A comparative study on 7-year results of "All-on-Four™" immediate-function concept for completely edentulous mandibles: metal-ceramic vs. bar-retained superstructures.

The study aims to document the clinical outcomes over a 7-year period of two techniques used for the rehabilitation of edentulous mandibles according to the "All-on-Four™" concept: (1) fixed complete-arch prostheses fabricated with metal-ceramic implant-supported fixed prosthesis with a titanium framework and all-ceramic crowns and (2) bar-retained implant-supported removable prosthesis with acrylic resin prosthetic teeth. The study was performed on 32 patients who received immediately loaded "All-on-Four™" fixed mandibular prostheses. (Fixed prostheses with ceramic superstructures, n:16; bar-retained removable acrylic prostheses, n:16). The patients were evaluated for up to 7 years after prosthesis completion. The endpoints included the evaluation of prosthodontic complications, bone resorption, plaque accumulation, bleeding on probing, periodontal probing depth and an oral health impact profile (OHIP). Bone loss remained under 1.2 mm in all of the implants, and no difference was observed between two groups. Plaque accumulation increased gradually in both groups, and the bar-retained acrylic-bearing implants showed significantly higher values during the first 5 years. Immediate improvement was assessed by the OHIP score in both groups. The observed bone loss and the subjective outcomes showed equivalent levels of clinical success for bar-retained and ceramic superstructures over a 7-year period. The higher level of plaque accumulation observed around implants with bar-retained superstructures requires that patients with acrylic superstructures be highly motivated to maintain their personal oral hygiene. Further studies are needed to clarify the occurrence of prosthodontic complications and assess their economic aspects.

Prosthetic rehabilitation of edentulous mandible with two-implant retained fixed hybrid prosthesis: A case report.

Removable complete dentures have been the most costeffective treatment option for edentulous jaws since decades. However, certain problems are encountered by the patients such as stability of the lower dentures resulting in poor masticatory efficiency. Ridge resorption and inadequate bony support are the long-term complications comprising the stability of the denture and patient finding it difficult to control denture movement during speaking and eating reducing patient compliance. Mandibular implant retained over dentures or hybrid dentures have shown to be better alternatives in terms of retention, stability and patient satisfaction. Two implants provide cost-effective, stabilized and comfortable treatment options. The present case report discusses the management of the patient with compromised dentition in which all teeth were extracted followed by conventional upper complete denture and lower two implant supported fixed hybrid dentures with splinted bar attachment.

Comparative Assessment of the Adhesion Forces of Soft Silicone Materials to the Denture Base Material (PMMA) Conditioned with Sandblasting.

BACKGROUND: In patients undergoing surgery for oral cancer, soft support materials are used to minimise trauma to the soft tissues. Silicone-based liners are widely used in prosthetic dentistry. A prerequisite for long-term Adhesion of the liner to the denture base is largely dependent on the surface preparation of the denture material. OBJECTIVES: The aim of the present study was to investigate whether surface preparation of the acrylic material by sandblasting increases the adhesion of the silicone support material to the acrylic denture plate. MATERIAL AND METHODS: The study included adhesion testing of four silicone-based soft cushioning materials (Silagum Comfort, Elite Soft Re-lining, Ufi Gel SC, Mucopren Soft) on a total of 270 samples. Each material was tested on 15 samples. Three subgroups with different surfaces were separated: 1 raw-standard surface treatment with a cutter, and 2 sandblasted, with 100 and 350 µm alumina grain at 90°. The samples were subjected to seasoning: 24 h and six weeks. The adhesion force of silicone to acrylic was measured by performing a tensile test using a universal two-column testing machine. RESULTS: The highest bond strength was recorded for Silagum on the surface prepared using 100 µm abrasive and seasoned for 6 weeks (291.5 N). The smallest among the maximum forces was recorded for the Mucopren material (81.1 N). For the Mucopren system with a raw and sand-blasted surface (350 µm), the adhesion strength increased after six weeks. In contrast, the durability of the joint decreased for the 100 µm sandblasted surface. The Elite material exhibited similar values for maximum forces (271.8 N) and minimum forces (21.1 N). The highest strength (226.1 N) was recorded for the sample from the group prepared with 350 µm abrasive and seasoned for 24 h. The lowest value (72.6 N) occurred for the sample from the group with 100 µm abrasive and seasoned for 6 weeks. CONCLUSIONS: Sandblasting of acrylic plastic improves adhesion to selected relining silicones. 2. The size of the abrasive employed has an impact on the adhesion between the acrylic plastic and the bedding silicone. 3. In the case of some relining systems (Mucopren), an increase in roughness through sandblasting has the effect of reducing the durability of the bonded joint.

Longevity of acrylic and cobalt-chromium removable partial dentures-A ten-year retrospective survival analysis of 1246 denture-wearing patients.

OBJECTIVES: to assess the survival rates of removable partial dentures (RPDs) and identify factors impacting their longevity. METHODS: electronic health records were retrieved of patients aged ≥18 who received RPDs between 2010 - 2021 with a follow-up of ≥ three months. Data extracted included demographics, medical history, dental charting, periodontal screening and recording scores, prostheses details and related interventions, including new dentures/denture remakes, and maintenance. Multivariate Mixed-Effect Cox regression was performed to identify potential RPD survival risk factors. Reduced model selection was reached using a backward step-down by comparing the performance of these multivariable models using the ANOVA test. RESULTS: 1893 RPDs from 1246 patients were included, with a median follow-up of 21.8 months (range from 3 to 131.3 months). Three hundred and twelve patients received a maxillary RPD, 460 received a mandibular RPD, and the remaining 474 patients received both maxillary and mandibular RPDs. Metal-based RPDs had a median survival of 73 months (95%CI: 70 - 82) versus 45 months (95% CI: 37-67) for acrylic ones. Multivariable mixed effects Cox model showed that the lifespans of RPDs were longer amongst patients receiving more maintenance care within three months [Hazards Ratio (HR)=0.89 (0.83, 0.96)] and after three months [HR=0.53 (0.46, 0.61)] of denture delivery, patients wearing both maxillary and mandibular RPDs [HR=0.67 (0.52, 0.87)], and patients receiving metal-based RPDs [HR=0.31 (0.23, 0.42)]. CONCLUSIONS: Metal-based dentures, dual arch restoration, and increased maintenance positively impact the survival of RPDs. CLINICAL SIGNIFICANCE: Adapting consent and warranty practices is advised to reflect RPD performance variations.

Numerical Analysis of the Bond Strength between Two Methacrylic Polymers by Surface Modification.

The creation of acrylic dentures involves many stages. One of them is to prepare the surfaces of artificial teeth for connection with the denture plates. The teeth could be rubbed with a chemical reagent, the surface could be developed, or retention hooks could be created. Preparation of the surface is used to improve the bond between the teeth and the plate. Choosing the right combination affects the length of denture use. This work focuses on a numerical analysis of grooving. The purpose of this article is to select the shape and size of the grooves that would most affect the quality of the bond strength. Two types of grooves in different dimensional configurations were analyzed. The variables were groove depth and width, and the distance between the grooves. Finally, 24 configurations were obtained. Models were analyzed in terms of their angular position to the loading force. Finite element method (FEM) analysis was performed on the 3D geometry created, which consisted of two polymer bodies under the shear process. The smallest values of the stresses and strains were characterized by a sample with parallel grooves with the grooving dimensions width 0.20 mm, thickness 0.10 mm, and distance between the grooves 5.00 mm, placed at an angle of 90°. The best dimensions from the parallel (III) and cross (#) grooves were compared experimentally. Specimens with grooving III were not damaged in the shear test. The research shows that the shape of the groove affects the distribution of stresses and strains. Combining the selected method with an adequately selected chemical reagent can significantly increase the strength of the connection.

Four narrow dental implants and conventionally cast bar-supported removable hybrid acrylic complete denture as a therapeutic modality for terminal dentition.

The report portrays four narrow implants and cast bar-supported removable hybrid acrylic complete dentures and other terminal dentition treatment options in the maxilla. The therapeutic module could be efficient and satisfactory to patients.

Antimicrobial Activity of Cold Plasma Treatment on Acrylic Denture Bases: An In Vitro Evaluation.

Introduction: Cross-contamination between dental office and prosthetic laboratories is of utmost importance. The dental prosthesis could harbor tones of microorganisms harmful to health staff. It has been estimated that more than 60% of the prostheses delivered to clinics from laboratories or vice versa are contaminated with pathogenic microorganisms. Several disinfection methods and chemicals have been proposed for sanitizing prostheses. Cold plasma, or nonthermal plasma, has been introduced as a new method in medical equipment disinfection. The current study aimed to compare the antimicrobial effect of cold plasma and the routinely used alcohol-based impression disinfectant ASEPTOPRINT® on disinfecting dentures. Methods: In this experimental study, 30 maxillary complete dentures were used as the microbial source. Dentures were randomly divided into 3 groups: (1) cold plasma treatment for 30 seconds, (2) cold plasma for 60 seconds, (3) ASEPTOPRINT® spray. Microbial culturing was taken before and after disinfection in each group on both Blood Agar plates and Soborou Dextrose Agar (SDA) plates. After 48 hours incubation at 37°C, the number of colonies was counted using a digital colony counter and differences between the groups were analyzed. Results: A significant reduction in microbial colonies was observed after using all disinfection methods. ASEPTOPRINT® spray showed more antimicrobial effects comparing to cold plasma. Conclusion: The antimicrobial effect of ASEPTOPRINT® spray solution is more than cold plasma application on both microbial and fungal microorganisms. The time of plasma application was not accompanied by any significant differences in the results.

Oral health-related quality of life: acrylic versus flexible partial dentures.

BACKGROUND: Teeth lost are usually replaced by all-acrylic removable partial dentures (RPD) because of its affordability and ease of fabrication. The all-acrylic RPD is said to cause significant periodontal injury and consequently affect the oral health related quality of life (OHRQoL) of denture wearers. OBJECTIVE: To determine and compare OHRQoL of all-acrylic and flexible RPD wearers at baseline and after use of dentures. DESIGN AND SETTING: Study was quasi-experimental using a cross-over design, involving 30 patients with Kennedy class IV and anterior class III arches. Patient recruitment and review were done over an eight-month period in the Prosthetic Unit of a tertiary health facility. OHRQoL was assessed with the oral health impact profile-14 questionnaire. Data were analysed using descriptive and multivariate analysis at asignificant level of p <.05. RESULTS: Mean age of patients was 33.8 ±10.0 years; at baseline, patient reported occasionally, fairly often or very often for 11(78.6%) OHIP items. However, after using the acrylic and flexible partial dentures, 11(36.6%) patients reported having trouble pronouncing words and 9(30.0%) found it uncomfortable to eat respectively. At baseline, there was a difference in mean OHIP scores with age (p=.02); scores reduced from 12.4 ± 9.8 to 4.8±5.3 (CI= 3.3-12.0, p=.001) after using the all-acrylic denture and 3.8±5.6 (CI= 4.3-13.0, p<.001) with the flexible denture. CONCLUSION: There was improvement in the OHRQoL of patients with use of flexible partial dentures. Therefore, thermoplastic materials are possible alternative RPD base materials in patient management. FUNDING: None declared.

Bite Force Evaluation in Complete Denture Wearer with Different Denture Base Materials: A Randomized Controlled Clinical Trial.

AIM: The aim of this study is to evaluate the maximum bite force (MBF) with different denture base materials in completely edentulous patients. MATERIALS AND METHODS: MBF was evaluated in randomly selected 100 completely edentulous patients. Patients were selected from the Outpatient Clinic, College of Dentistry, Aljouf University, Saudi Arabia. The patients were randomly divided into two equal groups: Group I (control group): Patient received a conventional heat-cured acrylic complete denture (Vertex™ Regular, Vertex-Dental B.V., The Netherlands) and Group II (experimental group): Patient received a thermoplastic complete denture (Vertex™ ThermoSens, Vertex-Dental B.V., The Netherlands). MBF measurements were taken at the time of new denture placement and after 6 months of denture use. Statistics were analyzed using independent t-test to compare the MBF measurements between both groups. RESULTS: At the time of denture placement, there was no significant difference in bite force measurements between both groups. Bite force is increasing considerably after 6 months of denture use, and it was higher than MBF recorded at the time of new prosthesis placement in the same group. The MBF values were considerably higher in patients with a thermoplastic denture than patients with conventional acrylic denture with statistically significant difference after 6 months of denture use. CONCLUSION: After 6 months of denture use, patients with a thermoplastic denture have a higher biting force than patients with a conventional acrylic denture. Therefore, it could be considered a treatment plan option according to the ridge nature and quality to solve the problem of diminished bite force in old age patients.

Denture impaction in the oesophagus experience of a young ENT practice in Nigeria.

INTRODUCTION: The effect of dental loss and associated desire to restore its function and aesthesis has led to an increase in the number of people wearing dentures. This study therefore reviews the cases of impacted acrylic dentures in the oesophagus. METHODS: A retrospective review of patients that were managed for oesophageal denture impaction at Ladoke Akintola University of Technology Teaching Hospital, Osogbo, Osun State, Nigeria, over an eight year period from 2005 to 2012. RESULTS: A total of 14 patients (M:F 2.5:1). The age ranged from 32-75 years. Majority 64.3%) were 51 years and above. Over 70% presented early. Major presenting symptoms were throat pain (100%), odynophageal (92.9%) and dysphageal (78.6%). The radiographic findings were air entrapment (64.3%) and increase in prevertebral soft tissue shadow (78.6%). Majority (87.5%) were impacted at the upper (cervical) oesophagus. Over 78% had successful extraction with rigid oesophagoscopy. Two (14.3%) had spontaneous expulsion of the denture and 1 (7.1%) discharged himself against medical advice. Complications were mucosa tear (28.6%), laryngeal spasm/ airway obstruction (14.3%), mucosa oedema/ erythema (57.1%), neck abscess (7.1%). CONCLUSION: Impaction of esophageal dentures is relatively common in our locality; most patients present early for medical attention and associated with successful rigid oesophagoscopies and denture extraction under GA, and generally good outcome. Education of the wearers of dentures was emphasized as a way of preventing dentures impaction.

Flexible denture base material: A viable alternative to conventional acrylic denture base material.

Although clinician's skills and experience play a major role in designing and fabrication of the optimum prosthodontic restorations, the selection of denture resins is equally important, especially when the patient has been using the prostheses since long. Eighteen cases who were not satisfied with their conventional acrylic dentures were selected. They were provided flexible dentures along with a questionnaire to precisely evaluate the advantages of new material. Prosthodontic planning & observations regarding this material are discussed on various parameters.