Press-Fit Placement of a Rectangular Block Implant in the Resorbed Alveolar Ridge: Surgical and Biomechanical Considerations.

Rectangular Block Implant (RBIs) were manufactured, using computer-aided-design lathe turning, surface roughened with grit blasting and gamma irradiated. Implants were surgically placed into the resorbed edentulous mandibular ridges of both greyhound dogs (ex vivo and in vivo) and humans; the pooled total was 17 placements. The aim was to achieve mechanical stability and full implant submergence without damage to the mandibular canal and without bone fracture: fulfilment of all of these criteria was deemed to be a successful surgical outcome. Rectangular osteotomy sites were prepared with piezo surgical instrumentation. Sixteen implants were fully submerged and achieved good primary stability without bone fracture and without evidence of impingement of the mandibular canal. One implant placement was deemed a failure due to bone fracture: the event of a random successful outcome was rejected (p < 0.01 confidence, binomial analysis). Technique of placement yielded excellent mechanical retention: key biomechanical factors that emerged in this process included under preparation of the osteotomy site with the use of specifically designed trial-fit gauges, the viscoelastic property of the peri-implant bone, the flat faces and cornered edges of the block surfaces which enhance stress distribution and mechanical retention, respectively. It was concluded that the surgical protocol for the RBI placement in the resorbed alveolus is a predictable clinical procedure tailored to its specific, unique biomechanical profile.

Radiographic alveolar bone assessment in correlation with primary implant stability: A systematic review and meta-analysis.

INTRODUCTION: The radiographic examination of alveolar bone using 3D radiographic examination is essential in dental implant treatment planning. Our study aimed to systematically review and quantitatively analyze the correlation between alveolar bone parameters, specifically bone density and cortical bone thickness, assessed using cone beam computed tomography (CBCT) and/or multidetector computed tomography (MDCT); and primary implant stability (PIS) determined using implant stability quotient (ISQ), Periotest® value (PTV), and insertion torque value (ITV). METHODS: This review was registered in the PROSPERO database (registration number CRD42022307245). An electronic literature search was conducted on the PubMed, SCOPUS, and Web of Science databases for papers published until February 2022. The Quality Assessment in Prognostic Studies (QUIPS) tool was used to assess risk of bias. Meta-analyses were conducted to calculate the estimated average correlation coefficient based on a multilevel random-effects model, followed by subgroup analysis. RESULTS: Twenty-six studies were included in this review, consisting of 17 prospective cohort studies, eight retrospective cohort studies, and one nonrandomized controlled trial. A total of 3109 implants placed in 1171 subjects were analyzed. Twenty-three studies were evaluated using meta-analysis. The alveolar bone condition was significantly correlated with ISQ (r = 0.60; p < .001), IT (r = 0.52; p < .001), and PTV (r = -0.42; p < .05). CONCLUSION: Alveolar bone condition is significantly associated with PIS. Low bone density and thin cortical bone can lead to low PIS; therefore, modification of treatment planning and surgical procedures might be needed to avoid poor osseointegration.

Modulation of MG-63 Osteogenic Response on Mechano-Bactericidal Micronanostructured Titanium Surfaces.

Despite recent advances in the development of orthopedic devices, implant-related failures that occur as a result of poor osseointegration and nosocomial infection are frequent. In this study, we developed a multiscale titanium (Ti) surface topography that promotes both osteogenic and mechano-bactericidal activity using a simple two-step fabrication approach. The response of MG-63 osteoblast-like cells and antibacterial activity toward Pseudomonas aeruginosa and Staphylococcus aureus bacteria was compared for two distinct micronanoarchitectures of differing surface roughness created by acid etching, using either hydrochloric acid (HCl) or sulfuric acid (H2SO4), followed by hydrothermal treatment, henceforth referred to as either MN-HCl or MN-H2SO4. The MN-HCl surfaces were characterized by an average surface microroughness (Sa) of 0.8 ± 0.1 µm covered by blade-like nanosheets of 10 ± 2.1 nm thickness, whereas the MN-H2SO4 surfaces exhibited a greater Sa value of 5.8 ± 0.6 µm, with a network of nanosheets of 20 ± 2.6 nm thickness. Both micronanostructured surfaces promoted enhanced MG-63 attachment and differentiation; however, cell proliferation was only significantly increased on MN-HCl surfaces. In addition, the MN-HCl surface exhibited increased levels of bactericidal activity, with only 0.6% of the P. aeruginosa cells and approximately 5% S. aureus cells remaining viable after 24 h when compared to control surfaces. Thus, we propose the modulation of surface roughness and architecture on the micro- and nanoscale to achieve efficient manipulation of osteogenic cell response combined with mechanical antibacterial activity. The outcomes of this study provide significant insight into the further development of advanced multifunctional orthopedic implant surfaces.

Measuring tooth movement with treatment using the Dahl principle: An observational study.

STATEMENT OF PROBLEM: Research on the quantification of 3-dimensional tooth movements in patients undergoing treatment using the Dahl principle is lacking. PURPOSE: The purpose of this observational clinical study was to measure the magnitude, direction, duration, and rate of tooth movement occurring in patients to reestablish tooth contact and create restorative space. MATERIAL AND METHODS: A total of 104 paired preoperative and postoperative physical and virtual casts from 26 patients were obtained. Commencement and completion dates were recorded to calculate movement duration to reestablish occlusion. Dental casts were digitized, and the 3-dimensional digital casts obtained were superimposed via a surface matching and analysis software program by using the global registration function. Color maps were used to visualize direction, and the annotation feature quantified magnitude of tooth movement in millimeters when specific reference points were selected. Teeth within the arch were categorized as per their location to evaluate their impact on occlusal reestablishment. The average rate of movement was determined by time taken for extrusive and intrusive movements over the treatment duration. Post hoc Tukey tests were applied if a significant difference was present in the magnitude of movement between different tooth categories. RESULTS: All participants showed evidence of tooth movement during treatment. Duration of occlusal reestablishment ranged from 3.9 to 28.2 months, with more posterior tooth extrusive movements (56.9%) than anterior tooth intrusive (43.1%) movements occurring. A comparison of magnitude of extrusive or intrusive movement between categories (molar-anterior, premolar-anterior, and premolar-molar) showed that premolar and molar extrusive movements and anterior intrusive movements were significantly different (P<.001). The amount of buccal and lingual movement for molars and premolars was similar. Anterior teeth demonstrated more buccal than lingual movements. All teeth showed more mesial than distal movements. The extrusive and intrusive movement rate was 0.13 and 0.11 mm/mo, respectively. CONCLUSIONS: Tooth movement occurred in patients regardless of age and sex. The results of this study indicated that tooth movements have a 3-dimensional nature. Occlusal reestablishment mainly occurred via a combination of extrusive and intrusive movements. The study further highlighted the advantages of digital technology such as surface scanners and 3-dimensional software programs that can be used to quantify change in patients undergoing treatment.

The Biomechanical Profile of an Osseo-Integrated Rectangular Block Implant: A Pilot In Vivo Strain Analysis.

Aim: To load-test the osseo-integrated rectangular block implant (RBI), measure the generated cortical peri-implant strains, and relate these findings to known human physiological parameters. Materials and methods: Two RBIs were placed into the posterior mandibular saddle in a mature greyhound dog and allowed to osseo-integrate. The half mandible (implants in situ) was mounted in a servohydraulic system. Four triple-stacked rosette gauges were placed cortically (mesial, distal, buccal, and lingual). A modified ISO-14801 protocol was used (1000 N, 300, 2 Hz, 1 h) and the generated principal strains (ep, eq) and their angular orientations (F), were calculated. Results: (1) Bucco-lingual "horizontal" dimension: dominant "horizontal" compressive stresses were on the lingual aspect and "horizontal" tensile stresses on the buccal aspect. The buccal cortex was elastically tensile-stretched, while the lingual cortex was elastically compressed. (2) Bucco-lingual "vertical" dimension: dominant vertical torsional stresses were oriented buccally and apically, with an overall buccally inclined torsional effect. This was also evidenced on the lingual aspect, where there remained high torsional rotation elements (high F and e2). (3) Mesio-distal "horizontal" dimension: dominant torsional stresses oriented as a distal-lingual "counter-clockwise" rotation. Conclusions: The applied off-axial loads generated a heterogeneous pattern of bucco-lingual and mesio-distal cortical strains, both vertically and horizontally. The short dimensioned osseo-integrated RBI design appeared to biomechanically withstand the applied loads and to maintain the strains generated to levels that were within physiological limits. More studies and statistical analyses are needed to confirm these findings.

Effect of Aging on the Load-to-Failure of Molar Implant-Supported Monolithic Zirconia Crowns: A Laboratory Study.

PURPOSE: To evaluate the effect of hydrothermal aging on the load to failure and number of cycles to failure of implant-supported monolithic zirconia molar crowns under cyclic loading. MATERIALS AND METHODS: Twenty identical implant-supported monolithic zirconia crowns with molar morphology were produced. Half of the crowns were aged according to ISO standard 13356 to simulate 5 years in vivo. The non-aged crowns served as a control group. All crowns were subjected to cyclic loading with increasing increments of load until failure. The load to failure, the number of cycles to failure, and the failure pattern were determined for each crown. RESULTS: The load to failure values were 3,630 N (SD: 547.8 N) and 3,640 N (SD: 389.3 N) for the non-aged and aged crowns, respectively. The non-aged crowns failed after 33,480.1 cycles (SD: 23,138.4 cycles), and the aged crowns failed after 28,456.1 cycles (SD: 10,158.7 cycles). There was no significant difference between the two groups for the load to failure or number of cycles to failure. The predominant form of failure was catastrophic crown fracture, which was observed for all the non-aged crowns and 9 of the aged crowns. CONCLUSION: Within the limitations of this study, aging of the implant-supported monolithic zirconia crowns with molar morphology did not affect the load to failure or the number of cycles to failure under cyclic loading. Since all the crowns failed at much higher loads than the expected physiologic loads, clinical application of implant-supported monolithic zirconia crowns to replace missing molars seems reasonable.

The biomechanical profile of an osseo-integrated rectangular block implant: A pilot in vivo experimental study.

OBJECTIVE: A novel implant design, the rectangular block implant (RBI), was investigated as a possible solution to the restoration of the posterior resorbed ridge. AIM: To maximally load test the osseo-integrated RBI in shear and tensile loads and relate these findings to known human masticatory loads as biomechanical proof of the study concept. MATERIALS AND METHODS: Twelve RBIs were design-manufactured and placed into posterior mandibular saddles in 3 mature greyhound dogs.-2 per left and right. After 12 weeks of healing, osseo-integration was confirmed using resonance frequency analysis (RFA) and wrench torque tests. Three bone blocks each with two RBIs were dissected and mounted in acrylic. Micro-computerized tomography (µ-CT) was performed to assess bone to implant contact (BIC), and load analysis was performed using a Universal Test System. Three force applications were conducted until failure: pull-out (tensile), buccal push from the lingual (shear) and distal push from the mesial (shear). The osteotomy sites were examined using light magnification and scanning electron microscopy (SEM). RESULTS: Pull-out, buccal and distal force failures occurred at differing levels. Post-detachment sites showed complex patterns of bone failure, including trabecular and cortical fracture, as well as shearing at varying distances from the BIC. Interfacial shear strength was calculated at 14.4 MPa. CONCLUSION: The osseo-integrated RBIs were able to withstand simulations of the demanding axially, bucco-lingually and mesio-distally oriented biomechanical challenges of the posterior saddle, under conditions of reduced bone volume. These values exceeded equivalent force components of maximal masticatory loads in humans.

Influence of the application of a pre-sintered surface augmentation on zirconia and lithium disilicate bonding using an adhesive composite resin cement.

OBJECTIVE: The purpose of this laboratory study is to evaluate the application of a pre-sintered surface augmentation to zirconia (Zir) and lithium disilicate (LDS) ceramics on the delamination strength of adhesive resin cement. The applied surface augmentation was the ruling of lines to the pre-sintered surface of the ceramics. METHODS: Ninety milled Zir and sixty pressed LDS specimens (3mm×0.5mm×25mm) were created and divided into five groups (n=30). Group 1: Zir no surface treatment (control Zir-NT); Group 2: Zir airborne particle abraded (Zir-APA) with 30µm CoJet; Group 3: Zir pre-sintered surface augmentation (Zir-SA); Group 4: LDS etched (control LDS-etched) and; Group 5: LDS with pre-sintered surface augmentation and etching (LDS-SA). A resin adhesive cement (3mm×1mm×8mm) was then applied and cured to the ceramic specimens. The delamination strength values of the resin cement from the ceramic were recorded. The delamination strength data were analysed statistically using one-way ANOVA and Turkey post hoc analysis. RESULTS: The mean delamination strength and standard deviation, when comparing only the Zir-SA to the resin cement were statistically different (p<0.001); Zir-SA 63.42±11.85, Zir-NT 26.82±12.07, and Zir-APA 48.11±17.85MPa. Comparison between LDS groups were not significantly different (p=0.193); LDS-etched 33.49±16.07 and LDS-SA 28.83±10.15MPa. The delaminated Weibull modulus was highest for surface augmentation Zir specimens (m=13.56) but decreasing to less than half for Zir-APA (m=6.27) and Zir-NT (m=5.68). The Weibull values for the LDS-SA and LDS-etched specimens was 5.63 and 3.38 respectively. SIGNIFICANCE: Incorporating the pre-sintered surface augmentation to zirconia improved the delamination strength and reliability of Zir to the resin cement but not for LDS.

Implications of Implant Framework Misfit: An Animal Study on an Ovine Model.

Although clinicians routinely aim to provide a prosthesis with an accurate fit on implants, a degree of prosthesis misfit is inevitable. This exploratory pilot animal study evaluated the effects of framework vertical misfit and the timing of implant loading on implant position and screw loosening. Four implants were placed in healed ridges of each side of mandibles of 3 sheep. On the right side, 2 immediate frameworks were placed after 2 days. One framework was fitting, and the other one had a vertical gap of 0.5 mm on the distal implant. After 8 weeks (first review), the left side received 2 conventional frameworks with similar fit conditions to the right side. All animals were euthanized after 8 weeks (second review). At the first and second reviews, implant-level impressions were taken to measure the vertical displacement of distal implants, and the loosening torque values of the retaining screws were measured. The loosening torque values for the immediate fitting frameworks were considerably greater than the immediate misfitting frameworks. This was noticeable at the first review. At the second review, the loosening torque values were comparable to the immediate fitting and misfitting frameworks. Vertical implant displacement was observed for all misfitting frameworks. However, much greater implant displacement occurred under the immediate frameworks. Therefore, implant frameworks with vertical misfit in the present study were associated with less screw stability and more implant displacement. Retightening the retaining screws during the maturation of bone seemed to maintain the torque values.

Encode Protocol Versus Conventional Protocol for Single-Implant Restoration: A Prospective 2-Year Follow-Up Randomized Controlled Trial.

The Encode protocol for restoring single dental implants simplifies the implant impression technique by using a specially coded transmucosal healing abutment. It allows recording of the implant position without the removal of the healing abutment. This prospective randomized controlled clinical trial compares the 2-year clinical performance of the Encode and the conventional protocols for restoring single implants. A total of 47 implants were randomly allocated for restoration by the Encode (24 implants) and the conventional (23 implants) protocols. The implants were reviewed after 2 years to evaluate patient satisfaction, esthetics, prosthesis cleansability, mucosal health, bleeding on probing (BoP), metallic discoloration, probing pocket depth (PPD), marginal bone level (MBL), and quality of the proximal and occlusal contacts. In addition, all forms of complications were reported. Twenty Encode and 17 conventional implants were reviewed. The 2 protocols were comparable in all variables. A consistent increase of open proximal contacts was detected for the 2 protocols. Two Encode (10.0%) and 4 conventional (21.1%) crowns had screw loosening that was predominantly associated with cross-pins. This had led to the failure of 2 conventional crowns. Three Encode (15.0%) and 2 conventional (11.8%) crowns displayed ceramic chipping. The Encode and the conventional crowns had survival rates of 100.0% and 89.5%, respectively. From the biologic, prosthetic, and esthetic perspectives, the Encode and the conventional protocols provided a comparable clinical outcome over a 2-year duration.

A 5-Year Retrospective Assay of Implant Treatments in Private Practice: The Restorative Complications of Long-Span Implant-Supported Fixed and Removable Dental Prostheses.

PURPOSE: To describe and analyze the restorative complications of long-span (> three units) implant-supported dental prostheses (LIDPs) in 27 private practices in the state of Victoria, Australia, during the period from January 1, 2005, to December 31, 2009. MATERIALS AND METHODS: Private dental practitioners providing implant treatment were invited to enroll in this study, which was conducted through a dental practice-based research network. Clinical records of the implant treatments, which were provided during the specified period, were accessed for data collection. LIDPs included implant-supported prostheses of fixed or removable design; namely, fixed partial dentures (IFPDs), fixed complete dentures (IFCDs), removable partial dentures (IRPDs), and complete overdentures (IODs). Descriptive statistics and generalized linear mixed modeling were used for data analysis. RESULTS: The range of observation time for 627 LIDPs was 3 to 72 months (mean ± SD: 3.22 ± 1.49 years). For fixed prostheses, the complication with the highest annual rate was veneer fracture (acrylic: 21%; ceramic: 2.9%), followed by loss of retention for cement-retained IFPDs (14.7%). For mandibular IODs, the highest annual complication rate was for retention complications, whereas for maxillary IODs, it was for acrylic veneer fracture (11.5% and 6.4%, respectively). The peak incidence of complications was during the first year of function in fixed protheses and in IODs. Acrylic veneer fracture in IFCDs and IOD base fracture were more common in patients with preoperative clinician-reported attrition (estimated odds ratios [ORs] = 4.5 and 11.3, respectively; P < .05). Ceramic veneer fracture in fixed protheses and acrylic veneer fracture in IODs were reported more commonly for maxillary compared to mandibular prostheses (ORs = 5 and 22, respectively; P < .05). Mandibular IODs had more frequent retention complications when supported by two compared to four implants (OR = 5.9, P < .05). CONCLUSION: Restorative complications were observed in all categories of LIDPs at various annual rates. Clusters of these complications occurred during the first year of prosthesis function. Patient- and prosthesis-related variables influenced the incidence rate of some of these complications.

Laboratory Evaluation of Novel Implant Metal-Acrylic Prosthesis Design: Influence of Monolithic Acrylic Veneer.

PURPOSE: To test a novel implant metal-acrylic prosthesis design in comparison to a conventional prosthesis design through simulation of cyclic masticatory loading. The novel design involved digital designing and fabrication of the framework and the matched veneering acrylic resin material. MATERIALS AND METHODS: Ten prostheses were fabricated for each group. All the prostheses exhibited a similar external design on two implants with a distal cantilever. The conventional group comprised a milled metal framework with mechanically retained acrylic denture teeth via vertical pins. The digital prosthesis group incorporated an inverted T-shape bar and a monolithic milled acrylic resin veneer. The resin veneer was subsequently adhesively attached on the bar. All prostheses were thermally aged and subjected to laboratory cyclic loading at the cantilever region. The load-to-failure and the number of cycles until failure were collected. Furthermore, failed specimens were analyzed to determine the mode of failure. RESULTS: The digital prostheses failed at significantly greater load-to-failure (1,570.0 N ± 116.0 N) and number of cycles (124,857 ± 21,608) than the conventional prostheses (load-to-failure = 1,015.0 N ± 47.4 N; number of cycles = 28,452 ± 6,559). The conventional prostheses failed by fracturing of the acrylic teeth and veneering material that led to exposure of the metal framework. Half of the digital prostheses failed by superficial chipping of the veneering material, while the other half failed by the deformation and fracture of screws. CONCLUSION: Within the limitations of this study, the digital prostheses with the novel design and monolithic veneering material showed significantly higher strength compared with the conventional prostheses. The mode of acrylic failure of the digital prostheses was more favorable.

Body dysmorphia in dentistry and prosthodontics: A practice based study.

The prevalence of Body Dysmorphic Disorder (BDD) and dysmorphic concern in dentistry and prosthodontics have not been properly assessed, yet the mouth and the teeth are amongst the top preoccupation for these individuals. OBJECTIVES: To evaluate the prevalence of dysmorphic symptoms and BDD using validated tools in patients presenting to general and specialist prosthodontic practice. METHODS: Patients were recruited by two prosthodontics practices and three general dentist practices. Patients were given a Dysmorphic Concern Questionnaire (DCQ) integrated into a medical history form. Treating clinicians also completed a Baseline Rating Form assessing the patients´ reason for presentation. Two DCQ score cut-offs were used (9 and 12). RESULTS: Two hundred and thirteen patients were recruited, the majority of patients showed DCQ scores below 9 (84%). The prevalence of BDD was 7% (cut-off ≥ 9) or 4% (cut-off ≥12). Women were more likely to present with high DCQ scores as well as people with a history of mental health problems. The cosmetic practice, the implant clinic, and the prosthodontic practice received a higher proportion of patients with high DCQ scores when compared with the general family practice. The type of procedure was not related to DCQ scores. The defect severity assessment and whether this was amenable to correction was moderately correlated with DCQ scores. CONCLUSIONS: The DCQ seems to be a suitable tool to be used by dentists as part of history taking and patient examination due to its brevity, simplicity and the good sensitivity/specificity reported in the literature. CLINICAL SIGNIFICANCE: Identifying patients with dysmorphia is important before irreversible treatment is carried out due to high levels of dissatisfaction, poor patient centred outcomes and the question of whether these individuals have the capacity to consent.

A Five-Year Retrospective Assay of Implant Treatments and Complications in Private Practice: Restorative Treatment Profiles of Long-Span, Implant-Supported Fixed and Removable Dental Prostheses.

PURPOSE: To describe the restorative treatment profiles of long-span (> three units), implant-supported dental prostheses (LIDPs) prescribed in 27 private practices in the state of Victoria, Australia, during the period from January 1, 2005, to December 31, 2009. The restorative treatment profiles of these prostheses refer to the framework/veneering materials, number of prosthetic units/supporting implants, location in the oral cavity, retention methods, and cantilever designs. LIDPs refer to implant-supported prostheses of fixed or removable design; namely, fixed partial dentures (IFPDs), fixed complete dentures (IFCDs), removable partial dentures (IRPDs), and complete overdentures (IODs). MATERIALS AND METHODS: Private dental practitioners providing implant treatment in Victoria, Australia, were invited to enroll in this study, which was conducted through a dental practice-based research network (the eviDent Foundation). The enrolled practitioners' clinical records of the implant treatments provided during the specified period were accessed for data collection. Descriptive statistics, cross-tabulations, and linear mixed models were conducted for data analyses. RESULTS: During the study period, 627 LIDPs were prescribed to 556 patients by 18 general dentists and 5 prosthodontists. LIDPs were more common in the maxilla than in the mandible except in the case of IODs. Of the fixed prostheses, 60% replaced missing teeth in more than one sextant, 33% in the anterior sextant, and 7% in the posterior sextant. The average number of prosthetic units per implant was higher in mandibular compared to maxillary IFPDs/IFCDs (2.5 vs 1.9, respectively, P < .001). Cantilever pontic(s) were present in 68% of IFCDs (more often in the mandible than in the maxilla) compared to 28% of IFPDs (use of cantilever pontics was about the same in the maxilla and mandible). Screw retention was the most commonly reported retention method in IFPDs/IFCDs (95%). Locator attachment was used for the majority of IRPDs/IODs (83%). CONCLUSION: The clinicians enrolled in this study preferred fixed over removable LIDPs for partially dentate and maxillary edentulous cases. For mandibular edentulous patients, IODs were prescribed more often than IFCDs. A retrievable retention design was favored for IFPDs/IFCDs. IFPDs were predominantly metal-ceramic, and metal-acrylic designs were more popular for IFCDs.

A comparative study of encode protocol versus conventional protocol for restoring single implants: One-year prospective randomized controlled clinical trial.

BACKGROUND: The Encode protocol (Biomet 3i, Palm Beach Gardens, Fla) has been proposed as a simplified implant restoration protocol. PURPOSE: To compare the 1-year clinical outcome of the Encode and conventional protocols for restoring single implants. MATERIALS AND METHODS: Forty-seven implants were inserted in 44 patients. After randomizing the implants, 24 implants were allocated to the Encode protocol and 23 implants were allocated to the conventional protocol. After 1 year, changes in esthetics, patient satisfaction, proximal contacts quality, occlusal contacts quality, marginal bone level (MBL), and probing pocket depth (PPD) were evaluated. Further, the prosthesis cleansability, mucosal health, bleeding on probing (BoP), metallic discoloration, and all forms complications were recorded. RESULTS: Forty patients with 41 implants (22 Encode and 19 conventional) were recalled. One conventional crown failed due to excessive looseness. Esthetics, patient satisfaction, and prosthesis cleansability were favorable for the two protocols. One Encode crown (4.5%) and six conventional crowns (33.3%) had slight mucosal redness. BoP was present around 8 Encode crowns (36.4%) and eight conventional crowns (45.4%). Only two conventional crowns showed metallic discoloration of the mucosa. The two protocols had similar PPD alteration (Encode = 0.04 mm, conventional = 0.13 mm), and MBL loss (Encode = 0.71 mm, conventional = 0.78 mm). Similar proximal contacts and occlusal contacts were observed for the two protocols. CONCLUSIONS: After 1 year, the Encode protocol for restoring single implants appears to be comparable to the conventional protocol from the biological, prosthetic, and esthetic perspectives.

The Effect of Coded Healing Abutments on Treatment Duration and Clinical Outcome: A Randomized Controlled Clinical Trial Comparing Encode and Conventional Impression Protocols.

PURPOSE: To compare the Encode impression protocol (Biomet 3i) with the conventional impression protocol in terms of treatment duration, clinical accuracy, and outcome up to the first postplacement review of single-implant crowns. MATERIALS AND METHODS: A total of 45 implants were included in this study. The implants were randomly allocated to the Encode group (23 implants) or the conventional group (22 implants). At the time of surgery, all implants received two-piece Encode healing abutments. The implants were restored 3 months after insertion. In the conventional protocol, open-tray implant-level impressions were taken and the implants were restored with prefabricated abutments and porcelain-fused-to-metal (PFM) crowns. For the implants in the Encode group, closed-tray impressions of the healing abutments were taken. The generated casts were sent to the Biomet 3i scanning/milling center for custom abutment manufacturing on which PFM crowns were fabricated. Treatment duration (laboratory and clinical), clinical accuracy of occlusal and proximal contacts, and outcome (esthetics, patient satisfaction, and crown contour) were evaluated with the aid of a series of questionnaires. RESULTS: The Encode protocol required significantly less laboratory time (18 minutes) than the conventional protocol for adjustment of the abutments. The impression pour time, time for the laboratory to return the crown, time for crown insertion at the final appointment, and total clinical time for crown insertion did not differ significantly between the two protocols. Likewise, clinical accuracy, esthetics, and patient satisfaction were similar for the two protocols. CONCLUSION: The two protocols were clinically comparable. The Encode protocol is advantageous in reducing the laboratory time before crown fabrication.

A 5-Year Retrospective Assay of Implant Treatments and Complications in Private Practice: The Restorative Complications of Single and Short-Span Implant-Supported Fixed Prostheses.

PURPOSE: This report aims to describe the restorative outcome of 5,491 implant-supported single crowns, fixed partial dentures, and splinted restorations that were prescribed or had implants placed during the study period. Timing of the complications and the relationship between the complications and different factors (practitioner, patient, and restoration) are examined. MATERIALS AND METHODS: Dental clinicians qualified in or before December 2004, registered in Victoria, and placing and/or restoring implants in private practice were invited to participate in the study. Data extraction was conducted by two trained and calibrated research assistants with specific training in implant terminology and previous research experience extracting data from dental records. Prostheses average time observed/in function was calculated using the difference between the definitive restoration date and the patient record examination date or the date of implant/restoration lost. Both descriptive statistics and generalized linear mixed modeling were used to describe the restorative complications. RESULTS: Over the study period a total of 499 mechanical complications were recorded. Single-implant crowns had the largest sample size (n = 4,760) and a recorded complication rate of 2.56 per 100 prostheses per year. The majority of screw loosenings recorded in this study were inadequately described. In single-implant crowns, abutment screw loosening occurred at a rate of 0.07 per 100 per year while unspecified screw loosening occurred at a rate of 0.53. Lateral screw loosening was more common in lateral screw-retained implant crowns (1.06) than decementation was in cement-retained implant crowns (0.57). Esthetics (0.25), veneer chipping or fracture (0.41), and food packing/contact point issues (0.53) also represent significant portions of the restorative complications. Each type of complication presented with a slightly different timing profile. Clustering within the first year was common. The ratio of screw loosening between the group who prescribed between 1 and 100 during the study period and those who prescribed more than 501 implant restorations was 1:0.15 (P = .005). Patients with operator-reported attrition had double the rate of veneer fracture (P = .005). Contact point issues were approximately three times more common in the posterior segment (P = .001). CONCLUSION: During the period of January 2005 to December 2009, screw loosening, lateral screw loosening, decementation, esthetic complication, veneer chipping or fracture, and food packing/contact point issues were recorded at different rates for different types of prostheses in the private practices included in this study. Clusters of several complications within the first year were observed. For single-implant crowns, screw-loosening complications were less frequent in the more experienced group. Operator-reported attrition was related to higher rate of veneering material fracture. More contact point complications were found in the posterior regions of the oral cavity.

Five-Year Retrospective Assay of Implant Treatments and Complications in Private Practice: Restorative Treatment Profiles of Single and Short-Span Implant-Supported Fixed Prostheses.

PURPOSE: The aim of this study was to describe and analyze the restoration profiles of 5,491 implant-supported single crowns, fixed partial dentures (FPDs), and splinted restorations prescribed between January 2005 and December 2009. MATERIALS AND METHODS: Dental clinicians qualified in or before December 2004, registered in Victoria, and placing and/or restoring implants in private practice were invited to participate in the study. Data was extracted by two trained and calibrated research assistants from dental records. Cross tabulation was carried out in SPSS (IBM) to provide descriptive statistics on clinician profiles, patient demographics, and restoration information. RESULTS: A total of 34 practitioners participated in the study: 25 general dentists and 9 specialists. Clinicians that graduated between 1970 and 1989 (16 to 40 years of experience) prescribed most of the prostheses (82.0%). Female patients were present in higher numbers across most age and restoration groups. Of the implant-supported prostheses, 5,491 fit the criteria for simple basic restorations and were included in this report. The majority of the prostheses (86.7%) were single-tooth restorations. Metal-ceramic was the material of choice for the majority of the restorations (3,382/5,491). The use of single implant-supported crowns in the anterior mandible was rare. More than 65% of the implant-supported restorations in this study were screw retained directly to the implant. The specialist clinicians in this study largely used the screw-retained method to retain single implant-supported crowns (82.0%). General dentists provided 1,066% more cement-retained single implant-supported crowns compared with other practitioners. CONCLUSION: This report showed that during the period of January 2005 to December 2009, private practice clinicians in Victoria, Australia favored porcelain-fused-to-metal material over all-ceramic for implant restorations. Most implant restorations were single crowns. More female patients received implant-supported restorations in the posterior region of the mouth. The clinicians included in this study, particularly the specialists, generally favored a retrievable design in choosing the retention method for the prostheses.

Effect of Implant Diameter And Alloy on Peri-Implant Strain: An In Vitro Quantitative Strain Analysis.

This study aimed to evaluate the impact of implant diameter and alloy on peri-implant strains. Three implant types were investigated: regular commercially pure titanium (RcpTi), narrow commercially pure titanium (NcpTi) and narrow titanium-zirconium alloy (NTi-Zr) implants. Strain gauge models were fabricated from epoxy resin. All the implants were loaded in identical fashion. The greatest peri-implant strains were recorded around NTi-Zr implants, followed by NcpTi implants. The RcpTi implants were associated with the least strain values. The difference between the implant types was significant. Therefore, it can be concluded that the implant diameter and material can influence the peri-implant strain magnitude.

Fracture force of cantilevered zirconia frameworks: an in vitro study.

STATEMENT OF PROBLEM: Little evidence is available showing the effect of connector dimension and cantilever length on the ultimate fracture force of computer-aided design/computer-aided manufacturing (CAD/CAM) zirconia implant frameworks. PURPOSE: The purpose of the study was to determine the impact of variations in the cross-sectional dimension of connector sites and variations in the effective cantilever length (load point) on zirconia implant frameworks. This would allow verification of the fracture force with 2 proposed mathematical models. MATERIAL AND METHODS: Forty zirconia implant-supported frameworks with 12-mm distal cantilevers were divided into 4 equal test groups (n=10). Connector dimensions (3×5 mm, 3×4 mm) and cantilever loading distance (7 mm, 10 mm) were tested for ultimate fracture force. A 2-way analysis of variance (ANOVA) was used to examine the ultimate fracture force and examine the relationship between connector dimension and ultimate fracture force. The data obtained from all 4 groups were compared and verified with calculations from 2 theoretical mathematical models. RESULTS: Two-way ANOVA revealed significant effects for cross-sectional area connector dimension on fracture force (P<.001) and cantilever length (P=.009). No statistically significant interaction was observed between the 2 factors (P=.229). The observed data were consistent with the data from the proposed mathematical models, with group comparisons showing no statistical significance. The largest difference between the mathematical results and mathematical models was in the 7 mm 3×5 mm group of the fixed cantilever bending model (P=.032). The predominant mode of failure was fracture of the zirconia framework, without damage or plastic deformation of the abutment screws or implant analogs. The 10 mm 3×5 mm specimens fractured at a mean load of 923.7 ±234.5 N; the 10 mm 3×4 mm specimens at a mean load of 474.8 ±122.9 N; the 7 mm 3×5 mm specimens at a mean load of 1011.7 ±185.3 N; and the 7 mm 3×4 mm specimens at a mean load of 700.9 ±152.4 N. CONCLUSIONS: Zirconia implant frameworks loaded 7 mm from the distal abutment failed at higher fracture loads than specimens loaded 10 mm from the distal abutment. Zirconia implant frameworks with cross-sectional area connector dimensions of 3×5 mm failed at higher fracture loads than specimens with cross-sectional area connector dimensions of 3×4 mm. No statistically significant interaction was observed between the cross-sectional connector area dimension and cantilever length. Calculations from the mathematical models closely approximated the observed data, which supports the use of the mathematical models as a predictor of fracture force.