Functionalization of a Volume-Stable Collagen Matrix Using Liquid Platelet-Rich Fibrin: A Case Report Presenting a New Approach for Root Coverage

This case report presents a novel approach for root coverage of multiple gingival recessions with a volume-stable collagen matrix functionalized with injectable platelet-rich fibrin (i-PRF). A patient with multiple gingival recessions in the anterior maxilla was submitted to root coverage by coronally advanced flap with split-full-split incisions. Blood collection was performed before surgery and i-PRF was obtained after centrifugation (relative centrifugal force (RCF) 400 g, 2700 rpm, 3 minutes). A volume-stable collagen matrix was soaked with i-PRF and applied as a substitute for autogenous connective tissue graft. A mean root coverage of 83% was observed after a 12-month follow-up period, and only slight modifications were detected in a 30-month follow-up consultation. The association of a volume-stable collagen matrix with i-PRF successfully treated multiple gingival recessions with reduced morbidity since a connective tissue collection was avoided.

Multivariate analysis of the influence of peri-implant clinical parameters and local factors on radiographic bone loss in the posterior maxilla: a retrospective study on 277 dental implants

OBJECTIVES

The aim of the present study was to investigate whether peri-implant clinical parameters (modified plaque index (mPI), bleeding and/or suppuration on probing (B/SOP)) and local factors (type of prostheses, screw emergence, platform diameter, and abutment angulation) might contribute to the development of additional bone loss and peri-implantitis around dental implants.

MATERIALS AND METHODS

Two hundred seventy-seven external hex connection implants placed in the posterior maxilla of 124 patients were retrospectively evaluated. They were divided into two groups: physiologic bone loss < 2 mm (PBL) or additional bone loss ≥ 2 mm (ABL). GEE logistic regression was applied to evaluate the influence of type of prostheses (implant-supported single crown (ISSC), fixed partial denture (ISFPD), and full denture (ISFD)) and clinical parameters (mPI and S/BOP) on bone loss.

RESULTS

Among the 277 implants, 159 (57.4%) presented PBL and 118 (42.6%) presented ABL. Within the ABL group, 20.6% implants were diagnosed with peri-implantitis. mPI significantly correlated with the type of prosthesis and the highest value of mPI (index = 3) was observed in ISFD (23.8%). Moreover, peri-implantitis was more frequently associated with ISFD (32.79%) than ISSC and ISFDP (13.79% and 13.48, respectively) CONCLUSIONS: ISFD in the posterior maxilla presented high rates of ABL and showed a higher prevalence of peri-implantitis. None of the local factors seemed to contribute to the development of these conditions. Further investigations are needed to prospectively support the results of the present study.

CLINICAL RELEVANCE

Patients rehabilitated with ISFD should be carefully monitored and have more frequent maintenance visits to prevent or control peri-implant bone loss.

Rehabilitation Challenge in Patient With a High Smile Line: Case Report and Review of Surgical Protocols

INTRODUCTION

Defects in the maxillary anterior teeth are delicate and difficult to solve because of the esthetic, functional, and psychological impairment that may arise if the rehabilitation treatment does not return the damaged tissues to the naturalness. Esthetic predictability and reduced surgical interventions are some great reasons to simplify dental treatments. During the presurgical evaluation, the clinician should review the implant esthetic risk profile, considering the patient's smile line, the esthetic demands, the hard and soft tissue thickness and width, and the gingival biotype. Thus, achieving long-term esthetic results initiates with a detailed case planning before surgical intervention.

CASE PRESENTATION

The present report described a complex esthetic clinical case involving teeth and dental implant related to a high smile line. The clinical case was solved through immediate implant placement and immediate loading using a personalized prosthetic abutment and finalized with the installation of metal-free prosthetic restorations.

CONCLUSION

The use of a personalized prosthetic abutment helped to achieve a better emergence of the prosthesis under the periodontal tissues. Although it was a challenging esthetic case, especially because of the high smile line, the result was a natural smile while the adjacent soft tissues maintained their esthetics and health.

Bioactive-Enhanced Polyetheretherketone Dental Implant Materials: Mechanical Characterization and Cellular Responses

The aim of this study was to characterize the mechanical properties of a bioactive-modified polyetheretherketone (PEEK) manufacturing approach for dental implants and to compare the in vitro biological behavior with titanium alloy (Ti6Al4V) as the reference. PEEK, PEEK with 5% hydroxyapatite (HA), PEEK with 5% beta-tricalcium phosphate (βTCP), and Ti6Al4V discs were produced using hot pressing technology to create a functionally graded material (FGM). Surface roughness values (Ra, Rz), water contact angle, shear bond strength, and Vickers hardness tests were performed. Human osteoblasts and gingival fibroblasts bioactivity was evaluated by a resazurin-based method, alkaline phosphatase activity (ALP), and confocal laser scanning microscopy (CLSM) images of fluorescent-stained fibroblasts. Morphology and cellular adhesion were confirmed using field emission gun-scanning electron microscopy (FEG-SEM). Group comparisons were tested using analysis of variance (Tukey post hoc test), α = .05. All groups presented similar roughness values (P &gt; .05). Ti6Al4V group was found to have the highest contact angle (P &lt; .05). Shear bond strength and Vickers hardness of different PEEK materials were similar (P &gt; .05); however, the mean values in the Ti6Al4V group were significantly higher when compared with those of the other groups (P &lt; .05). Cell viability and proliferation of osteoblast and fibroblast cells were higher in the PEEK group (P &lt; .05). PEEK-βTCP showed the highest significant ALP activity over time (P &lt; .05 at 14 days of culture). An enhanced bone and soft-tissue cell behavior on pure PEEK was obtained to the gold standard (Ti6Al4V) with equivalent roughness. The results substantiate the potential role of chemical composition rather than physical properties of materials in biological responses. The addition of 5% HA or βTCP by FGM did not enhance PEEK mechanical properties or periodontal cell behavior.

On the synthesis and characterization of β-tricalcium phosphate scaffolds coated with collagen or poly (D, L-lactic acid) for alveolar bone augmentation

Objectives:

After tooth loss, dimensional alterations on the alveolar bone ridge can occur that can negatively affect the placement of dental implants. The purpose of this study was to evaluate the synthesis, and mechanical properties of β-tricalcium phosphate (β-TCP) scaffolds coated with bioabsorbable polymers, namely, collagen and poly (D, L-lactic acid) (PDLLA).

Materials and Methods:

β-TCP powder was obtained by reactive milling and then characterized by X-ray diffraction and scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS). β-TCP scaffolds were obtained by replica method, in which polyurethane foams are immersed in β-TCP suspension and thereafter submitted to a thermal treatment to remove the polyurethane and sinter the ceramic. Type-I collagen or PDLLA were used to coat the β-TCP scaffolds by dip-coating method. Scaffolds were separated in four groups depending on the coating material: noncoated (Group A), double immersion in collagen (Group B), double immersion in PDLLA (Group C), and ten immersions in PDLLA (Group D). Samples were characterized by compressive tests and SEM/EDS. Data were statistically analyzed through two-way ANOVA (p = 0.05).

Results:

Chemical and microscopic analyses revealed proper morphology and chemical composition of powder particles and scaffolds with or without polymeric coatings. Scaffolds coated with PDLLA showed higher compressive strength (0.11 ± 0.054 MPa) than those of collagen (0.022 ± 0.012 MPa) or noncoated groups (0.024 ± 0.012 MPa).

Conclusions:

The coating method of β-TCP with PDLLA revealed a potential strategy to increase the mechanical strength of porous ceramic materials while collagen can enhance cell migration.

Abutment misfit in implant-supported prostheses manufactured by casting technique: An integrative review

The aim of this study was to perform an integrative review of the literature on the clinically usual prosthesis-abutment misfit over implant-supported structures manufactured by conventional casting technique. The present integrative review used the PRISMA methodology. A bibliographical search was conducted on the following electronic databases: MEDLINE/PubMed (National Library of Medicine), Scopus (Elsevier), ScienceDirect (Elsevier), Web of Science (Thomson Reuters Scientific), Latin American and Caribbean Center on Health Sciences Information (BIREME), and Virtual Health Library (BVS). A total of 11 relevant studies were selected for qualitative analysis. The prosthetic-abutment vertical misfit considered clinically usual ranged from 50 to 160 μm. The vertical misfit depends on several steps during technical manufacturing techniques, which includes the materials and technical procedures. Lower values in misfit are recorded when precious metal or titanium alloys are utilized. Although a vertical misfit mean value of 100 μm has been considered clinically usual, most of the previous studies included in this revision showed lower mean values.

Titanium coated with poly(lactic-co-glycolic) acid incorporating simvastatin: Biofunctionalization of dental prosthetic abutments

OBJECTIVE

To propose a biofunctionalized prosthetic abutment by analyzing physico-chemical and morphological properties, simvastatin (SIM) release, and biocompatibility of titanium (Ti) disks coated with poly(lactic-co-glycolic) acid (PLGA) incorporating SIM.

METHODS

Titanium disks (8 × 3 mm) were distributed into four groups: Ti: pure Ti; Ti + PLGA: Ti coated with PLGA; Ti + PLGA + SIM6%: Ti + PLGA with 6% SIM; and Ti + PLGA + SIM0.6%: Ti + PLGA incorporating 0.6% SIM. PLGA was prepared through chloroform evaporation technique. After complete dissolution of PLGA, SIM was diluted in the solution. Ti + PLGA, Ti + PLGA + SIM6%, and Ti + PLGA + SIM0.6% were dip coated with PLGA and PLGA + SIM, respectively. Samples were sterilized by ethylene oxide. For SIM release assay, disks were submerged in PBS, pH 7.4, 37°C, 30 rpm up to 600 hours. At different time intervals, SIM was quantified by spectrophotometry (238 nm). For characterization of the biomaterial components, it was performed Fourier-transform infrared spectroscopy, differential scanning calorimetry, scanning electron microscopy (SEM), optical profilometry, and atomic force microscopy. Biocompatibility analyses were performed by MTS colorimetric assay on murine fibroblasts L929, human gingival fibroblasts (HGFs), and stem cells from human exfoliated deciduous teeth (SHEDs). Absorbance was measured at 490 nm, and percentages of viable cells were calculated in relation to positive control (Ti). SEM images were obtained to verify cell adhesion and morphology. One-way ANOVA followed by Tukey's post hoc test was applied (P < 0.05) for statistical analyses.

RESULTS

SIM release was slow and continuous, reaching about 21% of the incorporated SIM after 600 hours. Topographical analyses revealed success in coating Ti disks with PLGA incorporating SIM. Regarding biocompatibility test, Ti + PLGA + SIM0.6% showed the highest percentage of L929 viability at days 3 and 7. There was no significant difference for Ti, Ti + PLGA, and Ti + PLGA + SIM0.6% groups on cell viability of both SHEDs and HGFs at days 3 and 7. SEM corroborates that SHEDs and HGFs were able to adhere and proliferate on Ti, Ti + PLGA, and Ti + PLGA + SIM0.6% surfaces.

CONCLUSION

A slow and controlled release of SIM was achieved, attributed to a diffusional mass transfer mechanism. Moreover, a homogenous coating topography was obtained. Additionally, 0.6% SIM incorporated into PLGA coating improved fibroblasts L929 viability compared to titanium or PLGA. Also, 0.6% SIM incorporated into PLGA promoted cell viability of about 100% for HGFs and approximately 150% for human mesenchymal stem cells. Therefore, this study allows to consider the use of PLGA-coated titanium incorporating SIM as a biofunctionalized abutment for dental implants.

Surface damage of dental implant systems and ions release after exposure to fluoride and hydrogen peroxide

OBJECTIVE

The aim of this study was to evaluate surface changes on dental implant systems and ions release after immersion in fluoride and hydrogen peroxide.

METHODS

Ten implant-abutment assemblies were embedded in acrylic resin and cross-sectioned along the implant vertical axis. Samples were wet ground and polished. Delimited areas of groups of samples were immersed in 1.23% sodium fluoride gel (F) or in 35% hydrogen peroxide (HP) for 16 min. Gels (n = 3) were collected from the implant surfaces and analyzed by inductively coupled plasma mass spectrometry (ICP-MS), to detect the concentration of metallic ions released from the implant systems. Selected areas of the abutment and implant (n = 15) were analyzed by atomic force microscopy (AFM) and scanning electron microscopy (SEM).

RESULTS

SEM images revealed surface topographic changes on implant-abutment joints after immersion in fluoride. Implants showed excessive oxidation within loss of material, while abutment surfaces revealed intergranular corrosion after immersion in fluoride. ICP-MS results revealed a high concentration of Ti, Al, V ions in fluoride after contact with the implant systems. Localized corrosion of implant systems could not be detected by SEM after immersion in hydrogen peroxide although the profilometry showed increase in roughness. ICP-MS showed the release of metallic ions in hydrogen peroxide medium after contact with dental implants.

CONCLUSION

Therapeutical substances such as fluorides and hydrogen peroxide can promote the degradation of titanium-based dental implant and abutments leading to the release of toxic ions.

Polymer coatings based on sulfonated-poly-ether-ether-ketone films for implant dentistry applications

Poly-ether-ether-ketone (PEEK) is one of the most important biocompatible polymers and its sulfonation has been studied for biomedical applications. The aim of the present study is to produce, to characterize and to assess bioactivity of PEEK coatings with sulfonated PEEK (SPEEK) films. Biomedical grade PEEK (Invibio®, Batch: D0602, grade: NI1) was functionalized using sulfuric acid 98%. SPEEK was dissolved into DMSO or into DMF, both at 10% mass/volume. PEEK bars (N = 18) and cylinders (N = 27) were manufactured by compression molding and heating. SPEEK/DMSO and SPEEK/DMF were drop casted at PEEK bars and dip coated at PEEK cylinders (PEEK + SPEEK/DMSO and PEEK + SPEEK/DMF). Characterization was performed through Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM) and contact angle measurements. Bioactivity was assessed by immersion of samples at SBF for 1, 7 and 21 days, followed by SEM, energy-dispersive analysis (EDX) and FTIR analysis. Statistical analysis was carried out by one-way analysis of variance (ANOVA) (p = 0.05). Characteristic bands of PEEK and SPEEK, were identified through FTIR spectrum analysis, while semicrystallinity was confirmed by XRD. PEEK + SPEEK/DMF showed more evident physicochemical modifications. PEEK + SPEEK/DMSO provided a more regular and hydrophobic surface, observed through SEM and contact angle measurements. SEM/EDX showed that precipitates of calcium were formed at PEEK + SPEEK/DMSO and PEEK + SPEEK/DMF at all experimental times, but materials were not considered bioactive. Interesting surface properties were achieved with SPEEK coatings but the production of SPEEK films at PEEK surface has to be further improved and biologically tested. Schematic diagram showing the methodology applied in this study to prepare PEEK and SPEEK samples, as well as the promising application of the material.

Can degradation products released from dental implants affect peri-implant tissues?

This study aimed to assess the literature available on the effects, on peri-implant tissues, of degradation products released from dental implants as a consequence of therapeutic treatment for peri-implantitis and/or of wear-corrosion of titanium. A literature review of the PubMed medline database was performed up to December 31, 2016. The following search terms were used: "titanium wear and dental implant"; "titanium corrosion and dental implant"; "bio-tribocorrosion"; "peri-implantitis"; "treatment of peri-implantitis"; "titanium particles release and dental implant"; and "titanium ion release and dental implant". The keywords were applied to the database in different combinations without limits of time period or type of work. In addition, the reference lists of relevant articles were searched for further studies. Seventy-nine relevant scientific articles on the topic were retrieved. The results showed that pro-inflammatory cytokines, infiltration of inflammatory response cells and activation of the osteoclasts activity are stimulated in peri-implant tissues in the presence of metal particles and ions. Moreover, degenerative changes were reported in macrophages and neutrophils that phagocytosed titanium microparticles, and mutations occurred in human cells cultured in medium containing titanium-based nanoparticles. Debris released from the degradation of dental implants has cytotoxic and genotoxic potential for peri-implant tissues. Thus, the amount and physicochemical properties of the degradation products determine the magnitude of the detrimental effect on peri-implant tissues.

Biofilm Formation on Different Materials Used in Oral Rehabilitation

The aim of this study was to evaluate the density and the morphological aspects of biofilms adhered to different materials applied in oral rehabilitation supported by dental implants. Sixty samples were divided into four groups: feldspar-based porcelain, CoCr alloy, commercially pure titanium grade IV and yttria-stabilized zirconia. Human saliva was diluted into BHI supplemented with sucrose to grow biofilms for 24 or 48 h. After this period, biofilm was removed by 1% protease treatment and then analyzed by spectrophotometry (absorbance), colony forming unit method (CFU.cm-2) and field-emission guns scanning electron microscopy (FEG-SEM). The highest values of absorbance and CFU.cm-2 were recorded on biofilms grown on CoCr alloys when compared to the other test materials for 24 or 48 h. Also, FEG-SEM images showed a high biofilm density on CoCr. There were no significant differences in absorbance and CFU.cm-2 between biofilms grown on zirconia, porcelain and titanium (p<0.05). Microbiological assays associated with microscopic analyses detected a higher accumulation of oral biofilms on CoCr-based materials than that on titanium or zirconia that are used for prosthetic structures.

Biofilm Affecting the Mechanical Integrity of Implant-Abutment Joints

PURPOSE

This in vitro study evaluated the effect of biofilms on abutment torque loss and wear of implant internal connection surfaces.

MATERIALS AND METHODS

Morse taper abutments were torqued to corresponding implants and then the implant-abutment assemblies were immersed in a biofilm medium for 72 hours. After detorque evaluation, the abutments were removed and the inner implant surfaces were observed via scanning electron microscopy and profilometry.

RESULTS

The removal torque values and the implant damaged areas decreased after contact with biofilms.

CONCLUSION

The lubricating effect of biofilms decreased the friction between contacting surfaces, negatively affecting the mechanical integrity of the implant-abutment connection.

Biofilm behavior on sulfonated poly(ether-ether-ketone) (sPEEK)

Poly(ether-ether-ketone) (PEEK) has also shown to be very attractive for incorporating therapeutic compounds thanks to a sulfonation process which modifies the material structure resulting in a sulfonated-PEEK (sPEEK). Concerning biomedical applications, the objective of this work was to evaluate the influence of different sulfonation degree of sPEEK on the biofilm growth. PEEK samples were functionalized by using sulphuric acid (98%) and then dissolved into dimethyl-sulfoxide. A dip coating technique was used to synthesize sPEEK thin films. The sulfonation degree of the materials was analyzed by FT-IR, H NMR, TG and IEC. The surfaces were characterized by scanning electron microscopy, profilometry and contact angle analyses. Subsequently, the biofilm formation on sulfonated-PEEK based on Streptococcus mutans and Enterococcus faecalis was measured by spectrophotometry, colony forming units (CFUmL^-1) and SEM. Results obtained from thermal and chemical analyses showed an intensification in sulfonation degree for sPEEK at 2 and 2.5h. The E. faecalis or S. mutans biofilm growth revealed statistically significant differences (p<0.05) between 2 and 3h sulfonation groups. A significant decrease (p<0.05) in CFUmL^-1 was recorded for S. mutans or E. faecalis biofilm grown on 2.5 or 3h sPEEK. Regarding the thermal-chemical and microbiologic analyses, the sulfonation degree of sPEEK ranging from 2 up to 3h was successful capable to decrease the biofilm growth. That revealed an alternative strategy to embed anti-biofilm and therapeutic compounds into PEEK avoiding infections in biomedical applications.

Chemical, microscopic, and microbiological analysis of a functionalized poly-ether-ether-ketone-embedding antibiofilm compounds

Poly-ether-ether-ketone (PEEK) is currently introduced as an alternative material for orthopedic implants due to its biocompatibility and low elastic modulus compared to titanium. Also, a sulphonation treatment can functionalize PEEK to embed therapeutical substances. The objective of this work was to functionalize a PEEK film to incorporate novel lactam-based antibiofilms compounds. PEEK samples were functionalized by sulphuric acid treatment and then dissolved in dimethylsulfoxide, where lactams were added to be incorporated into the polymer. A dip-coating technique was used to synthesize a thin film on a glass-based substrate. The degree of sulfonation (DS) and the incorporation of lactams into sulphonated PEEK (sPEEK) were analyzed by Fourier transform infrared spectroscopy, nuclear magnetic resonance, thermogravimetric analysis (TGA), and scanning electron microscopy. A DS of 65% was obtained and TGA curves confirmed the presence of SO₃ H and lactams in the sPEEK structure. The growth of Streptococcus mutans biofilm decreased on sPEEK surface containing lactams when compared to sPEEK free of lactams. That indicated the antibiofilm activity of those compounds was maintained after incorporation into sPEEK. Planktonic growth analysis showed no long distant effects of sPEEK containing lactams, indicating that no systemic effects should be expected upon clinical uses of medical devices produced with lactam-treated sPEEK. Results revealed that inclusion of lactams into sPEEK represents a good alternative for the production of biomaterials resistant to bacterial accumulation. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 3015-3020, 2016.

Lactam inhibiting Streptococcus mutans growth on titanium

The aim of this work was to analyze the activity of novel synthetic lactams on preventing biofilm formation on titanium surfaces. Titanium (Ti6Al4V) samples were exposed to Streptococcus mutans cultures in the presence or absence of a synthetic lactam. After 48h incubation, planktonic growth was determined by spectrophotometry. Biofilm was evaluated by crystal violet staining and colony forming units (CFU·ml(-)(1)), followed by scanning electron microscopy (SEM). Results showed that the average of adhered viable cells was approximately 1.5×10(2)CFU/ml in the presence of lactam and 4×10(2)CFU/ml in its absence. This novel compound was considerable active in reducing biofilm formation over titanium surfaces, indicating its potential for the development of antimicrobial drugs targeting the inhibition of the initial stages of bacterial biofilms on dental implants abutments.

Morse taper dental implants and platform switching: The new paradigm in oral implantology

The aim of this study was to conduct a literature review on the potential benefits with the use of Morse taper dental implant connections associated with small diameter platform switching abutments. A Medline bibliographical search (from 1961 to 2014) was carried out. The following search items were explored: “Bone loss and platform switching,” “bone loss and implant-abutment joint,” “bone resorption and platform switching,” “bone resorption and implant-abutment joint,” “Morse taper and platform switching.” “Morse taper and implant-abutment joint,” Morse taper and bone resorption,” “crestal bone remodeling and implant-abutment joint,” “crestal bone remodeling and platform switching.” The selection criteria used for the article were: meta-analysis; randomized controlled trials; prospective cohort studies; as well as reviews written in English, Portuguese, or Spanish languages. Within the 287 studies identified, 81 relevant and recent studies were selected. Results indicated a reduced occurrence of peri-implantitis and bone loss at the abutment/implant level associated with Morse taper implants and a reduced-diameter platform switching abutment. Extrapolation of data from previous studies indicates that Morse taper connections associated with platform switching have shown less inflammation and possible bone loss with the peri-implant soft tissues. However, more long-term studies are needed to confirm these trends.

The use of bovine screws to promote bone formation using a tibia model in dogs

The objective of this study was to evaluate the use of a unique resorbable bovine bone screw to stimulate bone formation. Bovine bone screws were inserted in the tibia of beagle dogs. Each animal received 8 screws, divided into groups A (screws + no membranes), B (screws + titanium reinforced membranes), and C (bone defects treated with autogenous bone grafts). Animals were killed at 2, 4, and 6 months. New bone was measured with a periodontal probe and reported an average of 7.4 mm in vertical bone gain for group B, 3.6 mm for group A, and 1.7 mm for group C. Submission to Kruskal-Wallis test showed statistical differences among groups (P < .05). Histologic examination revealed an intimate contact between the newly formed bone and the resorbing bone screws. We conclude that bovine bone screws provide an environment for new bone formation and thus may provide an alternative therapy for enhancing bone formation vertically, including for regenerative procedures as well as before implant therapy.

Are sectioning and soldering of short-span implant-supported prostheses necessary procedures?

The aim of this study was to evaluate the fit between dental abutments and the metal framework of a 3-unit fixed prosthesis screwed to two implants to determine whether sectioning and soldering of the framework are in fact necessary procedures. The study was based on a model of a metal framework of a 3-unit prosthesis screwed to two implants. A total of 18 metal frameworks were constructed and divided into 3 groups: (1) NS group - each framework was cast in one piece and not sectioned; (2) CS group - the components of each sectioned framework were joined by conventional soldering; and (3) LW group - the components of each sectioned framework were joined by laser welding. The control group consisted of six silver-palladium alloy copings that were not cast together. Two analyses were mperformed: in the first analysis, the framework was screwed only to the first abutment, and in the second analysis, the framework was screwed to both abutments. The prosthetic fit was assessed at a single point using a measuring microscope (Measurescope, Nikon, Japan) and the marginal gap was measured in micrometers. Statistical analysis was performed using analysis of variance (ANOVA), Scheffe's test, Student's t-test, and Mann-Whitney U test. The NS group had larger marginal gaps than the other groups (p<0.01), while the CS and LW groups had a similar degree of misfit with no significant difference between them. The results revealed that, in the case of short-span 3-unit fixed prostheses, the framework should be sectioned and soldered or welded to prevent or reduce marginal gaps between the metal framework and dental abutments.

Histomorphologic and histomophometric evaluation of immediately and early loaded mini-implants for orthodontic anchorage

INTRODUCTION

The purpose of this study was to evaluate the bone response to statically loaded 2.5-mm diameter mini-implants of 6 and 10 mm lengths activated after various healing periods in a dog model.

METHODS

Seventy-eight machined-surface Ti-6Al-4V mini-implants were bilaterally placed in the mandibular premolar and molar regions of 6 beagle dogs. The left (experimental) and the right (control) hemi-arches received 6 and 7 mini-implants, respectively. Experimental mini-implants healing periods of 0 days (immediately activated), 1 week, and 3 weeks were followed by a 12-week load activation period (250 g between parallel implant pairs). Control (nonloaded) mini-implant groups were placed for 12 weeks, 3 weeks, and 1 week before the dogs were killed they provided data concerning the experimental groups' bone to mini-implant scenarios at load activation times. The mandibles were exposed by sharp dissection, and decalcified specimens were prepared for histomorphologic and histomorphometric (bone to mini-implant contact) assessment.

RESULTS

Survival rates were 100% and 77.78% for the control and the experimental groups, respectively. Survival rates were 88.89% for the 10-mm and 66.67% for the 6-mm experimental groups. All failed devices had tissue inflammation and were lost after spring placement. The control groups showed classic bone-healing events, and the experimental groups showed mature bone morphology after 12 weeks in vivo regardless of placement time before load activation. Bone to implant contact values were not significantly different between the experimental and the control groups that remained 12 weeks in vivo.

CONCLUSIONS

These results showed that low-intensity immediate or early orthodontic static loads did not affect mini-implant performance.

Clinical and radiographic evaluation of periodontal and peri-implant conditions in patients with implant-supported prosthesis

The aim of the present study was to clinically and radiographically assess the peri-implant and periodontal conditions in partially edentulous patients with implant-supported fixtures installed, at least, one year prior to the study. 41 patients were examined by a calibrated examiner in relation to the following implant-associated parameters: Modified Plaque Index (mPlI), Modified Bleeding Index (mBI), probing depth (PD), clinical attachment level (CAL) and bleeding on probing of the bottom of the crevice (BOP). Also, the remaining teeth were assessed in terms of Plaque Index (PlI), Gingival Index (GI), PD, CAL and BOP. The peri-implant bone loss was evaluated by means of periapical radiographs. Measurements of pre-operatory and final bone levels allowed an estimation of bone loss associated to teeth and a comparison with bone loss around implants. None of the individuals presented late loss of implants until the examination took place. No statistically significant differences were observed between PlI (0.90+/-0.07) and mPlI (0.82+/-0.13), or between GI (0.11+/-0.02) and mBI (0.10+/-0.02). However, PD, CAL and BOP values were higher in implants than in teeth (Wald Test, p<0.01). Implants presented a mean annual bone loss during the study period of 0.77 mm (SE=0.06). Teeth virtually did not present any bone loss (mean value of 0.36%) whereas implants exhibited a bone loss value of 17.11%. Plaque accumulation and marginal inflammation did not differ between teeth and implants. However, subgingival inflammation was higher in implants than in teeth. The destruction measurements suggest greater losses in implants, as expected because of tissue remodelation.

A Newly Designed Template Device for Use With the Insertion of Immediately Loaded Implants

This article describes a newly designed surgical template that was used to facilitate dental implant placement. The implants were planned to function by loading them immediately. A case report describing the device and the benefits of its use for a patient with an edentulous mandible is presented. Four implants were placed in the anterior region of the mandible to support an immediately fixed prosthesis. Clinical and radiographic analyses were conducted postoperatively to evaluate bone loss and peri-implant soft-tissue healing. The salutary results demonstrated the positive value of this therapeutic approach and presented the advantages of shorter treatment times, fewer patient visits, lower costs, and elimination of secondary surgical procedures.