Effect of tribocorrosion on surface-treated titanium alloy implants: A systematic review with meta-analysis.

The purpose of this systematic review and meta-analysis was to compare the results of tribocorrosion in titanium alloys of dental implants submitted to surface treatment with those whose treatment was not performed. An electronic search was carried out on the MEDLINE (PubMed), Web of Science, Virtual Health Library and Scopus databases. The search strategy used was PECO: Participants (P): titanium alloys; Exposure (E): surface treatment; Comparison (C): absence of surface treatment; and Result/Outcome (O): tribocorrosion. The search found a total of 336 articles, where 27 was selected by title or abstract, resulted to 10 after reading in full. The treatments that formed the rutile layer had better tribological results and therefore better protected the material from mechanical and chemical degradation, contrary to the technique with the addition of nanotubes. It was concluded that the surface treatment proves to be efficient to protect metals from mechanical and chemical wear.

Needle-free anesthetic polymeric device for dental anesthesia in children: A randomized clinical trial.

PURPOSE: To evaluate efficacy of an anesthetic mucoadhesive film with a polymeric device (PD) in promoting anesthesia compared to conventional local infiltration (LA) in children. METHODS: 50 children aged 6-10 years (both genders) needing similar procedures on homologous teeth on the maxilla were included. The parents and children were asked about perception of dental treatment. The child's heart rate per minute (bpm) and blood pressure were evaluated before and after each anesthetic technique (AT) procedure. Anesthesia efficacy was measured by reporting pain using Wong-Baker Faces Scale. Children's behavior and AT preferences were also evaluated. Paired T-test, chi-square and Wilcoxon test were used for statistical comparisons. RESULTS: Fear of anesthesia was reported by 50% of caregivers and by 66% of children. No difference was observed in systolic (P= 0.282) and diastolic (P= 0.251) blood pressure, comparing both AT. Difference was observed regarding the child's behavior when the PD was used (P= 0.0028). Evaluating the face scale, 74% of the children selected the "no pain" (face 0) (P< 0.0001) for PD, and 26% for LA. PD was preferred by 86% of children. Only 20% of the PD anesthesia needed to be complemented by LA. CLINICAL SIGNIFICANCE: The polymeric device presented promising results since most children did not report pain and dental procedures could be performed without local infiltration.

Bacterial Leakage Evaluation Through DNA-DNA Checkerboard Hybridization Technique in Morse Taper Implant-Abutment Connections: An In Vitro Study.

Purpose: The objective of this in vitro study was to evaluate the activity of local gel containing metronidazole (MN) in the leakage area, which was analyzed by the DNA-DNA checkerboard hybridization method. Materials and Methods: Thirty-six sets of Morse taper/mini-pillar implants were used in this study. These implants were equally divided into the following three groups: MN gel (test group), no MN gel (negative test group), and no gel (control). The gel was prepared with metronidazole (15%). Unstimulated saliva samples were collected, transferred to a Falcon tube, and stored at 37°C. The sets were partially immersed in microtubes containing 300 µL of saliva and were incubated at 37°C ± 1°C for 7 days. Microbial infiltration was evaluated (37 bacterial species and 5 species of Candida). The results were analyzed with Wald-Type, ANOVA, and multiple comparisons analysis between groups. Results: After comparing the quantity of microorganisms, both gel-treated groups (no MN gel and MN gel) had more significant microorganism presence than the control group (P < .001), and no significant result was found between the no MN gel and MN gel groups (P > .05). Regarding the bacteria found, the most common were Aggregatibacter actinomycetemcomitans, Prevotella melaninogenica, Bacteroides fragilis, and Candida tropicalis. Conclusion: Within the limitations of this study, it was concluded that the gel containing metronidazole used in this study was not effective in preventing the infiltration of microorganisms through the Morse taper implant-abutment interface.

Retromolar canal diagnosed by cone-beam computed tomography and its influence in inferior alveolar nerve block / Canal retromolar diagnosticado por tomografía computarizada de haz cónico y su influencia en el bloqueo del nervio alveolar inferior

The aim of this study was to observed the anesthetic efficacy of the alveolar nerve block on nine patients that CBCT diagnosed unilateral retromolar canal on a double-blind, split-mouth approach. The assessments of patient response to thermal (pulp vitality test) and pressure (compression of soft tissue) stimuli were carried out before and 5 minutes after the inferior alveolar nerve block procedure, using both visual analog scale (VAS) and Mc Gill pain questionnaires (McG). The mean percentage of patient response decreased after alveolar nerve block, according to both VAS and McG, and was statistically similar among hemi mandibles with and without retromolar canal (Wilcoxon>0.05); however, those without retromolar canal presented greater reduction in patient response in 6 out of 9 cases. Therefore, the retromolar canal is not a determinant factor of inferior alveolar nerve block failure.

El objetivo de este estudio fue observar la eficacia anestésica del bloqueo del nervio alveolar en nueve pacientes que CBCT diagnosticó canal retromolar unilateral en un abordaje de boca dividida doble ciego. Las evaluaciones de la respuesta del paciente a los estímulos térmicos (prueba de vitalidad pulpar) y de presión (compresión de los tejidos blandos) se realizaron antes y 5 minutos después del procedimiento de bloqueo del nervio alveolar inferior, utilizando tanto la escala analógica visual (VAS) como los cuestionarios de dolor de Mc Gill ( McG). El porcentaje medio de respuesta de los pacientes disminuyó tras el bloqueo del nervio alveolar, según EVA y McG, y fue estadísticamente similar entre hemimandíbulas con y sin canal retromolar (Wilcoxon>0,05); sin embargo, aquellos sin canal retromolar presentaron mayor reducción en la respuesta del paciente en 6 de 9 casos. Por lo tanto, el canal retromolar no es un factor determinante del fracaso del bloqueo del nervio alveolar inferior.

Clinical and In Situ Oral Biofilm Formation on Dental Implant Abutment Materials: A Systematic Review.

PURPOSE: This review aimed to summarize the current literature on the oral biofilm formation on alternative abutment materials compared with titanium (Ti) or Ti alloy in clinical and in situ conditions. MATERIALS AND METHODS: An electronic database search was conducted in PubMed, Cochrane Library, EMBASE, Scopus, Web of Science, LIVIVO, BVS, ProQuest, and OpenGrey up to November 2020. Clinical and in situ studies evaluating the biofilm formed on metallic, ceramic, or polymeric abutment materials compared with Ti or Ti alloy were included. Outcome measures were microbial counts/profile, cell viability, and biofilm coverage/thickness. Clinical parameters were deemed secondary outcomes. Risk of bias was assessed by RoB 2 and ROBINS-I tools. RESULTS: A total of 10 clinical and 9 in situ studies were included. Meta-analysis was not performed due to heterogeneity across studies. The abutment materials polytetrafluoroethylene, gold alloy, gold-platinum alloy, cobalt-chromium, alumina, and zirconia were reported. Six out of ten clinical studies (60%) and four out of nine in situ studies (44%) found no qualitative or quantitative microbiologic differences between tested materials. When significant differences were detected, conflicting results were reported. Clinical outcomes were consistent with healthy conditions for all investigated materials. CONCLUSION: There is not enough evidence to support the existence of relevant microbiologic differences in the biofilm formed on alternative abutment materials over Ti and its alloys in oral conditions. No evident relationship between microbiologic results and clinical outcomes were found. In situ studies and polymicrobial analyses showed a higher tendency to find significant differences between materials.

Needle-free anesthesia: clinical efficacy of a mucoadhesive patch for atraumatic anesthesia in dental procedures.

This study showcases the clinical efficacy of mucoadhesive patches designed for the buccal delivery of lidocaine and prilocaine hydrochlorides (1:1, 30 mg/patch). Such patches were developed for needle-free pre-operative local anesthesia in dentistry, aiming at mitigating the use of infiltrative anesthesia for medium-complexity clinical procedures. The patches were manufactured encompassing drug-release, mucoadhesive and backing layers, all prepared through film casting using biocompatible materials. Fifty-eight (n = 58) adult patients (65% women and 35% men) were randomly selected and included in a one-arm open clinical prospective cohort study. The average age of the subjects was of 50 years. The majority (59%) of the subjects, mostly women (82%), reported needle-phobia or anxiety due to dental procedures, which was assessed through a questionnaire approved by the ethical council for human use in research. The patches were positioned in the gingival region of the teeth involved in the procedure (86% on the maxillary and 14% on the mandibular bone). Two anesthetic patches were applied on each patient: one in the vestibular region and another in the palate/lingual portion, and these patches remained attached to the placement sites throughout the procedures. Concerning the dental procedures performed, 40% were cavity preparations and dental restorations of medium cavities; 29% staple facilities; 10% gingival retractions; 9% subgingival scrapings; 3% gingivalplasties; 3% supragingival preparations; 3% occlusal adjustments; and 2% subgingival preparations. In 90% of the cases, it was not necessary to complement with conventional infiltrative local anesthesia during the procedures. Patients did not report any discomfort or side effect during or after the administration of the patches. Among the cases in which there was the need for complementation, 50% were cavity preparations and dental restorations; 33% supragingival preparations; and 17% gingivoplasties. The complementary anesthesia volume was of 0.63 ± 0.23 mL and women corresponded to 83% of the participants who needed such intervention. Furthermore, in most cases, the patch was capable of initiating the anesthesia within a short time frame (5 minutes) and reaching the maximum anesthetic effect within 15 and 25 min, lasting at least 50 min. Undesirable side effects were not reported either 2 h after the administration or within the 6-month follow-up. Therefore, the anesthetic patches developed provide needle-free, painless, safe, and patient/dentist-friendly advances in performing routine medium-complexity dental procedures.

Herpes Labialis: A New Possibility for Topical Treatment with Well-Elucidated Drugs.

Mucocutaneous infections caused by Herpes simplex virus (HSV-1 and HSV-2) are characterized by the appearance of vesicles that cause pain and embarrassment to the carrier. The standard treatment is based on the use of antivirals in gels or ointments, however, relapses are common. Local anesthetics decrease the pain caused by the lesion, in addition to showing antiviral properties. Semi-solid form facilitates application and its transformation into a thin film favors the maintenance of the formulation in place, with a more discreet final aspect. The objective of this study was to develop and evaluate formulations containing anesthetics for the treatment of cold sores. For this purpose, two semi-solid film-forming formulations were developed and evaluated, containing HPMC K100, lidocaine (LIDO) and prilocaine (PRILO) combined with adjuvants, in the presence (F1T) or not (F1) of the absorption promoter Transcutol®. The mixture of PRILO and LIDO resulted in the formation of a eutectic mixture (EM), essential for penetration of drugs into the skin. The quantification of drugs was performed by HPLC (High Performance Liquid Chromatography), and Transcutol® did not influence the release of drugs from the formulation. The bioadhesiveness of the formulation was evaluate and the drugs did not impair the adhesive potential of the polymers used. The formulations were evaluated in vivo for skin irritation and did not show any negative sign on macroscopic examination. The in vivo efficacy test proved the anesthetics' ability to decrease the lesions caused by HSV-1. Thus, the proposed formulations proved to be good alternatives to the treatment of oral lesions caused by HSV-1.

Towards the advance of a novel iontophoretic patch for needle-free buccal anesthesia.

The aim of this work was to develop a mucoadhesive iontophoretic patch for anesthetic delivery in the buccal epithelium. The patch was comprised of three different layers, namely i) drug release (0.64 cm2); ii) mucoadhesive (1.13 cm2); and iii) backing (1.13 cm2). Prilocaine and lidocaine hydrochlorides were used as model drugs (1:1 ratio, 12.5 mg per unit). An anode electrode (0.5 cm2 spiral silver wire) was placed in between the drug release and mucoadhesive/backing layers to enable iontophoresis. Surface microscopy; mechanical and in vitro mucoadhesive properties; drug release kinetics and mechanism; and drug permeation through the porcine esophageal epithelium were assessed. Topographic analysis evidenced differences in the physical structures for the several layers. All layers presented suitable handling properties i.e., flexibility, elasticity and resistance. Both the release and mucoadhesive layers presented features of a soft and tough material, while the backing layer matched the characteristics of a hard and brittle material. A synergy between the drug release and mucoadhesive layers on the mucoadhesive force and work of adhesion of the tri-layered patch was observed. Passive drug release of both drugs fitted to First-order, Hixson-Crowell and Weibull kinetic models; and the release mechanism was attributed to anomalous transport. Iontophoresis remarkably enhanced the permeation of both drugs, but mainly prilocaine through the mucosa as evidenced by the permeability coefficient parameter (3.0-fold). The amount of these amino amide salts retained in the mucosa were also equally enhanced (4.7-fold), while the application of a tiny constant electric current (1 mA·cm-2·h-1) significantly decreased the lag time for lidocaine permeation by about 45%. In view of possible in vitro / in vivo correlations, the buccal iontophoretic patch displays a promising strategy for needle-free and patient-friendly local anesthesia in dentistry.

Quality by Design-driven investigation of the mechanical properties of mucoadhesive films for needleless anesthetics administration

Objectives: To systematically evaluate the effects of hydroxypropyl methyl cellulose (HPMC) type (E5LV, E15LV, and K100LV); plasticizer type (glycerol and mannitol), plasticizer loading (0.12 and 0.24% w/w); and loading of prilocaine and lidocaine hydrochlorides combined at 1:1 ratio (0 and 47 mg/cm2) in the mechanical properties of buccal films. Methods: A quality by design (QbD) approach based on a full factorial design (3 x 23) and complementarily multivariate statistical tools i.e., principal component analysis (PCA), response surface methodology (RSM), and correlation matrix were used in this pursuit. The thickness, elongation at break, tensile strength, force at break, and Young`s modulus of the anesthetic buccal films obtained by solvent casting were assessed. Results: The QbD, PCA and RSM altogether demonstrated that all studied formulation variables, mainly the drug loading, affect the mechanical properties of the films at different significance levels. The multivariate analysis yielded the modelling of elongation at break, tensile strength, and force at break, which significantly correlated with each other. The drugs exerted a synergic plasticizing effect on the films, and the use of HPMC K100 LV (with greater hydroxypropyl substitution degree and viscosity) and mannitol favored their elasticity and resistance. Furthermore, the majority of the films fulfilled the requirements for buccal administration due to their softness and mechanical resistance. Conclusion: Mannitol is suitable plasticizer for manufacturing HPMC anesthetic buccal films with improved mechanical properties. These results are a step forward in the rational development of formulations for the replacement of needles in dentistry

A New Approach to Ex Vivo Permeation Studies in In-Situ Film-Forming Systems.

The skin is the largest human organ and an important topical route. Even with some challenges, it is an important ally in medication administration, mainly because it is painless and easy-to-apply. Semisolid formulations are the most used dosage forms for drug administration via this delivery route and can be optimized when transformed into a film, favoring on-site maintenance, and promoting drug permeation. However, in situ film-forming systems are difficult to assess and characterize using Franz-type diffusion cells once this apparatus is ideal to formulations without transition phases. The present study proposed a different method to characterize these formulations and provide complementary data on drug and penetration enhancer behaviors, as close as possible to real application conditions. This characterization method allowed us to analyze drug concentration on three necessary occasions: remaining in the polymer film, stratum corneum using adhesive tape, and skin to check where drugs will have a desirable effect. As a proof-of-concept, the proposed ex vivo permeation method was used to evaluate a film-forming system containing lidocaine and prilocaine. We could also evaluate transition phases of drug compositions and quantify drugs at key times after application. Hence, the developed method may be used to provide complementary data to the Franz diffusion cell method, in terms of drug and penetration enhancer behaviors incorporated into film-forming delivery systems.

Surrogate endpoints: when to use and when not to use? A critical appraisal of current evidences.

Clinical research needs to formulate a question, which must be answered by obeying ethical precepts with well-defined inclusion/exclusion criteria and approval of the study on platforms of ethical appreciation and clinical trial records. In comparing the results or clinically relevant outcomes should be prioritized in the study of techniques, products, inputs, drugs and therapies. However, it is not always possible to use long study drawings, with many participants, and with many costs, then look for study designs with surrogate outcomes, usually a shorter path, with less sample size and considerably lower costs to the research, with shorter intervention time. Considering these outcomes as major challenges in clinical research, the premise of this work was to examine in relevant research platforms, studies on the feasibility of using surrogate endpoints for clinically relevant parameters in dentistry, with a critical evaluation of the advantages, disadvantages, and need for validation of substitute parameters for clinical studies. After a critical analysis of the results, it could be concluded that surrogate endpoints may have an important role in the initial process of developing new drugs, faster, with less sampling, and lower risk of side effects for the patient. Careful use of the surrogate endpoints is advised because, even if validated, they can provide ambiguous evidence and not be extrapolated to other populations, and may lead to bias due to the individual interpretation of each researcher. The use of unplanned surrogate outcomes that arise during the study requires a lot of caution.

Local anesthetic improves individuals affected with herpes simplex type 1 labialis.

Infections caused by the herpes simplex virus 1 (HSV-1), commonly called herpes simplex labialis (HSL), are a public health problem, reaching around 40% of the world's population. Thus, the search for effective therapeutic alternatives in the control of the limitations caused by this virus during the stages of evolution of the disease, is necessary, since they have a direct impact on the quality of life of the patients. The aim of the present study was to evaluate the efficacy of the in situ film precursor semisolid composition in the treatment of herpes simplex lesions in human HSV-1. Ninety-eight (n = 98) patients with HSV-1 were used for this study. The initial exclusion criteria left 81 patients to be considered in the present study. Three applications were performed, the first at time zero (T0) and the other two at 8 and 16 hours, after initial application (T8 and T16). Photographs were taken in the first appointment and 24 and 72 hours after the last application. After the three periods, each patient received a total amount of 90 mg of anesthetic and the prognosis of the patients was followed for 6 months and 1 year after the application. Frequency analysis showed that 40.3% of patients had remission of symptoms 24 hours after the last application. For the present study, the film presented a positive therapeutic potential and an esthetic benefit that is absent in the current products (ointments and gels). The invent presents dosage convenience (only three applications in a 24-hour period) and a low production cost, with a much shorter healing time than that reported using topical antiretrovirals.

Topical pilocarpine for xerostomia in patients with head and neck cancer treated with radiotherapy.

OBJECTIVE: To evaluate a pilocarpine spray as a treatment for xerostomia in patients treated with radiotherapy (RT) for head and neck cancer (HNC). METHODS: This was a placebo-controlled, double-blind, crossover clinical trial of patients complaining of dry mouth after RT for HNC. Forty patients were randomly assigned to either placebo or pilocarpine (1.54%) spray and instructed to use three times a day for 3 months. After 1-month washout period, patients were crossed over to receive placebo or pilocarpine. The assessments were salivary flow (Stimulated Whole Saliva Flow - SWSF), xerostomia (Xerostomia Inventory - XI), and quality of life (QoL/Oral Health Impact Profile - OHIP-14), assessed at baseline, 1 hr (only SWSF), and at 1, 2, and 3 months of treatment. RESULTS: Posttreatment SWFS was not statistically different between pilocarpine and placebo regardless of the treatment sequence (paired T test; p > .05), except for the SWFS rates at 2 months after therapy. When comparing pilocarpine with placebo in the time points, there was no significant difference (p > .05) for QoL or XI. Significant differences in improvement in QoL and xerostomia experience appeared along time for pilocarpine group. CONCLUSION: The topical application of pilocarpine spray tested was similar to placebo on SWSF assessments in patients treated with RT for HNC.

A 3-year longitudinal prospective study assessing microbial profile and clinical outcomes of single-unit cement-retained implant restorations: Zirconia versus titanium abutments.

PURPOSE: The aim of this study was to assess the microbiological and clinical outcomes of implant-supported restorations on zirconia or titanium abutments after 3 years in function. MATERIALS AND METHODS: Twenty two-part dental implants were placed in 20 healthy individuals in need of single-tooth replacement. Ceramic-based reconstructions were cemented in either zirconia or titanium abutments. Clinical, radiographic, and microbiological outcomes were examined at implant loading and then yearly up to 3 years post-loading. RESULTS: Cumulative survival/success implant rates were 95% after 3 years. Mean total marginal bone loss was 0.76 ± 0.21 mm for zirconia and 0.99 ± 0.41 mm for titanium, with no significant differences (P > .05). Overall, titanium and zirconia abutments presented similar values of probing depth, gingival recession, and bleeding on probing over time (P < .05). Microbial profile of implants restored with titanium or zirconia is quite similar to that found in the remaining teeth. CONCLUSIONS: Zirconia and titanium presented different microbial profile and genome counts. Clinical findings for both zirconia and titanium abutments were similar and consistent with a healthy condition, reflecting a high survival rate and low bone loss. Microbiota did not impact the clinical outcomes after 3 years of function.

Synergy between surfactants and mucoadhesive polymers enhances the transbuccal permeation of local anesthetics from freeze-dried tablets.

We report on the advance of freeze-dried mucoadhesive orodispersible tablets (ODTs) loaded with prilocaine (PRC) and lidocaine (LDC) hydrochlorides, aiming to promote noninvasive buccal anesthesia. The influences of combining biocompatible polymers (pullulan and HPMC K100 LV) and a blend of surfactants (oleic acid, polysorbate 80 and propylene glycol) acting as chemical enhancers on the permeation of such drugs through the esophageal porcine epithelium and in vitro mucoadhesion were investigated. The ODTs were also characterized in terms of average weight, thickness, pH, drug content, in vitro release, thermal behavior and scanning electronic microscopy. A dissolution test showed fast drug release within one hour. The drug release data for all ODTs fitted first order. No significant influence of the type of mucoadhesive polymer on release was observed, while the drug release from ODTs decreased in the presence of chemical enhancers. For the ODT containing pullulan the drug release mechanism was anomalous transport, whist for all others it was case-II transport. A remarkable synergic effect between pullulan and chemical enhancers on the permeation flux, lag time, and permeability coefficient of both drugs, but mainly for PRC was observed. Pullulan together with permeation enhancers also substantially improved the work of mucoadhesion as compared to HPMC. In contrast, HPMC improved drug retention in the epithelium. The novel drug delivery platform achieved by combining a freeze-drying technique, mucoadhesive biocompatible polymers, and chemical permeation enhancers displayed an effective strategy for the transbuccal delivery of PRC and LDC that can be used to improve needle-free buccal anesthesia.

Surrogate endpoints: when to use and when not to use? A critical appraisal of current evidences

Abstract Clinical research needs to formulate a question, which must be answered by obeying ethical precepts with well-defined inclusion/exclusion criteria and approval of the study on platforms of ethical appreciation and clinical trial records. In comparing the results or clinically relevant outcomes should be prioritized in the study of techniques, products, inputs, drugs and therapies. However, it is not always possible to use long study drawings, with many participants, and with many costs, then look for study designs with surrogate outcomes, usually a shorter path, with less sample size and considerably lower costs to the research, with shorter intervention time. Considering these outcomes as major challenges in clinical research, the premise of this work was to examine in relevant research platforms, studies on the feasibility of using surrogate endpoints for clinically relevant parameters in dentistry, with a critical evaluation of the advantages, disadvantages, and need for validation of substitute parameters for clinical studies. After a critical analysis of the results, it could be concluded that surrogate endpoints may have an important role in the initial process of developing new drugs, faster, with less sampling, and lower risk of side effects for the patient. Careful use of the surrogate endpoints is advised because, even if validated, they can provide ambiguous evidence and not be extrapolated to other populations, and may lead to bias due to the individual interpretation of each researcher. The use of unplanned surrogate outcomes that arise during the study requires a lot of caution.

Influence of a Retentive Shoulder Design to Prevent Early Failure of Three Core Build-Ups.

This study evaluated the influence of a retentive shoulder design to prevent early failure of three resin composite build-ups on molars. Ninety-six intact extracted human maxillary third molars were assigned to two groups (n=48) based on occlusal, buccal cusps only and all cusps reduction. The groups were divided into two subgroups: pin retained and non-pin retained build-ups resulting in four groups (n=24), according the cusps reduction: pin retained/partial, pin retained/complete, non-pin retained/partial, non-pin retained/complete. Occlusal reduction was 3 mm with a semi-lunar retentive shoulder of 3 mm and an axial wall height of 1.5 mm. Groups were restored using a microhybrid, flowable or titanium reinforced resin composite. Modified self-curing acrylic resin provisional crowns were fabricated, cemented with non-eugenol temporary cement and thermal cycled. An instron machine applied tension to the provisional crowns parallel to the long axis of the tooth until dislodgement. A three-way analysis of variance was conducted on the influence of the variables on the retention of the core build-up. Ninety-three build-ups were retained under tensile load, while three core build-ups without pins were dislodged. Three-way analysis of variance showed no statistically significant difference between core build-ups using a retentive shoulder and pin retained core build-ups when tested under tensile load. With the advent of adhesive systems, increased surface area and retentive shoulder design can provide a retentive core foundation to prevent early failures of core build-ups during indirect restoration fabrication which will contribute to the longevity of final restorations.

Influence of a retentive shoulder design to prevent early failure of three core build-ups

Abstract This study evaluated the influence of a retentive shoulder design to prevent early failure of three resin composite build-ups on molars. Ninety-six intact extracted human maxillary third molars were assigned to two groups (n=48) based on occlusal, buccal cusps only and all cusps reduction. The groups were divided into two subgroups: pin retained and non-pin retained build-ups resulting in four groups (n=24), according the cusps reduction: pin retained/partial, pin retained/complete, non-pin retained/partial, non-pin retained/complete. Occlusal reduction was 3 mm with a semi-lunar retentive shoulder of 3 mm and an axial wall height of 1.5 mm. Groups were restored using a microhybrid, flowable or titanium reinforced resin composite. Modified self-curing acrylic resin provisional crowns were fabricated, cemented with non-eugenol temporary cement and thermal cycled. An instron machine applied tension to the provisional crowns parallel to the long axis of the tooth until dislodgement. A three-way analysis of variance was conducted on the influence of the variables on the retention of the core build-up. Ninety-three build-ups were retained under tensile load, while three core build-ups without pins were dislodged. Three-way analysis of variance showed no statistically significant difference between core build-ups using a retentive shoulder and pin retained core build-ups when tested under tensile load. With the advent of adhesive systems, increased surface area and retentive shoulder design can provide a retentive core foundation to prevent early failures of core build-ups during indirect restoration fabrication which will contribute to the longevity of final restorations.

Resumo Este estudo avaliou a influência de um preparo retentivo em forma de ombro para prevenir a falha precoce de núcleos de preenchimento realizados em molares com 3 diferentes tipos de resina composta. Noventa e seis terceiros molares superiores hígidos extraídos de humanos, foram divididos em dois grupos (n=48) de acordo com o tipo de redução oclusal: em todas as cúspides (total) ou nas cúspides vestibulares (parcial). Os grupos foram divididos em dois subgrupos: núcleos retidos a pinos e não retidos a pinos, resultando em quatro grupos (n=24): redução oclusal total/retido a pino, redução oclusal parcial/retido a pino, redução oclusal total/não retido a pino, redução oclusal parcial/não retido a pino. A redução oclusal foi de 3 mm com um ombro retentivo semilunar de 3 mm e uma altura de parede axial de 1,5 mm. Os grupos foram restaurados utilizando resina composta microhíbrida, fluível ou reforçada com titânio. Foram confeccionadas coroas provisórias de resina acrílica autopolimerizável modificada, cimentadas com cimento provisório sem eugenol e termocicladas. Uma máquina universal de ensaios foi utilizada para tracionar as coroas provisórias paralelamente ao longo eixo do dente até o seu deslocamento. Análise de variância de 3 fatores foi aplicada para avaliar o efeito dos fatores na retenção do núcleo. Noventa e três núcleos de preenchimento permaneceram retidos sob a carga de tração, enquanto três núcleos de preenchimento sem pinos foram deslocados. A análise de variância não mostrou diferença significante entre os núcleos de preenchimento com desenho retentivo e os núcleos de preenchimento retidos a pinos. Com o advento dos sistemas adesivos, o aumento da área de superfície e o desenho retentivo dos ombros podem fornecer um preparo retentivo para evitar falhas precoces nos núcleos de preenchimento durante a fabricação de restaurações indiretas, o que contribuirá para a longevidade das restaurações finais.

Iodoform and silver-coated abutments preventing bacterial leakage through the implant-abutment interfaces: In vitro analysis using molecular-based method.

OBJECTIVES: The aim of this in vitro study was to evaluate the effectiveness of an iodoform paste and silver-coated abutments in preventing the microbial colonization and leakage through the implant-abutment interface of morse taper and internal hexagon implants. MATERIAL AND METHODS: Seventy-two implants with morse taper (n = 36) or internal hexagon connections (n = 36) were investigated. Implants were treated with iodoform paste (n = 12), silver-coated abutments (n = 12), or control (n = 12). After saliva incubation, Checkerboard DNA-DNA hybridization was used to identify and quantify up to 43 microbial species colonizing the inner parts of the implants. ANOVA-Type and Wald-Type analyses of variance were used to investigate the relative effects and their interaction. Friedman- Conover test adjusted by Benjamini-Hockberg FDR were performed for pairwise multiple comparisons. Significance was set as p < 0.05. RESULTS: Analyses of variance indicate a significant interaction between connections, antimicrobial treatments, and species. The frequency of contamination was reduced in the implants submitted to the antimicrobial treatments. Iodoform and silver-coated abutments significantly reduced the total microbial counts in the internal hexagon implants. The lower microbial counts were recorded for morse taper implants with silver-coated abutments. CONCLUSIONS: Iodoform paste and silver-coated abutments have influenced the microbial leakage through the implant-abutment interface, by reducing both frequency of contamination and microbial levels. Treatments were not effective in reducing the counts of the target species.

WITHDRAWN: Hand and ultrasonic instrumentation for orthograde root canal treatment of permanent teeth.

BACKGROUND: Endodontic treatment of root canals or root canal treatment is a frequently performed dental procedure and is carried out on teeth in which irreversible pulpitis has led to necrosis (death) of the dental pulp (nerve). Removal of the necrotic tissue remnants and cleaning and shaping of the root canal are important phases of root canal treatment. Treatment options include the use of hand and rotary instruments and methods using ultrasonic or sonic equipment. OBJECTIVES: The objectives of this review were to determine the relative clinical effectiveness of hand instrumentation versus ultrasonic instrumentation alone or in conjunction with hand instrumentation for orthograde root canal treatment of permanent teeth. SEARCH METHODS: We searched the Cochrane Oral Health Group Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE and LILACS. We searched the reference lists of relevant articles in an attempt to locate additional published and unpublished trials. No language restriction was applied. The last electronic search was conducted in December 2007. SELECTION CRITERIA: Randomised controlled trials involving people over 18 years of age with single and multiple permanent teeth with a completely formed apex and with no evidence of internal resorption requiring root canal treatment were included. Patients undertaking re-treatment of a tooth were excluded. DATA COLLECTION AND ANALYSIS: Screening of eligible studies was conducted in duplicate and independently. Results were to be expressed as fixed-effect or random-effects models using mean differences for continuous outcomes and risk ratios for dichotomous outcomes with 95% confidence intervals. Heterogeneity was to be investigated including both clinical and methodological factors. MAIN RESULTS: No eligible randomised controlled trials were identified. AUTHORS' CONCLUSIONS: This review illustrates the current lack of published or ongoing randomised controlled trials and the unavailability of high level evidence, based on clinically relevant outcomes, for the effectiveness of ultrasonic instrumentation used alone or as an adjunct to hand instrumentation for orthograde root canal treatment.Future randomised controlled trials might focus more closely on evaluating the effectiveness of combinations of these interventions with an emphasis on not only clinically relevant but also patient-centred outcomes.