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Primary stability in low-density bone is crucial for the long-term success of implants. Tapered implants have shown particularly favourable properties under such conditions. The aim of this study was to compare the primary stability of tapered titanium and novel cylindrical zirconia dental implant systems in low-density bone. Fifty implants (25 tapered, 25 cylindrical) were placed in the anterior maxillary bone of cadavers meeting the criteria of low-density bone. The maximum insertion (ITV) and removal (RTV) torque values were recorded, and the implant stability quotients (ISQ) determined. To establish the isolated influence of cancellous bone on primary stability, the implantation procedure was performed in standardized low-density polyurethane foam bone blocks (cancellous bone model) using the same procedure. The primary stability parameters of both implant types showed significant positive correlations with bone density (Hounsfield units) and cortical thickness. In the cadaver, the cylindrical zirconia implants showed a significantly higher mean ISQ when compared to the tapered titanium implants (50.58 vs 37.26; P0.001). Pearson analysis showed significant positive correlations between ITV and ISQ (P = 0.016) and between RTV and ISQ (P = 0.035) for the cylindrical zirconia implants; no such correlations were observed for the tapered titanium implants. Within the limitations of this study, the results indicate that cylindrical zirconia implants represent a comparable viable treatment option to tapered titanium implants in terms of primary implant stability in low-density human bone.

Statement of problem Implant-supported prostheses have typically been retained by cement or screws, each of which has advantages and disadvantages. Two new types of prosthesis with complementary advantages and disadvantages have been proposed: the screw- and cement-retained prosthesis, which combines cement and screw retention, and the antiloosening inner-post screw (ALIPS) type, which uses lateral screws. Both esthetic and functional factors should be considered for anterior prostheses; however, clinical studies of the complication rates of these designs are lacking. Purpose The purpose of this retrospective clinical study was to evaluate the complications of dental implant-supported restorations with various prosthetic types in the anterior region and to analyze other factors that affect complications. Material and methods This study included 51 patients who had 83 implants placed in the anterior region by a single clinician between August 2009 and December 2016. Surgical and prosthetic features were recorded, and implant complications were analyzed. Results There were 45 (55.4%) cement-retained implants, 5 (6.0%) screw- and cement-retained prosthesis implants, and 32 (38.6%) ALIPS-retained implants. Peri-implant mucositis was observed most frequently in the ALIPS type (21.9%), but the biological complications did not differ significantly with the prosthetic type. The most common mechanical complication was loss of retention in the cement type of prosthesis (30.4%) and screw loosening in the ALIPS type (43.8%). Implant complications varied with position (maxilla or mandible) and implantation timing (period from tooth extraction to implant placement). Conclusions The complications of implants placed in the anterior region were affected by different factors but did not differ significantly with the type of the retention.

Removing cement-retained implant-supported prostheses may be challenging for clinicians. A method combining a cone beam computed tomography (CBCT) and a digital scan with a virtual surgical planning software program is described to identify the perforation site of a cement-retained implant-supported prosthesis to locate the abutment screw.

Purpose This study compared piezoelectric (PE) and conventional drills (CD) for maxillary aesthetic zone implant insertion. Material and methods This was a prospective split-mouth study. Implants were divided into two groups. Beds were prepared with CDs in group I and PE in group II. The implant stability quotient (ISQ) of the mechanical implant stability (MIS) was measured intraoperatively. The ISQ of the biological implant stability (BIS) was recorded at postoperative second and fourth months. Marginal bone loss (MBL) and bone density (BMD) were measured in the first and second years after prosthetic loading. The osteotomy time was also documented for both techniques. P values Results Sixty implants in 30 patients were included. PE provided a significantly higher ISQ. All values were above 70 throughout the follow-up period. The mean of the ISQ for MIS was 63.78 ± 1.03 and 73.89 ± 1.05 in group I and group II, respectively (p = 0.003). PE needed significantly longer osteotomy time with a mean of 11.99 ± 0.839 min. The BIS quality had high stability in group II and medium stability in group I throughout the study period. Its values decreased in both groups. Group II had a lesser percentage of decrease. However, it was significant only at time intervals between intraoperative and two months' postoperative (p = 0.004). MBL and BMD demonstrated insignificant results. Conclusion The implant site preparation with PE devices should be preferred to CDs whenever possible, because they seem to enhance implant stability and osseointegration, especially at the initial stages of healing.

Statement of problem Components have been introduced that allow the screw channel of an implant crown to be angled lingually and the screws to be tightened in a non-axial direction to the implant. Information is lacking as to how the removal torque value (RTV) and force to failure (FTF) of these components compare with those of conventional screws. Purpose The purpose of this in vitro study was to evaluate and compare the RTV and FTF values of cyclically loaded implant-supported restorations. Specifically, values for conventional axially tightened gold screws were compared with those for non-axially tightened screws aligned at 3 different angulations. Material and methods A total of 28 external hexagon implants were embedded in acrylic resin and divided into 4 groups. Simulated restorations were fabricated on abutments capable of different screw channel angulations. Dynamic abutments (DA) were waxed at different angulations and then cast. Simulated restorations were placed on the implants and tightened: group 0GS: 0-degree angulation gold screw tightened to 35 Ncm (control group); group 0DAS, 0-degree angulation with dynamic abutment (DAS) screw; group 20DAS: 20-degree angulation with DA screw; group 28DAS: 28-degree angulation with DAS screw. In groups 0DAS, 20DAS, and 28DAS, the DAS screw was used and tightened to 25 Ncm. Screw removal torque values were recorded by using a digital torque gauge at baseline and, after reaching cyclic fatigue, by using a dual-axis mastication simulator for 1 200 000 cycles. The fracture strength (FS) of the implant restorations was tested under compression until failure by using a universal testing machine. Differences between baseline and removal torque (ΔRT) were calculated. Statistical analysis was performed by using 1-way ANOVA for ΔRT and FS separately (α=.05). Results ΔRT and FS values were not significantly different among the groups (P>.05). The screw fractured in 5 of 28 specimens (17.8%); the remaining specimens failed with fracture of the implant. Conclusions The removal torque and FS values of the angulated abutment screw were comparable to those of the gold screw. Angulation of the abutment had no significant influence on the screw removal torque values.

Made available in DSpace on 2018-12-11T17:21:16Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-01-01 Statement of problem: The decision to splint or to restore independently generally occurs during the planning stage, when the advantages and disadvantages of each clinical situation are considered based on the proposed treatment. However, clinical evidence to help clinicians make this decision is lacking. Purpose: The purpose of this systematic review and meta-analysis was to assess the marginal bone loss, implant survival rate, and prosthetic complications of splinted and nonsplinted implant restorations. Material and methods: This study was designed according to the Cochrane criteria for elaborating a systematic review and meta-analysis and adopted the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. Also, this review was registered at the International Prospective Register of Systematic Reviews (PROSPERO) (CRD42017080162). An electronic search in the PubMed/MEDLINE, Cochrane Library, and Scopus databases was conducted up to November 2017. A specific clinical question was structured according to the population, intervention, comparison, outcome (PICO) approach. The addressed focused question was “Should the restoration of adjacent implants be splinted or nonsplinted?” The meta-analysis was based on the Mantel-Haenszel and inverse variance methods to assess the marginal bone loss, implant survival, and prosthetic complications of splinted and nonsplinted implant restorations. Results: Nineteen studies were selected for qualitative and quantitative analyses. A total of 4215 implants were placed in 2185 patients (splinted, 2768; nonsplinted, 1447); the mean follow-up was 87.8 months (range=12-264 months). Quantitative analysis found no significant differences between splinted and nonsplinted restorations for marginal bone loss. The assessed studies reported that 75 implants failed (3.4%), of which 24 were splinted (99.1% of survival rate) and 51 were nonsplinted (96.5% of survival rate). Quantitative analysis of all studies showed statistically significant higher survival rates for splinted restorations than for nonsplinted restorations. Ceramic chipping, screw loosening, abutment screw breakage, and soft tissue inflammation were reported in the selected studies. The quantitative analysis found no statistically significant difference in the prosthetic complications of splinted and nonsplinted restorations. Conclusions: Within the limitations of this systematic review and meta-analysis, it was concluded that there was no difference in the marginal bone loss and prosthetic complications of splinted and nonsplinted implant restorations; this is especially true for restorations in the posterior region. However, splinted restorations were associated with decreased implant failure. Associate Professor Department of Prosthodontics Presidente Prudente Dental School University of Western São Paulo (UNOESTE) Adjunct Professor Department of Dental Materials and Prosthodontics Araçatuba Dental School São Paulo State University (UNESP) Doctoral student Department of Dental Materials and Prosthodontics Araçatuba Dental School São Paulo State University (UNESP) Graduate student Department of Dental Materials and Prosthodontics Araçatuba Dental School São Paulo State University (UNESP) Full Professor Department of Dental Materials and Prosthodontics Araçatuba Dental School (UNESP) Universidade Estadual Paulista Adjunct Professor Department of Dental Materials and Prosthodontics Araçatuba Dental School São Paulo State University (UNESP) Doctoral student Department of Dental Materials and Prosthodontics Araçatuba Dental School São Paulo State University (UNESP) Graduate student Department of Dental Materials and Prosthodontics Araçatuba Dental School São Paulo State University (UNESP) Full Professor Department of Dental Materials and Prosthodontics Araçatuba Dental School (UNESP) Universidade Estadual Paulista

Zirconia prostheses show a high rate of retention loss, and more information is needed regarding the treatment of the intaglios of zirconia prostheses to improve the bond strength between zirconia and resin cement.The purpose of this in vitro study was to evaluate the retention of titanium abutments and zirconia prostheses treated with silica-containing glass-ceramic liners. The effect of the abutment convergence angle on retention force was also examined.Titanium abutments and zirconia copings (n=90) were fabricated with 3 different convergence angles (6, 12, and 24 degrees). Specimens were divided into 2 groups according to surface treatment: an airborne-particle-abraded control group and a group that was coated with a silica-containing glass-ceramic liner after airborne-particle abrasion (liner group). The thickness of the liner was measured, and the inner spacing of the zirconia coping was modified in the liner group. The coping was cemented, and the retention was evaluated with a tensile bond strength test by using a universal testing machine. Retention was analyzed by using a 2-way analysis of variance. Modes of failure were evaluated by examining the fracture surface. Elemental analysis of the interface was also performed.The liner group showed a significantly higher retention force for the zirconia prosthesis (P.05). Regardless of surface treatment, the retention force at a convergence angle of 6 degrees was higher than that at 24 degrees (P.05). The control group showed mostly adhesive type failures, whereas the liner group exhibited mostly mixed type failures.Silica-containing glass-ceramic liner treatment increased the retention compared with airborne-particle abrasion treatment alone. Tensile bond strength increased with decreasing abutment convergence angle.

For screw-retained fixed implant prostheses, the cement that extrudes onto the margin can be easily removed, but the cement that may intrude into the screw-access opening (SAO) during the extraoral bonding process is difficult to eliminate. This article presents a manufactured auxiliary device that is applied to the extraoral bonding process of screw-retained fixed implant prostheses. This device will prevent excess cement from being left in the SAO.

Summary Introduction Retention during both the active and passive phases of treatment has given rise to numerous publications concerning its efficacy, the range of systems available and its variability over time. There are currently many different retention protocols regularly used by orthodontists; however, their efficacy and duration are still subject to debate. There is as yet no consensus as to which retention protocol is the most effective or for how long the retention device needs to be worn. The aim of this research was to perform a systematic review of the scientific literature in order to evaluate the efficacy of the different retention systems and clinical protocols among those most widely used, so as to make recommendations beneficial to both patient and practitioner. Materials and methods A search of the literature was performed in the following databases: PubMed (MEDLINE), ScienceDirect and Cochrane Library. The search was limited to publications in English and French during the period 2006–2016. Results Out of 1952 references initially identified, 17 articles corresponded to our inclusion criteria. The results show that: fixed retention is more effective than removable retainers for the maintenance of incisor alignment during the first six months of retention; there is no significant difference in efficacy between the different fixed retention systems; there is no significant difference in efficacy between the vacuum-formed systems and the Hawley retainer; part-time use of removable retainers (between 8–10 h/day) is sufficient; the most widely used retention protocol combines a vacuum-formed splint or Hawley retainer in the upper arch with mandibular fixed retention. Conclusion Despite the large number of studies devoted to orthodontic retention only a few articles corresponded to the methodological criteria of bio statistical analysis. Also, on account of the variations in experimental protocols, the levels of proof relating to the efficacy of different systems are very weak. Research into this topic should first seek to normalize methods of analysis and then perform randomized controlled long-term trials to shed light on this problem.

Primary stability of a dental implant system is an essential factor to maintain its long-term success. Thus, the objective of this study was to examine whether primary stability is different between threaded and porous dental implant systems placed in artificial bone blocks and human cadaveric mandibular bone.Forty-two threaded and 42 highly porous dental implants were placed in artificial polyurethane bone foams with 7 different thicknesses (3.5 to 12mm). In addition, 11 threaded and 11 porous implants were installed in 8 edentulous mandibles of human cadavers. Implant stability quotient values, insertion torque, static and dynamic stiffness, and viscoelastic tan δ of each implant system were measured. Mean gray values were obtained at the implantation sites in the human mandible.The porous implant group had substantially lower implant stability quotient values and insertion torque values than the threaded implant group that were equal or5.5mm in thickness of the artificial bone block (p0.026) with the exception of 8.5mm thickness, while static and dynamic stiffness values were not different between the two implant groups greater than 5.5mm in thickness (p0.132). Static and dynamic stiffness values of the porous group were significantly greater than the thread group in the human mandibular bone (p0.015).The porous layer supports axial loading better than lateral and shear loading of the dental implant system. This result indicates that trabecular shaped architecture of the porous layer may provide sufficient anchorage compromising reduction of the axial primary stability of the porous implant system to be comparable with the threaded implant system.

Objectives To answer the following PICO question (participant, intervention, comparator and outcome): Does flowable resin composite restorations compared with regular resin composites improve the marginal adaptation, marginal discoloration and retention rates of restorations placed in non-carious cervical lesions [NCCLs] of adults?, through a systematic review and meta-analysis. Source MEDLINE, Scopus, Web of Science, LILACS, BBO, Cochrane Library and SIGLE were searched without restrictions, as well as the abstracts of the IADR, clinical trials registries, dissertations and theses in May 2016 (updated in April 2017). Study selection We included randomized clinical trials (RCTs) that answered the PICO question. RCTs were excluded if cavities other than NCCLs were treated; indirect restorations; polyacid-based resins instead of composite resins were employed, restorations in primary teeth and restorations were placed in carious cervical lesions. The risk of bias tool of the Cochrane Collaboration was applied in the eligible studies and the GRADE tool was used to assess the quality of the evidence. Data After duplicates removal, 5137 articles were identified. After abstract and title screening, 8 studies remained. Six were at “unclear” risk of bias. The study follow-ups ranged from 1 to 3 years. No significant difference was observed between groups for loss of retention and marginal discoloration in all follow-ups. Better marginal adaptation was observed for restorations performed with flowable composites. At 1-year (risk ratio = 0.27 [0.10 to 0.70]) and 3-year (risk ratio = 0.34 [0.17 to 0.71]) follow-ups, flowable composites showed a risk 73% and 66% lower than regular composites for lack of adaptation, respectively. The evidence was graded as moderate quality for loss or retention at 3 years due to risk of bias and low and very low for all other outcomes due to risk of bias, imprecision and inconsistency. Conclusions We have moderate confidence that the resin composite viscosity does not influence the retention rates at 3 years. Similar marginal discoloration and better marginal adaptation was observed for flowable composites but the quality of evidence is doubtful. (PROSPERO CRD42015019560).

Objectives To evaluate the two-year survival rate (SR) and marginal bone loss (MBL) of fixed dental prostheses (FDPs) supported by straight (S) and tilted (T) implants under the influence of diverse study variables. Methods A prospective investigation comprising 21 patients provided with a total of 27 maxillary screw-retained restorations fixed to 70 dental implants was developed. Two groups of implants were considered depending on their inclination with respect to the occlusal plane: Group 1 (S, n = 37): straight/axial implants and Group 2 (T, n = 33): tilted/angled fixations. Each FDP was supported by a combination of S and T implants. SR and MBL were assessed at the time of loading and two years after surgery. Patient-, surgical- and/or rehabilitation-related information was gathered. Data were statistically analysed at the α = 0.05 significance level. Results After 24 months, a 100% SR was achieved and the MBL of S and T implants were statistically similar. T implants located in the molar region showed lower MBL than did those replacing premolars ( p = 0.031). Conclusions Upright and angled fixations inserted at posterior maxillary areas resulted in comparable survival rates and peri-implant MBL after two years. The marginal bone resorption around tilted implants depended on their location. Clinical significance Screw-retained restorations fixed to straight and tilted implants seem to be a safe treatment option in posterior atrophic maxillae.

Made available in DSpace on 2018-12-11T17:30:34Z (GMT). No. of bitstreams: 0 Previous issue date: 2017-05-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Statement of problem The rehabilitation of patients after a maxillectomy involves the use of an obturator to seal oral-nasal-sinus communication and to facilitate mastication, swallowing, and speech. Purpose The purpose of this in vitro study was to evaluate different attachment systems used for implant-retained obturators at dissipation loads and under shear forces. Material and methods Photoelastic models were fabricated with 3 external hexagon implants at the incisor, canine, and first molar regions. Subsequently, overdentures were made, and metal hooks were placed at the incisor and first molar regions to displace the prostheses in the vertical, anterior, and posterior directions, with a constant speed of 50 mm/min. A photoelastic model with an O-ring or bar-clip system was placed in a circular polariscope, and tested with a universal testing machine. The images were recorded and high-intensity fringes were counted using software. For strain gauge analysis, each strain gauge was placed horizontally at the mesial and distal sides of the implants. The registered strains were submitted to 2-way ANOVA (α=.05). Results The O-ring showed the lowest number of high-intensity fringes in photoelastic imaging, while the strain gauge analysis showed the lowest stress values in the bar-clip group (P=.007). Conclusions The stress around titanium implant necks was more damaging to surrounding bone, while the bar-clip attachment system had a better biomechanical performance. The bar-clip presented the lowest strain values around the dental implants and few high-intensity fringes. Professor Aracatuba Dental School São Paulo State University (UNESP) Graduate student Aracatuba Dental School Sao Paulo State University (UNESP) Postgraduate student Aracatuba Dental School São Paulo State University (UNESP) Professor Aracatuba Dental School São Paulo State University (UNESP) Graduate student Aracatuba Dental School Sao Paulo State University (UNESP) Postgraduate student Aracatuba Dental School São Paulo State University (UNESP) FAPESP: 2014/04919-1

Parallel labiolingual walls and the preservation of the cingulum in anterior tooth preparations have been advocated. However, their contribution to retention and resistance form has not been evaluated.The purpose of this in vitro study was to evaluate the retention and resistance failure loads of 2 preparation designs for maxillary anterior teeth.Forty metal restorations were fabricated and paired with 40 cobalt-chromium prepared tooth analogs. Twenty of the specimens had parallel buccolingual walls at the cervical part (group PBLW; the control group), whereas the remaining 20 had converging buccolingual walls (group CBLW; the experimental group). The restorations were cemented to the tooth analogs with a resin-modified glass ionomer luting agent. Ten specimens from each group were subjected to tensile loading with a universal testing machine; the rest were subjected to compression loading until failure. Descriptive statistics and the independent t test (α=.05) were used to determine the effect of failure loads in the tested groups.The independent t test revealed statistically significant differences between the tested groups in tensile loading (P.001) and in compressive loading (P.001). The PBLW group presented a higher tensile failure load than the CBLW. On the contrary, the PBLW group presented a smaller compression failure load than the CBLW.Parallelism of the buccolingual axial walls in anterior maxillary teeth increased the retention form but decreased the resistance form.

The optimal retention of implant-supported ceramic crowns on zirconia abutments is a goal of prosthodontic treatment.The purpose of this in vitro study was to evaluate the retentive strength of implant-supported IPS e.max CAD-CAM (e.max) crowns bonded to custom zirconia implant abutments with different cements.An optical scan of a zirconia custom abutment and a complete-coverage modified crown was designed using an intraoral E4D scanner. One hundred twenty lithium disilicate crowns (IPS e.max CAD) were cemented to 120 zirconia abutment replicas with 1 of 6 cements: Panavia 21 (P21), Multilink Hybrid Abutment (MHA), RelyX Unicem 2 (RXU), RelyX Luting Plus (RLP), Ketac Cem (KC), and Premier Implant (PI). The specimens were stored at 37°C in 100% humidity for 24 hours. Half of the specimens were thermocycled for 500 cycles. The retentive force was measured using a pull-out test with a universal testing machine. Mean retentive strengths (MRS) were calculated using 2-way ANOVA and the Tukey-Kramer test (α=.05).The MRS (MPa) after 24-hour storage were P21 (3.1), MHA (2.5), RXU (2.5), RLP (1.3), KC (0.9), and PI (0.5). The MRS after thermocycling were MHA (2.5), P21 (2.2), RLP (1.8), KC (1.4), RXU (1.1), and PI (0.3). P21 had the highest MRS after 24-hour storage (P.001), but after thermocycling MHA had the highest MRS (P.001). RXU showed a significant decrease in MRS after thermocycling (P.05). Cement residue was mostly retained on the zirconia abutments for P21, while for the other cements' residue was retained on the lithium disilicate crowns.The cements tested presented a range of retentive strengths, providing the clinician with a choice of more or less retentive cements. MHA was the most retentive cement after thermocycling. Thermocycling significantly affected the retentive strengths of the P21 and RXU cements.

Introduction Numerous factors may influence the survival/success of post-retained restorations of endodontically treated teeth (ETT). The aim of this review was to assess the influence of the number of remaining coronal walls, the use or disuse of posts, and their type on the clinical performance of these restorations. Methods Randomized controlled trials and controlled clinical trials for ETT restored with a combination of post/crown or no post/crown were searched for in MEDLINE, Embase, and the Cochrane Library. Two authors independently reviewed all identified titles and abstracts for eligibility. Tables were generated to summarize the included studies, and reports of randomized trials were assessed for bias using the Cochrane risk of bias tool. Results Nine articles were identified as meeting the inclusion criteria. Teeth without ferrule presented the highest values of variation of success/survival (0%–97%), whereas teeth with remaining coronal walls (1, 2, 3, or 4 walls with ferrule) presented lower variation. The use of posts with a high elastic modulus success/survival ranged between 71.8% and 100%, whereas posts with a low elastic modulus ranged between 28.5% and 100%. The survival of crowns without posts varied between 0% and 100%. The poor performance of posts with a low elastic modulus and without posts was associated with the absence of ferrule and the preservation of only 1 coronal wall. Conclusions The restoration of ETT should focus on the maintenance of the coronal structure. Until more studies with longer follow-up periods are available, posts with a high elastic modulus appear to present with better performance when restoring ETT with no ferrule.

This systematic review aimed to determine: (1) the expected bone volume gain with the split crest technique, and (2) how the use of surgical instruments affects the performance of this technique. An electronic search was performed in the Cochrane Central Register of Controlled Trials, ClinicalTrials.gov, Embase, PubMed/MEDLINE, Scopus, and Web of Science databases. Twenty-seven articles met the selection criteria and were subjected to meta-analysis of bone gain and survival rate; 17 reported the use of conventional surgical instruments and nine the use of surgical ultrasound. A total of 4115 implants were installed in 1732 patients (average patient age 52 years). The overall implant survival rate was 97%. The average bone gain in studies that used conventional surgical instruments was 3.61mm, while this was 3.69mm in those that used ultrasound. Only two studies presented a low risk of bias. The greatest problems identified during the qualitative analysis were related to random selection of the population and the absence of statistical analysis. The split crest technique appears to be a promising and effective technique to gain bone width, regardless of the surgical instruments used. Considering the diversity of the studies and implant types, no definitive recommendations can be made, especially with regard to the best instruments and implant design to be used.

Background Treatment of post-resective defects of the maxilla can be challenging and usually requires dental obturation or microvascular reconstruction. As compared to soft-tissue microvascular grafts, bone reconstruction can additionally allow for facial support and retention of dental implants. The aim of this study was to evaluate scapular tip grafts with respect to their applicability for maxillary reconstruction and their potential to retain dental implants for later dental rehabilitation. Materials and methods In this retrospective study, 14 patients with hemimaxillectomy defects were reconstructed with free scapular tip grafts, oriented horizontally, to rebuild the palate and alveolar ridge. After bone healing, three-dimensional virtual implant planning was performed, and a radiographic guide was fabricated to enable implant placement in the optimal anatomic and prosthetic position. All patients' mastication and speech were evaluated, along with the extent of defect closure, suitability of the graft sites for implant placement, and soft-tissue stability. Pre- and postsurgical radiographs were also evaluated. Results A good postoperative outcome was achieved in all patients, with complete closure of maxillary defects that were class II, according to the system of Brown and Shaw. Additional bone augmentation was necessary in two patients in order to increase vertical bone height. Patients were subsequently treated with 50 dental implants to retain dental prostheses. In all cases, additional soft-tissue surgery was necessary to achieve a long-term stable periimplant situation. No implants were lost during the mean observation period of 34 months. Conclusions Due to its specific form, the scapular tip graft is well suited to reconstruct the palate and maxillary alveolar ridge and to enable subsequent implant-retained rehabilitation. Due to the limited bone volume, an accurate three-dimensional graft orientation is essential. Furthermore, most cases require additional soft-tissue surgery to achieve a long-term stable periimplant situation.

Clinicians commonly contend that the screw-retained, implant-supported fixed dental prosthesis (FDP) should be fabricated with all nonengaging abutments to allow for the inherent nonparallelism of the implants and the inability of the abutment connections to draw together during insertion and removal. The problem with a fully nonengaging FDP is difficulty in handling and more strain on the abutment screws, ultimately leading to increased rates of breakage and loosening. The hemi-engaging FDP design regains much of the advantage afforded by the internal connection and improves prosthetic handing both clinically and in the laboratory. The benefits of this technique are best seen for short-span (fewer than 5 units), screw-retained, implant-supported FDPs.

This technique introduces a system of abutments with a pressure or friction fitting to retain implant-supported prostheses. The system combines the chief advantages of cement and screw-retained prostheses, which are passively fit and easily removed from the mouth, respectively. This system provides an alternative to conventional immediate loading systems, since it allows easier adjustment and modeling of the prosthesis with a snap-on connection and easier removal from the implants.

Currently, no standard luting protocol exists for fiber posts. In addition, no agreement has been reached on the time interval between canal obturation and post space preparation and cementation.The purpose of this in vitro study was to evaluate the retention of fiber posts cemented with 3 different types of cement: Paracore, Variolink II, and RelyX Unicem cement after 24 hours or 2 weeks in root canals obturated with gutta percha and a eugenol-based sealer.Seventy-two caries-free, freshly extracted, single-rooted human mandibular first premolar teeth with straight root canals were prepared and obturated with gutta percha and Endofil sealer. Specimens were divided into 2 groups (n=36): post spaces prepared 24 hours after obturation and post spaces prepared 2 weeks after obturation. Posts in both groups were luted with 1 of 3 different luting agents (n=12), ParaCore, Variolink II, or RelyX Unicem cement. Each tooth specimen was vertically secured in a universal testing machine, and a constant pull-out loading rate of 0.5 mm/min was applied until cement failure occurred. Data were statistically analyzed with 2-way and 1-way ANOVAs and t tests.Two-way ANOVA indicated statistically significant differences in mean post retention among the 3 cement types (P.001) and among the means of the different time intervals investigated (P.001). Significant differences were noted among all cement types tested between the 24-hour and 2-week time intervals (P.05).Time elapsed between canal obturation and post cementation significantly influenced fiber post retention, regardless of the type of resin cement. Fiber posts showed significantly higher retention if cemented after 24 hours of obturation than if cementation occurred after 2 weeks.

Statement of problem No consensus has been reached on which retention system, cement- or screw-retained, is best to avoid bone loss around the implant of a fixed implant-supported restoration. Purpose The purpose of this systematic review and meta-analysis was to compare cement- and screw-retained retention systems in fixed implant-supported restorations in terms of marginal bone loss, implant survival, and prosthetic complications. Material and methods A comprehensive search of studies published from January 1995 to March 2015 and listed in the PubMed/MEDLINE, Embase, Scopus and the Cochrane Library databases was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. The meta-analysis was based on the Mantel-Haenszel and inverse variance methods. Marginal bone loss was the continuous outcome measure evaluated by mean difference (MD), and implant survival and prosthetic complications were the dichotomous outcome measures evaluated by risk ratio (RR), both with corresponding 95% confidence intervals (CI). Results The 20 studies selected for review evaluated 2139 participants, whose mean age was 47.14 years and who had received 8989 dental implants. The mean follow-up was 65.4 months (range: 12-180 months). Results of the MD for marginal bone loss showed statistically significant differences in favor of the cement-retained prosthesis ( P =.04; MD: −0.19; CI: −0.37 to −0.01). The implant survival rate was higher for the cement-retained prosthesis ( P =.01; RR: 0.49; CI: 0.28 to 0.85), and the prosthetic complication rate was higher for the screw-retained prosthesis ( P =.04; RR: 0.52; CI: 0.28 to 0.98). Additional analysis of the mean plaque index did not show differences between retention systems ( P =.58; MD: 0.13; CI: −0.32 to 0.57). Conclusions The current meta-analysis indicated that cement-retained, fixed implant-supported restorations showed less marginal bone loss than screw-retained, fixed implant-supported restorations during the follow-up period, which ranged from 12 to 180 months. However, the small difference between the mean values may not show clinical significance. The rates of prosthetic complication and implant survival also compared favorably with cement-retained prostheses.

Objectives The animal study aims to evaluate a new experimental model for measuring sole the influence of the surface characteristics independent from implant macro-design on the level of osseointegration by registering the pull-out strength needed for removal of experimental devices with different surfaces from artificial defects. Material and methods Seventy-two test bodies (36 with the FRIADENT ® plus surface, 36 with the P15/HAp biofunctionalized surface) were inserted in six adult domestic pigs with artificial calvarial defects. The experimental devices were designed to fit in the defects leaving a gap between the test body and the local bone. After 21 days of healing, the animals were sacrificed and the test bodies were pulled out with a standardised reproducible pull-out device measuring the pull-out strength. The pull-out strength for both groups was compared. Results Twenty-one days after insertion a mean force of 412 ± 142 N for the P15/HAp group and 183 ± 105 N for the FRIADENT ® plus group was measured for the removal of the specimens from the calvarial bone. The difference between the groups was statistically significant (p Conclusion The experimental set-up seems to be a suitable method when measuring the impact of implant surfaces on the early stage of osseointegration.

Statement of problem The success rate of implant-retained prostheses in a postdoctoral prosthodontics program was unknown and could not be related to any set of potential clinical issues or patient characteristics. Purpose The purpose of this study was to determine the success rate of implant-retained prostheses placed by prosthodontic residents between 1997 and 2012 and to evaluate the associations between patient classifications and specific restoration characteristics as related to prosthesis success or failure. Material and methods A total of 272 prostheses in 119 patients were clinically evaluated. Success was defined as the absence of prosthetic complications or any implant-related complication that affected prosthesis survival. Logistic regression was used to evaluate associations between prosthesis success/failure and a wide array of study variables, adjusting for patient age, sex, and prosthesis longevity. Results The overall success rate was 71%, with a mean prosthesis age of 4.5 years (range: 4 months to 16.8 years). Implant single crowns were the most successful prosthesis type (81% success). The most common complications observed were porcelain fractures in fixed dental prostheses (15%) and lack of stability (31%) and retention (29%) in removable dental prostheses. Having a removable prosthesis (versus natural dentition) in the opposing occlusion significantly decreased the odds of success (OR=0.26, 95% CI: 0.11-0.64). Definitively cemented fixed prostheses were more successful than those cemented with an interim cement (OR=4.56, 95% CI: 1.37-15.22). Conclusions The overall success rate of the implant-retained prostheses placed in the program was low compared with previously published studies. This study revealed the need for an efficient, comprehensive recall system for patients receiving implant-retained prostheses, either fixed or removable.

Statement of problem Bond stability between zirconia crowns and luting cement and between cement and dentin is a main concern; however, only limited evidence is available as to its longevity. Purpose The purpose of this in vitro study was to measure the retentive strengths of 7 self-adhesive cements (RelyX Unicem Aplicap, RelyX Unicem Clicker, RelyX Unicem 2 Automix, iCEM, Maxcem Elite, Bifix SE, SpeedCem), 2 adhesive cements with self-etch primers (Panavia 21, SEcure), 1 glass ionomer cement (Ketac Cem), 1 resin-modified glass ionomer cement (Meron Plus), and 1 zinc phosphate cement for luting zirconia crowns (LAVA) to extracted teeth after thermocycling with or without 1 year of water storage. Material and methods Two-hundred-forty extracted human molars (2 treatments; n=10 per cement) were prepared in a standardized manner. All cements were used according to the manufacturers' recommendations. The intaglios of the crowns were treated with airborne-particle abrasion. After thermocycling (×5000, 5°C/55°C) with or without 1 year of water storage, the cemented ceramic crowns were removed by using a Zwick universal testing device. Statistical analyses were done with the Wilcoxon rank sum and the 2-independent-samples Kolmogorov-Smirnov test. Results Median retentive strengths [MPa] for specimens thermocycled only/thermocycled with 1 year of water storage were as follows: Panavia 21: 1.7/2.5, SEcure: 3.0/3.0, RelyX Unicem Aplicap: 3.1/3.4, RelyX Unicem Clicker: 4.1/4.2, RelyX Unicem 2 Automix: 3.8/3.1, iCEM: 2.3/2.7, Maxcem Elite: 3.0/3.2, Bifix SE: 1.7/1.7, SpeedCem: 1.3/1.6, Meron Plus: 3.1/2.7, Ketac Cem: 1.4/1.4, and zinc phosphate cement: 1.1/1.6. Statistically significant differences were found only among specimens thermocycled only or thermocycled with 1-year water storage ( P Conclusions Significant differences in retentive strengths were observed among cements after thermocycling only or thermocycling with 1 year of water storage, but not for the effect of the additional 1 year of water storage.

Statement of problem Maxillary resections jeopardize the stability and functional stress generated by implanted-supported prostheses. Purpose The purpose of this study was to evaluate the stability and functional stress caused by implanted-supported obturator prostheses in simulated maxillary resections of an edentulous maxilla corresponding to Okay Classes Ib, II, and III, with no surgical reconstruction. Material and methods Implants were positioned in the residual maxilla, and bar-clip retention systems were designed for each experimental model. The 3-dimensional models of the maxillary resection and corresponding implanted-supported obturator prosthesis, constructed from a computed tomography scan, were used to develop a finite element mesh. Loads were simultaneously applied to the occlusal (80 N) and anterior (35 N) platforms corresponding to the prosthetic teeth. Qualitative analysis was based on the scale of maximum principal stress; values obtained by means of quantitative analysis were expressed in MPa. Results The implant-supported obturator prostheses tended to rotate toward the surgical resection, the region with no osseous support. Tensile and compressive stresses in the gingival mucosa and in the cortical bone increased as the osseous support and the numbers of implants and clips diminished. Conclusions All evaluated bar-clip retention systems displayed a tendency toward dislodgment of the obturator prosthesis, increasing as the osseous resection area amplified. The osseous tensile and compressive stresses resulting from the bar-clip retention system for Okay Classes Ib, II, and III maxillectomy may not be favorable to the survival rate of implants.

Although criteria for assessing bone quality have been reported, an overall score that correlates bone quality with the primary stability and secondary stability of implants is not yet available.The purpose of this article was to propose a scoring index that will establish a correlation among the bone density values from computed tomography, maximum insertion torque values, and resonance frequency analysis in different phases of implant treatment.In this study, 60 implant sites were evaluated to assess bone density (Hounsfield units), insertion torque values (Ncm), and primary stability and secondary stability (implant stability quotient values obtained by using resonance frequency analysis). On the basis of computed tomography data, the bone was classified as D1 to D4. The insertion torque was noted and classified into 2 groups, A and B. The implant stability quotient values obtained from resonance frequency analysis depicting primary stability and secondary stability were classified into 5 groups. The primary score noted was a result of the values obtained for the 3 parameters at the time of implant placement. The secondary score was obtained by considering the values of the bone density and resonance frequency analysis recorded at different time intervals.Bone densities of D2, D3, and D4 were noted, dividing the bone type into 3 groups. The maximum torque noted in the study was 40 Ncm. The difference between various insertion torque values and bone types was found to be statistically nonsignificant. Higher mean implant stability quotient values were obtained for primary and secondary stability for the D2 bone than for D3 and D4 bone. When analyzed according to the time of insertion, the mean values increased at second stage surgery in all bone types. The difference in mean values among all bone types was found to be statistically significant (P.001). A comparison of primary and secondary implant stability quotient values in all bone types did not find any statistical significance (P=.780). A score was recorded at the time of implant placement and at the time of second stage surgery, and the prosthetic treatment was planned accordingly.The score highlights the importance of considering the association of bone quality, insertion torque values, and stability as denoted by implant stability quotient throughout treatment. Based on the variation in the score noted at recall visits, alterations in the treatment plan can be made with respect to the healing period and prosthetic design.

Statement of problem A validated universal method requiring no human input is needed to capture and evaluate preparation geometries in a manner that can be used to see the correlation of different parameters. Purpose The purpose of this study was to present a method of capturing and evaluating crown preparation geometry. Material and methods One manually machined acrylic resin block and 9 randomly selected preparations for ceramic complete crowns prepared by general dentists were selected and prepared. The specimens were scanned (3D scanner; Nobel Biocare), and buccolingual and mesiodistal cross section images were collected. The images were imported into digitizing software (Engauge Digitizer 4.1) to convert the outlines into x and y coordinates. Six points were chosen by using a set of algorithms, and the resulting parameters were calculated. Results The acrylic resin block was milled with a 12 degree total occlusal convergence (TOC) instrument producing a 12.83 degree TOC. For the other specimens, average TOC values ranged from 18 degrees to 52 degrees. The mean average margin width was 0.70 mm, and the mean average base dimension was 6.23 mm. The surface area/volume ratio, resistance length, and limiting taper were also calculated. Conclusions The method described provides a basis for accurately evaluating preparation geometry without human input.

Dental implants are ideally placed in an orientation that allows vertical transfer of occlusal forces along their long axis. Nevertheless, optimal situations for implant placement are seldom encountered resulting in implants placement in angulated positions, which may affect their long-term success. The resonance frequency (RF) is an objective tool used to monitor stability of the implant tissue integration; however, little is known of the effect of the implant orientation in bone on the RF and its potential significance. The purpose of this research was to determine the relation between the dental implant orientation and the corresponding RF of implant. Three-dimensional (3D) modelling software was used to construct a 3D model of a pig mandible from computed tomography (CT) images. The RF of the implant was analysed using finite element (FE) modal analysis in software ANSYS (v.12). In addition, a cubical model was also developed in MIMICS to investigate the parameters affecting the relationship between RF and implant orientation in a simplified environment. The orientation angle was increased from 0 to 10 degrees in 1 degree increments and the resulting RF was analysed using correlation analysis and one-way ANOVA. Our analysis illustrated that the RF fluctuation following altering implant orientation was strongly correlated (r=0.97) with the contacting cortical to cancellous bone ratio (CCBR) at the implant interface. The most extreme RF change (from 9.81kHz to 10.07kHz) occurred when the implant was moved 0.5mm in positive z-direction, which resulted in the maximum change of CCBR from 52.9 to 54.8.

Information about the influence of zirconia crown surface treatment and cement type on the retention of zirconia crowns is limited. It is unclear whether zirconia crowns require surface treatment to enhance their retention.The purpose of this in vitro study was to evaluate the effect of surface treatment on the retention of zirconia crowns cemented with 3 different adhesive resin cements after artificial aging.Ninety extracted human molars were prepared for ceramic crowns (approximately 20-degree taper, approximately 4-mm axial length) and were divided into 3 groups (n=30). Computer-aided design and computer-aided manufacturing zirconia copings were fabricated. Three surface treatments were applied to the intaglio surface of the copings. The control group received no treatment, the second group was airborne-particle abraded with 50 μm Al2O3, and the third group was treated with 30 μm silica-modified Al2O3, The copings were luted with a self-etch (RelyX Unicem 2), a total-etch (Duo-Link), or a self-etch primer (Panavia F 2.0) adhesive cement. They were stored for 24 hours at 37°C before being artificially aged with 5000 (5°C-55°C) thermal cycles and 100,000 cycles of 70 N dynamic loading. Retention was measured on a universal testing machine under tension, with a crosshead speed of 0.5 mm/min. Statistical analysis was performed with 1-way and 2-way ANOVA.Mean retention values ranged from 0.72 to 3.7 MPa. Surface treatment increased crown retention, but the difference was not statistically significant (P.05), except for the Duo-Link cement group (P.05). Analysis of the adhesives revealed that the Duo-Link cement resulted in significantly lower crown retention (P.05) than the other 2 cements.For zirconia crowns, retention seems to be dependent on cement type rather than surface treatment.

We used resonance frequency analysis to evaluate the implant stability quotient (ISQ) of dental implants that were installed in sites prepared by either conventional drilling or piezoelectric tips. We studied 30 patients with bilateral edentulous areas in the maxillary premolar region who were randomised to have the implant inserted with conventional drilling, or with piezoelectric surgery. The stability of each implant was measured by resonance frequency analysis immediately after placement to assess the immediate stability (time 1) and again at 90 days (time 2) and 150 days (time 3). In the conventional group the mean (SD) ISQ for time 1 was 69.1 (6.1) (95% CI 52.4-77.3); for time 2, 70.7 (5.7) (95% CI 60.4-82.8); and for time 3, 71.7 (4.5) (95% CI 64.2-79.2). In the piezosurgery group the corresponding values were: 77.5 (4.6) (95% CI 71.1-84.3) for time 1, 77.0 (4.2) (95% CI, 69.7-85.2) for time 2, and 79.1 (3.1) (95% CI 74.5-87.3) for time 3. The results showed significant increases in the ISQ values for the piezosurgery group at each time point (p=0.04). The stability of implants placed using the piezoelectric method was greater than that of implants placed using the conventional technique.

Limited information is available on the effect of LOCATOR abutment length and luting cement type on retention to intraradicular dentin in overdentures.The purpose of this in vitro study was to evaluate the effect of the length of a commercially available LOCATOR abutment and cement type on retention in the root canal.Eighty LOCATOR abutments with a standard length of 6 mm were obtained. Half of them were shortened to 3 mm. Eighty recently extracted single-rooted teeth were divided into 2 groups. The post space was prepared to 6 mm in the first group and 3 mm in the second. After preparation, the LOCATOR abutments were luted with one of the following cements: dual-polymerized glass-reinforced resin cement (Parapost Paracore), dual-polymerized resin cement (Variolink II), self-adhesive resin cement (RelyX Unicem), and conventional cement (zinc phosphate). The tensile force required for the removal of the LOCATOR abutments from their corresponding roots was recorded. Data were statistically analyzed with 2-way ANOVA and the Tukey multiple comparison test.Both the cement type (P.001) and the length of the LOCATOR abutment (P.001) significantly affected the mean tensile forces. Dual-polymerized glass-reinforced resin cement (Parapost Paracore) presented significantly higher mean tensile forces for the LOCATOR abutment retention among all cements (P.05).Regardless of the length, LOCATOR abutments luted with Parapost Paracore resin cement presented higher mean resistance to tensile forces compared with those luted with the other cements. LOCATOR abutments of 6 mm in length were more resistant to tensile forces than those of 3 mm in length in combination with all cements.

The purpose of this study was to determine and compare the times needed to dislodge prefabricated titanium posts of different luting lengths with various cements.Eighty-one intact extracted, single-canal human teeth were selected and endodontically treated. Specimens were randomly divided into 9 groups, which were arranged according to the post space length (5, 7, and 9 mm) and cement type (zinc phosphate, glass ionomer, and resin cement). Titanium posts were cemented into the post spaces, and after 1 week of storage they were subjected to ultrasonic vibration. The dislodging times were recorded and analyzed by using the Kruskal-Wallis and Mann-Whitney tests (P.05).A significant difference was observed between the dislodging times on the basis of post length and luting agent (P.001). There were also significant differences between different cements luted with the same length posts (P.001). Significant differences were observed between the 5-mm posts and both the 7- and 9-mm posts for each cement, but the differences between the 7-mm and 9-mm posts were not significant (P.05).Changes in the cement type and post length alter the time required to dislodge a post with an ultrasonic device.

This study evaluated the correlation between the initial stability of a dental implant, quantified as the implant stability quotient (ISQ), and the bone-implant contact percentage ( BIC%).Dental implants were inserted into specimens comprising an artificial cortical shell representing cortical bone and foam bone representing cancellous bone with 4 elastic moduli. Each specimen with an implant was subjected to microcomputed tomography (micro-CT) scanning, from which the 2D and 3D BIC% values were calculated. The values of the Spearman correlation coefficient (r) were calculated between the ISQ and the 2D and 3D BIC% values.Increasing the elasticity of the specimen enhanced the ISQ. There was statistically significant correlation between the ISQ and 3D BIC% values (r = 0.85, P.0001). However, the correlation between ISQ and 2D BIC% values was not statistically significance (r = 0.42, P = .062).The initial implant stability was strongly positively correlated with the 3D BIC%.

The implant stability quotient (ISQ) has been widely evaluated in clinical studies and animal experiments. However, accurate measurement is often difficult in animal models. In such cases, measurement of ISQ in bone is needed after formalin fixation. However, it is not yet clear how such fixation influences the measurement. The purpose of this study was to investigate the influence of formalin fixation on ISQ and the mechanical characteristics of bone. Fourteen tibias were harvested from rabbits; the samples from the left (length 60mm, control group) were soaked in saline and the samples from the right (length 60mm, fixation group) were fixed in 10% neutral-buffered formalin at 4°C for 4h. Three-point bending tests were done at 5mm/min to measure the maximum load and total absorbed energy. Twelve titanium implants (Brånemark System(®) Mk-III TiUnite, Nobel Biocare, Sweden) were placed into the edentulous molar site of the mandibles of 2 dogs and the ISQ was measured by Osstell(®) (control group) 3 months later. The implants involved in the bone block were then fixed for 4h (fixation group) and the ISQ measured. The maximum load values did not differ significantly between the control and fixation groups. Total absorbed energy was significantly higher in the control group than in the fixation group. ISQ did not differ significantly between the groups. These results suggest that formalin fixation of bone might affect some of the mechanical characteristics of bone, but not its ISQ.

Statement of problem In response to the Commission of Dental Accreditation (CODA) mandate of a competency in the "replacement of teeth including fixed, removable and implant" prostheses, a predoctoral implant curriculum was implemented at New York University College of Dentistry. The assessment of the success or failure of a program should include an assessment of patient satisfaction with the treatment received in the predoctoral clinics. Purpose The purpose of this study was to measure patient satisfaction with the mandibular 2-implant–retained overdenture therapy received in the predoctoral program at New York University College of Dentistry. Material and methods A telephone survey of patients who received an implant-retained overdenture in the predoctoral clinics at New York University, College of Dentistry (n=101) was conducted. Two of the authors contacted patients for participation in the survey and, using a prepared script, asked about their satisfaction with items such as function, comfort, and esthetics in addition to their overall satisfaction with the treatment they received. Data were analyzed with descriptive statistics. Results The study revealed that 79% of participants were satisfied with their masticatory ability, 84% were satisfied with the comfort of the prosthesis, and 89% were satisfied with the esthetics of their new prosthesis. Additionally, 85% of participants reported satisfaction with the overall treatment experience, and 90% would recommend that a friend receive the same treatment. Conclusions The results of this study support the incorporation of treatment with an implant-retained mandibular overdenture as part of the routine care provided in the predoctoral education program to meet the mandates of CODA.

Although cement-retained implant prostheses are widely used, the quantification of optimal retention remains controversial, and new dental luting agents should be evaluated.The purpose of this study was to compare, in vitro, the casting retention on implant abutments after cementation with 3 commercially available luting agents and an experimental luting agent (castor oil polyurethane, COP) with variable weight percentages (wt%) of calcium carbonate (CaCO3).Seventy-two palladium-silver cast copings were fabricated and divided into 6 groups: Temp Bond interim cement (TB); zinc phosphate cement (ZP); Rely X ARC resin cement (RX); pure COP (COP); COP + 10% wt% CaCO3 filler (COP 10); and COP + 50% wt% CaCO3 filler (COP 50). After cementation, the specimens were stored in distilled water at 37°C for 24 hours and subjected to removal force tests in a universal testing machine (5 kN; 0.5 mm/min). Statistical analyses were performed with the Kruskal-Wallis and Student-Newman-Keuls tests (α=.05).The median values of casting retention (N) were as follows: TB=57.20 ±10.4; ZP=343.56 ±50.3; RX=40.07 ±9.7; COP=258.98 ±41.4; COP 10=466.57 ±79.3; and COP 50=209.63 ±31.4. The Kruskal-Wallis test showed significant differences among the groups (P.01). TB and RX had the lowest mean retention values; COP, COP 10, and COP 50 were equal to ZP, and COP 10 had the highest retention.The casting retention on implant-abutments provided by COP was similar to that of copings cemented with zinc phosphate and may be influenced by the addition of calcium carbonate.

This study investigated the effects of bone stiffness (elastic modulus) and three-dimensional (3D) bone-to-implant contact ratio (BIC%) on the primary stabilities of dental implants using micro-computed tomography (micro-CT) and resonance frequency analyses. Artificial sawbone models with five values of elastic modulus (137, 123, 47.5, 22, and 12.4 MPa) comprising two types of trabecular structure (solid-rigid and cellular-rigid) were investigated for initial implant stability quotient (ISQ), measured using the wireless Osstell resonance frequency analyzer. Bone specimens were attached to 2 mm fibre-filled epoxy sheets mimicking the cortical shell. ISQ was measured after placing a dental implant into the bone specimen. Each bone specimen with an implant was subjected to micro-CT scanning to calculate the 3D BIC% values. The similarity of the cellular type of artificial bone to the trabecular structure might make it more appropriate for obtaining accurate values of primary implant stability than solid-bone blocks. For the cellular-rigid bone models, the ISQ increased with the elastic modulus of cancellous bone. The regression correlation coefficient was 0.96 for correlations of the ISQ with the elasticity of cancellous bone and with the 3D BIC%. The initial implant stability was moderately positively correlated with the elasticity of cancellous bone and with the 3D BIC%.

The present study evaluated the effect of different drilling dimensions (undersized, regular, and oversized) in the insertion and removal torques of dental implants in a beagle dog model.Six beagle dogs were acquired and subjected to bilateral surgeries in the radii 1 and 3 weeks before euthanasia. During surgery, 3 implants, 4 mm in diameter by 10 mm in length, were placed in bone sites drilled to 3.2 mm, 3.5 mm, and 3.8 mm in final diameter. The insertion and removal torque was recorded for all samples. Statistical analysis was performed by paired t tests for repeated measures and by t tests assuming unequal variances (all at the 95% level of significance).Overall, the insertion torque and removal torque levels obtained were inversely proportional to the drilling dimension, with a significant difference detected between the 3.2 mm and 3.5 mm relative to the 3.8 mm groups (P0.03). Although insertion torque-removal torque paired observations was statistically maintained for the 3.5 mm and 3.8 mm groups, a significant decrease in removal torque values relative to insertion torque levels was observed for the 3.2 mm group. A different pattern of healing and interfacial remodeling was observed for the different groups.Different drilling dimensions resulted in variations in insertion torque values (primary stability) and stability maintenance over the first weeks of bone healing.

Purpose The objective was to analyze the factors that influence the stability of dental implants at 12 weeks after implant placement as measured by resonance frequency analysis using the Osstell system. Materials and Methods This prospective clinical study was performed in 235 implants placed in 93 patients at the Oral Surgery and Implantology Clinic of the University of Granada. The gathered predictor variables were grouped into patient variables, implant variables, operative variables, and baseline implant stability quotient (ISQ). All variables were analyzed in a multivariate model to determine their influence on the ISQ score at 12 weeks after implant insertion (outcome variable). SUDAAN software was used for clustered sampling (multiple implants in patients). Results Two hundred thirty-five dental implants were placed in 47 men (50.5%) and 46 women (49.5%; total, 93 patients; mean age, 52.13 ± 11.23 years; range, 27 to 76 years). No association was found between the patient variables and the ISQ values at 12 weeks. Among implant variables, worse ISQ values at 12 weeks were observed for a narrow diameter ( P P = .006). Among surgical technique variables, the use of plasma rich in growth factors ( P = .011) showed the best ISQ values at 12 weeks. Conclusions The diameter and localization of implants and the application of plasma rich in growth factors influenced the stability of implants measured at 12 weeks of wound healing. Accordingly, stability was less with a narrower implant diameter and maxillary localization and greater with implants humidified with plasma rich in growth factors.

Statement of problem The influence of different joining techniques on passive fit at the interface structure/abutment of cobalt-chromium (Co-Cr) superstructures has not yet been clearly established. Purpose The purpose of this study was to compare 3 different techniques of joining Co-Cr superstructures by measuring the resulting marginal misfit in a simulated prosthetic assembly. Material and methods A specially designed metal model was used for casting, sectioning, joining, and measuring marginal misfit. Forty-five cast bar-type superstructures were fabricated in a Co-Cr alloy and randomly assigned by drawing lots to 3 groups (n=15) according to the joining method used: conventional gas-torch brazing (G-TB), laser welding (LW), and tungsten inert gas welding (TIG). Joined specimens were assembled onto abutment analogs in the metal model with the 1-screw method. The resulting marginal misfit was measured with scanning electron microscopy (SEM) at 3 different points: distal (D), central (C), and mesial (M) along the buccal aspect of both abutments: A (tightened) and B (without screw). The Levene test was used to evaluate variance homogeneity and then the Welsch ANOVA for heteroscedastic data (α=.05). Results Significant differences were found on abutment A between groups G-TB and LW ( P =.013) measured mesially and between groups G-TB and TIG ( P =.037) measured centrally. On abutment B, significant differences were found between groups G-TB and LW ( P P =.007) measured distally; and groups G-TB and TIG ( P =.001) and LW and TIG ( P =.007) measured centrally. Conclusions The method used for joining Co-Cr prosthetic structures had an influence on the level of resulting passive fit. Structures joined by the tungsten inert gas method produced better mean results than did the brazing or laser method.

Objectives Occlusal overloading is one of the causes of peri-implant bone resorption, and many studies on stress distribution in the peri-implant bone by three-dimensional finite element analysis (3D FEA) have been performed. However, the FEA models previously reported were simplified and far from representing what occurs in clinical situations. In this study, 3D FEA was conducted with simulation of the complex structure of dental implants, and the influences of neck design and connections with an abutment on peri-implant bone stress and abutment micromovement were investigated. Methods Three types of two-piece implant CAD models were designed: external joint with a conical tapered neck (EJ), internal joint with a straight neck (IJ), and conical joint with a reverse conical neck (CJ). 3D FEA was performed with the setting of a “contact” condition at the component interface, and stress distribution in the peri-implant bone and abutment micromovement were analyzed. Results The shear stress was concentrated on the mesiodistal side of the cortical bone for EJ. EJ had the largest amount of abutment micromovement. While the von Mises and shear stresses around the implant neck were concentrated on the labial bone for IJ, they were distributed on the mesiodistal side of the cortical bone for CJ. CJ had the least amount of abutment micromovement. Significance Implants with a conical joint with an abutment and reverse conical neck design may effectively control occlusal overloading on the labial bone and abutment micromovement.

To study patient satisfaction and masticatory efficiency of single implant-retained mandibular overdentures using the stud and magnetic attachments in a randomized clinical trial with a crossover design.Patients received a single implant placed in the midline of the mandible and either a stud (Locator) or a magnetic (Magfit) attachment, assigned at random. Patient satisfaction, including patient comfort, speech, chewing ability and retention, and masticatory efficiency measured by chewing peanuts, were assessed before and 3 months after attachment insertion. Patient satisfaction and masticatory efficiency were evaluated again 3 months after insertion of the alternate attachment bodies. The outcomes were compared before and after insertion of the attachments and between the two types of attachments using Wilcoxon signed rank tests.Patient overall satisfaction, comfort, speech, chewing ability, and retention improved significantly after insertion of both types of attachment bodies (p0.05). Masticatory efficiencies also increased in both the Locator and the Magfit groups (p0.05). There were no statistically significant differences in patient overall satisfaction, comfort, speech, and retention between the two types of attachments (p0.05). The Locator attachments performed better in perceived chewing ability than the Magfit (p0.05), but there was no statistically significant difference in masticatory efficiency between the two attachment types (p0.05).Clinical outcomes were significantly improved in single implant-retained mandibular overdentures using either the Locator or the Magfit magnetic attachments. There was no difference in masticatory efficiency between the two attachment types.

Subgingival positioning of a single dental implant may result in a less stable impression coping in a polymerized impression material.The purpose of this study was to evaluate the influence of a single dental implant placement depth and different impression materials on the stability of an open tray impression coping.Six polyvinyl chloride-based plastic models with single embedded internal hexagon implant analogs were fabricated. The implant analogs were placed equally with their surface 0, 1, 2, 3, 4, or 5 mm below the simulated gingival margin. Open tray impression copings were connected to the embedded implant analogs, and impressions were made with different vinyl polysiloxane (VPS) impression materials, polyethers, and an addition silicone-based occlusal registration material. The laboratory analogs were connected to the impression copings and the plastic trays were placed in a locking device. A measuring device, consisting of a compression force gauge connected to a platform moving at a speed of 3.2 mm/s, was fabricated. The impression trays were fixed so that the pole of the force gauge would touch the surface of the implant analog in the same place and push it 1.0 mm. Measurements of each specimen were made 5 times. Statistical analysis was performed with a 1-way ANOVA, the Tukey test, and the Pearson correlation coefficient (α=.05).There was a significant negative correlation between the dental implant placement depth and the force needed to move the impression coping (P.05). In all depth groups, the impression coping was significantly more stable when the impressions were made with the occlusal registration material (P.05).As the dental implant placement depth increased, the force needed to move the impression coping decreased. The coping was significantly more stable when an occlusal registration material was used to make the impression.

Context: A procedure using 4 dental fixtures with an immediate-loaded prosthesis for totally edentulous patients is the focus of an evidence-based analysis that uses modern methodologies to review an innovative clinical technique. The long-term outcomes for this surgical and prosthetic treatment for previously or newly edentulated patients by clinical teams worldwide, as well as the author’s clinical personal data in a referral-based private practice, are reported in this investigation. Evidence Acquisition: An independent research dentist performed the literature review using terms that would identify articles commensurate with this article. The search years for keywords were limited to 2010 and 2011 because the purpose of the article was limited to current thinking and evidence on this specific technique. In this article, the author elected to restrict the literature search to journals that are commonly read and received in his clinical practice on a monthly basis. Because of the specific nature of this procedure, all historical references to the “all-on-4” procedure were also included in the database inquiries. Evidence Synthesis: The literature search revealed that the investigated technique has been reported worldwide by multiple authors using retrospective clinical analyses. In the maxillary jaw, the range of implants placed was 27 to 980 fixtures with 1 to 7 years of follow-up, demonstrating a cumulative implant success rate range of 92.5% to 100%. The mandibular arch demonstrated cumulative success rates of 93.8% to 100% with 1 to 10 years of follow-up with a range of 18 to 980 fixtures being placed. The investigator’s own personal clinical statistics compared favorably with other clinical teams, with a total of 120 fixtures being placed in both jaws with 6 years of follow-up with a cumulative survival implant success rate of 100%. Continuous stability of the definitive final prosthesis was above 99% in the largest reported review and 100% for this author’s private practice. Conclusion: Based on extensive reporting by multiple clinicians, the technique investigated is grounded in good bioengineering basic science, and demonstrates long-term clinical outcomes that can provide highly predictable long-term prosthetic stability for the edentulous patient. This highly focused critically appraised review of individual articles using 4 implants to support a fixed dental prosthesis provides clinicians and patients with a protocol that conservatively and immediately reduces the morbidity associated with the loss of teeth and removable prostheses traditional used to negate edentulism.

Panfacial fractures involve trauma to the lower, middle, and upper facial bones and often require a team approach for management. Early and complete restoration of preinjury facial contours and function should be the goal of the oral and maxillofacial surgeon and the prosthodontist. When the intraoral landmarks are lost, overall facial anatomic landmarks can be used to restore the oral cavity. A patient with complex clinical panfacial fractures, including a vertically and horizontally malpositioned native alveolar bone and severe facial asymmetry, is presented. A functional and esthetic rehabilitation was successfully accomplished by using a partial removable dental prosthesis retained with telescopic crowns and magnetic attachments in the maxilla and osseointegrated implants to support a definitive dental prosthesis in the mandible.

Alveolar bone quality is considered to be an important prognostic factor in dental implant stability. Although numerous methods have been described, no technique allows for reliable diagnostics. The purpose of this study was to determine if strain measurements on the shaft of a contra angle handpiece during implant bed preparation could be used for the determination of bone quality. Experiments in polyurethane foam and human cadaver bone were conducted to investigate whether strain measurements could be correlated with other diagnostic parameters, such as the surgeon's tactile sensation during drilling, implant insertion torque, implant stability, elastic modulus of bone and bone quality as assessed radiographically. Tests were also performed to determine if strain measurements could be used to distinguish various types of bone. As axial feed and contact pressure during the drilling process could not be standardized under simulated clinical conditions, substantial deviations in the time needed to complete the drilling occurred. Under controlled circumstances using polyurethane foam, this problem could be addressed by a normalization procedure, but great variations occurred in human cadaver bone. As bone quality could not be reliably determined, especially when a cortical layer was present, strain measurements on a contra angle handpiece appears to be inappropriate for this purpose.