In Vitro Evaluation of Translucency and Color Stability of CAD/CAM Polymer-Infiltrated Ceramic Materials after Accelerated Aging.

PURPOSE: To investigate and compare the translucency and color stability of a newly introduced polymer-infiltrated ceramic network (PICN) material (Crystal Ultra) to those of clinically well-established restorative materials. MATERIALS AND METHODS: A total of 80 specimens measuring (12 × 14 × 1 mm ± 0.05 mm) were prepared from five CAD/CAM (IPS e.max (IPS), Lava Ultimate (LU), Cerasmart (CS), Vita Enamic (VE), Crystal Ultra (CU)) high translucency (HT) blocks in A2 or equivalent shades. Specimens were randomly allocated into two groups (A and B) (n = 8), and were subjected to 5,000 thermal-cycles (TC). This was followed by one-week immersion of group A specimens in coffee (staining) solution and group B specimens in distilled water. Following immersion, the specimens from both groups were further subjected to 5,000 TC. A spectrophotometer was used to measure the translucency parameter (TP) and color change (ΔE00 ) of the samples using CIELAB color coordinates at baseline, after 5,000 TC, following immersion, and after further 5,000 TC. Color stability was evaluated using the CIEDE2000 formula. Data were analyzed by non-parametric tests (α = 0.05). RESULTS: The TP values of the CAD/CAM materials ranged from 18.0-22.0. Following the initial TC, the changes in TP values were significant for VE (p = 0.012). Coffee immersion and further TC significantly impacted the TP values of PICN (VE and CU) materials compared to glass- ceramics (IPS), and resin nanoceramic (CS and LU) materials (p = 0.012). The comparison between CAD/CAM materials at different intervals showed a significant difference in the TP values (p < 0.01). The materials showed perceptible color changes following the initial TC except for PICN materials which demonstrated acceptable color changes. The major color difference was noticed for the resin nanoceramic specimens immersed in coffee; LU and CS showed higher color changes (ΔE00 = 2.45 and 2.09, respectively) than VE and CU (ΔE00 < 1.8). CONCLUSIONS: The translucency of the newly introduced Crystal Ultra PICN material was low compared to the resin nanoceramics and lithium disilicate glass-ceramic. The Crystal Ultra material exhibited better color stability compared to resin nanoceramics, but higher color change when compared with Vita Enamic PICN and lithium disilicate glass-ceramic CAD/CAM materials.

Effect of the Unfilled Space Size of the Abutment Screw Access Hole on the Extruded Excess Cement and Retention of Single Implant Zirconia Crowns.

PURPOSE: To evaluate in vitro the effect of the size of the unfilled space of the abutment screw access hole on the amount of extruded excess cement and the retention of zirconia copings. MATERIALS AND METHODS: Twelve dental implant replicas were attached to the corresponding abutments and embedded in acrylic resin blocks. A total of 36 CAD/CAM zirconia copings were fabricated by one technician using the standard technique. Abutments were divided into group I: the entire screw access channel was completely filled (nonspaced); group II: 1-mm-spaced; and group III: 2-mm-spaced. The copings were air-abraded and temporarily cemented under constant load of 60 N for 10 minutes. The excess cement was calculated as the difference between the post-cementation and post-excess-removal weights using a digital scale. Retention test was performed by a universal testing machine at a 0.5 mm/min crosshead speed. The ultimate force and tensile strength required for separation were recorded. One-way ANOVA and Tukey's test were used for statistical analysis at p ˂ 0.05. RESULTS: The average amount of extruded cement in groups 1, 2, and 3 was 33.48 ± 1.55, 23.05 ± 5.48, and 15.58 ± 5.98 mg, respectively. Multiple comparisons showed significant differences in the amount of extruded excess cement between the three groups (p ˂ 0.001). The maximum load at decementation in groups 1, 2, and 3 was 98.8, 87.5, and 88.6 N, respectively. Groups 1, 2, and 3 separated at 6.90 ± 1.2, 6.12 ± 0.7, and 6.21 ± 0.9 MPa, respectively, with no significant differences between them. CONCLUSIONS: The amount of extruded excess cement was reduced by more than half when a 2-mm space of the screw access hole was left unfilled in comparison to the nonspaced counterpart. The retention of zirconia copings was not affected by the reported technique.

Effects of Gingival Retraction Paste and Subsequent Cleaning with Hydrogen Peroxide on the Polymerization of Three Elastomeric Impression Materials: An In Vitro Study.

PURPOSE: It has been hypothesized that there are no effects of Expasyl and subsequent cleaning with hydrogen peroxide on polymerization of selected commonly used impression materials. Therefore, the aim of this study was to evaluate the effect of Expasyl paste on the polymerization of three impression materials with and without subsequent cleaning using 3% hydrogen peroxide (H2 O2 ). MATERIALS AND METHODS: Nine standardized stainless steel specimens were fabricated. One hundred and eighty impressions were made using 3 materials (60 each) as follows: group I: poly(vinyl siloxane) (PVS) (Virtual); group II: polyether (Monophase); group III: polyether (Impregum). Groups were subdivided into 3 categories: control without intervention (n = 20), pre-application of Expasyl and subsequent 1-minute washing with water and air-drying (n = 20), and pre-application of Expasyl and subsequent cleaning with 3% H2 O2 for 10 seconds (n = 20). All impressions were made by one operator using auto-mixing cartridges under standardized conditions at room temperature. Evaluation of the polymerization inhibition was blindly and independently performed by three practitioners with comparable experience using a visual scale. The observation was subjectively categorized as noninhibited or inhibited. Data were tabulated and analyzed using Fisher's exact test with significance level set at p ˂ 0.05. RESULTS: Significant differences were found between the control group and the impressions made after contamination with Expasyl (p < 0.001). Polymerization inhibition of PVS and Impregum was similar (in 85% and 90% of the specimens, respectively) when washed with water. There was a statistically significant reduction in polymerization inhibition in both upon cleaning with H2 O2 (p < 0.001); however, polymerization inhibition occurred in 100% of Monophase specimens when contaminated with Expasyl despite the washing technique used. CONCLUSIONS: Under these in vitro conditions, it can be concluded that the remnants of Expasyl on specimens caused a significant polymerization inhibition of the 3 impression materials tested. Subsequent cleaning with 3% H2 O2 significantly reduced this inhibitory effect on polymerization. Expasyl should not be used with Monophase polyether material.

A comparative study of the bone contact to zirconium and titanium implants after 8 weeks of implantation in rabbit femoral condyles.

Zirconium (Zr) has been found to have comparable characteristics to titanium with a favorable modulus of elasticity. In addition, the release of Zr-ions of a Zr implant is supposed to further increase the bone-to-implant response. Therefore, the objective of this study is to compare the bone contact to Zr and Ti implants in the femoral trabecular bone of rabbits. In addition, implants provided with a hydroxyapatite (HA) coating were included, as such a coating was proven before to enhance the secondary implant stability. A total of 32 implants consisting of 16 Zr (8 HA coated) and 16 Ti (8 HA coated) implants were installed in the femoral condyle of 16 rabbits. After 8 weeks of healing the femoral condyles including the implants were retrieved and studied histologically. The bone-to-implant contact (BIC) percentage was assessed and analyzed statistically. The BIC values of the uncoated Zr and Ti implants showed comparable BIC values (45.1 ± 14.8 vs. 45.5 ± 13.1). The BIC percentage was slightly higher for HA coated Zr and Ti implants (60.3 ± 17.1, 59.8 ± 16.4, respectively) compared to uncoated, but statistical testing indicated that this difference was not significant. It can be concluded that Zr and Ti implants show a comparable bone-implant contact after 8 weeks of implantation in the currently used rabbit model. In addition, the deposition of a sputtered HA coating on both Zr and Ti implants did not further improve their bone integration.

Influence of space size of abutment screw access channel on the amount of extruded excess cement and marginal accuracy of cement-retained single implant restorations.

STATEMENT OF PROBLEM: The detrimental effect of extruded excess cement on peri-implant tissue has been well documented. Although several techniques have been proposed to reduce this effect by decreasing the amount of extruded cement, how the space size of the abutment screw access channel (SAC) affects the amount of extruded cement and marginal accuracy is unclear. PURPOSE: The purpose of this in vitro study was to evaluate the effect of the size of the unfilled space of the abutment SAC on the amount of extruded excess cement and the marginal accuracy of zirconia copings. MATERIAL AND METHODS: Twelve implant replicas and corresponding standard abutments were attached and embedded in acrylic resin blocks. Computer-aided design and computer-aided manufacturing (CAD-CAM) zirconia copings with a uniform 30-µm cement space were fabricated by 1 dental technician using the standard method. The copings were temporarily cemented 3 times at different sizes of the left space of the SAC as follows: the nonspaced group (NS), in which the entire SAC was completely filled, the 1-mm-spaced group (1MMS), and the 2-mm-spaced group (2MMS). Abutments and crowns were ultrasonically cleaned, steam cleaned, and air-dried. The excess cement was collected and weighed. To measure the marginal accuracy, 20 measurements were made every 18 degrees along the coping margin at ×300 magnification and compared with the pre-cementation readings. One-way ANOVA was calculated to determine whether the amount of extruded excess cement differed among the 3 groups, and the Tukey test was applied for multiple comparisons (α=.05). RESULTS: The mean weights (mg) of extruded excess cement were NS (33.53 ±1.5), 1MMS (22.97 ±5.4), and 2MMS (15.17 ±5.9). Multiple comparisons showed significant differences in the amount of extruded excess cement among the 3 test groups (P<.001). The mean marginal discrepancy (µm) of the pre-cemented group (29.5 ±8.2) was significantly different (P<.01) from that of the NS (72.3 ±13.7), the 1MMS (70.1 ±19), and the 2MMS group (70.1 ±18.8). No significant differences were found in marginal accuracy among the 3 test groups (P=.942). CONCLUSIONS: Within the limitations of this in vitro study, leaving a 2-mm space in the SAC reduced the amount of extruded excess cement by 55% in comparison with the nonspaced abutments. However, no effect was found on the marginal accuracy of zirconia copings.

Effects of Evaluator's Fatigue and Level of Expertise on the Global and Analytical Evaluation of Preclinical Tooth Preparation.

PURPOSE: To investigate the effects of evaluator fatigue and level of expertise on the grading of preclinical tooth crown preparations, by global and analytical methods of evaluation. MATERIALS AND METHODS: The study had a double-blind design. Two faculty members, each with more than 10 years of clinical and teaching experience, and two demonstrators with no teaching experience evaluated tooth preparations on maxillary central incisors and mandibular first molars. As a test of the effect of fatigue, preparations were globally (subjective grading) and analytically (criteria-based grading) graded on day 1 (after evaluators had been on duty continuously for 8 hours) and day 2 (in the morning after evaluators had sufficient sleep). Evaluators worked under the same circumstances and did not communicate with each other. The assigned textbooks were used to develop the criteria for grading (rubric) and the predefined exclusion criteria. Grades were recorded and statistically analyzed using statistical software. The paired-sample t-test and Mann-Whitney U test were used for multiple comparisons. Level of significance was set at p ˂ 0.05. RESULTS: An inconsistency in preclinical tooth preparation evaluation was found to exist by both global and analytical methods. Junior faculty tended to award higher grades than senior faculty did. Furthermore, higher grades were scored by the analytical method. More clinical and academic experience did not guarantee intra- and interexaminer reliability. Younger faculty appeared to tolerate fatigue better than older faculty. Likewise, global evaluation appeared to be more influenced by fatigue than was the analytical method. CONCLUSION: There were variations in grading, with no consistently preferred grading method. Evaluator performance after continuous 8-hour duty had no significant effect on preclinical tooth preparation evaluation. Level of expertise did not affect preclinical evaluation regardless of the grading method used.

Comparison of Clinical, Radiographic, and Immunologic Inflammatory Parameters around Crestally and Subcrestally Placed Dental Implants: 5-Year Retrospective Results.

PURPOSE: To compare changes in clinical (bleeding on probing [BOP] and probing pocket depth [PPD]), radiographic (crestal bone loss [CBL]), and immunologic inflammatory (interleukin-1beta [IL-1ß] and matrix metalloproteinase-9 [MMP-9]) parameters around crestally and subcrestally placed dental implants 5 years after implant placement. MATERIALS AND METHODS: Fifty-two patients were divided into 2 groups: group 1 (n = 27): patients with single implants placed approximately 2 mm below the alveolar crest; group 2 (n = 25): patients with single implants placed at bone level. In both groups, peri-implant BOP, PPD, and CBL were measured, and levels of IL-1ß and MMP-9 were determined in duplicates using enzyme-linked immunosorbent assay. Full-mouth debridement was performed biannually in both groups. Statistical analysis was performed using the Mann-Whitney U test (significance set at p < 0.05). RESULTS: All measurements in groups 1 and 2 were performed 5.3 ± 0.2 and 5.2 ± 0.1 years after implant placement, respectively. The mean CBL was 1.2 ± 0.2 mm and 1.4 ± 0.2 mm in groups 1 and 2, respectively. There was no significant difference in mean BOP, PPD, CBL and in levels of IL-1ß, and MMP-9 among implants in both groups. CONCLUSION: Clinical, radiographic, and immunologic inflammatory parameters are comparable around crestally and subcrestally placed single dental implants up to 5 years after placement. The depth of implant placement appears to have no effect on clinical status and performance of single dental implants.

Comparison of clinical and radiographic status of platform-switched implants placed in patients with and without type 2 diabetes mellitus: a 24-month follow-up longitudinal study.

OBJECTIVE: The purpose of the present 24-month follow-up longitudinal study was to compare the clinical and radiographic status of platform-switched implants placed in patients with and without type 2 diabetes mellitus (T2DM). MATERIAL AND METHODS: In total, 45 male non-smokers were included. In Group-1, there were 23 patients with T2DM, and patients in Group-2 comprised of 22 self-reported non-diabetic controls. Under local anesthesia, platform-switched implants were placed in the mandible. Peri-implant bleeding on probing (BOP), probing depth (PD), marginal bone loss (MBL) and hemoglobin A1c (HbA1c) levels were measured at 12 and 24 months of follow-up. Participants were also enrolled in a biannual oral hygiene maintenance program. RESULTS: The mean age of participants in groups 1 and 2 were 42.4 years (40-46 years) and 41.8 years (39-44 years), respectively. In Group-1, the mean duration of T2DM was 14.5 ± 0.7 months. At 12 and 24 months of follow-up, there was no significant difference in the mean HbA1c levels among patients in groups 1 and 2. At 12 and 24 months of follow-up, there was no significant difference in peri-implant BOP, PD and MBL in both groups. CONCLUSIONS: Platform-switched implants can remain clinically and radiographically stable in patients with T2DM in a manner similar to non-diabetic individuals. However, it is emphasized that bone loss around implants is influenced by several factors (such as oral hygiene status, glycemic control and tobacco smoking) and not merely platform switching.

Comparison of clinical and radiographic status around dental implants placed in patients with and without prediabetes: 1-year follow-up outcomes.

OBJECTIVE: We hypothesized that peri-implant soft tissue inflammation is worse and peri-implant marginal bone loss (MBL) is higher around dental implants placed in patients with prediabetes compared to healthy subjects. The aim of the present 12-month follow-up study was to compare the clinical and radiographic status around dental implants placed in patients with and without prediabetes. MATERIAL AND METHODS: Twelve patients with medically diagnosed prediabetes (Group-1) and 12 controls (Group-2) were included. All patients were indicated for single tooth maxillary or mandibular premolar replacement with the adjacent teeth intact. Success of the restored implants was assessed by comparing clinical (peri-implant bleeding on probing [BOP], and probing pocket depth [PPD]) and radiographic (peri-implant MBL) parameters at baseline and at 12-months follow-up. Statistical analysis was performed using one-way analysis of variance, and P-values <0.05 were considered statistically significant. RESULTS: At 12 months of follow-up, there was no clinical evidence for the presence of plaque, BOP and peri-implant pockets with PPD ≥ 4 mm in both groups. At 12-month follow-up, the mean MBL among implants placed in groups 1 and 2 were 0.2 ± 0.1 mm and 0.1 ± 0.01 mm, respectively. Overall, the periodontal status (PI, BOP and PPD ≥ 4 mm) at 12-month follow-up was comparable among patients in both groups. CONCLUSION: Within the limitations of this study, it is concluded that dental implants inserted in prediabetic and healthy patients have similar success rates and remain clinically and radiographically stable after 1-year follow-up.

Comparison of clinical and radiographic parameters around short (6 to 8 mm in length) and long (11 mm in length) dental implants placed in patients with and without type 2 diabetes mellitus: 3-year follow-up results.

OBJECTIVE: To compare the clinical and radiographic parameters around short (6 to 8 mm in length) and long (11 mm in length) dental implants placed in patients with and without type 2 diabetes mellitus (T2DM). MATERIAL AND METHODS: Forty-five male patients with T2DM (Group-1) and 42 male non-diabetic controls (Group-2) who had undergone implant therapy in the posterior mandible were included. Depending upon the length of the implant, patients were divided into two subgroups: (a) patients with short implants (6-8 mm long) and (b) patients with long implants (11 mm long). Peri-implant plaque index (PI), bleeding on probing (BOP), probing depth (PD) and crestal bone loss (CBL) were measured at 18 and 36 months of follow-up in both groups. Hemoglobin A1c (HbA1c) levels were measured at baseline and after 18 and 36 months of follow-up in both groups. P-values less than 0.05 were considered statistically significant. RESULTS: The mean age of patients in groups 1 and 2 was 42.5 and 40.6 years, respectively. The mean HbA1c levels at baseline among patients in groups 1 and 2 were 7.7% and 4.5%, respectively. At 18 and 36 months of follow-up, the mean HbA1c levels among patients in groups 1 and 2 were 6.6% and 4.5% and 6.5% and 4.4%, respectively. The mean duration of T2DM among patients that received short and long implants was 4.3 years and 4.1 years, respectively. There was no significant difference in PI, BOP, PD and CBL around implants placed in both groups at 18 and 36 months of follow-up. Success rate of short and long dental implants was 100% in both groups. CONCLUSION: Short implants can demonstrate clinical and radiographic stability in a manner similar to conventional long implants in patients with and without T2DM. The role of oral hygiene and glycemic maintenance in this scenario cannot be disregarded.

Soft tissue changes and crestal bone loss around platform-switched implants placed at crestal and subcrestal levels: 36-month results from a prospective split-mouth clinical trial.

OBJECTIVE: The aim of the present 36-month prospective split-mouth clinical trial was to investigate the peri-implant soft tissue changes and crestal bone loss (CBL) around delayed loaded platform-switched implants placed at crestal and subcrestal levels. MATERIAL AND METHODS: Twenty-three individuals with bilaterally missing either mandibular first or second molars were included. The test and control sites were defined as follows: (i) test sites: implants placed 2 mm below the alveolar crest (subcrestal); (ii) control sites: implants placed at bone level (crestal). Forty-six implants (23 implants in test sites and 23 in control sites) were placed in the center of the healed alveolar ridge in the posterior mandible. Peri-implant bleeding on probing (BOP), probing depth (PD ≥ 4 mm), and CBL was compared at 6, 18, and 36 months of follow-up. P < 0.05 was considered statistically significant. RESULTS: Sixteen males and seven females with a mean age of 43.5 years (29-50) were included. In the control group (n = 23), the highest mean percentage of sites that showed BOP and PD ≥ 4 mm were at 6 months (7.4% and 1.4%, respectively). In the test group (n = 23), the highest mean percentage of sites that showed BOP and PD ≥ 4 mm were at 6 months (2.4% and 1.2%, respectively). The total amount of CBL around crestal and subcrestal implants after 36 months of loading was 0.45 ± 0.2 and 0.3 ± 0.2 mm, respectively. At all follow-up intervals, all intragroup and intergroup comparisons showed no significant differences in BOP, PD ≥ 4 mm, and CBL around implants placed at crestal and subcrestal levels. CONCLUSION: Up to 36 months of follow-up, soft tissue parameters and crestal bone levels can remain equally stable around dental implants placed at crestal and subcrestal levels. The need for long-term follow-up clinical trials is also emphasized.

Crestal Bone Loss Around Adjacent Dental Implants Restored with Splinted and Nonsplinted Fixed Restorations: A Systematic Literature Review.

PURPOSE: The aim of this systematic review was to compare the crestal bone loss around splinted and nonsplinted adjacent implants. MATERIALS AND METHODS: To address the focused question, "Is crestal bone loss around adjacent implants different with splinted from that with nonsplinted restorations?," indexed databases were searched from 1965 up to and including May 2016 using various combinations of the following keywords: "implant," "splinted," "nonsplinted," "unsplinted," "connected," "unconnected," "nonconnected," and "bone loss." Letters to the editor, commentaries, historic reviews, case reports, case series, animal studies, and studies on full-arch rehabilitation were excluded. RESULTS: Six studies were included with titanium implants ranging from 114 to 1187 implants. All studies had nonsplinted and splinted restorations that ranged from 20 to 234 restorations and from 60 to 970 restorations, respectively. In all the studies, the follow-up period after the restoration placement ranged between 1 and 22 years, with a mean follow-up ranging between 3 and 10.18 ± 3.18 years. In all studies, the mean crestal bone loss for implants restored with nonsplinted restorations ranged between 0.30 ± 0.65 and 1.3 ± 0.2 mm, whereas the mean crestal bone loss for implants restored with splinted restorations ranged between 0.50 ± 0.8 and 1.22 ± 0.95 mm. CONCLUSION: Within the limitations of this review it is concluded that adjacent implants restored with splinted and nonsplinted fixed restorations did not exhibit a difference in crestal bone loss. The evidence from this systematic review suggests further investigation.

Dental Implant Length and Diameter: A Proposed Classification Scheme.

PURPOSE: To propose a length-and-diameter-based classification scheme for dental implants to standardize terminology in the dental literature and communication between interested parties. MATERIALS AND METHODS: This study was mainly based on searching two major resources: published scientific research papers and 14 of the most popular dental implant manufacturers. Indexed databases were searched from January 2004 up to and including February 2016 using the keywords "dental implant length" and "dental implant diameter." Retrieved titles and abstracts were screened, and related full-text articles were reviewed. Full-text articles that clearly stated the terms and measurements of implants used were included and considered for proposing this classification scheme. RESULTS: The initial search for implant diameter and length yielded 1007 and 936 articles, respectively. A total of 85 studies (41 about diameter, 44 about length) were selected and reviewed. The remaining studies (966 about diameter, 892 about length) that did not abide by the eligibility criteria were excluded. The terms "long," "short," "standard," "wide," and "narrow" were the most commonly used terms in the literature. A classification scheme for implants by diameter and length was proposed. CONCLUSIONS: Indexed publications contain a variety of terms used by authors to describe diameter and length of dental implants without conformity and standardization. The classification scheme proposed in this article could serve as a reference for interested parties.

Effect of oral hygiene maintenance on HbA1c levels and peri-implant parameters around immediately-loaded dental implants placed in type-2 diabetic patients: 2 years follow-up.

OBJECTIVE: The aim of the present 2-year follow-up study was to assess the effect of oral hygiene maintenance on hemoglobin Alc (HbA1c) levels and peri-implant parameters around immediately-loaded dental implants placed in type-2 diabetic patients with varying glycemic levels. MATERIAL AND METHODS: Ninety-one individuals were divided into three groups. In group 1, 30 systemically healthy individuals were included (HbA1c < 6%). Patients in group 2 and 3, comprised of 30 patients with T2DM (HbA1c 6.1-8%); and 31 patients with T2DM (HbA1c 8.1-10%) respectively. In all groups, patients received immediately loaded bone level implants. All participants were enrolled in a 6 monthly periodontal/peri-implant maintenance program. Peri-implant bleeding on probing (BOP), probing depth (PD), and marginal bone loss (MBL) were measured at 6, 12, and 24 months of follow-up. RESULTS: Mean preoperative HbA1c levels in patients in groups 1, 2, and 3 were 4.5%, 6.8%, and 8.7% respectively. In group-1, there was no significant difference in HbA1c levels at all follow-up durations. Among patients in groups 2 and 3, there was a significant decrease in HbA1c levels at 24-months follow-up than 6-months follow-up. At 6 months follow-up, BOP, PD, and MBL were significantly higher among patients in group-3 than group-1. At 12 and 24 months follow-up, there was no significant difference in BOP, PD, and MBL in all groups. CONCLUSIONS: Oral hygiene maintenance reduces hyperglycemia and peri-implant inflammatory parameters around immediately loaded dental implants placed in type 2 diabetic patients.

Efficacy of parathyroid hormone supplementation on the osseointegration of implants: a systematic review.

OBJECTIVE: The aim of the present systematic review was to assess the efficacy of parathyroid hormone supplementation on the osseointegration of implants. METHODS: The addressed focused question was Does parathyroid hormone supplementation affect osseointegration around implants? Indexed databases were searched from 1965 up to and including April 2015 using various key words including: Bone to implant contact; implant; parathyroid hormone; and osseointegration. Letters to the Editor, case-reports/case-series, historic reviews, commentaries and articles published in languages other than English were excluded. The pattern of the present systematic review was customized to primarily summarize the pertinent data. RESULTS: Eighteen studies fulfilled the eligibility criteria. Evidence was limited to preclinical animal studies only (11 studies in rodents, 4 in dogs and 3 in rabbits). Number of titanium implants placed ranged between 20 and 80 implants. Results from 16 studies showed that PTH supplementation enhanced new bone formation and/or BIC around implants. One study suggests that PTH-coated implants improve BIC and BA. One study showed no significant difference in BIC and new bone formation around implants with PTH hydrogel placement. CONCLUSION: Efficacy of PTH supplementation on osseointegration of implants shows promising results in animal models, however further investigation is necessary to assess the effectiveness in humans.

Crestal bone loss around submerged and nonsubmerged dental implants: A systematic review.

STATEMENT OF PROBLEM: To my knowledge, there is no systematic review of crestal bone loss (CBL) around submerged and nonsubmerged dental implants. PURPOSE: The purpose of this review was to systematically assess CBL around submerged and nonsubmerged dental implants. MATERIAL AND METHODS: The addressed focused question was, "Does crestal and subcrestal placement of dental implants influence crestal bone levels?" Databases were searched from 1986 through October 2015 using different combinations of the following keywords: crestal, sub-crestal, bone loss, dental implant, submerged, and nonsubmerged. Reference lists of potentially relevant original and review articles were hand-searched to identify any further studies. Letters to the editor, case reports, commentaries, studies on platform-switched implants, and studies published in languages other than English were excluded. RESULTS: In total, 13 studies (6 human and 7 animal), which were performed at universities, were included. In the human studies, the number of participants ranged from 8 to 84 individuals. The follow-up period ranged from 1 to 5 years. CBL at the test sites ranged from 0.17 mm to 0.9 mm and at control sites from 0.02 mm to 1.4 mm. Five human studies reported no significant difference in CBL around implants placed at the test and control sites. All animal studies were performed in dogs with a mean age ranging from 1 to approximately 2 years. The follow-up period ranged from 2 to 6 months. Four animal studies reported no significant difference in CBL around submerged and nonsubmerged implants. CONCLUSION: No significant difference in CBL was found around submerged and nonsubmerged dental implants.

Influence of interimplant distance on the crestal bone height around dental implants: A systematic review and meta-analysis.

STATEMENT OF PROBLEM: Indexed publications lack a systematic review and meta-analysis of the influence of interimplant distance on the interproximal crestal bone height (ICBH) around implants. PURPOSE: The purpose of this systematic review and meta-analysis was to assess the influence of interimplant distance on ICBH around implants. MATERIAL AND METHODS: The question addressed was, "Does interimplant distance influence the ICBH around implants?" Indexed databases from 1978 up to April 2015 were searched by using the keywords "crestal bone level", "bone loss", "bone height", and "interimplant distance." Reference lists of potentially relevant original and review articles were searched manually to identify any unidentified studies. Articles available online in electronic form ahead of print were eligible for inclusion. Letters to the Editor, case reports, case series, commentaries, studies involving bone augmentation procedures, and studies published in languages other than English were excluded. A meta-analysis of mean differences in ICBH among study groups was also performed. RESULTS: In total, 5 animal studies with relatively short follow-up periods (2-12 months) were included. Results from 4 studies showed no significant differences in ICBH around implants placed 1 to 3 mm apart. However, 1 of the 5 studies found that vertical bone loss was significantly lower in implants that had an interimplant distance of 5 mm than those placed at a distance of 1 mm. Platform switched and rough surface implants were used in all studies. CONCLUSIONS: The influence of interimplant distance on ICBH around dental implants remains unclear.

Customized CAD-CAM healing abutment for delayed loaded implants.

When conventional prefabricated healing abutments are used, the surrounding soft tissue profile may be unfavorable at the time for restorative treatment, requiring additional time-consuming recontouring. This article presents a technique for fabricating a customized computer-aided design and computer-aided manufacturing (CAD-CAM) healing abutment for a delayed loaded dental implant placed in the region of a missing maxillary right first premolar. A surgical guide was fabricated and a definitive cast was made from the surgical guide. The cast was digitized using a scanner, and a customized healing abutment was digitally designed using computer software. The presented technique provides guided implant placement and predicts optimum soft tissue contours that enhance the implant emergence profile.

Management of a Fractured Multiunit Maxillary Implant-Supported Fixed Prosthesis with Stripped Abutment Screws Using a Hybrid Cement-Retained and Screw-Retained Design: A 5-Year Follow-Up Clinical Report.

Fracture and loosening of implant-supported prostheses (ISPs) are complications encountered in routine dental practice. In the present report, management of a fractured maxillary full-arch cement-retained (CR) fixed dental prosthesis supported by six implants is presented. Due to stripped screws, complications were encountered that prevented the retrieval of two of the six abutment screws, which was managed by using a hybrid retention approach, whereby a single full-arch CR and screw-retained (SR) ISP was used. The techniques used to successfully retrieve four of the abutment screws are described. The final retention design involved a combination of three CR and three SR restorations, which offers the advantages of both retention designs.

Reasons for not using Implants to retain Complete Denture: Patients' Survey.

OBJECTIVE: This study aimed to gain more information from complete denture (CD) wearers who did not receive dental implants, of the reasons preventing them from using implants to retain their CD in a selected sample of dental patients in Riyadh, Saudi Arabia. MATERIALS AND METHODS: A paper-and-pencil questionnaire containing 20 direct questions of the possible reasons preventing CD wearers from receiving implants to retain their dentures was distributed in three different places in Riyadh, Saudi Arabia. RESULTS: A total of 270 subjects were included in this survey. The results showed that 180 (66.7%) patients indicated that the fear of pain associated with implant placement was the main reason preventing them from receiving an implant treatment, followed by fear of the surgical procedure (175, 64.8%), fear of postoperative complications (166, 61.5%), information from other people about the various problems associated with implant treatment (154, 57%), and finally cost of the implant (141, 52.2%). CONCLUSION: Fear is the main reason preventing CD wearers from receiving implant treatment. Therefore, it is essential for dentists to be familiar with the reasons for implant refusal to overcome a common, yet an influential obstacle.