Journal of prosthodontic research最新文献

Purpose: Poor contour of the implant restoration causes plaque accumulation and increases the risk of peri-implantitis. This study aimed to investigate whether the prosthodontic components of dental implants were associated with the prevalence of peri-implantitis.

Methods: We enrolled 185 patients with 348 implants who underwent at least 1-year follow-up after the delivery of the prosthesis from February 2010 to January 2021. Demographic data of the patients and implants and the follow-up period were recorded. The emergence angle, type of cervical crown contour, and contour angle were analyzed using annual bite-wing radiographs. Peri-implantitis in this study was diagnosed if the peri-implant bone loss was greater than 2 mm between the bite-wing radiographs taken at baseline and the latest. Chi-square test, two-sample t-test, and multivariate logistic regression were used to investigate the differences and odds ratios between the peri-implantitis and non-peri-implantitis groups.

Results: The incidence of peri-implantitis was 14.9% during a follow-up period of 1509 days after the delivery of the prosthesis for at least 1-year. Based on the prevalence of non-peri-implantitis and after adjusting for confounding factors, the risk factors identified were bone types for implants (native bone vs. alveolar ridge preservation: adjusted odds ratio = 2.43, P = 0.04). Sex, arch, and guided bone regeneration vs. alveolar ridge preservation have the potential for a statistical difference.

Conclusions: Compared with implants at alveolar ridge preservation sites, implants in the native bone were more prone to peri-implantitis. Further randomized controlled trials are required to determine these associations.

Purpose: The maintenance of peri-implant health relies significantly on the integrity of the peri-implant seal, particularly vulnerable at the interface between implant abutment and soft tissue. Early healing stages around implants involve cellular exposure to oxidative stress. This study aimed to investigate whether vacuum ultraviolet (VUV)-treated titanium augments the growth and functionality of human gingival fibroblasts while mitigating cellular stress.

Methods: Machined titanium plates underwent treatment with 172 nm VUV light for one minute, with untreated plates as controls. Human gingival fibroblasts were cultured on treated and untreated plates, and their behavior, growth, and functionality were assessed. Functionally impaired fibroblasts, treated with hydrogen peroxide, were also cultured on these titanium plates, and plate-to-plate transmigration ability was evaluated.

Results: Fibroblasts on VUV-treated titanium exhibited a 50% reduction in intracellular reactive oxygen species production compared to controls. Additionally, glutathione, an antioxidant, remained undepleted in cells on VUV-treated titanium. Furthermore, the expression levels of inflammatory cytokines IL-1β and IL-8 decreased by 40-60% on VUV-treated titanium. Consequently, fibroblast attachment and proliferation doubled on VUV-treated titanium compared to those in the controls, leading to enhanced cell retention. Plate-to-plate transmigration assays demonstrated that fibroblasts migrated twice as far on VUV-treated surfaces compared to those in the controls. In particular, the transmigration ability, impaired in functionally impaired fibroblasts on the controls, was preserved on VUV-treated titanium.

Conclusions: VUV-treated titanium promotes the growth, function, and migration of human gingival fibroblasts by reducing cellular stress and enhancing antioxidative capacity. Notably, the transmigration ability significantly improved on VUV-treated titanium.

Patient: A 67-year-old woman presented to our clinic with chief complaints of headache and mandibular heaviness. Physical examination revealed bilateral tenderness in the temporalis and masseter muscles, corresponding to the patient's chief complaint. Thus, a diagnosis of temporomandibular disorders (TMDs)-related headache was made. However, sleep disorders were identified after further consultation. Hence, sleep apnea-related headache was suspected due to a snoring habit with a Mallampati classification of Class IV. Out-of-center sleep testing (OCST) revealed a respiratory event index (REI) of 10.1/h and a low peripheral oxygen saturation (SpO₂) of 76%. Consequently, a diagnosis of obstructive sleep apnea (OSA) was made, and treatment using the mandibular advancement device (MAD) was recommended. Following MAD treatment, the patient's sleep quality improved, and morning headaches ceased. Subsequent OCST performed while wearing the MAD showed a significant reduction in the REI to 1.6/h and an increase in the SpO₂ to 86%, indicating the therapeutic efficacy of the MAD in treating OSA.

Discussion: MAD treatment effectively alleviated the patient's morning headaches, suggesting that sleep bruxism should not be considered the only cause of headaches. OSA should also be considered and addressed when investigating the potential causes of morning headaches in patients.

Conclusions: In patients experiencing TMDs symptoms and morning headaches, TMDs should not be presumed as the sole cause. Dentists should discuss the likelihood of sleep disorders during consultations. If sleep disorders are suspected, the possibility of OSA should be considered, and sleep tests should be conducted when necessary.

Purpose: This study aimed to analyze how the wall thickness of 3D-printed hollow zirconia teeth affects shape accuracy.

Methods: Datasets with measurement points were created for different artificial teeth resembling the mandibular right first molar (Geomagic Design X, 3D Systems). Reference distances were 9.8 mm for mesio-distal direction (M-D), 10.9 mm for bucco-lingual direction (B-L), 7.0 mm for MB-BB and DB-BB, and 4.5 mm for ML-LB and DL-LB. The outer geometry was identical for all artificial teeth with wall thicknesses of 0.30, 0.50, 0.75, and 1.00 mm. Twenty zirconia teeth were fabricated using a 3D printer (CeraFab 7500 Dental, Lithoz) for each group and sintered before support removal. After performing analog distance measurements using a micrometer screw, the digital distance measurements and angular deviations between measurement points on 3D scans were analyzed. Possible effects were investigated using nonparametric ANOVA, followed by Tukey's honest significant difference (HSD) test for multiple comparisons.

Results: The shape accuracy was acceptable for artificial teeth with wall thicknesses of ≥0.5 mm. The largest distance deviation was observed for a wall thickness of 0.3 mm. In particular, DB-BB showed a median deviation of >56.2 µm, which is significantly larger than that for other test groups, ranging from 7.4-9.5 µm (P < 0.05). In most cases, angular deviations were the largest for teeth with 0.3-mm wall thickness (11.6°) and remained below 5.0° for the other test groups.

Conclusions: Acceptable accuracy was obtained for artificial teeth with wall thicknesses of at least 0.5 mm.

Purpose: Acute stroke often leads to dysphagia. In the oral stage of dysphagia, there is a potential for immediate benefit from using a palatal augmentation prosthesis (PAP). We investigated whether our quickly fabricated, simple, and expedited version of PAP would result in an immediate improvement in swallowing function after an acute stroke.

Methods: We analyzed the records of stroke patients that were hospitalized between October 2019 and March 2022 and met the following criteria: they had a rehabilitation prescription and had paralysis of facial or hypoglossal nerves and either repeated salivary swallowing test ≤2 times or modified water swallow test ≤3, they were fasting, were within 3 weeks of onset, and had a simple PAP made for them. Outcomes included with/without PAP, maximum tongue pressure, repeated salivary swallowing test, and modified water swallow test on the day after starting to wear PAP was started. In addition, within one week, a videofluoroscopic examination was performed to measure the oral transit time, pharyngeal transit time, and penetration aspiration scale. Statistical analyses were performed using Wilcoxon signed-rank tests. Statistical significance was set at P < 0.05.

Results: Fifteen patients met the inclusion criteria and were included in this study. The mean age of the subjects was 76.9 ± 9.0 years. The use of PAP significantly increased maximum tongue pressure (P < 0.0001*) and shortened oral transit time (P < 0.0091*). There were no significant differences among the other items.

Conclusions: Simple PAP immediately increased the maximum tongue pressure and improved swallowing function during the oral stage.

Purpose: This study aimed to evaluate the risk of bone loss around single short molar crown-supporting implants in an atrophic mandible.

Methods: Implants of different lengths (L = 4 or 6 mm) and diameters (Ø = 4.1 or 4.8 mm) were placed in the molar area of an atrophic mandible. Additional control mandible models were simulated for 4.1 mm diameter implants (L = 4, 6, 8, and 10 mm). A vertical masticatory load of 200 N was applied to three or six occlusal contact areas (3ca or 6ca) of the prosthetic crown. The bone strain energy density (SED) of 109.6 µJ/mm³ was assumed to be the pathological threshold for cortical bone. The peri-implant bone resorption risk index (PIBRri) was calculated by dividing the maximum SED of the crestal cortical bone by the SED pathological threshold.

Results: Increasing the implant length from 4 to 6 mm, implant diameter from 4.1 to 4.8 mm, and number of contact areas from 3 to 6 reduced the SED and PIBRri values by approximately 20%, 35%, and 40%, respectively, when comparing pairs of models that isolated a specific variable. All models with 6ca had a low bone resorption risk (PIBRri<0.8), while the Ø4.1 short implant with 3ca had a medium (0.8≤PIBRri≤1.0) or high (PIBRri>1.0) resorption risk.

Conclusions: Increasing the diameter or occlusal contact area of a 4 mm short implant in an atrophic mandible resulted in reduced bone resorption risks, similar to or lower than those observed in a regular mandible with standard-length implants.

Patients: An 18-year-old woman sought treatment for caries of the anterior teeth after completing orthodontic treatment. Direct composite resin restoration was chosen because the patient preferred a minimally invasive and cost-effective treatment whenever possible. Based on diagnostic wax-up, veneer-shaped indices for composite resin injection were designed to replicate and restore tooth defects rapidly and accurately. The overall esthetic result was excellent after a 1-year of follow-up.

Discussion: Direct freehand composite resin restorations are clinically challenging. The recently proposed 3D printing index for the composite resin injection technique is helpful for direct restoration but is challenging to remove. The veneer-shaped indices avoid the formation of an undercut in the direction of removing the index, making them easy to remove after finishing the restorations.

Conclusions: Using veneer-shaped indices for composite resin injection enables rapid esthetic rehabilitation of labial tooth defects caused by caries. This approach reduces chairside time and operational difficulty while allowing for easy index removal after completing the restorations.

Patients: This case report describes a procedure for assessing changes in occlusal relationships in patients with acquired open bites due to temporomandibular joint disease using an intraoral scanner (IOS). A digital impression was made using the IOS at the initial visit. Subsequent impressions were made every 6 months using the IOS and magnetic resonance imaging (MRI) or computed tomography (CT). Standard triangulated language (STL) image files of two digital impressions at different points in time were superimposed, including the occlusal relationship with reference to the maxillary dentition. Finally, three-dimensional (3D) changes in the occlusal relationship over time were evaluated.

Discussion: In Case 1, the superimposed STL image indicated almost no evident deviation of the mandible. Therefore, an orthodontic treatment was initiated. In contrast, in cases 2 and 3, where changes in the occlusal relationship continued, secondary treatment was postponed and patients continued to be monitored periodically. In case 3, even though left condyle resorption was progressive, the degree of open bite on the right side improved after 6 months. However, the open bite continued to progress for another 6 months despite the stability of the condyle.

Conclusions: Changes in the condylar shape observed using imaging may not always reflect changes in the occlusal relationship. In addition to changes in the condyles and eminences of the temporomandibular joint (TMJ), changes in the occlusal relationships of patients with acquired open bite should be evaluated using an intraoral scanner.

Purpose: This review aims to summarize the available technologies, material categories, and prosthodontic applications of additive manufacturing (AM) dental ceramics, evaluate the achievable accuracy and mechanical properties in comparison with current mainstream computer-aided design/computer-aided manufacturing (CAD/CAM) subtractive manufacturing (SM) methods, and discuss future prospects and directions.

Study selection: This paper is based on the latest reviews, state-of-the-art research, and existing ISO standards on AM technologies and prosthodontic applications of dental ceramics. PubMed, Web of Science, and ScienceDirect were amongst the sources searched for narrative reviews.

Results: Relatively few AM technologies are available and their applications are limited to crowns and fixed partial dentures. Although the accuracy and strength of AM dental ceramics are comparable to those of SM, they have the limitations of relatively inferior curved surface accuracy and low strength reliability. Furthermore, functionally graded additive manufacturing (FGAM), a potential direction for AM, enables the realization of biomimetic structures, such as natural teeth; however, specific studies are currently lacking.

Conclusions: AM dental ceramics are not sufficiently developed for large-scale clinical applications. However, with additional research, it may be possible for AM to replace SM as the mainstream manufacturing technology for ceramic restorations.