The modern theory of complete denture retention using suction was applied to wooden plate dentures in Japan from the first half of the 16th century, which is an astonishing achievement since it was clinically applied in North America and Europe in the latter half of the 19th century nearly 300 years later. Wooden dentures are unique to Japan resulting from skilled Japanese craftsmanship and are not found in other countries. We comprehensively reviewed reports on wooden plate dentures, analyzed 145 complete and partial dentures, and discussed their history. Japanese wooden plate dentures are mainly made of box wood, and artificial teeth are made of pagodite, ivory, and natural teeth. Small nails were driven into the molar region. Many existing dentures revealed attrition on the occlusal faces, thereby indicating that the wearers were able to masticate sufficiently. Wooden plate dentures have been used for 400 years in the early 20th century. Although Japanese wooden dentures have not been mentioned in the history of dentistry in Western literature, they comprise an important part of the history of denture development.

UNASSIGNED: The applications of personalized abutments and abutment crown bridge products have increased year by year, but there is no clear requirement for clinical evaluation of the same variety of such products. This study mainly introduces the clinical evaluation concerns of personalized abutments and abutment crown bridge products, in order to provide reference for the declaration and registration of such products.
UNASSIGNED: The clinical evaluation of personalized abutments and crown bridge products are summarized, and the research content of clinical evaluation is clarified.
UNASSIGNED: The clinical evaluation requirements that need to be considered by enterprises are introduced.
UNASSIGNED: Personalized abutment and abutment crown bridge products can refer to this study when they are launched in China, mainly using in vitro performance comparison tests for equivalence verification.
UNASSIGNED: 个性化基台及基台冠桥产品申报量逐年增加，但目前对于该类产品的同品种临床评价没有明确要求，该研究主要介绍了个性化基台及基台冠桥产品的临床评价关注点，以期对该类产品的申报注册提供参考。.
UNASSIGNED: 通过总结个性化基台及冠桥产品的临床评价审评情况，明确其临床评价时的研究内容。.
UNASSIGNED: 该研究中介绍了注册申请人需要考虑的性能要求及同品种产品临床数据的具体要求。.
UNASSIGNED: 个性化基台及基台冠桥产品在中国境内上市时可参考本研究相关内容，主要通过体外测试研究论证等同性。.

There is a lack of data regarding the hygiene practices and sources of care among individuals in Yemen who wear removable complete and partial dentures. The purpose of this study was to explore the behaviors, hygiene habits, and sources of care information among patients who utilize complete and partial dentures in Yemen.
A descriptive cross-sectional research design was utilized, and a sample of 217 consecutive participants who wore removable complete and/or partial dentures were enlisted. A questionnaire was employed to collect data on demographic information, educational attainment, denture habits, denture cleaning practices, and encountered difficulties. Statistical analysis was conducted using SPSS software, and significance was determined using chi-square tests, with a significance level of .05.
The data analysis revealed that a majority of the participants were male (72.4%) and had an average age of 65.14 years. Fifty-three percent of the participants wore partial dentures, while 34.6% wore complete dentures. Only 6.5% of the participants wore both complete and partial dentures, and 6% wore overdentures. The majority of participants (88.47%) had dentures made of acrylic material. Additionally, 43% of participants wore dentures while sleeping, and 61.3% stored their dentures in dry places without a water-filled container when not in use. The most commonly reported cleaning methods were water only (24.4%), followed by water and soap (19.4%). Furthermore, a large portion of the participants (59.4%) received denture care information from dentists. However, the majority (59%) did not visit a dentist for regular denture maintenance or any denture-related issues. The data analysis did not reveal any significant association between age or education level and denture cleaning methods.
This cross-sectional survey provides insight into the hygiene knowledge and practices of removable denture wearers in Yemen. The findings underscore the necessity for enhanced oral hygiene education and awareness within this population. The study offers valuable insights for oral health professionals to design targeted interventions and educational initiatives aimed at promoting proper denture care and maintenance. These efforts have the potential to enhance the oral health and overall well-being of removable denture wearers.

BACKGROUND: The prevalence of adults with partially dental arches is expected to be more than imagined and patients requiring replacement of missing teeth are slowly increasing in number too. Removable partial dentures are known to provide for substantial replacement for the missing teeth with also added advantages when compared to fixed or implant prosthesis, mainly in elderly patients. Denture base material performance and durability are greatly influenced by wettability and water contact angle. In the case of dentures; adequate moisture distribution is necessary to ensure excellent wettability which has an influence on comfort and oral health. The purpose of conducting this study was to find out whether the advancements made using PEEK (Polyether ether ketone) would prove to be more beneficial than the current upgrades in the current material spectrum.
METHODS: This study was performed under in vitro conditions. All the fabrication and processing was done only by one operator. The materials used were divided into three groups each comprising 20 samples. Group A was modified polymethylmethacrylate (Bredent Polyan), Group B was polyoxymethylene acetal resin (Biodentaplast) and Group C was PEEK. An Ossila Goniometer was used to measure the contact angle. The three types of liquids used for the testing included distilled water, natural saliva and mouth wetting solution (Wet Mouth Liquid, ICPA India). Human saliva was collected from an individual with no medical conditions and normal salivary secretion.
RESULTS: The data was analyzed using One-way ANOVA test and a pairwise comparison using the Post Hoc Tukey\'s Honest Significant Difference. Table 1 consists of the mean water contact angles of the denture base materials and mean contact angles of various denture base materials. In saliva, mouth wetting solution and distilled water, the highest mean and least mean contact angle was seen in Polyan and Biodentaplast respectively. A signicant difference was seen between PEEK and Polyan and Biodentaplast and Polyan on further comparison.
CONCLUSIONS: From the resources and the materials at our disposal, it could be concluded that Polyan, Biodentaplast and PEEK and could be used as viable options in cast partial denture framework.

OBJECTIVE: The aim of this study was to analyze and compare the stress distribution on dental implants in various positions when used with implant-assisted removable partial dentures.
METHODS: This was an in vitro study.
METHODS: A model representing a mandibular bilateral partially edentulous condition, with missing premolars and molars, was fabricated using epoxy resin. Two implants of similar diameter measuring 4.0 mm × 10 mm (Dentium, Korea) were inserted in the second molar and the second premolar region on either side of the model for comparing the biomechanical effect of various implant locations. Two types of loads 100N and 125N were applied vertically using universal testing machines in the premolar and molar regions. The loads on the implants beneath the cast partial denture were measured by physical stress analysis using a microstrain gauge.
METHODS: A comparison of maximum stress observed at the premolar versus molar regions due to the application of the 100N and 125N loads was done using the Mann-Whitney U-test.
RESULTS: In physical stress analysis, obtained results were statistically analyzed, and the result was statistically not significant (P = 0.435 at 100N and P = 0.718 at 125N) in positional changes of implant.
CONCLUSIONS: In the current study, the statistical analysis of physical stress revealed no significant differences in stress values between the loadings at the premolar and molar regions. This suggests that the implant can be placed in either the premolar or molar region based on the availability of bone without affecting stress distribution.

BACKGROUND: Traditional removable partial denture (RPD) manufacture is being phased out in favor of computer-aided design and computer-aided manufacturing (CAD-CAM) techniques and rapid prototyping (RP), which provide more efficient methods of producing RPD frameworks. However, studies comparing the accuracy and surface roughness of these approaches on RPD frameworks are still scarce.
OBJECTIVE: The purpose of this in vitro study was to evaluate the accuracy and surface roughness of class I cobalt chromium (Co-Cr) removable partial denture frameworks digitally constructed using 2 different CAD-CAM technologies: direct milling (DM) and selective laser melting (SLM).
METHODS: An educational maxillary stone cast was scanned to create a resin model after rest seat preparation. The resin model was scanned, and an RPD framework was digitally designed. Sixteen frameworks were constructed (n=8). Two groups were defined. In the direct milling (DM) group, the standard tessellation language (STL) file of the RPD framework was used to mill the design from a Co-Cr blank directly. In the selective laser melting (SLM) group, the STL file of the RPD framework was used to print the design from Co-Cr powder using the selective laser melting technique. Geomagic Control X software program was used to measure the accuracy of the fabricated frameworks. Surface roughness was tested using optical profilometry. An unpaired t test was used to compare the 2 groups (α=.05).
RESULTS: The DM group showed significantly higher mean ±standard deviation accuracy (189 ±9 µm) (P<.001) compared with the SLM group (456 ±122 µm). Regarding the surface roughness, the DM group (0.157 ±0.001 mm) showed significantly lower surface roughness (P<.001) compared with the SLM group (0.256 ±0.001 mm).
CONCLUSIONS: The direct milling fabrication technique enabled the fabrication of Co-Cr RPD frameworks with higher accuracy and less surface roughness when compared with the 3-dimensionally printed SLM technique.

OBJECTIVE: To analyze the potential association between the occlusion features and the incidence of temporomandibular joint (TMJ) arthralgia in patients with partial dentures.
METHODS: A total of 101 partial denture wearers were collected, 45 with unilateral TMJ arthralgia diagnosed according to the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD). Binary logistic regression analysis was adopted. The TMJ asymptomatic group (n = 45) was quantified as 0, while the TMJ arthralgia group (n = 56) was quantified as 1. In total, 13 occlusion variables were analyzed: gender, age, number of prosthetic teeth, number of dentition quadrants with a prosthetic tooth, anterior or posterior prosthesis location in maxillary or mandibular dentition, occluded prosthesis pair, anterior overjet, and overbite relation. Simple and multiple binary logistic models were adopted, accordingly, for the risk impact of them on TMJ arthralgia.
RESULTS: Overbite (OR = 2.238) and maxillary anterior prosthesis (OR = 0.305) were entered into the simple binary logistic model; while overbite (OR = 2.774) plus maxillary anterior prosthesis (OR = 0.347), overbite (OR = 3.425) plus unilateral maxillary posterior prosthesis (OR = 4.672), and overbite (OR = 3.476) plus overjet (OR = 0.436) and mandibular anterior prosthesis (OR = 0.177) were entered into the multivariate logistic regression model (all, P < .05).
CONCLUSIONS: Partial denture wearers with a deep overbite, especially those with a unilateral maxillary posterior prosthesis, had a higher prevalence of unilateral TMJ arthralgia.

OBJECTIVE: To develop a protocol for setting artificial teeth in a complete removable denture without landmarks on the bite ridges.
METHODS: Based on the analysis of the literature of various areas of dentistry and the clinical experience of doctors corresponding to each of the disciplines of the specialty, a protocol for setting teeth in a full prosthesis was developed and its theoretical justification was given.
RESULTS: Using the method proposed by us, 324 prostheses were made for 162 patients with complete secondary adentia of two jaws. A clinical study and comparison with the generally accepted method of manufacturing prostheses using wax rollers was carried out. The method proposed by us showed greater efficiency based on a comparison of the results of functional tests after prosthetics.
CONCLUSIONS: The described method is part of the concept of manufacturing a functional prosthesis, is used in removable prosthetics, but can also be used in non-removable prosthetics, allows highly accurate, in accordance with individual anatomical parameters and features, to restore the occlusion of the patient during the reconstruction of the dentition, taking into account individual anatomical and functional parameters.
UNASSIGNED: Разработать протокол постановки искусственных зубов в полном съемном протезе без ориентиров на прикусных валиках.
UNASSIGNED: Исследование проводили в двух группах пациентов с полным отсутствием зубов: в 1-й группе зубные ряды были поставлены по общеизвестной методике, во 2-й группе — по предложенной нами методике. В каждой группе было исследовано качество восстановления функции речи и жевания. Измерения проводили через 1 нед после установки протезов, через 3 мес и 6 мес после окончания лечения.
UNASSIGNED: Было изготовлено 324 протеза для 162 пациентов с полным отсутствием зубов. Проведено клиническое исследование и сравнение с общепринятым методом изготовления протезов с использованием восковых валиков. Предложенный нами метод показал бóльшую эффективность на основании сравнения результатов функциональных тестов после протезирования.
UNASSIGNED: Описанный способ является частью концепции изготовления функционального протеза. Возможно его применение как при съемном, так и при несъемном протезировании. Позволяет с высокой точностью восстановить окклюзию пациента при реконструкции зубного ряда с учетом индивидуальных анатомических и функциональных параметров.

OBJECTIVE: Newly developed non-invasive methods for replace a missing tooth and closing single-tooth gaps in the poster- ior region using resin composite are presented.
METHODS: Four different non-invasive methods and the technical procedures, materials and instruments used are presented in a case series. These include the direct intraoral insertion of composite (with and without individual shaping aids) and indirect restorations, which are fabricated conventionally or digitally and bonded.
RESULTS: The case series showed that all four methods can be used to replace single missing teeth in the posterior region, meeting current clinical requirements. Particular attention was paid to the design of the pontics, the dimension of the connector area, firm proximal contacts to the adjacent teeth, hygiene, and appearance of the non-prep bridges (NPBs). The advantages and disadvantages for both the direct and indirect techniques illustrated in this case series were com- pared in detail.
CONCLUSIONS: Several direct and indirect non-invasive methods for single-tooth replacement are available today. Although the evidence is still limited, there is a potential for frugal dental interventions with NPBs. Further experimental and clinical studies are necessary to demonstrate that they reliably meet quality requirements (including sufficient survival rates), satisfy the criteria of cost-effectiveness (compared to treatment alternatives) and that there is a demand from the population.

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