Four-year assessment of masticatory function in mandibular overdenture wearers: A randomised clinical trial comparing two to four implants to retain the prosthesis.

BACKGROUND: Limited data exist on the mid- to long-term masticatory capacity of mandibular overdenture (IOD) wearers, particularly regarding the use of posterior implants to retention. OBJECTIVES: To periodically evaluate mastication of IOD wearers, comparing the effectiveness of two to four implants to retain the prosthesis. METHODS: In a randomised controlled clinical trial, 20 complete edentulous patients (14 women), aged 51-84 years (mean age 69.1 ± 9.6), received new bimaxillary complete dentures (CD). After adaptation, baseline measurements of masticatory performance (X50) and swallowing threshold were conducted using the sieving method. Patients were then randomly assigned to groups: control (two intra-foraminal regular implants) and experimental (two intra-foraminal regular implants and two extra-short posterior implants) (n = 10 each). After 4 months, implants were splinted, and a new mandibular IOD was fabricated with bar/clip retention. Mastication was reassessed after 6, 12, and 48 months, and data analysed with repeated measures ANOVA and Sidak's post hoc (α = 0.05). RESULTS: Despite a loss of two patients per group, masticatory performance significantly improved after mandibular IOD installation (p = .031) in both groups (p = .670). A second improvement was observed after 6 months (p = .027), with no subsequent changes (p > .05). Swallowing threshold improvements were noted with IOD, and no discernible differences between groups were observed (p > .05). CONCLUSION: Masticatory function significantly improved after mandibular IOD installation, with the number of implants demonstrating minimal influence. CLINICAL TRIAL REGISTRATION: The present study was not registered in a public database, as mandated. It is important to note that the recommendation for registration was initiated in 2017 by the Committee of Medical Journal Editors, while patient inclusion in the research took place in 2016. Given that the data presented in this manuscript cover a follow-up period of up to 4 years post-surgical intervention, delayed registration was not feasible.

Digital workflow to produce 3D-printed incisal facial indirect restoration with lingual rest seats to support a removable partial denture.

A technique for fabricating lingual rest seats and indirect incisal restorations using a digital workflow is described. After intraoral scanning, the incisal edge position of the restoration and lingual rest seats for a subsequent removable partial denture (RPD) were designed digitally. Adaptation was evaluated with trial restorations, and definitive restorations were printed from a 3-dimensional resin (Varseo Smile Crown Plus Bego; Wilcos). The restorations were cemented with a heated composite resin (Tetric N; Ivoclar AG) polymerized for 40 seconds. The RPD was fabricated and delivered following a conventional technique. This standard, rapid, cost-effective, and straightforward approach allows a controlled and standardized process to obtain lingual rest seats and incisal restorations simultaneously, providing support for a successful Kennedy Class I RPD.

Digital and Analog Analysis of Occlusion in Conventional and Implant-Retained Complete Dentures: Preliminary Results of a Prospective Clinical Trial.

PURPOSE: To digitally evaluate the static and dynamic occlusion of patients treated with both removable conventional complete dentures (CCDs) and implant-retained removable overdentures (IODs) and to correlate two different methods of occlusal analysis. MATERIALS AND METHODS: Eleven totally edentulous patients were treated with bimaxillary CCDs. Later, mandibular CCDs were replaced by IODs retained by either two or four implants. The distribution of the occlusal contacts in static and dynamic occlusion was compared by means of the digital method (DM; T-Scan III) and the analog method (AM; articulating paper). Scores 0, 1, and 2 were assigned for inadequate, satisfactory, and adequate distribution of the occlusal contacts, respectively. The frequencies of scores were compared in relation to the types of denture by means of Fisher exact test (P < .05). The correlation between methods was assessed by means of the kappa agreement coefficient (κ) and the correlation coefficient phi (φ) (P < .05). RESULTS: Significant differences between CCDs and IODs were found in the right lateral mandibular movement (DM, P = .024; AM, P = .008), as well as in the left lateral mandibular movement (DM, P = .035). The methods of analysis of the occlusion showed a moderate agreement (κ = 0.604; P < .001) and a moderate correlation (φ = 0.605; P < .001). CONCLUSION: The digital and analog methods showed a significant agreement and moderate correlation, irrespective of the type of complete denture. The T-Scan III digital system seems to be a consistent and reproducible method to analyze occlusion.

Adhesion to high-performance polymers applied in dentistry: A systematic review.

OBJECTIVE: The aim of this systemic review, conducted in accordance with the PRISMA statement, was to investigate the impact of surface pretreatments on the bonding strength of high performance polymers (HPPs). METHODS: Eight databases were searched through March 2019. Risk of bias was assessed and random effects meta-analyses were applied to analyze mean differences in shear bond strength (SBS) and tensile bond strength (TBS), considering surface pretreatments and bonding agents after 24h and thermocycling. RESULTS: A total of 235 relevant titles and abstracts were found, yielding 11 final selections. Low risk of bias was observed in most studies. For polyetheretherketone (PEEK) specimens, random-effect models showed that, compared to non-treated controls, pretreatments associated with Visio.link® (Bredent, Senden, GE) increased TBS by 26.72MPa (95% confidence interval (CI), 19.69-33.76; p<0.00001) and increased SBS by 4.86MPa (95% CI, 2.61-7.10; p<0.00001). Air abrasion improved SBS by 4.90MPa (95% CI, 3.90-5.90; p<0.00001) (50µm alumina) and 4.51MPa (95% CI, 1.85-7.18; p=0.0009) (silica-coated CoJet). In comparison to non-treated controls, Visio.link® and Signum PEEK Bond® (Heraeus Kulzer, Hanau, GE) increased SBS by 33.76MPa (95% CI, 18.72-48.81; p<0.00001) and 33.28MPa (95% CI, 17.48-49.07; p<0.00001), respectively. No differences were found between Visio.link® and Signum PEEK Bond® or Monobond Plus/Heliobond® (Ivoclar Vivadent, Schaan, LH) (p>0.05). Similar results were observed for polyetherketoneketone (PEKK) specimens. SIGNIFICANCE: This review shows improved HPP bonding following the application of various surface pretreatments, including air abrasion and bonding agents.

Determinação da dimensão vertical proteticamente conveniente / Determination of the prosthetically convenient vertical dimension

Este artigo descreve as principais técnicas utilizadas para garantir uma maior coincidência de achados clínicos, que se traduz no posicionamento mandibular em um dado espaço conhecido como conveniência protética.(AU).

This article describes the main techniques used to assure a greater coincidence of clinical findings, translated in the mandibular position in a space known as prosthetically convenient.

Fixed and Removable Full-Arch Restorations Supported by Short (≤ 8-mm) Dental Implants In the Mandible: A Systematic Review and Meta-Analysis.

PURPOSE: To evaluate, through a systematic review of the literature, the published data regarding marginal bone loss, implant failure proportion, biologic and prosthetic complications, and risk factors associated with short (≤ 8-mm) implants supporting fixed or removable full-arch restorations in the edentulous mandible. MATERIALS AND METHODS: Two reviewers performed a search of five databases, with handsearching through the reference lists and grey literature. Controlled clinical trials and prospective cohort studies were selected in a two-phase process. The data were independently gathered for the same two reviewers. Quality assessment of the studies was done using the Cochrane Handbook for Systematic Reviews of Interventions for Randomized Clinical Trials and the Newcastle-Ottawa Scale for Prospective Cohort Studies. Marginal bone loss and Implant failure proportion were meta-analyzed using random (R-Em) and fixed-effects models (FEm), respectively, with a 95% confidence interval. A descriptive analysis was performed of the prevalence of biologic and prosthetic complications. Meta-regression analysis was run as fixed-effect models for risk factors. RESULTS: Six studies met the eligibility criteria and had data extracted. A total of 291 short implants (lengths 5 to 8 mm) were placed in 122 patients (82 females; mean age, 64.7 ± 10.8) supporting 23 fixed and 99 removable full-arch restorations. The pooled marginal bone loss overall was 0.12 mm (0.07 to 0.17 mm). Marginal bone loss for fixed full-arch restorations was 0.11 mm (0.01 to 0.21 mm) and for removable full-arch restorations was 0.14 mm (0.07 to 0.21 mm). The pooled implant failure proportion was 2.0% (1.0% to 5.0%) for the overall studies. Implant failure proportion for fixed and removable restorations was 2.0% with a confidence interval of (0.0% to 9%) and (0.0% to 6%), respectively. The prevalence of prosthetic complications was 34.5% for fixed restorations and 2.6% for removable restorations. No biologic complications were found for fixed restorations, while 13.1% of removable restorations did have biologic complications. Risk factors did not demonstrate statistical differences regarding Implant failure proportion and marginal bone loss. All included studies demonstrated a high methodological quality. CONCLUSION: Findings from this systematic review and meta-analysis suggest that full-arch restorations supported by short implants in atrophic edentulous mandibles might be a viable treatment option, presenting minimal marginal bone loss and implant failure in the short-term. However, further well-performed prospective clinical trials with long-term observation are needed.

Surface treatments to improve the repair of acrylic and bis-acryl provisional materials.

PURPOSE: To evaluate the in vitro effects of the Composite Primer and different surface treatments on the shear bond strength (SBS) of acrylic and bis-acryl repairs with resin composite (RC). METHODS: Acrylic (Alike) and bis-acryl (Protemp 4) blocks were prepared. Surface roughness was standardized (0.16 µm) and grit blasting was applied to half of the samples. Blocks were divided randomly into groups according to surface treatment [methyl methacrylate monomer (MMA) for 180 seconds or bonding agents (Composite Primer and Scotchbond Multi Purpose), applied alone or following MMA]. Two consistencies of RC [ regular (Filtek Z350XT and Solare composite) or flowable (Filtek Z350XT flowable and G-aenial flowable composite) ] were used to test bond repair. Cylinders (2 mm diameter) of each RC (n= 10/group) were attached to the block surface, and SBS was measured using a universal testing machine at 0.5 mm/minute. Failure (adhesive, cohesive or mixed) was assessed under ×3.5 magnification. SBS data were analyzed using factorial ANOVA, followed by Tukey post-hoc, and Weibull moduli estimation (α = 0.05). RESULTS: The highest SBS, Weibull modulus (m) and scale parameter (σ0) were found in combined use of MMA and bonding agents (P< 0.001), regardless of the substrate, RC consistency or brand. The use of the Composite Primer and flowable RC also increased SBS (P< 0.001). Significant interaction between surface treatment and RC consistency was observed for the PMMA substrate (P< 0.001). Sandblasting did not influence SBS (P> 0.05). Adhesive failure was most prevalent (93.5%) and SBS values were significantly higher in mixed fractures (19.2± 3.8 MPa) compared to the adhesive ones (9.7± 6.0 MPa) (P< 0.001). No cohesive fracture was observed. CLINICAL SIGNIFICANCE: Composite Primer improved the adhesion of acrylic and bis-acryl repairs, especially when a flowable composite was used. When such product is not available, the combined use of MMA and a bonding agent is necessary, increasing the number of clinical steps, cost, and time required.

Estudo da resistência de união entre dentes de resina acrílica e bases de resina acrílica ativada termicamente por energia de microondas e poliamida em função de duas alturas de recobrimento cervical / Study of bond strength between acrylic resin teeth and acrylic resin bases thermally activated by microwave energy and polyamide according to two heights covering cervical

Esta pesquisa avaliou a resistência de união entre dentes de resina acrílica, uma base de RAAT e uma base de poliamida. Os corpos de prova foram preparados e divididos em seis grupos: quatro de poliamida e dois de resina acrílica ativada por microondas, que foi utilizada como controle. O teste de cisalhamento em 45º, foi feito em uma máquina de testes universal. Realizamos a análise dos dados através do teste não paramétrico de Kruskal-Wallis para comparação das medianas e o teste de comparações múltiplas de Dunn. As medianas de adesão variaram de 6,96 a 27,54Kgf. As maiores médias foram encontradas nos grupos controle (CB=28,89 e CI=14,23Kgf), no entanto, na maioria dos corpos de prova estudados não houve separação entre os dentes e a base de poliamida, em razão das características flexurais deste material.

This study investigated the bond strength between acrylic resin teeth, a polyamide base and a microwave polymerized acrylic resin denture bases. The specimens were prepared and divided in six groups: four of polyamide and two of acrylic resin, used as a control. A shear test was conducted in 45º, in an universal testing machine. Data were analysed using Kruskal-Wallis and multiple comparison Dunn’s test. The mean bond strength ranged from 6,96 to 27,54Kgf. Control group showed the greatest bond strength (CB=28,89 e CI=14,23Kgf), although in the great majority of the tested groups, there was no separation between the resin teeth and the polyamide base, due to flexural proprieties of this...