Purpose: In dental implant treatment, ridge preservation and immediate or early implant placement are recommended to minimize bone resorption after tooth extraction and achieve esthetic outcomes. However, there is no consensus concerning the efficacy of this surgical method. There is also no consensus on the efficacy of bone and soft tissue grafts and surgical methods for alveolar ridge reconstruction. Study selection: This paper reports ridge alteration in the anterior maxilla after tooth extraction, and summarizes the efficacy of various ridge preservation methods and imme- diate or early implant placement as alveolar ridge preservation methods to minimize bone resorption after tooth extraction. The advantages and complications of alveolar ridge reconstruction methods, and the efficacy and surgical method of soft tissue graft are reviewed. Results: The anterior maxilla is in the esthetic zone, and the thickness of the bone on the labial side around the natural tooth is less than 1 mm in many cases. Therefore, it is impossible to prevent bone resorption completely, even if ridge preservation and immediate or early implant placement are performed after tooth extraction. It is necessary to obtain stable and long-term esthetics by combining connective tissue and free gingival grafts, in addition to hard tissue augmentation. Conclusions: It is important to consider the burden and level of satisfaction of patients, such as in terms of donor site morbidity in hard and soft tissue grafting, and to pay attention to appropriate indications to avoid overtreatment.

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Purpose: There are two key considerations for successful esthetic dental treatments. This article systematically describes the two key considerations: the end points of esthetic dental treatments and assessments of esthetic outcomes, which are also important for acquiring clinical skill in esthetic dental treatments. Study selection: The end point and assessment of esthetic dental treatment were discussed through literature reviews and clinical practices. Results: Before designing a treatment plan, the end point of dental treatment should be established. The section entitled ‘‘End point of esthetic dental treatment'' discusses treat- ments for maxillary anterior teeth and the restoration of facial profile with prostheses. The process of assessing treatment outcomes entitled ‘‘Assessments of esthetic dental treat- ment'' discusses objective and subjective evaluation methods. Conclusions: Practitioners should reach an agreement regarding desired end points with patients through medical interviews, and continuing improvements and developments of esthetic assessments are required to raise the therapeutic level of esthetic dental treatments.

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Purpose: The aim of this study was to compare the repeatability of intraoral digital impres- sion scanning with the repeatability of extraoral scanning by using Geomagic Qualify 12 as the software of analysis. Methods: One Nissin Dental Study Model (upper jaw) with prepared abutments were designed to form 5 set of arrangements according to the layout of prepared abutments (arrangement 1: single prepared maxillary central incisor; arrangement 2: single prepared maxillary first molar; arrangement 3: prepared central incisor and canine with the lateral incisor absent; arrangement 4: half of upper arch with 7 prepared teeth; arrangement 5: entire upper arch with 14 prepared teeth). Each arrangement of Nissin Dental Study Model was scanned by TRIOS intraoral digital scanner (experimental group) and D800 extraoral scanner (control group) for 10 times exporting 100 STL files in total. The data were processed and analyzed using Geomagic Qualify 12 software to evaluate the repeatability of intraoral digital scanning. Results: 3D standard deviations were 13.33, 7.0, 16.33, 41.56, 88.44 mm for arrangements 1-5 respectively in experimental group and 14.89, 8.67, 24.33, 14.22, 12.67 mm for arrangements 1-5 respectively in the control group. Mann-Whitney test revealed a significant difference between the 2 groups with regard to arrangements 2-5 ( p < 0.05). Conclusions: Precision decreases with the increased scanning scope. Precision was clinically acceptable when scanning scope was less than half arch. Precision of extraoral scanning was acceptable in scanning any scope of arch region.

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Purpose: This study aimed to clarify whether the absence of occlusal support would lead to a decline in the activities of daily living (ADL) in elderly people receiving home care. Methods: The subjects of this study were 322 elderly individual aged 65 and older who were receiving home care during a one-year observation period. The subjects were divided into two groups according to the change in the total score of the Barthel Index (BI) during the prospective cohort study period (the dependent variable): the maintained/improved activi- ties of daily living group, in which the score was unchanged or improved, and the worsened activities of daily living group, in which the score decreased. The relationship between occlusal status (the presence or absence of occlusal support) at the baseline measurement and each BI score change was evaluated in the slightly, moderately and totally dependent ADL subgroups. Results: The number of subjects in the maintained/improved and the worsened ADL groups was 152 and 170, respectively. The baseline characteristics of cognitive function and occlusal support were significantly different between the maintained/improved and the worsened ADL groups ( p < 0.05). Among the ADL subgroups, significantly reduced scores in mobility and toilet use were observed only in the slightly dependent group ( p < 0.05). Conclusions: Our results suggest that the loss of occlusal support may be an important factor in the decline of ADL in elderly people receiving home care, especially slightly dependent people.

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^{Purpose: We examined the clinical appearance (color, gloss, and surface roughness) of TiO}2 coating on polymethyl methacrylate (PMMA) resin dentures. ^{Methods: A spraying method, using air brushes, was used to generate thin uniform TiO}2 ^{coating. PMMA resin, primer-coated PMMA, and TiO}2^{-coated PMMA (with primer) speci-} mens were compared. Results: The Commission Internationale de l'Eclairage (CIE) color system revealed color ^{variations between the with/without coated samples. The TiO}2^{-coated PMMA specimen} displayed high levels of glossiness, highlighting the efficient self-cleansing actions of the denture. The measured surface roughness decreased upon primer coating, and increased ^{following TiO}2 ^{coating. Conclusions: The thin TiO}2 ^{coating afforded high levels of glossiness while maintaining the} color of the denture base material.

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Purpose: The selective impression technique is recommended for removable prosthodon- tics. However, the viscoelastic rheological properties of impression materials, particularly the time-dependent viscoelastic changes in impression material immediately after tray seating, are unknown. The objective of this study is to clarify the viscoelastic rheological properties of impression materials by focusing on tray seating. Methods: In this study, eight types of polyvinylsiloxane (PVS), two types of polyether, and two types of alginate impression materials were used. The storage modulus (G⁰; degree of stiffness) and loss tangent (tan d; degree of hardening) were determined as functions of time from 0 to 360 s, commencing immediately after the completion of mixing, using a stress control-type rheometer. Thus, G⁰ and tan d at 0 s and 20 s were compared. Results: Stiffness was found to be widely distributed (4.49-0.26 10⁴ Pa) among PVS-types, ? even immediately after mixing the impression material. There was also variation among polyethers (1.55-0.5 10⁴ Pa) and among alginates (0.64-0.21 10⁴ Pa). The hardening of all ? ? impression materials progresses beyond 20 s after the completion of mixing. Conclusions: The G⁰ values varied with each impression material, even immediately after mixing, and the accurate impression-taking time was determined from the results of tan d. These results provide unique insight into the selective impression technique.

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Purpose: We evaluated the effects of gum chewing on the response to psychological stress induced by a calculation task and investigated the relationship between this response and masticatory performance. Methods: Nineteen healthy adult volunteers without dental problems undertook the Uchida-Kraepelin (UK) test (30 min of reiterating additions of one-digit numbers). Before and immediately after the test, saliva samples were collected from the sublingual area of the participants. Three min after the UK test, the participants were made to chew flavorless gum for 3 min, and the final saliva samples were collected 10 min after the UK test. The experiment was performed without gum chewing on a different day. Masticatory perfor- mance was evaluated using color-changing chewing gum. Results: Salivary CgA levels at immediately and 10 min after the UK test were compared with and without gum chewing condition. Two-way repeated measures analysis of variance revealed significant interaction between gum chewing condition and changes in CgA levels during post 10 min UK test period. A significant correlation was found between changes in CgA levels and masticatory performance in all participants. Conclusion: Our results indicate that gum chewing may relieve stress responses; however, high masticatory performance is required to achieve this effect.

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