Accuracy of multi-unit implant impression: traditional techniques versus a digital procedure.

OBJECTIVES: The objective of this study was to evaluate the accuracy of different impression techniques on multiple implants. MATERIAL AND METHODS: A master cast simulating a jaw with four implants was used. Eight impression techniques were tested: open tray-polyether#1, open tray plus splint of impression copings with acrylic resin-polyether#1, closed tray-polyether#1, open tray-polyether#2, open tray-splint-polyether#2, closed tray-polyether#2, open tray-impression plaster, and digital impression (DI). Five impressions of the master cast were taken with each traditional impression (TI) technique, pouring 35 sample casts. Three different clinicians took 5 DI each (n = 15). A three-dimensional coordinate measurement machine (CMM) was used to measure implant angulation and inter-implant distances on TI casts. TI data and DI Standard Tessellation Language datasets were compared with the master cast. The best and the worst impressions made with TI and DI were selected to fabricate four milled titanium frameworks. Passive fit was evaluated through Sheffield test, screwing each framework on the master cast. Gaps between framework-implant analogs were measured through a stereomicroscope (×40 magnification). RESULTS: Statistically significant differences in accuracy were found comparing the different impression techniques by CMM (p < 0.01). DI performed the best, while TI techniques revealed a greater variability in the results. Sheffield test revealed a mean gap of 0.022 ± 0.023 mm (the best TI), 0.063 ± 0.059 mm (the worst TI), 0.015 ± 0.011 mm (the best DI), and 0.019 ± 0.015 mm (the worst DI). CONCLUSIONS: Within the limits of this in vitro study, the digital impression showed better accuracy compared to conventional impressioning. CLINICAL RELEVANCE: The digital impression might offer a viable alternative to traditional impressions for fabrication of full-arch implant-supported prostheses with satisfactory passive fit.

A Luting Technique for Passive Fit of Implant-Supported Fixed Dentures.

Several factors contribute to distortion of implant prostheses during fabrication and could prevent passive, accurate adaptation between implants and implant frameworks. The misfit between implants and restorative components may be significant and possibly lead to biologic or mechanical complications. The aim of this article is to describe a laboratory luting technique used to lute implant cylinders to metal frameworks in implant prostheses. This technique provides accurate, passive fits. According to this technique, titanium implant cylinders provided with corresponding external castable cylinders are used. Implant cylinders are screwed into the analogs in the master cast while the castable cylinders on top are splinted together using castable resin to realize a castable resin pattern. After casting, the framework is adjusted and cemented to the titanium cylinders on the master cast. Due to its ease and quickness of use and clinical efficiencies, this technique is deemed particularly useful in immediate loading rehabilitations.

Brånemark Novum® immediate loading rehabilitation of edentulous mandibles: 11-year retrospective study.

OBJECTIVES: Short-term results indicated that the Brånemark Novum® protocol (Nobel Biocare AB, Goteborg, Sweden) allowed successful rehabilitation of mandibular edentulism with immediately loaded implants. Yet, long-term studies are lacking. The aim of the present retrospective study was to report the 11-year outcomes for patients treated according to this protocol. MATERIAL AND METHODS: Four patients treated according to the Brånemark Novum protocol (Nobel Biocare AB) were followed-up to evaluate implant and prosthesis cumulative survival rate (CSR), implant stability (RFA), marginal bone loss by periapical radiographs, probing depth (PD), and possible complications. Clinical and radiographic parameters were evaluated immediately after completion of the treatment and 1, 5, and 11 years after loading. RESULTS: The 11-year implant and prosthesis CSRs were 100%. Implant stability (RFA values) remained stable over the 11-year follow-up. Small bone resorption was found next to distal implants (median 1 mm) after 11 years, while central implants showed greater bone resorption (median 4.5 mm). The PD (mean 3.75 mm at 11 years) grew together with marginal bone loss. One implant complication was detected on a central implant (crater-form bone destruction), and 10 prosthetic complications (fractures of resin or teeth), 80% of which registered on the same parafunctional patient. CONCLUSIONS: The 11-year results demonstrated that the Brånemark Novum protocol (Nobel Biocare AB) is a predictable technique with favorable long-term outcomes. This was a rigid protocol, which could be applied only in patients with specific anatomical characteristics of the lower jaw, but it had the merit of indicating the key factors for full-arch immediate loading rehabilitations.

Morphological and chemical characteristics of different titanium surfaces treated by bicarbonate and glycine powder air abrasive systems.

OBJECTIVES: This in vitro study investigated possible morphological and chemical changes induced by glycine or sodium bicarbonate powder air polishing on machined and acid-etched titanium surfaces. MATERIALS AND METHODS: The glycine powder (granulometry <65 µm) and sodium bicarbonate powder (granulometry <150 µm) were applied on 2 machined healing abutments and on 2 acid-etched healing abutments. The samples were characterized by scanning electron microscopy coupled with energy dispersive x-ray spectroscopy. The analyses were performed at different steps: (1) as received, right after opening the abutment packaging; (2) after 20 minutes air exposure; (3) after aging in artificial saliva; (4) after glycine or sodium bicarbonate powder air polishing for 5 seconds; (5) after repetition of steps 3 and 4 with longer time of polishing (20 seconds). CONCLUSIONS: Air polishing using glycine and sodium bicarbonate powder seemed to be safe for professional oral hygiene of titanium dental implants, although acid-etched abutments and abutments treated with bicarbonate harbored more salts. This might indicate a greater plaque accumulation in a clinical situation. However, this result has to be investigated in vivo to understand its clinical relevance.

Systematic review of some prosthetic risk factors for periimplantitis.

STATEMENT OF PROBLEM: The recent literature underlines a correlation between plaque and the development of periimplantitis but neglects the importance of the prosthetic factors. PURPOSE: The purpose of this systematic review was to appraise the available literature to evaluate the role played by cement excess and misfitting components on the development of periimplantitis. MATERIAL AND METHODS: An electronic search restricted to the English language was performed in PubMed, Embase, and the Cochrane Register up to September 1, 2014, based on a selected search algorithm. Only cohort studies and case-control studies were included without additional restrictions. The presence of periimplantitis and implant failure were considered primary and secondary outcome variables. RESULTS: The search produced 275 potentially relevant titles, of which only 2 were found eligible. They showed a correlation in cemented implant prostheses between cement excess and the presence of periimplant disease, especially in patients with a history of periodontal disease. After cement excess removal by means of debridement, disease symptoms disappeared around most of the implants. CONCLUSIONS: Scientific articles on prosthetic risk factors for periimplantitis are scarce. Although the studies found on cement remnants have a high risk for bias, cement excess seems to be associated with mucositis and possibly with periimplantitis, especially in patients with a history of periodontal disease.

The role of surface implant treatments on the biological behavior of SaOS-2 osteoblast-like cells. An in vitro comparative study.

OBJECTIVES: The aim of this study was an in vitro comparison of osteoblast adhesion, proliferation and differentiation related to six dental implants with different surface characteristics, and to determine if the interaction between cells and implant is influenced by surface structure and chemical composition. MATERIAL AND METHODS: Six types of implants were tested, presenting four different surface treatments: turned, sandblasted, acid-etched, anodized. The implant macro- and microstructure were analyzed using SEM, and the surface chemical composition was investigated using energy-dispersive X-ray analysis. SaOS-2 osteoblasts were used for the evaluation of cell adhesion and proliferation by SEM, and cell viability in contact with the various surfaces was determined using cytotoxicity MTT assays. Alkaline phosphatase (ALP) enzymatic activity in contact with the six surfaces was evaluated. Data relative to MTT assay and ALP activity were statistically analyzed using Kruskal-Wallis not parametric test and Nemenyi-Damico-Wolfe-Dunn post hoc test. RESULTS: All the implants tested supported cell adhesion, proliferation and differentiation, revealing neither organic contaminants nor cytotoxicity effects. The industrial treatments investigated changed the implant surface microscopic aspect and SaOS-2 cell morphology appeared to be influenced by the type of surface treatment at 6, 24, and 72 h of growth. SaOS-2 cells spread more rapidly on sandblasted surfaces. Turned surfaces showed the lowest cell proliferation at SEM observation. Sandblasted surfaces showed the greatest ALP activity values per cell, followed by turned surfaces (P < 0.05). CONCLUSIONS: On the base of this in vitro investigation, differently surfaced implants affected osteoblast morphology, adhesion, proliferation, and differentiation. Sandblasted surfaces promoted the most suitable osteoblast behavior.

Comparison of Bone-Level and Tissue-Level Implants: A Pilot Study with a Histologic Analysis and a 4-Year Follow-up.

This study clinically and histologically evaluated the performance of implants with different crestal morphologies: tissue-level implants and bone-level implants. Nine patients received at least two adjacent implants in an edentulous area: one bone-level implant (EO) and one tissue-level implant (TG) (total: 23 implants), placed beside each other using a single-stage delayed loading protocol. The implants were rehabilitated with screw-retained fixed partial dentures. Plaque Index (PI), bleeding on probing (BOP), probing depth (PD), and peri-implant bone level were recorded at various postsurgical follow-ups, including 2 and 6 months as well as 1 and 4 years. At 3 months postsurgery, soft tissue biopsy samples were taken from all implant sites and histologically analyzed. Longitudinal assessment of the results (TG vs EO implants) was performed using a linear mixed model with random intercept and by using Spearman correlation or chi-square after visual inspection of the probability distribution. Student t test was used to compare means, and chi-square test was used for dichotomic variables. P < .05 was considered statistically significant. All implants were functional at 4 years. Peri-implant bone resorption was limited, with means of 1.20 ± 0.71 mm and 1.24 ± 0.82 mm for TG and EO implants, respectively. No significant differences in clinical parameters were identified between EO and TG implants. Histologic analysis revealed normal peri-implant soft tissue healing with poor inflammatory infiltrate. Differences in the histologic appearance of soft tissues were more related to patients than implant type. Both implants appeared to be suitable for partial rehabilitation of edentulous arches without differences in the investigated clinical and histologic parameters. However, TG implants showed a greater risk of implant collar exposure.

Dental implants osteogenic properties evaluated by cDNA microarrays.

OBJECTIVE: This study aims at applying cDNA microarray analysis in vitro for establishing and comparing the osteogenic properties of dental implants with different surface characteristics. MATERIALS AND METHODS: Saos-2 osteoblasts were cultured in bottom-cone tubes in presence of 5 different dental implants with various surface characteristics. Cells adherent to dental implants were detached and RNA purified. The expression of 18,401 genes was tested by cDNA microarray. RESULTS: The number and viability of cells adherent to different dental implants varied but without any significant statistical difference. Conversely, gene expression was revealed to be a more sensitive biomarker being remarkably different in cells adherent to different implants. The 5 dental implants significantly modulated the expression of 14 osteogenic activities mainly including bone morphogenetic proteins, osteomodulin, and osteoprotegerin. CONCLUSION: Despite no significant differences having been found in in vitro cell number and viability, cells adherent to 5 differently surfaced implants showed different gene expression profiles. Thus, to evaluate osteogenesis as related to dental implants, it is important to analyze not only the number of adherent cells but also the activation of genes encoding for osteogenic activities.

The influence of cantilever length and implant inclination on stress distribution in maxillary implant-supported fixed dentures.

STATEMENT OF PROBLEM: The benefits and limitations of jaw treatments with tilted versus vertical implants, as well as prosthesis design with and without posterior cantilevers, have been extensively discussed. However, biomechanical advantages associated with cantilevers in fixed dentures (FDs) and tilted implants in the maxillae are less well documented. PURPOSE: The purpose of this study was to compare and analyze, via 3-dimensional (3-D) finite element analysis, stresses transmitted to tilted versus vertical implants and the surrounding periimplant bone in the maxillae. MATERIAL AND METHODS: A 3-D edentulous maxillary model was created using customized computer software (FEMAP 8.3). Four implants were virtually placed in the premaxilla and splinted with an FD. Keeping the prosthesis length constant, 4 different configurations were evaluated with the distal implants inclined 0, 15, 30, and 45 degrees; cantilever extensions were 13, 9, 5, and 0 mm, respectively. A vertical load (150 N) was applied to the distal portion of the posterior cantilevers. Von Mises' stress values transmitted to periimplant bone and at the metal framework of FDs on implants were evaluated in cancellous and cortical bone. RESULTS: The maximum stresses recorded in periimplant bone for the vertical implants were 75.0 MPa (distal implants), 35.0 MPa (mesial implants), and 95.0 MPa for the metal frameworks. Tilted distal implants, with consequent reduction of the posterior cantilevers, resulted in decreased stress values for all of the variables: -12.9%, -18.3%, and -11.5% for the 15-degree configuration; -47.5%, -52.6%, and -31.3% for the 30-degree configuration; and -73.5%, -77.7%, and -85.6% for the 45-degree configuration CONCLUSIONS: Finite element analysis data regarding rehabilitation of atrophic maxillae revealed that tilted distal implants, rigidly splinted with an FD, decrease stress in the periimplant bone and frameworks. This treatment modality seems to be a valid therapeutic alternative to conventional maxillary fixed complete prostheses supported by vertical dental implants with posterior cantilevers.

Pulp vitality during ultrasonic tooth preparation. Part 2.

BACKGROUND: Ultrasonic devices have a lot of dental application specially in hygiene and surgery. However there are some disadvantages like cut slowness and heat production. Prosthodontics application is less investigated. In particular the heat production could be an important factor for the clinician. In fact more than 5.5 °C temperature increasing could determine pulp necrosis during tooth preparation. The aim of this study is to investigate the increasing of temperature during finishing line repositioning and polishing phases using ultrasounds inserts and to verify if it remains within the limit of 5.5 °C. METHODS: A sample of 32 human molars (extracted for periodontal reasons) was selected. The teeth were endodontically treated and prepared with burs in order to obtain a prosthetic round chamfer preparation, leaving the apical portion pervious for inserting the thermocouple probe. Then, they were inserted in plaster cubes up to the cement-enamel junction. A wall has been selected for each tooth for margin repositioning and finishing and prepared with the piezoelectric instrument (Multipiezo Touch with TipHolder DB2, Mectron, Carasco, Genoa, Italy). A mechanical arm was used to standardize the operator-dependent parameters. These parameters were: the pressure exerted on the dental wall, the cutting length and the time required for margin repositioning and finishing. The test phase consisted in a first stage of margin repositioning using an regular ultrasound tip with a diamond grain of 120 micron (DB120, Mectron, Carasco, Italy) (group 1), followed by a second finishing step conducted by a extra fine ultrasound tip with a diamond grain of 60 micron (DB60, Mectron, Carasco, Italy) (group 2). Each test lasted 60 seconds: this was the time that the mechanical arm needed to accomplish 32 rides. During these stages the intrapulpal temperature has been recorded thanks to a thermocouple. The obtained temperature data were analyzed by Kruskal-Wallis test and Mann-Withney post-hoc test, without Bonferroni correction (P<0.001). RESULTS: The average pulpal temperature increase was 4.65 °C with a standard deviation of 0.99 °C for the DB 120 ultrasonic tip and 5.40 °C with a standard deviation of 0.84 °C for the DB 60 ultrasonic tip. However, neither of the instruments reach the medium critical level of 5.5°C reported in the literature, there are some single values who exceed it. There is statistically significant difference using tips with different granulometries within the two groups (P value =0.013). CONCLUSIONS: Ultrasonic tools are very performing to achieve results in repositioning and polishing of prepared tooth. The in-vitro analysis show that the pulp temperature increasing remains within the safe limits literature shows. It is important underline the polishing phase is the most critical and the clinicians have to pay attention to irrigation and pression to avoid pulp damages. Additional clinical studies have to be performed to confirm these results.

Temperature variations in pulp chamber: an in-vitro comparison between ultrasonic and rotating instruments in tooth preparation. Part 1.

BACKGROUND: The purpose of this study was to analyze pulpal temperature increase generated by prosthodontic margin repositioning and finishing with ultrasonic and rotating instruments. The temperature changes recorded were also correlated with the residual dentin thickness. METHODS: A sample of 32 human extracted molars was selected. The teeth were endodontically treated and prepared with prosthetic round chamfer preparation. Then, they were inserted in plaster cubes up to the cement-enamel junction, leaving the apical portion pervious for inserting the thermocouple probe. The conventional technique, which involves the use of a high-speed contra-angle handpiece, was compared with an ultrasonic method (Crown Prep, Mectron, Carasco, Italy). For margin repositioning and finishing, two walls were randomly selected for each tooth: one was included in the test group and cut with the piezoelectric instrument (Multipiezo Touch TipHolder DB2, Mectron, Carasco, Genoa, Italy), the other one was inserted in the control group and cut with the high speed contra-angle handpiece (Kavo, Biberach, Germany). To standardize the operator-dependent parameters, it was used a mechanical arm controlled by a computer. These parameters were the pressure exerted on the dental wall, the cutting length and the time required for margin repositioning and finishing. For both test and control group, test phase consisted in a first stage of margin repositioning using an ultrasound tip or a diamond bur with a greater granulometry (120 µm for the ultrasound tip and 125 µm for the diamond bur), followed by a second finishing step conducted by an ultrasound tip or a diamond bur with smaller granulometry (60 µm for the ultrasound tip and 30 µm for the diamond bur). During these stages the intrapulpal temperature was recorded thanks to a thermocouple. Before and after these steps, the thickness of the remaining dental walls was measured with a caliber. RESULTS: The average pulpal temperature increase was 5.03±0.98 °C for the ultrasonic preparation (test group) and 3.55±0.95 °C for the conventional technique (control group). The difference was statistically significant (P value <0.001). However, neither of the instruments reached the critical level of 5.5 °C reported in the literature. The mean initial dentin thicknesses was 1.82±0.47 mm for the control group and 1.59±0.54 mm for the test group but the analysis of the residual dentin thicknesses revealed a greater reduction of the walls worked up with high speed contra-angle handpiece (mean 0.9±0.5 mm), which was therefore more aggressive than the ultrasonic instrument (mean 1.1±0.5 mm). A very weak negative correlation was present between the thickness of the wall at baseline and the increment of temperature. CONCLUSIONS: Within limitations of this study, temperature increasing of ultrasonic instruments shows a statistical difference related to rotary ones. But, as literature shows, the ultrasonic advantages are margin precision, preservation of soft tissues and reduction of operating times. Furthermore, in relation with results of this study, they could be considered safe for pulp vitality because the increase in pulpal temperature is similar to traditional instruments and it does not exceed the critical level of 5.5 °C.

Brånemark Novum Immediate Loading Rehabilitation of Edentulous Mandibles: Case Series with a 16-Year Follow-up.

The aim of the present report was to evaluate the clinical outcomes of edentulous jaws rehabilitated with the Brånemark Novum protocol over a 16-year period. Between April and November 2001, four patients (three males, one female) were rehabilitated with fixed full-arch rehabilitations supported by three immediately loaded implants following the Brånemark Novum protocol. Cumulative survival rates (CSRs) of the implants and prosthesis, bleeding on probing (BOP), Plaque Index (PI), probing depth (PD), implant stability quotient (ISQ; as measured through resonance frequency analysis [RFA]), and peri-implant bone resorption were evaluated over time, up to the 16-year follow-up. At 16 years of follow-up, no implant failed (CSR 100%) and no prosthesis needed to be substituted (CSR 100%). During the period between the 11th and 16th year of follow-up, bone level (mean: 2.2 mm at 16 years) and RFA values remained stable. At the 16-year follow-up, the implants presented high PI (79.2%) but low BOP (10.4%) values. Mean PD was 3.30 mm (range: 2 to 6 mm). One biologic complication was detected on a central implant (crater-form bone destruction), and several prosthodontic complications occurred during the 16 years (fractures of resin or teeth), the majority of which were registered on the same parafunctional patient. This is the first description of the Brånemark Novum protocol rehabilitation with a 16-year follow-up. The outcomes demonstrated very good long-term outcomes for this protocol.

Piezoelectric implant surgery and immediate loading in the aesthetic zone.

BACKGROUND: Replacement of missing teeth in the anterior aesthetic zone has challenged clinicians with fixed, removable or implant prosthodontics. Problems have been encountered could void aesthetic and functional results. The aim of this study was to present a clinical case report in which clinician challenged a very strong aesthetic case with an innovative surgical and prosthetic approach. METHODS: A patient who presented to the authors with a maxillary central incisor that had a hopeless prognosis secondary to acute localized severe periodontitis. The patient was treated by extracting the tooth and replacing it immediately with a platform switched implant using piezoelectric surgery. The implant was then restored with an immediate, non-occlusal loading provisional restoration. RESULTS: The implant became osseointegrated and was ultimately restored with a definitive abutment and crown restoration. CONCLUSIONS: Innovative approaches could represent a valid alternative to restore patients functionally and aesthetically.

Comparison of biofilm removal using glycine air polishing versus sodium bicarbonate air polishing or hand instrumentation on full-arch fixed implant rehabilitations: a split-mouth study.

OBJECTIVES: To compare the cleaning efficacy of glycine air polishing against two different professional oral hygiene techniques on implants supporting full-arch fixed prostheses. METHOD AND MATERIALS: Thirty patients with a total of 32 implant fixed full-arch rehabilitations in the maxilla and/or mandible (134 implants) were included. After the removal of the screw-retained prostheses, baseline peri-implant spontaneous bleeding (SB), Plaque Index (PI), probing depth (PD), and bleeding on probing (BOP) were recorded (T0). Three oral hygiene treatments were assigned randomly following a split-mouth method: all the patients received glycine air polishing (G) in one side of the arch (n = 32), and sodium bicarbonate air polishing (B) (n = 16) or manual scaling with carbon-fiber curette (C) (n = 16) was performed in the opposite side. After the hygiene procedures, PI and SB were recorded and patient's comfort degree towards the three techniques was analyzed by questionnaires using a rating scale from 1 to 5 (T1). RESULTS: PI reduction was significantly higher for G (T0, 2.88 ± 1.37; T1, 0.04 ± 0.21) and B (T0, 3.13 ± 1.34; T1, 0.0 ± 0.0) as compared with C (T0, 2.15 ± 1.46; T1, 0.44 ± 0.7) (P < .001). B reported the highest mean value of SB (T0, 0.0 ± 0.0; T1, 3.42 ± 0.75) compared with G (T0, 0.05 ± 0.21; T1, 1.60 ± 1.05) and C (T0, 0.07 ± 0.24; T1, 0.73 ± 0.91) (P < .001). A significant difference in comfort mean score was found between G (4.8 ± 0.5) and B (3.5 ± 1.7) (P = .014), no difference between G and C (4.7 ± 0.7) (P = .38). CONCLUSION: Professional oral hygiene on implants using glycine air polishing showed high levels of both cleaning efficacy and patients' acceptance.

Immediate Versus Delayed Loading of Dental Implants Supporting Fixed Full-Arch Maxillary Prostheses: A 10-year Follow-up Report.

PURPOSE: To compare clinical outcomes of immediate vs delayed implant loading in edentulous maxillae with full-arch fixed prostheses. MATERIALS AND METHODS: Two patient groups were identified for this study: (1) the test group (TG), which included 34 patients (19 women, 15 men; mean age 56.7 years) treated with the Columbus Bridge Protocol with 4 to 6 postextractive implants loaded within 24 hours (163 implants total); and (2) the control group (CG), which included 15 patients (6 women, 9 men; mean age 59.96 years) treated with a traditional two-stage delayed loading rehabilitation using 6 to 9 implants inserted in healed sites (97 implants total). All patients were rehabilitated with full-arch fixed prostheses in the maxilla. RESULTS: At the 10-year follow-up, no difference in the implant cumulative survival rate between the TG (93.25%) and CG (94.85%) was found. Mean bone loss was significantly lower in the TG (mean: 2.11 mm) compared to the CG (mean: 2.65 mm). All original prostheses were maintained and functioning satisfactorily. CONCLUSION: Maxillary full-arch immediate loading represents a valid alternative to the traditional delayed loading rehabilitation.

Prediction of Titanium Implant Success by Analysis of microRNA Expression in Peri-Implant Tissue. A 5-Year Follow-Up Study.

The aim of the present study is to evaluate the expression of microRNA (miRNA) in peri-implant soft tissue and to correlate epigenetic information with the clinical outcomes of the implants up to the five-year follow-up. Seven patients have been rehabilitated with fixed screw-retained bridges each supported by implants. Peri-implant bone resorption and soft tissue health parameters have been recorded over time with a five-year follow-up. Mini-invasive samples of soft peri-implant tissue have been taken three months after implant insertion. miRNA have been extracted from cells of the soft tissue samples to evaluate gene-expression at the implant sites by microarray analysis. The epigenomic data obtained by microarray technology has been statistically analyzed by dedicated software and compared with measured clinical parameters. Specific miRNA expression profiles predictive of specific clinical outcomes were found. In particular, some specific miRNA signatures appeared to be "protective" from bone resorption despite the presence of plaque accumulation. miRNA may be predictors of dental implant clinical outcomes and may be used as biomarkers for diagnostic and prognostic purposes in the field of implant dentistry.

Peri-implant Tissue Health and Bone Resorption in Patients with Immediately Loaded, Implant-Supported, Full-Arch Prostheses.

PURPOSE: To evaluate plaque accumulation, peri-implant soft tissue inflammation, and bone resorption in patients with immediately loaded implants supporting fixed full-arch prostheses. MATERIALS AND METHODS: A convenience sample of 72 patients treated with fixed full-arch prostheses supported by four to six immediately loaded implants was selected. Bleeding on probing (BOP), Plaque Index (PI), and peri-implant bone loss were measured. The Sixth European Workshop on Periodontology definitions of mucositis and peri-implantitis were used, and collected data were analyzed using a nonparametric test (Spearman's rank correlation). Correlation coefficients (ρ) were defined as follows: < 0.2 = very weak; 0.2 to 0.39 = weak; 0.4 to 0.59 = moderate; 0.6 to 0.79 = strong; 0.8 to 1.0 = very strong. RESULTS: A total of 331 implants were analyzed. The mean follow-up observation time was 5.8 years (range: 1 to 14 years); mean PI and BOP were 61.7% and 21.1%, respectively; and mean bone loss was 0.89 mm (standard deviation [SD] 1.09). The mean probing depth was 1.8 mm (range: 0.5 to 5 mm). Five patients presented with one implant each affected by peri-implantitis (6.9%), and 15 patients presented with at least one implant affected by mucositis (20.8%). No correlation was found between PI and bone resorption (P = .08). Very weak correlations were found between BOP and bone resorption (ρ = 0.18; P = .001) and between PI and BOP (ρ = 0.13, P = .019). CONCLUSION: The results suggest that plaque accumulation is correlated with peri-implant mucositis; however, plaque accumulation alone does not appear to be associated with bone resorption.

Evaluation of a New Ultrasonic Insert for Prosthodontic Preparation.

PURPOSE: This paper describes a new ultrasonic instrument (tipholder DB1 with crown prep tip inserts) designed to optimize prosthodontic margin repositioning and finishing. MATERIALS AND METHODS: The insert movement was assessed, and it was demonstrated that tipholder DB1 provides its inserts with an elliptical-like movement, making the entire insert surface able to cut. Then, 20 extracted teeth were prepared using tipholder DB1, sonic instruments, and traditional drills. Dental surface roughness produced using each of the three tools was measured using a roughness tester. Results were compared using univariate analysis of variance and Bonferroni post hoc test. RESULTS: The roughness produced using tipholder DB1 with crown prep insert presented no statistically significant differences compared to the roughness produced using sonic instruments and traditional drills. CONCLUSION: Tipholder DB1 with crown prep inserts is a promising treatment for margin repositioning and finishing.

Biological and mechanical characterization of carbon fiber frameworks for dental implant applications.

OBJECTIVES: The aim of the present study was to investigate the biocompatibility and mechanical characteristics of dental implant frameworks made of carbon fiber composite. METHODS: The biocompatibility of intact samples and fragments was evaluated by cell count and MTT test according to EN-ISO 10993-5:2009 directions. Destructive and non-destructive mechanical tests were performed in order to evaluate: porosity, static and dynamic elastic modulus of carbon fiber samples. These tests were conducted on different batches of samples manufactured by different dental technicians. The samples were evaluated by optical microscope and by SEM. A compression test was performed to compare complete implant-supported fixed dentures, provided with a metal or carbon fiber framework. RESULTS: Carbon fiber intact and fragmented samples showed optimal biocompatibility. Manufacture technique strongly influenced the mechanical characteristics of fiber-reinforced composite materials. The implant-supported full-arch fixed denture provided with a carbon fiber framework, showed a yield strength comparable to the implant-supported full-arch fixed denture, provided with a metal framework. SIGNIFICANCE: Carbon fiber-reinforced composites demonstrated optimal biocompatibility and mechanical characteristics. They appear suitable for the fabrication of frameworks for implant-supported full-arch dentures. Great attention must be paid to manufacture technique as it strongly affects the material mechanical characteristics.

Tooth loss and obstructive sleep apnoea.

BACKGROUND: Complete tooth loss (edentulism) produces anatomical changes that may impair upper airway size and function. The aim of this study was to evaluate whether edentulism favours the occurrence of obstructive sleep apnoea (OSA). METHODS: Polysomnography was performed in 48 edentulous subjects on two consecutive nights, one slept with and the other without dentures. Upper airway size was assessed by cephalometry and by recording forced mid-inspiratory airflow rate (FIF50). Exhaled nitric oxide (eNO) and oral NO (oNO), were measured as markers of airway and oropharyngeal inflammation. RESULTS: The apnoea/hypopnoea index (AHI) without dentures was significantly higher than with dentures (17.4 +/- 3.6 versus 11.0 +/- 2.3. p = 0.002), and was inversely related to FIF50 (p = 0.017) and directly related to eNO (p = 0.042). Sleeping with dentures, 23 subjects (48%) had an AHI over 5, consistent with OSA, but sleeping without dentures the number of subjects with abnormal AHI rose to 34 (71%). At cephalometry, removing dentures produced a significant decrease in retropharyngeal space (from 1.522 +/- 0.33 cm to 1.27 +/- 0.42 cm, p = 0.006). Both morning eNO and oNO were higher after the night slept without dentures (eNO 46.1 +/- 8.2 ppb versus 33.7 +/- 6.3 ppb, p = 0.035, oNO 84.6 +/- 13.7 ppb versus 59.2 +/- 17.4 ppb, p = 0.001). CONCLUSION: These findings suggest that complete tooth loss favours upper airway obstruction during sleep. This untoward effect seems to be due to decrease in retropharyngeal space and is associated with increased oral and exhaled NO concentration.