Reinforcement in removable prosthodontics: a literature review

Removable prosthodontics are often associated with mechanical troubles in daily use, such as fracture or deformation. These troubles render prostheses unusable and reduce wearers’ QOL. Various reinforcements are used to prevent such problems, but consensus on reinforcement has not been reached. This review aimed to summarise the effects of reinforcement and to propose favourable reinforcement based on material, design and position in the prostheses. Initially, 139 articles were selected by electronic and manual searches. After exclusion of 99 articles based on the exclusion criteria, 40 articles were finally included in the review. Electronic searches were performed for articles published from 2005 to 2015 in PubMed, EMBASE, MEDLINE and Cochrane Library, and manual searches were performed in 10 journals relevant to the topic of removable prosthodontics. For in vitro studies, certain dental alloys and fibres were mainly used. Their forms were different, including complicated forms in dental alloys and various forms in fibres. The materials were examined for mechanical properties like fracture strength, flexural strength and elastic modulus and compared with one another or without reinforcement. There were a few clinical studies and one longitudinal study. Cast metal reinforcement seemed to be most favourable in terms of fracture toughness and stiffness. The most favourable forms differed depending on the prostheses, but placement around thin and deformable areas was effective. However, randomised or longitudinal clinical reports and comparative clinical studies on the use of reinforcement were still lacking and such studies are necessary in the future.     

Effect of prosthetic restoration on masticatory function in patients with shortened dental arches: a multicentre study

The aim of this multicentre study was to investigate the effect of prosthetic restoration for missing posterior teeth on mastication in patients with shortened dental arches (SDAs). Partially dentate patients who had an intact teeth in anterior region and missed distal molar(s) (2–12 missing occlusal units) classified as Kennedy Class I or Class II were recruited from seven university‐based dental hospitals in Japan. Of the 125 subjects who underwent baseline (pre‐treatment) and follow‐up/post‐treatment evaluation, 53 chose no replacement of missing teeth and 72 chose treatment with removable partial dentures (n = 53) or implant‐supported fixed partial dentures (n = 19). Objective masticatory performance (MP) was evaluated using a gummy jelly test. Perception of chewing ability (CA) was rated using a food intake questionnaire. In the no‐treatment group, mean MP and CA scores at baseline were similar to those at follow‐up evaluation (P > 0·05). In the treatment group, mean MP after treatment was significantly greater than the pre‐treatment mean MP (P < 0·05). However, the mean perceived CA in the treatment groups was similar at pre‐ and post‐treatment (P > 0·05). In a subgroup analysis of subjects in the treatment group, subjects with lower pre‐treatment CA showed a significant CA increase after treatment (P = 0·004), but those with higher pre‐treatment CA showed a significant decrease in CA (P = 0·001). These results suggest that prosthetic restoration for SDAs may benefit objective masticatory performance in patients needing replacement of missing posterior teeth, but the benefit in subjective chewing ability seems to be limited in subjects with perceived impairment in chewing ability before treatment.     

Reliability of a two‐colour chewing gum test to assess masticatory performance in complete denture wearers

The aim of this study was to test the reliability of a method to measure the masticatory performance of complete denture wearers employing a colour‐mixing ability test and assessment by visual and electronic colourimetric analysis. A sample of 75 subjects was selected from patients who received new conventional complete dentures. Masticatory tests were performed using a two‐colour chewing gum that was masticated for 5, 10, 20, 30 and 50 chewing cycles, performed in a random order. The mixing level of the two colours of the chewed gum was assessed visually by two independent raters based on a 5‐point ordinal scale. The specimens were flattened into a 1‐mm‐width wafer, scanned and saved as a two‐sided digital image. Each pair of images was submitted to an electronic colourimetric analysis to assess the level of colour mixture, measured by the circular variance of hue (VOH ). Overall inter‐ and intra‐rater agreements in visual analysis were 64% and 68%, respectively (almost 99% of scores ranged within ±1 point), whilst overall weighted kappa was >0.80. A proportional increase in the level of mixture occurred with increased number of chewing cycles (P  < .001). Similarly, VOH and the visual analysis were highly correlated (r = ?.89; P  < .001). Bland‐Altman plots revealed excellent agreement and extremely low systematic error between duplicated VOH measures. It was concluded that the two‐colour chewing gum test is a reliable method to assess the masticatory performance in complete denture wearers using both visual and electronic colourimetric analyses.     

Oral health‐related quality of life in patients with non‐metal clasp dentures: a randomised cross‐over trial

We investigated the efficacy of non‐metal clasp dentures (NMCDs) with regard to the oral health‐related quality of life (OHRQoL) and compare the findings with those for conventional metal clasp‐retained dentures (MCDs). This single‐centre, randomised controlled, two‐phase, open label, cross‐over trial included 28 partially dentate individuals. The patients were randomised to receive MCDs followed by NMCDs, or the opposite sequence (n = 14 in each group); each denture was worn for 3 months. OHRQoL was evaluated using the Oral Health Impact Profile‐Japanese version (OHIP‐J) at entry (T‐entry; before treatment with the first denture) and at 3 months after treatment with each denture (T3). An examiner evaluated denture stability, oral appearance and surface roughness before denture delivery (T0) and at T3 and denture hygiene at T3. A total of 24 patients completed the trial. There were no complications related to the dentures, abutment teeth or denture‐bearing mucosa during the follow‐up periods for both dentures. The mean OHIP summary score was lower for NMCDs than for MCDs, and the difference (9 points) was greater than the minimal important difference (6 points), indicating the difference was clinically relevant. The effect size was medium (0·70). Statistical analyses with linear mixed models found a significant effect of the denture type on the OHIP summary score and scores for the Oro‐facial appearance, Oro‐facial pain and Psychological impact domains (NMCD < MCD; P < 0·05). The results of our study suggest that NMCDs allow for better OHRQoL compared with MCDs.     

The influence of vertical dimension of occlusion changes on the electroencephalograms of complete denture wearers

PurposeThe present study was conducted to identify how changes in the vertical dimension of occlusion (VDO) affect the sensory perception and activity of the brain in complete denture wearers using an electroencephalogram (EEG).MethodsSubjects were 21 individuals wearing complete dentures who regularly visited the Division of Prosthodontics at Tsurumi University Dental Hospital for checkups (12 males and 9 females, average age: 76.6). Based on their original dentures, two duplicate dentures with different VDO (−3 mm and +5 mm) were fabricated. EEG activity and occlusal force were measured before and after gum chewing with each denture in all subjects. Negative indicator scores for psychological conditions and stable neuronal activity (Dα) were calculated using EEG data. Statistical analysis was performed using the Wilcoxon test to compare changes in the sensory perception, activity of the brain, and occlusal force (α = 0.05).ResultsAfter gum chewing with the +5-mm denture, a significant increase was observed in the negative indicator score (p < 0.05). No significant difference was found in the Dα values before and after gum chewing with any of the dentures (p > 0.05). A significant decrease was observed in the occlusal force between the original denture and the −3-mm denture (p < 0.05).ConclusionPsychological condition and occlusal force were influenced by immediate changes in the VDO of the complete denture.     

Plasmodium falciparum synthetic LbL microparticle vaccine elicits protective neutralizing antibody and parasite-specific cellular immune responses

Epitopes of the circumsporozoite (CS) protein of Plasmodium falciparum, the most pathogenic species of the malaria parasite, have been shown to elicit protective immunity in experimental animals and human volunteers. The mechanisms of immunity include parasite-neutralizing antibodies that can inhibit parasite motility in the skin at the site of infection and in the bloodstream during transit to the hepatocyte host cell and also block interaction with host cell receptors on hepatocytes. In addition, specific CD4+ and CD8+ cellular mechanisms target the intracellular hepatic forms, thus preventing release of erythrocytic stage parasites from the infected hepatocyte and the ensuing blood stage cycle responsible for clinical disease. An innovative method for producing particle vaccines, layer-by-layer (LbL) fabrication of polypeptide films on solid CaCO₃ cores, was used to produce synthetic malaria vaccines containing a tri-epitope CS peptide T1BT* comprising the antibody epitope of the CS repeat region (B) and two T-cell epitopes, the highly conserved T1 epitope and the universal epitope T*. Mice immunized with microparticles loaded with T1BT* peptide developed parasite-neutralizing antibodies and malaria-specific T-cell responses including cytotoxic effector T-cells. Protection from liver stage infection following challenge with live sporozoites from infected mosquitoes correlated with neutralizing antibody levels. Although some immunized mice with low or undetectable neutralizing antibodies were also protected, depletion of T-cells prior to challenge resulted in the majority of mice remaining resistant to challenge. In addition, mice immunized with microparticles bearing only T-cell epitopes were not protected, demonstrating that cellular immunity alone was not sufficient for protective immunity. Although the microparticles without adjuvant were immunogenic and protective, a simple modification with the lipopeptide TLR2 agonist Pam₃Cys increased the potency and efficacy of the LbL vaccine candidate. This study demonstrates the potential of LbL particles as promising malaria vaccine candidates using the T1BT* epitopes from the P. falciparum CS protein.     

��ͬĥ�ij̶Ⱥ�������ֲ��ݶ����ٴ���Ч����

??Objective    To compare the short-term clinical effect of different degrees of wear in the posterior area of the implant denture. Methods    From January 2009 to December 2013??469 patients??the average age was 50.9??with partial loss of posterior teeth were followed up for 6 - 72 months. According to the degree of wear of natural teeth??they were divided into three groups??the non-wear group of 201 cases??457 implants????163 cases in mild-wear group??289 implants????105 cases in severe-wear group??235 implants??. The five-year cumulative survival rates of implants in the three groups were counted and the numerical values of bone resorption around the implants were measured. Results    Three groups of patients had no implant loss??the 5-year retention rate was 100%??there was no significant difference in bone resorption at the end of 3 months??6 months??1 year and 2 years after the repair??P > 0.05????there was no significant difference in the incidence of postoperative complications??P > 0.05??. Conclusion    In short time??the patients with mild wear and severe wear can have good clinical effect??whereas long-term effect need to be followed up.     

重度深覆患者活动义齿修复的临床体会

目的:探讨重度深覆患者采用活动义齿修复的临床效果。方法:选择36例中青年重度深覆患者,采用矫治性活动义齿治疗,评价其临床效果。结果:34例患者解除了重度深覆牙合,后牙达到了完全接触;2例患者放弃了治疗。结论:矫治性活动义齿对中青年重度深覆患者有较好的治疗效果。