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.

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.

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.

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.

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.

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.

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.

Differences in crestal bone-to-implant contact following an under-drilling compared to an over-drilling protocol. A study in the rabbit tibia.

OBJECTIVES: The objective of this study is to compare bone-to-implant contact (BIC) between implants inserted at high torque due to under-drilling of the crestal bone to those inserted at low torque due to over-drilling of the crestal bone. MATERIALS AND METHODS: Forty implants with diameters of 3.75 mm (group A) or 3.55 mm (group B) were inserted in the proximal tibiae of NZW rabbits in two separate surgeries on day 0 or 21. Osteotomy of the crestal bone was finalized with a 3.65-mm drill. In group A, implants were inserted at torque ≥35 Ncm (under-drilling) and in group B with torque <10 Ncm (over-drilling). Implants and their surrounding bone were retrieved on day 42, thus creating 3- and 6-week observation periods, processed for non-decalcified histology and stained with toluidine blue. Crestal BIC (c-BIC) and total BIC (t-BIC) were measured. Wilcoxon test was used to evaluate differences between groups. RESULTS: Three weeks post-surgery, the mean c-BIC in group A was 16.3 ± 3.3 vs 31.5 ± 3.4 % in group B (P < 0.05). At 6 weeks, a similar trend was observed (group A: 28.7 ± 3.6 %; group B: 38.4 ± 4.9 %) (P > 0.05). No differences in t-BIC were noted at 3 weeks and at 6 weeks between the groups. CONCLUSIONS: Insertion of implants with an over-drilling protocol of the crestal aspect of the osteotomy resulted in increased short-term crestal bone-to-implant contact. CLINICAL RELEVANCE: Insertion of implants with a high torque following an under-drilling protocol, commonly used for immediate loading, may reduce crestal bone-to-implant contact at early healing stages.

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.

One Piece Immediately Loaded Implants Versus 1 Piece or 2 Pieces Delayed: 3 Years Outcome.

PURPOSE: To compare time-dependent outcome of immediately loaded 1-piece (1P) implants with delayed loaded 1P and 2-piece (2P) implants. MATERIALS AND METHODS: A cohort of 33 patients divided into 3 groups: group A, 13 patients, 49 immediately placed and loaded 1P implants; group B, 11 patients, immediately placed and delayed loaded 1P implants; and group C, 10 patients, 39 2P implants delayed placed and loaded in a two-stage procedure. Marginal bone loss (MBL) was analyzed using x-ray radiography every 6 months, 1 year, and 3 years. RESULTS: A statistically significant mean MBL was observed between baseline, 6 months, 1 year, and 3 years in all groups. There was no statistical significant difference in MBL between immediate and delayed loaded 1P implants. MBL around mandibular implants was lower compared with maxillary implants. CONCLUSIONS: 2P implants showed less MBL compared with 1P implants in both maxilla and mandible. There was no statistical difference in MBL between immediate and delayed loaded 1P implants. Immediate loaded implants show more MBL in maxilla.

Effect of implant insertion and loading protocol on long-term stability and crestal bone loss: A comparative study.

STATEMENT OF PROBLEM: Different insertion and loading protocols have been used to implement implant therapy; the consequences of these methods are unclear. PURPOSE: The purpose of this retrospective study was to compare the long-term outcomes of different implant insertion and loading protocols on crestal bone loss. MATERIAL AND METHODS: This was a nonrandomized retrospective study investigating data of patients in a private practice. Data were collected by an independent Tel Aviv University group from the patient records of a general practitioner's private practice. A total of 1688 implants were inserted in 343 patients whose records met the inclusion criteria, that is, 1317 immediately placed implants (IP group), 310 early placed implants (EP group) placed 6 to 8 weeks after implant placement, and 61 delayed placement implants (DP group) placed 4 to 6 months after extraction. The groups were also divided by implant loading method, giving 1203 immediately loaded implants (IL group), 273 early loaded implants (EL group) loaded within 4 to 10 weeks after implant placement, and 212 delayed loading implants (DL group) loaded within 3 to 6 months. Mixed model analysis was used to account for the different number of implants for each patient. RESULTS: The average follow-up time was 107 months, with a cumulative implant survival rate of 95.6% and an average crestal bone loss of 2.03 mm. No statistical differences (P>.05) were found among the insertion or loading protocols. However, additional statistical analysis showed the influence of implant type on marginal bone loss (P<.05). CONCLUSIONS: The 3-implant insertion and loading protocols exhibited minimal crestal bone loss and a high survival rate.

Evaluation of heat conduction in dental implants after exposure to hot beverages.

STATEMENT OF PROBLEM: It is unknown if the consumption of hot beverages after implant placement poses a danger of overheating at the bone-implant interface. PURPOSE: The purpose of this study was to investigate the effect of simulated consumption of hot beverages on the heat transfer to different dental implant types, implant sizes, and the presence of an interim restoration. MATERIAL AND METHODS: A model that consisted of 2 plastic containers was constructed to simulate the oral cavity and endosseous region of the jaw. One-piece and 2-piece implants with abutments were placed into a block of bovine mandibular bone without any healing tissue, surrounded by water maintained at 37°C in the lower compartment. The abutments, which extended into the upper container, were covered with water heated to 60°C to simulate consumption of a hot substance and then were cooled down spontaneously to 37°C during 100 to 600 seconds. Five thermocouple electrodes with an accuracy of ±0.1°C were attached to each test specimen and to a computer with data recording and analysis software to record temperature changes. Repeated measures ANOVA (α=.05)was performed to determine the effect of each major factor. RESULTS: Heat conduction from the abutment exposed to hot liquid was significantly higher in the cervical as opposed to the apical areas of the implants. Implant type (1 piece), diameter (wider), and the absence of an interim coping had a significant effect on the maximum temperature measured and on the temperature change rate. CONCLUSIONS: Abutment exposure to hot liquids resulted in heat conduction to the cervical region of the implant, which could be biologically harmful in healing tissues. Heat conduction was mitigated by implant design and diameter, and by the presence of an interim prosthesis. Results may differ in clinical models.

Fluoride ion release and solubility of fluoride enriched interim cements.

STATEMENT OF PROBLEM: Interim and definitive restorations cemented with interim cements for a prolonged interval are susceptible to bacterial infiltration and caries formation. PURPOSE: The purpose of this in vitro study was to evaluate the long-term fluoride release and solubility of aged ZnO-based interim cements enriched separately with 0.4% NaF and SnF2. MATERIAL AND METHODS: Four different brands of cements (Tempbond, Tempbond NE, Procem, and Freegenol) were tested for fluoride release and solubility. For every test, 6 disk specimens of each cement with NaF and SnF2, and 6 with no fluoride enrichment (control) were fabricated, for a total of 72 specimens. The disks were incubated in deionized water. Fluoride ion release was recorded at 1, 7, 14, 21, 63, 91, and 182 days. Solubility was calculated as weight percent after 90 days of incubation. The data were analyzed by analysis of variance with repeated measures and the Tukey honestly significant difference post hoc test (P<.05). RESULTS: Cements mixed with fluorides released fluoride ions for at least 182 days. Cements mixed with NaF released more fluoride ions than those mixed with SnF2 (P<.001). The cumulative release rates from all the tested cements mixed with either NaF or SnF2 were linear with respect to t(½) (r>.97), indicating a diffusion-controlled fluoride release. Cement and fluoride types were the main affecting factors in fluoride ion release. The addition of fluorides slightly increased the solubility of the cements. CONCLUSIONS: Given their long-term sustained and diffusive controlled release, these fluorides, particularly NaF when mixed with ZnO-based interim cements, may be useful for caries prevention under provisionally cemented restorations.

Long-term results of implants immediately placed into extraction sockets grafted with ß-tricalcium phosphate: a retrospective study.

PURPOSE: The aim of this 10 year retrospective study was to evaluate the crestal bone loss around immediate implant placed in tricalcium phosphate (TCP) grafted extraction sockets MATERIALS AND METHODS: Data were collected from files of 58 patients (33 females, 25 males, average age 54.78 years) undergoing immediate implant placement into fresh extraction socket with or without the use of TCP (Cerasorb, Curasan AG, Kleinostheim, Germany) grafting. After implant placement, horizontal gaps larger than 1.5 mm between the implant surface and the bony plate were grafted with TCP without the use of a membrane, while smaller gaps were not grafted. Two hundred fifty-four implants were inserted: 79 were placed immediately with the use of ß-TCP as grafting material (group A), 175 were placed in healed extraction sites, with 61 implants placed with the use of ß-TCP graft material (group B), and 114 implants were placed without any grafting material (group C). Bone loss recordings were performed using periapical radiography. Measurements were performed from the neck of the implant to level of the surrounding bone in the vertical dimension. RESULTS: No implant was lost during the follow-up period. Statistical analysis showed no correlation between implant placement timing (delayed or immediate), the use of bone graft, and extent of bone loss. CONCLUSION: The use of TCP (Cerasorb) as a grafting material during immediate implant placement allowed no bone loss in 72.1% of the implants, which was very similar to the nongrafted cases for which implants were placed in favorable conditions.

Heat generation in 1-piece implants during abutment preparations with high-speed cutting instruments.

OBJECTIVES: Evaluation of heat generation in 1-piece implants according to 3 variables: preparation time, bur type, and preparation environment. MATERIALS AND METHODS: Study implants were 1-piece designs with the same endosseous dimensions and surface microtexture, but with abutment sections that were either conical in shape, which required clinical preparations to shape and establish a restorative finish line (test), or with a pre-machined shape and restorative margin, which required minimal preparations (control) to accommodate a cemented crown. Burs were either carbide (group 1) or diamond (group 2), and the preparation environment was either ambient air or under water spray. An infrared camera was used to measure temperature changes in the exposed endosseous implant threads during grinding procedures. Three endosseous zones of the implant body were defined for heat measurements: crestal bone region (SP01), middle of the threaded region (SPO2), and apical region (SPO3). Grinding was performed in either ambient air or under water spray. The abutment was reduced to a 2.0 mm height, and one side was ground down to a 30 degree angle. RESULTS: Highest heat elevations were concentrated in SP01, followed by SP02 and SP03. Average temperature changes in SP01 showed that preparation time and environment significantly affected heat generation but not bur type. Lowest temperatures were exhibited by control implants prepared under water spray. Bur type (carbide or diamond) did not affect temperature changes. CONCLUSION: Intraoral implant abutment preparations can transfer heat to the bone capable of impairing osseointegration.

One-year survival rate outcomes of innovative dental implants: a prospective clinical study.

PURPOSE: The aim of this research was to evaluate an innovative implant design for different placement and loading protocols. The unique implant is a combination of tapered and cylindrical shape, which is aimed to enhance initial stability and long-term osseointegration. MATERIALS AND METHODS: Four hundred and sixty implants were placed in 141 patients under different placement and loading protocols in similarity to those encountered in a dental office. Implants were followed and evaluated for 1 year to assert the survival rate of the newly introduced implant. RESULTS: The results showed a total of 97.4% survival rate, ranging from 92% to 98.6% depending on the different protocols. There was no statistical difference between the different protocol groups. CONCLUSION: The new implant design showed good results for 1 year of follow-up, comparable with the literature, and could be a good choice for every implant-based procedure.

Bone microstrain values of 1-piece and 2-piece implants subjected to mechanical loading.

PURPOSE: The purpose of this study was to measure and compare the strain levels in peri-implant bone as generated by 1-piece (1P) and 2-piece (2P) implant systems. MATERIALS AND METHODS: The implants (1P and 2P) were placed into bovine bone according to the manufacturer's protocol. Four linear strain gauges were placed around each implant neck and apex. Each model was loaded in static loading by a material testing machine in ascending forces ranging from 20 to 120 N. Microstrains (µ[Latin Small Letter Open E]) generated in the surrounding bone were measured by a strain gauge and recorded. RESULTS: Recorded microstrains were significantly higher for 1P implants than for 2P implants. Average recorded microstrain values were significantly lower in the neck (71.6 and 17.3 µs) compared with the apical (132 and 60 µs) regions of 1P and 2P implants, respectively (P < 0.0001). CONCLUSIONS: Within the limitations of this study, highest microstrains were generated in apical regions regardless of implant design, but the 2P implant ap-peared to provide a stress-damping effect in both the cervical and apical regions compared with the 1P implant.