Proposal regarding horizontal and vertical positioning of single implants placed in healed sites: Effect on cervical crown form and the need for bone grafting.

STATEMENT OF PROBLEM: When single implants are placed in healed sites, guidelines are lacking on the horizontal and vertical implant positions that optimize cervical crown form and the implant locations that would require bone grafting to develop the optimal crown form. PURPOSE: The purpose of this clinical study was to evaluate the cervical contour of wax patterns formed on casts of single implants placed in healed sites and to determine which horizontal and vertical implant positions produced the best cervical crown form and which indicated the need for bone grafting. MATERIAL AND METHODS: Fifty-eight wax patterns were fabricated on casts where implants had been placed in healed sites without bone grafting. The wax patterns were subjectively assessed by 5 dental faculty members and 5 graduate students as having good, fair, or poor cervical crown form. Horizontal measurements were made between the facial surface of the implant and a round metal wire connecting the gingival zeniths of the adjacent teeth. Vertical measurements were also made between the wire and implant platform. The subjective assessments along with the horizontal and vertical implant position measurements were used to propose guidelines for optimal implant placement in healed sites. RESULTS: Horizontal distances of 2.0 to 3.0 mm produced good cervical crown contours, with distances >3.0 mm and <2.0 mm resulting in fair or poor assessments. Vertical distances of 3.0 to 4.0 mm were judged to have good cervical crown contour, whereas depths of 1.0 mm or less were assessed as poor. CONCLUSIONS: Based on the subjective assessment of wax patterns formed on casts of single implants placed in healed sites, a guideline of 2.0 to 3.0 mm is proposed for the horizontal distance between a line connecting the adjacent gingival zeniths and the facial surface of the implant. A vertical distance guideline of 3.0 to 4.0 mm is proposed between the adjacent gingival zeniths and the implant platform.

Orthodontic tooth extrusion to regenerate missing papilla adjacent to maxillary anterior single implants: A 2- to 7-year retrospective study.

INTRODUCTION: Regeneration of the missing papilla adjacent to single implants in the esthetic zone has always been challenging, despite advances in vertical hard and soft tissue regeneration. Orthodontic tooth extrusion has been shown to effectively gain alveolar bone and gingival tissue. This retrospective study evaluated the effectiveness of orthodontic tooth extrusion on regenerating missing papilla between existing maxillary anterior single implant and its adjacent tooth. METHODS: Patients who underwent orthodontic tooth extrusion to regenerate missing papilla adjacent to a single implant in the esthetic zone were included in this study. The gingival phenotype, orthodontic extrusion movement, proximal bone level, dento-implant papilla level, facial gingival level, mucogingival junction level, and keratinized tissue width, of the extruded tooth were recorded at pre-orthodontic extrusion (T0 ), post-orthodontic extrusion and retention (T1 ), and latest follow-up (T2 ). RESULTS: A total of 17 maxillary single tooth had orthodontic tooth extrusion to regenerate missing papilla adjacent to 14 maxillary anterior single implants in 14 patients. After a mean follow-up time of 48.4 months, implant success rate was 100% (14/14), with none of the orthodontically extruded teeth being extracted. After a mean extrusion and retention period of 14.3 months, a mean orthodontic extrusion movement of 4.62 ± 0.78 mm was noted with a mean proximal bone level gain of 3.54 ± 0.61 mm (77.0% efficacy), dento-implant papilla level gain of 3.98 ± 0.81 mm (86.8% efficacy), and facial gingival tissue gain of 4.27 mm ± 0.55 mm (93.4% efficacy). A mean keratinized tissue width gain of 4.17 ± 0.49 mm with minimal mean mucogingival junction level change of 0.10 ± 0.30 mm were observed. The efficacy of orthodontic eruption movement on dento-implant papilla gain was less in the thin (80.5%) phenotype group when compared with that in the thick (91.5%) phenotype group. CONCLUSIONS: Within the confines of this study, orthodontic extrusion is an effective, noninvasive method in regenerating mid-term stable proximal bone and papilla adjacent to maxillary anterior single implants. CLINICAL SIGNIFICANCE: This retrospective study presents a mid-term result on orthodontic extrusion as a mean to regenerate dento-implant papilla defect. The extended retention period following orthodontic extrusion showed stable and efficacious proximal bone and papilla gain.

Effects of cyclic loading on loss of abutment screw torque of angled screw channel single implant crowns on narrow diameter implants.

STATEMENT OF PROBLEM: Screw access channels that emerge on the facial aspect of anterior screw-retained implant crowns can compromise esthetics. Recently, angled screw channels (ASCs) have been developed that can alter screw access channel angulations to improve esthetics. While ASCs can be used on narrow-diameter implants, information is limited on the loss of abutment screw torque on narrow-diameter implants with ASCs. PURPOSE: The purpose of this in vitro study was to compare the loss of abutment screw torque after thermocycling and the cyclic loading of ASCs from 3 different companies connected to narrow-diameter implants. MATERIAL AND METHODS: A total of 40 narrow-diameter implants (NobelReplace Conical Connection 3.5×11.5 mm) were mounted individually in acrylic resin blocks and divided equally into 4 groups. The first group, NB-0 (Control), consisted of screw-retained zirconia crowns fabricated on ASCs at 0-degree angulation (n=10). The other 3 groups consisted of a total of 30 screw-retained zirconia crowns fabricated on ASCs at 20-degree angulation: NB-20 (Angulated Screw Channel Solutions), ATL-20 (Atlantis Custom Base Solution with angulated screw access), and DA-20 (Dynamic TiBase). Each crown was secured on the mounted implant with its corresponding titanium base insert and screw and then tightened to the manufacturer's recommended torque with a digital torque gauge. The initial reverse torque value (RTVI) was obtained and recorded at baseline. Subsequently, a new set of screws were tightened to recommended values, and each specimen underwent thermocycling and then cyclic loading at 0 to 100 N at 10 Hz for 1 million cycles to simulate 1year of functional loading. After cyclic loading, the final reverse torque values (RTVF) were recorded and compared with the RTVI to evaluate the percentage torque loss (PTLF). Statistical analysis was performed using the Kruskal-Wallis analysis, Rank base analysis of covariance (ANCOVA), and the Tukey HSD post hoc comparisons (α=.05). RESULTS: Significant differences were found for the PTLF among all groups after cyclic loading (P<.001). The PTLF in ATL-20 (51.4%) was significantly higher than in NB-0 (22.2%) (P<.001) and NB-20 (29.2%) (P=.010). No significant difference was found in the PTLF among other groups (P>.05). CONCLUSIONS: The abutment screw torque loss after cyclic loading of the ASCs on narrow diameter implants among the 4 groups did not perform comparably. The largest percentage torque loss was recorded for the ATL-20 group. The NB-20 group demonstrated the lowest percentage torque loss. DA-20 showed percentage torque loss less than ATL-20; however, its RTVF was the lowest.

Facial Contour Preservation of Anterior Immediate Single-Tooth Replacement With the Socket Shield Technique Versus Connective Tissue Graft: A Case Report.

The socket shield technique and subepithelial connective tissue graft following immediate implant placement with provisionalization had been advocated for peri-implant facial contour and gingival architecture preservation. This case report used three-dimensional volumetric analysis to longitudinally assess the peri-implant facial contour change before and after these procedures. The results demonstrated comparable and acceptable preservation of peri-implant facial contour between the two procedures after 2 years of function.

Inter-implant Papilla Changes Following Anterior Immediate Tooth Replacement with Socket Shields: A 1- to 10-Year Retrospective Study.

This retrospective study investigates the efficacy of the socket shield (SS) in preserving inter-implant papilla and bone in anterior adjacent implant sites. Clinical and radiographic records of 23 patients were evaluated. A total of 31 implants were placed immediately into extraction sockets with SS, resulting in 26 inter-implant sites, and 7 implants were placed without SS. After a mean follow-up of 41.5 months (range: 12 to 124 months), 30/31 (96.8%) implants with SS and 7/7 (100%) implants without SS were clinically successful. The mean changes in inter-implant papilla and bone heights were -0.40 mm and -0.46 mm, respectively. The effects of implant placement timing and the socket shield number, shape, and crestal level on inter-implant tissue height changes were found to be insignificant (P > .05). Supracrestal shield level (31.6% vs 16.6% in equicrestal), U-shape shield (41.2% vs 7.1% in C-shape), and shield-to-implant contact (40.0% vs 12.5% in no contact) were associated with increased occurrence of exposures. The application of SS in adjacent anterior implant situations is a viable treatment option for maintaining inter-implant papilla.

Effect of implant abutment screw materials and tightening protocols on reverse tightening values: An in vitro study.

STATEMENT OF PROBLEM: Implant abutment screw loosening is the most common prosthetic complication of implant-supported single crowns. However, few studies have objectively evaluated the effectiveness of different tightening protocols on reverse tightening values (RTVs). PURPOSE: The purpose of this in vitro study was to determine the optimal tightening protocol for implant abutment screws with different screw materials. MATERIAL AND METHODS: Sixty implants from 2 implant systems (Keystone and Nobel Biocare) with different definitive screw materials were selected. One group used diamond-like carbon (DLC) coated screws (DLC Group), and the other used titanium nitride (TiN) screws (TiN Group). Each group consisted of 30 implants. The implants in each group were distributed randomly into 3 subgroups (n=10). The implants from both manufacturers were mounted in resin blocks by following a clinical component connection protocol: a cover screw was placed, then an impression coping, and finally an original manufacturer prefabricated abutment. The abutment screws were tightened to the manufacturer's recommended tightening value using 3 different protocols: tighten the screw once (1T); tighten the abutment screw to the recommended tightening value, wait 10 minutes, and then retighten (2T); and tighten the abutment screw to the recommended tightening value, countertighten, tighten, countertighten, and then tighten (3TC). RTVs were measured after 3 hours. The Shapiro-Wilk test was performed to test for normal distribution of the data. The Kruskal-Wallis test was applied to each system's group that was not normally distributed (P<.05). Where differences existed, a post hoc analysis using the Dwass-Steel-Critchlow-Flinger (DSCF) pairwise comparisons test was conducted. RESULTS: No significant differences were found among the 3 different tightening groups in the TiN group (P>.05). However, significant differences were found among the 3 different tightening protocols in the DLC group (P<.05). CONCLUSIONS: Abutment screw systems from different manufacturers behave differently with respect to how they are tightened. For the TiN screw group, statistically similar RTVs were found for the 3 tightening protocols. The most efficient tightening protocol for the DLC-coated screw was the 3TC-DLC.

Facial Mucosal Level Change Following Maxillary Anterior Single Immediate Tooth Replacement in Extraction Sockets With Facial Bone Wall Defects: A 4- to 15-Year Retrospective Study.

An intact extraction socket has been considered a prerequisite for an immediate implant placement and provisionalization (IIPP) procedure. Recent studies, however, have shown successful outcomes when IIPP was performed in sockets with a facial bone wall defect. This retrospective study evaluated the facial implant mucosal stability following IIPP in extraction sockets with a facial bone wall defect in the esthetic zone. The study included 16 cases in 16 patients who received maxillary anterior single IIPP with contour bone graft (C-BG) and contour connective tissue graft (C-CTG) in compromised extraction sockets (V- or U-shaped defect). After a mean follow-up of 6 years, the implant success rate was 100% (16/16). Minimal and non-statistically significant changes were noted in the facial implant mucosal and marginal bone level. Statistically significant changes were observed in facial implant mucosal thickness gain (2.5 mm [1.8 mm to 3.5 mm]) and midfacial bone sounding reduction (6 mm). Within the confines of this study, IIPP with simultaneous C-BG and C-CTG in fresh extraction sockets exhibiting a V- or U-shaped facial bone wall defect can lead to long-term successful outcomes in terms of mucosal stability, contour bone gain, and marginal bone level stability.

Frequency of screw-retained angulated screw channel single crown following immediate implant placement and provisionalization in the esthetic zone: A cone beam computed tomography study.

OBJECTIVE: The purpose of this cone beam computed tomography (CBCT) study was to determine the frequency percentage of screw-retained crown using angulated screw channel (ASC) abutment for single immediate implant placement and provisionalization (IIPP) in the esthetic zone. METHODS: The CBCT images of 200 patients without disease and without metal restorations in maxillary anterior teeth were evaluated. The mid-sagittal-sectional CBCT images of maxillary anterior teeth (#6-#11) were created in an implant planning software, screen-captured, and transferred to a presentation program. Template of tapered implants with diameter of 3.5 mm (for central and lateral incisors) and 4.3 mm (for central incisors and canines) and lengths of 13, 15, and 18 mm were applied to the sagittal images to identify the IIPP cases. To qualify for IIPP, the implant must engage >35% bone with at least 1 mm of surrounding bone and no perforations. The IIPP cases were further divided into straight screw channel (IIPPSSC) abutment or 25-degree angulated screw channel abutment (IIPPASC), based upon its restorability. The frequency percentages of possible IIPP, IIPPSSC, and IIPPASC were reported and compared among all maxillary anterior teeth. RESULTS: A total of 1200 maxillary anterior teeth sagittal images from 200 patients (88 male and 112 female) with a mean age of 51.3 years (range 20-83 years) were evaluated in this study. The overall frequency percentages of IIPP, IIPPSSC, and IIPPASC possibility were 84% (74%-92%), 14% (10%-24%), and 75% (66%-87%), respectively. CONCLUSION: Within the limitations of this CBCT study, 90% of single IIPP in the esthetic zone can be restored with screw-retained crown when utilizing ASC. In addition, the possibility of using a screw-retained restoration following IIPP increases about five times with ASC abutment compared to the SSC abutment.

Management of Root Sensitivity following Socket Shield Technique with Anterior Single Immediate Implant Placement and Provisionalization.

Maintaining facial soft tissue contour and inter-implant papilla are challenging for implants in the esthetic zone. To counteract the inevitable hard and soft tissue changes after tooth extraction, the socket shield technique (SST) has been advocated as means to maintain the facial and/or interproximal osseous and gingival architecture. Because SST is a technique-sensitive procedure, various complications related to SST have been reported. This article presents a unique complication after a socket shield procedure and a novel management of the complication. Int J Periodontics Restorative Dent 2023;43:157-165. doi: 10.11607/prd.5426.

Complications Associated with Metal Resin Fixed Complete Dentures Based on Implant Distribution.

PURPOSE: To compare prevalence and type of complications associated with metal resin fixed complete dentures based on implant distribution. MATERIALS AND METHODS: This retrospective study included data collected for a period of 12 years for patients treated with maxillary and mandibular implant-supported fixed complete dentures at Loma Linda University School of Dentistry. In total, 223 patient's charts were reviewed which included 100 maxillary and 123 mandibular fixed complete dentures. Implant distribution and prevalence of complications associated with each implant-supported fixed complete denture were documented. Tooth delamination, the most common complication associated with fixed complete dentures, was compared between 2 implant distribution groups in each arch. Covariates including age, sex, opposing arch, cantilever occluding units, and number of implants were evaluated to determine their association with tooth delamination. Data and hypotheses were statistically analyzed using descriptive statistics along with logistic regression model. All tests of hypotheses were considered statistically significant at an alpha level of 0.05. RESULTS: In the maxillary arch, some effect of the prevalence of tooth delamination was seen for the group that had implants placed posterior to canine eminence but it was not statistically significant. Denture tooth delamination had the highest prevalence among complications irrespective of implant distribution. Significant denture tooth delamination was seen for patients with opposing fixed complete dentures in comparison to patients with removable opposing arch prostheses. CONCLUSIONS: Implant distribution is not a significant factor related to metal resin fixed complete dentures. Opposing fixed complete dentures have a significantly higher association with denture tooth delamination.

Facial implant gingival level and thickness changes following maxillary anterior immediate tooth replacement with scarf-connective tissue graft: A 4-13-year retrospective study.

OBJECTIVE: A scarf-shaped connective tissue graft can be placed at the facial and proximal aspect of the peri-implant soft tissue zone during immediate implant placement and provisionalization (IIPP) procedures in the esthetic zone to optimize implant esthetics without the need of flap reflection. This retrospective study evaluated soft tissue stability after scarf-connective tissue graft (S-CTG) in conjunction with IIPP procedures in the esthetic zone. MATERIALS AND METHODS: Patients who received IIPP with S-CTG with a minimum 1-year follow-up were evaluated. Mid-facial gingival level (MFGL) change and mid-facial gingival thickness (MFGT) change were measured and compared at the pre-op (T0), IIPP + S-CTG surgery (T1), follow up appointment with MFGT measurement (T2), and latest follow-up appointment (T3). Implant success rate and graft necrosis were also recorded. RESULTS: A total of 22 IIPP and S-CTG procedures in 20 patients were evaluated in the study. After a mean follow-up of 8.2 years (3.9-13.4) (T3), all implants remained osseointegrated (22/22 [100%]), with statistically insignificant mean midfacial gingival level change of -0.19 mm (-1.5 to 0.8). Statistically significant difference in midfacial gingival thickness (MFGT) was noted (2.5 mm [1.8-3.5 mm]) after a mean follow-up time (T2) of 2.3 years (1-8.6) when compared with MFGT at baseline (1.1 mm [0.6-1.3 mm]) (T1). Necrosis of S-CTG during initial healing phase was noted in 9% (2/22) of the sites. CONCLUSIONS: Within the confines of this study, scarf-connective tissue graft at time of immediate implant placement and provisionalization can thicken the gingiva and maintain the gingival level at the critical soft tissue zone. CLINICAL SIGNIFICANCE: Managing the soft tissue zone is as important as that of the hard tissue zone for peri-implant esthetics. Connective tissue graft is one of the methods that can enhance the final esthetic outcomes. This retrospective study has demonstrated that Scarf-CTG technique is an effective treatment modality to maintain soft tissue stability.

Management of Root Sensitivity following Socket Shield Technique with Anterior Single Immediate Implant Placement and Provisionalization.

It is challenging for implants in the esthetic zone to maintain the facial soft tissue contour and interimplant papillae. To counteract the inevitable hard and soft tissue changes after tooth extraction, the socket shield technique (SST) has been advocated as means to maintain the facial and/or interproximal osseous and gingival architecture. As SST is a technique-sensitive procedure, various complications related to SST have been reported. This article presents a unique complication after a socket shield procedure and a novel management of the complication.

Radiographic protrusion of dental implants in the maxillary sinus and nasal fossae: A multidisciplinary consensus utilising the modified Delphi method.

The aim of the present study was to generate an international and multidisciplinary consensus on the clinical management of implant protrusion into the maxillary sinuses and nasal fossae. A total of 31 experts participated, 23 of whom were experts in implantology (periodontologists, maxillofacial surgeons and implantologists), 6 were otolaryngologists and 2 were radiologists. All the participants were informed of the current scientific knowledge on the topic based on a systematic search of the literature. A list of statements was created and divided into three surveys: one for all participants, one for implant providers and radiologists and one for otolaryngologists and radiologists. A consensus was reached on 15 out of 17 statements. According to the participants, osseointegrated implants protruding radiographically into the maxillary sinus or nasal fossae require as much monitoring and maintenance as implants fully covered by bone. In the event of symptoms of sinusitis, collaboration between implant providers and otolaryngologists is required. Implant removal should be considered only after pharmacological and surgical management of sinusitis have failed.

Scanning accuracy with splinted and unsplinted implant scan bodies for the edentulous arch at implant level: an in vitro study.

Accuracy of completely edentulous arch scanning with implant scan bodies has not been completely validated for intraoral scanners. For desktop laboratory scanners validations were found in the literature. The aim of this in vitro study was to compare the dimensional accuracy of scanning with splinted and unsplinted scan bodies on a completely edentulous maxillary arch with 6 implants. A maxillary edentulous master cast with 6 implants was used as control for all implant level impressions. 6 implants were digitally planned and placed at different angulation of 0, 0  17° and 30°. A contact coordinate measuring machine (CMM) was used to generate baseline linear measurements of the master cast. Four test groups included: 2 intraoral scanners Trios (3shape, Copenhagen, Denmark) and True Definition (3M ESPE, St Paul, MN), one industrial scanner Atos (Core optical 3D scanner) and one conventional impression group scanned with laboratory scanner Dental Wings 7 Series. Each scan recording was made with splinted and unsplinted scan bodies. Digital datasets of all measurements were compared with the CMM baseline values using PolyWorks® InnovMetric Software in order to assess the linear and angular deviations and determine the accuracy of complete arch digital impression. Factorial ANOVA showed significant effect with splinting, scanner type, inter-implant distance and implant angulation for linear deviations. Splinted scan bodies revealed elevated linear and angular deviation values for all scanners with significantly highest deviations for True Definition scanner. Significant correlation was found between inter-implant distance and linear deviation (r =0.45, P =<0.001) with increased linear deviations among all scanners, regardless of splinting. ( P <0.05). Significant effect on accuracy was seen for angular deviation with splinting, scanner type and implant angulation; significant difference was found between 0° and 30° implant angulation ( P =0.035) with more deviation with 30° implant angulation. The accuracy of the complete arch implant digital impression using splinted scan bodies was significantly reduced for measurements that crossed the arch midline. The digital impression technique using a broad splint design to connect scan bodies was not found to improve the scan accuracy for intraoral scanners.

Exposure of Barriers Used in Guided Bone Regeneration: Rate, Timing, Management, and Effect on Grafted Bone-A Retrospective Analysis.

The purpose of this study is to compare the exposure rate of 3 different barrier types after a guided-bone regeneration procedure as well as to compare the percentage grafted bone dimensional loss with and without exposed barriers. Patient records from September 2007 to May 2015 were reviewed to identify subjects who had received a bone graft followed by implant placement procedure after the graft had completely healed. The subjects were divided into 3 groups: (1) resorbable barrier, (2) nonresorbable barrier, and (3) titanium-mesh barrier. Incidences of barrier exposure were recorded. Cone-beam computerized tomography images before treatment (T0), right after grafting (T1), and after healing (T2) were used to determine the percentage of grafted bone dimensional loss and am quantitative amount of grafted bone remaining (mm2). Three cross-sectioned areas, at 1-mm apart, of preplanned implant positions at the grafted site were measured using cone-beam computerized tomography to calculate the remaining grafted bone and grafted bone dimensional change. The exposure rate of all guided bone regeneration was 36.9%. The exposure rate of the resorbable barrier (23.3%) was significantly lower than titanium mesh (68.9%) and nonresorbable (72.7%; χ2, P < .001). The results of this study revealed that barrier types have a significant effect on the exposure rate. There was also a significant difference in grafted bone dimensional loss between sites with barrier exposure (58.3%) and sites with no barrier exposure (44.1%) during the healing period (Mann-Whitney U test, P = .008).

Heat and Sound Generation During Implant Osteotomy When Using Different Types of Drills in Artificial and Bovine Bone Blocks.

The purpose of this study was to compare heat and sound generated during implant osteotomy when different types of drill were used in artificial bone and bovine bone blocks. A total of 80 implant osteotomies were formed using 4 implant drilling systems: N1 (OsseoShaper) (Nobel), NobelActive (Nobel), V3 (MIS), and BLX (Straumann) in both artificial bone and bovine bone blocks. Thermocouple probes were used to record temperature change at the depths of 5.0 mm and 13.0 mm of each implant osteotomy formed by the final drill. In addition, thermographic images, drilling sound, and drilling time were recorded and evaluated. Statistical analyses were performed at α = 0.05. The mean temperature changes as recorded by thermocouple probes and thermocamera were significantly lower in OsseoShaper than most other drill-bone combinations (P < .05). The mean drilling times and sound generation for OsseoShaper were significantly higher and lower than most other drill-bone combinations (P < .05), respectively. Minimal heat and sound generation can be expected when implant osteotomies are performed using OsseoShaper at a low rotational speed (50 rpm) even without irrigation. However, extended drilling time is required.

Incidence of Straight-Channel Screw-Retained Single Crown Following Immediate Implant Placement and Provisionalization in the Esthetic Zone: A CBCT Study.

PURPOSE: The purpose of this cone beam computed tomography (CBCT) study was to investigate the probability of using straight screw-channel screw-retained restorations following an immediate implant placement and provisionalization protocol in maxillary anterior teeth utilizing implant planning software. MATERIALS AND METHODS: A retrospective review of CBCT images was done. The midsagittal images of maxillary anterior teeth (right canine to left canine) were created in implant planning software, screen-captured, and transferred to a presentation program. The digital implant templates were created for 3.5-mm-diameter (used for central and lateral incisors) and 4.5-mm-diameter (used for central incisors and canines) tapered implants with lengths of 13, 15, and 18 mm. The frequency percentages of immediate implant placement and provisionalization and immediate implant placement and provisionalization with straight screw-channel screw-retained restorations were recorded and compared among all maxillary anterior teeth. RESULTS: CBCT images from 1,200 teeth were evaluated. The overall frequency percentages of immediate implant placement and provisionalization and immediate implant placement and provisionalization with straight screw-channel screw-retained restoration were 84% (range = 74% to 92%) and 14% (range = 10% to 24%), respectively. CONCLUSION: Although the probability of being able to employ immediate implant placement and provisionalization with a straight screw-channel screw-retained restoration in the esthetic zone is low, the use of smaller-diameter implants can substantially increase the probability.

Abutment screw torque changes with straight and angled screw-access channels.

STATEMENT OF PROBLEM: Angle-correcting options allow the use of screw-retained implant prostheses in situations where an implant has been placed with a facial inclination. However, manufacturers have different recommended torque values, and it is unclear whether the performance of these designs is equivalent to that of the traditional screw-retained crowns (SRCs) when subjected to cyclic loading forces. PURPOSE: The purpose of this in vitro study was to compare torque differences between conventional straight-line screw access and angulated access SRCs before and after simulated functional loading. MATERIAL AND METHODS: Five groups consisting of 10 SRCs and implants were formed: Nobel Biocare zirconia crowns with 20-degree access channels (NB-20); Dynamic Abutment Solution zirconia crowns (DA-20) with 20-degree access channels; Core3dcentre angle correction zirconia crowns with 20-degree access channels (C3D-20); Nobel Biocare zirconia crowns with 0-degree access channels (NB-0); and gold alloy crowns cast to Nobel Biocare Gold-Adapt abutments (GA-0). Each specimen underwent thermocycling before cyclic loading. A preload torque based on the manufacturer's recommendation was applied to each crown placed on an implant. Reverse torque measurements were obtained for each specimen before cyclic loading. Each implant-abutment assembly was then cyclic loaded at 0 to 100 N at 10 Hz for 1 million cycles. Reverse torque measurements were obtained after cyclic loading and the percentage difference calculated. RESULTS: No significant percentage torque loss differences were observed between the 0-degree and 20-degree SRCs after cyclic loading. No significant differences were seen among the angulated access channel crowns. DA-20 and C3D-20 specimens had significantly higher torque loss compared with the NB-0 group. The C3D-20 group reported the largest percentage torque loss (34.5%) among the angulated access screw channel groups. The GA-0 group reported the largest percentage torque loss of all the groups (35.9%). No crown mobility or other complications were observed in any of the groups after cyclic loading. CONCLUSIONS: Angulated access channel crowns performed comparably with conventional straight-line screw access SRCs with regard to percentage torque values after cyclic loading. Angulated access channel crowns with lower manufacturer recommended torque values had higher percentage torque differences.

Long-term crestal bone changes in implants placed in augmented sinuses with minimal or moderate remaining alveolar bone: A 10-year retrospective case-series study.

OBJECTIVES: To evaluate long-term clinical and radiographic outcomes of dental implants placed after lateral window sinus augmentation utilizing the sagittal sandwich technique. MATERIALS AND METHODS: Patients treated with sinus augmentation were included in this retrospective case-series study. The surgical procedure was performed with particulate autogenous bone- and anorganic bovine bone-derived mineral (3:7 ratio). Implants were grouped based on baseline residual alveolar ridge height: group S (residual alveolar ridge height of 0.1-3.5 mm), group M (height of 3.5-7mm), and group C (native bone). Radiographs were taken at baseline (abutment installation) and annually throughout the 10-year follow-up. RESULTS: A total of 86 patients (92 sinus lifts) and 209 implants were included. Ten sinus membrane perforations were recorded (11% incidence), and graft infections occurred in 3 cases (3.2% incidence). During the 10-year follow-up, 3 implants (1.4%) failed. No significant differences in the mean implant marginal bone loss (MBL) between the three groups were found after 1-, 2-, and 5-year follow-up (p > .05). At 10 years, group C exhibited more MBL than group M with a mean difference of -0.53 mm (p = .01). After 10 years, MK III implants displayed significantly more bone loss in native bone than those in augmented bone with a mean difference of 0.48 mm (p = .02). Five patients and 7 implants developed peri-implantitis with no significant differences between the groups (p = .570). CONCLUSION: Implant placement after two-stage sinus grafting utilizing the sagittal sandwich technique is a relatively safe and predictable procedure with minimal complications and MBL after 10-year follow-up.

Facial Gingival Changes With and Without Socket Gap Grafting Following Single Maxillary Anterior Immediate Tooth Replacement: One-Year Results.

This 1-year prospective study evaluated horizontal and vertical facial gingival tissue changes after immediate implant placement and provisionalization (IIPP) with and without bone graft in the implant-socket gap (ISG). During IIPP, 10 patients received bone graft material in the ISG (G group), while the other 10 patients did not (NG group). The implants were evaluated for implant stability quotient (ISQ), modified plaque index (mPI), modified bleeding index (mBI), marginal bone level (MBL), facial gingival level (FGL), and facial gingival profile (FGP) changes. The mean ISQ value at 9-month follow-up was statistically significantly greater than on the day of implant surgery (P < .05). The mPI and mBI scores demonstrated that patients were able to maintain a good level of hygiene. There were no statistically significant differences in the mean MBL changes between the G and NG groups (P > .05). There were statistically significant differences in FGL changes between the G (-0.77 mm) and NG (-1.35 mm) groups (P = .035). There were no statistically significant differences in FGP changes between the G and NG groups (P > .05). However, statistically significant differences were noted in FGP change between the 3-12 and 0-12 month intervals in both groups (P < .05). Within the limitations of this study, although no significant differences were noted in FGP changes between groups, G group experienced significantly less FGL changes than NG group. Bone graft material placement into ISG seems to be advantageous for tissue preservation during IIPP. However, future long-term studies, with larger sample size, are needed to validate the efficacy of such procedure.