Journal of Prosthetic Dentistry最新文献

Statement of problem: Healthcare-related information provided by artificial intelligence (AI) chatbots may pose challenges such as inaccuracies, lack of empathy, biases, over-reliance, limited scope, and ethical concerns.

Purpose: The purpose of this study was to evaluate and compare the validity and consistency of responses to prosthodontics-related frequently asked questions (FAQ) generated by 4 different chatbot systems.

Material and methods: Four prosthodontics domains were evaluated: implant, fixed prosthodontics, complete denture (CD), and removable partial denture (RPD). Within each domain, 10 questions were prepared by full-time prosthodontic faculty members, and 10 questions were generated by GPT-3.5, representing its top frequently asked questions in each domain. The validity and consistency of responses provided by 4 chatbots: GPT-3.5, GPT-4, Gemini, and Bing were evaluated. The chi-squared test with the Yates correction was used to compare the validity of responses between different chatbots (α=.05). The Cronbach alpha was calculated for 3 sets of responses collected in the morning, afternoon, and evening to evaluate the consistency of the responses.

Results: According to the low threshold validity test, the chatbots' answers to ChatGPT's implant-related, ChatGPT's RPD-related, and prosthodontists' CD-related FAQs were statistically different (P<.001, P<.001, and P=.004, respectively), with Bing being the lowest. At the high threshold validity test, the chatbots' answers to ChatGPT's implant-related and RPD-related FAQs and ChatGPT's and prosthodontists' fixed prosthetics-related and CD-related FAQs were statistically different (P<.001, P<.001, P=.004, P=.002, and P=.003, respectively), with Bing being the lowest. Overall, all 4 chatbots demonstrated lower validity at the high threshold than the low threshold. Bing, Gemini, and ChatGPT-4 chatbots displayed an acceptable level of consistency, while ChatGPT-3.5 did not.

Conclusions: Currently, AI chatbots show limitations in delivering answers to patients' prosthodontic-related FAQs with high validity and consistency.

Statement of problem: Studies examining the influence of different fabrication techniques on the fracture load (FL) of monolithic zirconia restorations are sparse.

Purpose: The purpose of this in vitro study was to compare the FL of monolithic zirconia restorations manufactured with different technologies.

Material and methods: A typodont model with a missing left first molar was used and laboratory scanned (inEos X5; Dentsply Sirona). Data were transferred to a computer-aided design software program (InLab 16.1; Dentsply Sirona). The cement space for the 3-unit fixed partial dentures was set at 50 µm, and the connector area was specified as 9 ±0.2 mm². The subtractive technique was designated as the control group (GC Initial Zirconia HT; GC Corp), while 3 experimental groups were created by using different additive techniques (Gr^SLA [3DMix Zirconia 3Y; 3D Ceram], Gr^DLP [Inni Cera; Aon], and Gr^LCM [LithaCon 3Y 210; Lithoz]) (n=8). In all groups, 3 mol% yttria-stabilized tetragonal zirconia polycrystalline was used. The FL test was conducted on models fabricated from glass-filled resin-based methacrylate and postpolymerized. After thermal cycling (5000 cycles, 5-55 °C), all specimens were loaded with a stainless-steel ball at a crosshead speed of 1 mm/minute until fracture in a precision universal testing device. The maximum loads at fracture were recorded in N. Weibull analysis was used to determine the characteristic strength and reliability. The fracture lines were analyzed by scanning electron microscopy at magnifications of ×50 and ×500. The elemental compositions were compared with energy dispersive spectroscopy. A 1-way ANOVA and Tukey post hoc test were used for statistical analysis (α=.05).

Results: Significant differences in FL values were found among the groups (P<.001). Gr^DLP had the lowest FL (821 ±160 N), while the highest FL belonged to the control group, followed by Gr^LCM (1132 ±209 N). Weibull analysis showed Gr^DLP had the highest reliability. Failure analysis indicated that there were fractures and cracks in the pontic region in all groups.

Conclusions: Although the control group performed better, the FL values of monolithic zirconia restorations fabricated by using different additive manufacturing methods exceeded the clinically relevant threshold (790 N), demonstrating their suitability for posterior use.

Statement of problem: The provision of a nasal prosthesis is an important method of restoring the morphological integrity of the face in patients with nasal defects. In the digital design and manufacture of nasal prostheses, constructing the nasal prosthesis morphology is a critical procedure that significantly affects the repair outcome; however, studies on constructing nasal prosthesis morphological data are lacking.

Purpose: The purpose of this study was to assess using the Procrustes Analysis-Nonrigid Iterative Closest Point (PA-NICP) algorithm, which follows the principle of nonrigid registration, to achieve rapid construction of the nasal prosthesis morphological data. The effects of the PA-NICP algorithm and MeshMonk program in constructing nasal prosthesis morphological data were compared.

Material and methods: The 3-dimensional (3D) facial data of 30 adult male patients were collected using a 3D facial scanner (FaceSCAN), and 30 total nasal defect 3D facial datasets were constructed using the Geomagic Wrap 2021 software program. The PA-NICP algorithm proposed in this study (experimental group) and the MeshMonk program reported in previous literature (control group), also based on nonrigid registration, were used with the 3D face template developed in previous research to construct nasal prosthesis morphological data for the total nasal defect 3D facial datasets. The 3D morphological deviation between the nasal prosthesis data and the patient's original nasal morphology, the edge tightness between the nasal prosthesis data and the nasal defect data, and the edge surface continuity of the nasal prosthesis data were calculated. The experimental and control groups were compared with paired-sample statistical analysis (α=.05).

Results: Regarding the 3D morphological deviation, the root mean square (RMS) value of the 3D deviation was 1.51 ±0.45 mm in the experimental group and 1.34 ±0.31 mm in the control group, with no statistically significant difference between them (P=.054). Regarding the edge tightness, the RMS value of the curve deviation was 0.22 ±0.05 mm in the experimental group and 0.38 ±0.09 mm in the control group, with a statistically significant difference between them (P<.001). Regarding the edge surface continuity, the average percentage of tangent continuous surfaces was 95.47% in the experimental group and 92.20% in the control group, with a statistically significant difference between them (P=.001).

Conclusions: Both the PA-NICP algorithm and MeshMonk program can construct relatively optimal nasal prosthesis data. The nasal prosthesis data constructed using the PA-NICP algorithm exhibited better edge tightness and morphological transition effects.

A new method of digitally acquiring patient-specific anatomic references by using an additively printed facebow facially scanned with an intraoral scanner is described. These data are then used for digital mounting with the aid of a free software program. The patient-specific digital arc of closure allows for a detailed occlusal analysis.

The socket shield technique has been used to enhance the esthetics of immediately placed implant-supported prostheses in the esthetic zone. However, the technique has rarely been used in clinical practice because of high technical sensitivity, limited field of view, and the risk of intraoperative and postoperative complications. A technique is presented for carefully preparing labial socket shields under oral microscopy, which can reduce surgical difficulty and improve the precision of socket preparation.

Statement of problem: An acceptable dental restoration needs to retain stable translucency and opalescence after years of service in the oral environment. Information about the optical properties of recently introduced computer-aided design and computer-aided manufacturing (CAD-CAM) monolithic ceramics and the effectiveness of bleaching on these materials has not yet been documented.

Purpose: The purpose of this in vitro study was to evaluate the effects of thermocycling and bleaching on the translucency and opalescence of monolithic ceramics, including zirconia, lithium disilicate (LDS), polymer infiltrated ceramic network (PICN), presintered zirconia reinforced lithium silicate (PS-ZLS), and PS-ZLS with additional sintering (PS-ZLS+AS).

Material and methods: A total of 50 plate-shaped specimens in A2 shade with 1 mm thickness were prepared (n=10). Each specimen underwent coffee thermocycling for a total of 20 000 cycles and a 20% carbamide peroxide bleaching for 14 days. The color coordinates on standard white and black backgrounds were measured for each specimen at 3 stages: initial, thermocycled, and bleached. The translucency parameter (TP) and opalescence parameter (OP) were calculated at each stage. A 2-way repeated measures ANOVA was conducted to assess the effects of material type and measurement stage, followed by Bonferroni-adjusted multiple comparisons for pairwise analyses (α=.05).

Results: Zirconia specimens showed the lowest TP, while the LDS group had the highest TP. The thermocycled PS-ZLS+AS group had significantly higher TP than the thermocycled PS-ZLS (P=.001). Thermocycling significantly decreased the TP of PS-ZLS (P=.018) and PICN (P=.012), while bleaching increased this parameter. The PS-ZLS and PS-ZLS+AS groups showed the highest OP, while the LDS and PICN groups had the lowest OP. Bleaching significantly decreased OP for the zirconia (P=.007), PICN (P=<.001), and PS-ZLS+AS (P=.01) groups.

Conclusions: Among the studied materials, zirconia and LDS showed the most stable TP and OP during thermocycling and bleaching. Bleaching can restore the translucency of PICN and PS-ZLS lost during thermocycling. Additional sintering for PS-ZLS material led to more stable translucency during thermocycling. The highest opalescence increases during thermocycling and reductions during bleaching were found in PS-ZLS, followed by PICN.

Statement of problem: The biocompatibility and cell response of additively manufactured ceramics, important for long-term clinical success, require additional investigation.

Purpose: The purpose of this in vitro study was to compare the biocompatibility and cell response of human gingival keratinocytes with 3-dimensionally (3D) printed and conventionally milled zirconia.

Material and methods: Cylindrical specimens of 3D printed and milled zirconia were prepared, and immortalized human gingival keratinocytes (IHGKs) were cultured on specimens of these materials. Cells cultured only in growth medium were the control. Cell adhesion, viability, and morphology were assessed by using water-soluble tetrazolium (WST-1) assays and scanning electron microscopy (SEM) of the disks after culturing. Eluates from the zirconia specimens were collected and tested to assess potential cytotoxicity over time and surface roughness measured by laser scanning microscopy. For cell adhesion, an independent t test for 2-samples with unequal variances (Welch t test) was performed. For the cytotoxicity tests, differences between groups were analyzed using the post hoc test for multiple comparisons with the Bonferroni correction (α=.05).

Results: After 24 hours, no significant difference in keratinocyte adhesion was found between 3D printed and milled zirconia (P>.05). Cell viability assays showed that, while both materials exhibited lower viability compared with the control, 3D printed zirconia displayed significantly reduced cell viability after 96 hours compared with milled zirconia (P<.001). Average surface roughness (Ra) was significantly higher (P=.001) for printed (0.26 ±0.04 µm) than milled (0.08 ±0.02 µm) zirconia. SEM images confirmed good cellular adhesion and spreading on milled zirconia, with similar attachment on 3D printed zirconia.

Conclusions: Both 3D printed and milled zirconia demonstrated good biocompatibility with human gingival keratinocytes. However, under extended direct surface contact, cells on 3D printed zirconia showed lower cell viability compared with milled zirconia. While 3D printed zirconia is promising for dental applications, further refinement of its surface properties and biocompatibility may be needed.

Statement of problem: Information relating to the use of the Jaw Motion Analyzer (JMA) ultrasonic facebow to evaluate the efficiency of an anterior repositioning occlusal device (AROD) is lacking.

Purpose: The purpose of this clinical study was to use an ultrasonic facebow to make a preliminary analysis of and explore mandibular movement function.

Material and methods: Temporomandibular disorders were treated with AROD for 3 months, and an ultrasonic facebow was used to accurately record changes in the condylar position and the mandibular border movement tracing of patients before and after AROD treatment. Finally, the changes and characteristics of the mandibular border movement tracing and the 3-dimensional position of the condyle process were compared and analyzed statistically. A comparison of parameter differences between groups, t test analysis, and variance chi-squared test and 1-way ANOVA were performed (α=.05).

Results: Before treatment, the difference in maximum mouth opening (MMO) between the control and experimental groups was statistically significantly different (P<.05). No statistically significant difference (P>.05) in MMO was found between the control group and the experimental group after treatment. However, a statistically significant difference (P<.05) was found between the experimental group before and after treatment.

Conclusions: After AROD treatment, a new balanced relationship was generated between the facial muscles, the temporomandibular joint, and occlusal states, thus resulting in an improvement in the coordinated position and motion function of the condyle. The JMA ultrasonic facebow was found to be a reliable instrument that can accurately record dynamic movements of the temporomandibular joint.