 5 and 55°C, whereby samples stayed in the bath for 20 seconds, at each temperature. Then, 10 µL of Streptococcus sanguinis suspension was placed on the discs. The samples were scanned for surface roughness before and after aging, and after incubation. Sp and Sa were measured with a confocal, visible light disk-scanning system (Sa expresses the difference in height of each point compared to the arithmetical mean of the surface. Sp is the height of the highest peak within the defined area). Optical density of the discs was evaluated by a spectrophotometer. One-way ANOVA was performed to assess differences after aging and incubation. RESULTS: Statistical analysis showed significant differences (p = 0.02) in surface roughness between the Cr-Co base metal, zirconia and lithium disilicate before and after aging. The mean Sa was 0.36 ± 0.12 µm, 0.638 ± 0.24 µm, and 1.23 ± 0.42 µm, respectively. Lithium disilicate had the highest surface roughness values. There was a significant difference (p = 0.001) after incubation. The mean and standard deviation surface roughness of Cr-Co base metal, zirconia and lithium disilicate were 0.99 ± 0.49 µm, 1.40 ± 0.46 µm, and 2.44 ± 1.21 µm, respectively. While no significant differences were found in the accumulation of S. sanguinis between zirconia and lithium disilicate, there was a significant difference (p = 0.02) in the optical density between these 2 test groups and the control group (metal). The optical density of metal (0.94 ± 0.15) was higher than for lithium disilicate (0.74 ± 0.10) and zirconia (0.75 ± 0.08). There was no statistical difference in bacterial adherence between lithium disilicate and zirconia. CONCLUSION: Dental crown materials differed significantly in terms of surface roughness and bacterial adhesion between Cr-Co base metal and zirconia and lithium disilicate. After aging and bacterial adherence, the zirconia discs had the smoothest surface, with similar bacterial accumulation as lithium disilicate; suggesting that lithium disilicate may be less sensitive to bacterial adhesion than zirconia.

Comparison of bone-to-implant contact and bone volume around implants placed with or without site preparation: a histomorphometric study in rabbits.

The objective of this in vivo study was to compare bone-to-implant contact (BIC) and bone area fraction occupancy (BAFO) values of a new implant, designed to be inserted without bone preparation, using two different preparation protocols: no site preparation and prior limited cortical perforation, versus the values of a control implant using a conventional drilling protocol. Forty-one implants were inserted in 13 rabbits. Thirteen test implants with a new thread design were inserted using no bone preparation (NP), 14 test implants were inserted with limited cortical perforation (CP), and 14 conventional implants served as control. Five animals were sacrificed after 21 days and eight animals after 42 days. Histomorphometric analysis was performed and percentage of BIC and BAFO values were measured. ANOVA with Tukey post hoc and Mann-Whitney nonparametric tests were calculated to compare between the groups. Statistical analysis showed no significant difference in the measured values between any of the groups, neither compered by implant nor by compered day. The results demonstrated that biological osseointegration parameters of implant that was inserted without any bone preparation was non-inferior compared to conventional preparation. The clinical relevance is that novel implant designs may not require bone preparation prior to placement.

Olfactory and Oral Manifestations of COVID-19: Sex-Related Symptoms-A Potential Pathway to Early Diagnosis.

OBJECTIVE: The coronavirus disease 2019 (COVID-19) pandemic poses a threat to global health. Early diagnosis is an essential key to limit the outbreak of the virus. STUDY DESIGN: Case series, study conducted between March 25, 2020, and April 15, 2020. SETTING: Ambulatory, nonhospitalized patients who were quarantined in a designated hotel for COVID-19 patients and were recruited by an advertisement at the hotel. SUBJECTS AND METHODS: In total, 140 patients participated in a web-based questionnaire assessing initial symptoms of common viral diseases, olfactory and taste functions, xerostomia, and orofacial pain. RESULTS: A total of 58 men and 70 women participated. Initial symptoms were cough (59.4%), weakness (47.7%), myalgia (46.9%), fever (42.2%), headache (40.6%), impaired sense of smell (38.3%), impaired sense of taste (32.8%), sore throat (26.6%), runny nose (26.6%), and nasal congestion (22.7%). All symptoms were more frequent among women; however, only runny nose was statistically significant (P = .018). The most common combination of symptoms was cough and weakness (37.5%). A total of 25.8% reported olfactory and taste dysfunctions in the absence of other symptoms. In a comparison between the sexes, cough and runny nose were the most common combination in women (P = .018). A total of 38.3% of patients reported olfactory dysfunction as an initial symptom. Anosmia and facial pain were more common among women (P < .001 and P = .01, respectively), and 56% of patients reported xerostomia. CONCLUSION: A considerable number of patients presented with olfactory and oral disorders. Interestingly, women presented with a different cluster of symptoms than men, which may suggest a new clinical approach to diagnosing COVID-19 disease.

Evaluation of the relationship between Periotest values, marginal bone loss, and stability of single dental implants: A 3-year prospective study.

STATEMENT OF PROBLEM: Although the Periotest has been shown to provide reliable information about initial implant stability, whether Periotest values (PTVs) can be correlated with the stability of implants in function for several years is unclear. PURPOSE: The purpose of this prospective clinical study was to investigate implant stability by using PTVs, as well as changes in stability and peri-implant marginal bone levels (as measured by radiographs) over a 3-year follow-up period. The exploratory hypothesis was that there is a significant correlation between PTVs and bone loss around the implant and that PTVs can provide predictive information about marginal bone-level changes and implant stability over time. MATERIAL AND METHODS: The study population included patients who needed single-tooth replacement with restoration of cemented fixed partial dentures. Clinical data, PTVs, and periapical radiographs were collected at the time points of implant placement, 3 to 6 months after insertion, and 1 year, 2 years, and 3 years after the final definitive prosthetic restoration. Pearson correlation coefficient tests were performed to estimate the correlation between the PTVs received at the first follow-up time point and the subsequent PTVs received during the follow-up period (up to 3 years after the restoration). The Pearson test was applied, as well as the t test and repeated-measures ANOVA, to evaluate PTVs and bone loss changes over time. The Pearson test was also applied to estimate the correlation between the bone loss values measured at the first follow-up visit and the subsequent bone loss values at the annual follow-up time points (up to and including 3 years after the restoration). RESULTS: A total of 43 implants were inserted in 34 patients (26 men and 8 women); the average patient age was 52.8 years. A significant reduction in implant stability was detected between implant insertion and the 3- to 6-month follow-up time point, which was then followed by a significant increase in stability at the 1-year follow-up time point and then stabilized during the 2- and 3-year follow-up time points (P<.014). Furthermore, a significant correlation was found between PTVs at the 1-year follow-up and the PTVs at all measured follow-up time points (P<.05). A positive correlation was obtained with high-strength correlation coefficient R (R>0.7) at all follow-up time points. Bone loss changes during the follow-up time points were significantly different and correlated with PTVs (P<.001). CONCLUSIONS: The Periotest is a reliable device for assessing implant stability and providing predictive information about marginal bone level changes around an implant.

The Effect of Moderately Controlled Type 2 Diabetes on Dental Implant Survival and Peri-implant Bone Loss: A Long-Term Retrospective Study.

PURPOSE: The objective of this study was to assess whether long-term implant survival rates and bone loss in patients with moderately controlled type 2 diabetes is similar to the rates reported in the nondiabetic population. MATERIALS AND METHODS: This retrospective observational study utilized patient medical records from a general practitioner's dental office. The records of patients who had moderately controlled type 2 diabetes with hemoglobin A1C (HbA1c) up to 8% and glucose level below 150 mg/dL were reviewed, as patients with HbA1c up to 7% are considered to be well-controlled type 2 diabetes. Follow-up data were recorded and analyzed. Inclusion criteria were as follows: partially edentulous patients with missing teeth who were subsequently treated with implant-supported prosthetic restorations; patients were at least 18 years of age and demonstrated the ability to maintain oral hygiene. Exclusion criteria were as follows: patients did not present for annual follow-up visits; patients presented with a neglected periodontal status; patient records had incomplete surgical or restorative data or nondiagnostic radiographs; implants with external hexagonal and machined surfaces. All the restorations were cement-retained. Three different implant insertion/placement methods were used: (1) implants immediately inserted following tooth extraction; (2) implants inserted 6 to 8 weeks after tooth extraction to allow for primary healing; and (3) implants inserted 4 to 6 months after tooth extraction. RESULTS: After review of more than 3,256 medical records, 169 patients were identified (with 1,112 implants) who met the inclusion criteria. The mean follow-up time was 8.7 years, with a minimum of 4.9 years. Sixty-seven implants failed, yielding a 94% overall implant survival rate. The overall mean bone loss around the implants was 1.98 (± 1.81) mm. Comparable to data published earlier, no statistical significance in survival rate was found between the nondiabetic and diabetic population. The delayed insertion protocol presented the least bone loss, compared with immediate insertion (P = .06), and compared with early insertion (P = .046). CONCLUSION: The results show that implant survival and bone loss levels were comparable to reported outcomes in the nondiabetic population. The delayed insertion protocol presented less bone loss compared with other insertion methods. Likewise, less bone loss was found in implants placed in the posterior region.

Effect of Restorative Configurations and Occlusal Schemes on Strain Levels in Bone Surrounding Implants.

AIM: This study investigated strain levels during and after implant insertion, and during and after simulated mastication, in splinted and nonsplinted restorations with different occlusal schemes. MATERIALS AND METHODS: Fresh bovine bone resembling type I jawbone was collected. Strain gauges were placed at each implant's neck, one horizontally and one vertically. Strains at and after implant insertion were recorded. The restoration was loaded with cyclic load simulating mastication. Loading and residual strains were recorded for 6 experimental loading types. RESULTS: At and after implant insertion, high horizontal strains were measured. Full splint loading presented higher vertical compared with horizontal strains (P < 0.05). Segmented cross-arch splint showed higher horizontal strains (P < 0.05). Premolar loading guidance presented the most favorable loading and residual strain results (P < 0.05). CONCLUSIONS: Splinting implant restorations may reduce strain levels at implant neck area and provide preferable strain distribution during cyclic loading.

Collaboration Patterns and Processes Between Dentists and Dental Laboratories When Planning and Fabricating Implant-Supported Restorations.

INTRODUCTION: The success of implant-supported restorations is dependent on proper treatment planning, effective communication within the clinical team, and the use of appropriate methods and materials in the dental laboratory. The objective of this study was to determine collaboration trends between dentists and laboratories and to assess the common methods and materials involved in fabricating implant-supported restorations. METHODS: Questionnaires were distributed to dental laboratories and technicians. Seventy questionnaires were answered and were included in the data analyses. RESULTS: Most of the impressions (87%) were taken using an individual custom-made open tray. In 83% of impressions, screw-retained transfer units were used, and in 61% of cases, the units were splinted. Bite registration was recorded in 91% of the cases. In 80% of cases, articulator setup was done. When matching the shade of a restoration in the anterior, 57% of the technicians do so in collaboration with the dentist, and 39% match the shade independently. Type of restoration and abutment selection were done mainly by the technicians. Abutment selection was reported to be carried out by 72% of the technicians. CONCLUSIONS: Generally, dentists and technicians follow the standards recommended in the contemporary literature, especially, in major procedures such as impression taking, bite registration, and articulator setup. However, principal decisions, such as abutment and color shade are done mainly by technicians.

Consequences of experience and specialist training on the fabrication of implant-supported prostheses: A survey.

STATEMENT OF PROBLEM: Fabricating fixed restorations on implants requires that dentists stay up-to-date with the scientific publications. MATERIAL AND METHODS: A questionnaire containing 29 questions was sent to dentists, members of the Israeli Society of Prosthodontics, and university faculty members. Differences were evaluated using the chi-square and Fisher exact tests and Mann-Whitney U and Wilcoxon tests for questions enquiring into the frequency of use of certain methods (α=.05). RESULTS: A total of 155 questionnaires were completed by 84 general dental practitioners and 71 specialists and residents. Statistical differences (P<.05) were found in the course of the fabrication of the implant-supported prostheses in the diagnostic waxing, trial restoration, and impression-making processes. Trial restorations were often used by residents and specialists before starting an esthetic restoration. Diagnostic waxing was used when treating patients with complex esthetic needs, mainly by prosthodontists (P=.019). A custom tray for impression making was used more by residents and specialists than by general dental practitioners (P<.001). The open tray technique for impression making of single or up to 3 implants was performed mainly by residents, specialists, and general dental practitioners with professional experience of fewer than 15 years. General dental practitioners used primarily plastic or metal trays for impression making. CONCLUSIONS: Significantly, impression techniques and the use of custom open trays, diagnostic waxing, and trial restorations were performed by residents, specialists, and dentists with fewer than 15 years of experience.

Histological and radiological evaluation of sintered and non-sintered deproteinized bovine bone substitute materials in sinus augmentation procedures. A prospective, randomized-controlled, clinical multicenter study.

OBJECTIVES: The objective of this study is to histologically and radiologically compare a sintered and a non-sintered bovine bone substitute material in sinus augmentation procedures. MATERIALS AND METHODS: Thirty-three patients were included in the clinically controlled randomized multicentre study resulting in a total of 44 treated sinuses. After lateral approach, sinuses were filled with either a sintered (SBM, Alpha Bio's Graft®) or a non-sintered (NSBM, Bio Oss®) deproteinized bovine bone substitute material. The augmentation sites were radiologically assessed before and immediately after the augmentation procedure as well as prior to implant placement. Bone trephine biopsies for histological analysis were harvested 6 months after augmentation whilst preparing the osteotomies for implant placement. RESULTS: Healing was uneventful in all patients. After 6 months, radiological evaluation of 43 sinuses revealed a residual augmentation height of 94.65 % (±2.74) for SBM and 95.76 % (±2.15) for NSBM. One patient left the study for personal reasons. Histological analysis revealed a percentage of new bone of 29.71 % (±13.67) for SBM and 30.57 % (±16.07) for NSBM. Residual bone substitute material averaged at 40.68 % (±16.32) for SBM compared to 43.43 % (±19.07) for NSBM. All differences between the groups were not statistically significant (p > 0.05, Student's t test). CONCLUSION: Both xenogeneic bone substitute materials showed comparable results regarding new bone formation and radiological height changes in external sinus grafting procedures. CLINICAL RELEVANCE: Both bone substitute materials allow for a predictable new bone formation following sinus augmentation procedures.

Dental Implant Thread Design and the Consequences on Long-Term Marginal Bone Loss.

AIM: The aim of this study was to present the implant macrostructure effect on marginal bone loss using 3 dental implant thread designs with differences in thread pitch, lead, and helix angle. All implants used were sourced from the same company and had the same microstructured surface. MATERIALS AND METHODS: This is a nonrandomized, retrospective, double-blind study. Data were collected by an independent Tel Aviv University group from a general practitioner's private practice patient records. In total, 1361 implants met the inclusion criteria representing the 3 types of implants macrostructure. RESULTS: Overall survival rate was 96.3% with 50 implants failing (3.7%) out of a total of 1361 implants. Survival rates for the 3 groups were: group A 96.6%, group B 95.9%, and in group C 100%. Average bone loss for groups A, B, and C were 2.02 (±1.70) mm, 2.10 (±1.73) mm, and 1.90 (±1.40) mm, respectively. Pairwise comparisons revealed that less bone loss occurred in group A compared with group B (P = 0.036). CONCLUSION: Favorable long-term bone loss results were found in implants with a larger pitch, deeper apical threads, and a narrower implant core. One-piece V-thread design implants demonstrated 100% survival rate.