Journal of Prosthodontics-Implant Esthetic and Reconstructive Dentistry最新文献

Alar webbing is a functional and aesthetic defect of the nasal structure noted in cleft lip and palate patients (CLP), which is thought to be due to a deficiency in nasal lining tissue. Surgical procedures have previously focused on the removal of lining or alar cartilage leading to worse post-operative defects. This case demonstrates a novel technique of releasing the tissue, followed by using a CAD-CAM splint to help mold the tissue during the healing process to better control esthetics, symmetry, and prevent relapse. The release of scarred tissue using a custom CAD-CAM stent is a promising technique that allows for symmetric healing and an overall aesthetic surgical result for patients.

Purpose: This study aimed to investigate the effect of crystallization and finish line curvature on the integrity of lithium disilicate crowns fabricated by using partially crystallized (P) and fully crystallized (F) blocks.

Materials and methods: Forty-eight lithium disilicate crowns were fabricated based on the designated lithium disilicate blocks and finish line curvatures. The specimens were divided into four groups (n = 12 each): P block with a curved finish line (PC), P block with a straight finish line (PS), F block with a curved finish line (FC), and F block with a straight finish line (FS). Using the silicone replica technique and triple scan method, the absolute marginal discrepancy was measured at four surfaces. Using the triple scan method, five sections were segmented for each surface. Global deviation was measured by using a best fit alignment. Three-way mixed analysis of variance followed by Fisher least significant difference test and the Kruskal-Wallis test were used for statistical analyses (α = 0.05).

Results: The block crystallization had a significant impact on the marginal integrity in the triple scan method, showing a greater marginal discrepancy in the F block crowns (p < 0.001). The finish line curvature significantly influenced the marginal integrity in both measurement methods, with curved finish line crowns exhibiting a greater marginal discrepancy (p < 0.05). However, the areas with the greatest marginal discrepancies differed depending on the analytical method used.

Conclusions: The marginal discrepancies of the crowns differed according to the fabricated blocks and finish line curvature.

Purpose: To investigate how varying ferrule heights and the number of glass fiber posts affect fracture resistance and behavior of endodontically treated maxillary first premolars with substantial loss of tooth structure.

Materials and methods: Twenty-four extracted endodontically treated human maxillary first premolars were divided into three groups (n = 8) based on ferrule height and post number. The groups were as follows: premolars of 2 mm ferrule height that were restored with single posts (control group), premolars of 0.5 mm ferrule height that were restored with single posts in palatal canals (single-post group), and premolars of 0.5 mm ferrule height that were restored with double posts in palatal and buccal canals (double-post group). All groups were then restored with composite core and metal-ceramic crowns cemented with zinc phosphate cement. All specimens were subjected to 10,000 thermal cycles at temperatures of 5°C and 55°C, as well as 1.2 million cyclic loadings of 49 N load at 1.2 Hz using a chewing simulator. The specimens were loaded to fracture in a universal testing machine and fracture behavior was examined under stereomicroscope and divided into restorable and unrestorable fracture modes. Fracture loads and modes were analyzed by one-way ANOVA, Tukey's post hoc test, and Fisher's exact probability test (p ≤ 0.05).

Results: The control group showed the highest mean fracture load (1127 ± 172) of all groups (p < 0.001). The specimens in the single-post group showed numerically higher mean fracture load (522 ± 171) but with no significant difference compared to the ones in the double-post group (518 ± 157; p > 0.967). In the control group, 75% of specimens showed unrestorable fractures compared to 50% and 12.5% in single-post and double-post groups. The specimens in the control group had similar unrestorable fractures, starting from the coronal part and extending obliquely to the cervical third of the root below resin level. Two specimens in the control group showed unrestorable fractures in the middle third of the root. No middle-third root fractures were observed in single-post and double-post groups, and unrestorable fractures in both groups were similar to those of the control group. The single-post group had two specimens with core-post crown complex restorable fractures, while the control and double-post groups had one specimen each. The remaining specimens showed cervical-third root restorable fractures above resin level.

Conclusion: The ferrule height significantly influences the fracture resistance of endodontically treated premolars compared to the number of placed posts. Nonetheless, more restorable fractures are seen in endodontically treated premolars restored with double posts than single posts regardless of ferrule height.

Purpose: To assess the impact of staining and multiple firings on the mechanical, optical, and surface characteristics of zirconia-containing lithium silicate ceramics (ZLS).

Materials and methods: Ninety ZLS discs (Suprinity, VITA Zahnfabrick) were divided according to the "Number of firings" protocol: Ctr-control, no characterization; SC-single firing cycle (for characterization, crystallization and staining simultaneously); and DC-double firing cycle (crystallization firing cycle was performed separately from the staining firing). Extrinsic pigmentation was performed to replicate the characterization of a monolithic restoration. A layer of stain and glaze was applied with a fine brush to the ceramic surface. Specimens were fired two or four cycles, designed to simulate additional staining firings for potential characterization adjustments, but without applying new stain, resulting in six groups (n = 15): Ctr_II, Ctr_IV, SC_II, SC_IV, DC_II, and DC_IV. X-ray diffraction, color, translucency, and surface roughness analysis were also performed, and the samples were subjected to the biaxial flexural strength test. Data were subjected to one-way ANOVA, Tukey's test (α = 0.05), and Weibull analysis.

Results: No changes in the diffractogram pattern were found, irrespective of the number of firings. The translucency (p = 0.02) and roughness (p < 0.01) of DC_IV were significantly reduced compared to DC_II. DC_IV also showed the highest flexural strength (325.52^AMPa), followed by SCII (271.64^BMPa).

Conclusions: Repeated firings increased the flexural strength of ZLS, where the double-step characterization technique demonstrated better statistical results than the other groups. Moreover, despite the ceramic showing good color stability, repeated firings significantly compromised its translucency.

Obstructive sleep apnea (OSA) is characterized by intermittent cessation of breathing during sleep due to the collapse of oropharyngeal tissues. This review examines the role of craniofacial growth in OSA and evaluates the efficacy of orthodontic and orthognathic treatments. Maxillary expansion and orthognathic surgery have demonstrated significant reductions in sleep apneas and hypopneas, although they do not consistently achieve cure levels, particularly in the presence of obesity and connective tissue disorders. Understanding the multifaceted pathophysiology of OSA and addressing confounding factors such as obesity and muscle tone are essential for enhancing treatment outcomes.

Recent focus has shifted toward refining the soft tissue emergence profile to enhance aesthetics, support peri-implant health, and ensure long-term success. Traditionally, titanium stock healing abutments or chairside-customized abutments were used to shape peri-implant tissues and develop the emergence profile for implant-supported prostheses. However, advancements in digital dentistry now allow for more precise customization and increased treatment efficiency. This case report introduces a novel approach to shape the peri-implant tissues using a 3D-printed emergence profile former retained by a titanium stock healing abutment. The 3D-printed emergence profile former reduced chairside time and simplified registering the gingival tissue contours and implant position with an intraoral scanner. Following removal, the peri-implant soft tissues displayed enhanced volume buccally, creating an aesthetically pleasing restoration in a site with a notable horizontal tissue deficiency.

Purpose: This study aims to evaluate the effectiveness of a case-based reasoning (CBR) system in predicting the design of definitive obturator prostheses for maxillectomy patients.

Materials and methods: Data from 209 maxillectomy cases, including extraoral images of obturator prostheses and occlusal images of maxillectomy defects, were collected from Institute of Science Tokyo Hospital. These cases were organized into a structured database using Python's pandas library. The CBR system was designed to match new cases with similar historical cases based on specific attributes such as aramany class, abutment details, defect extension, and oronasal connection size. The system's performance was evaluated by clinicians who assessed the accuracy of prosthesis designs generated for 33 test cases.

Results: A correlation analysis demonstrated a significant positive relationship (ρ = 0.84, p < 0.0001) between the CBR system's confidence scores and the number of correct prosthesis designs identified by clinicians. The median precision at five cases was 0.8, indicating that the system effectively retrieved relevant designs for new cases.

Conclusions: The study shows that the developed CBR system effectively predicts the design of obturator prostheses for maxillectomy patients. Clinically, the system is expected to reduce clinician workload, simplify the design process, and enhance patient engagement by providing prompt insights into their final prosthetic design.

Purpose: To compare the accuracy of four digital scanning methods in duplicating a complete denture.

Material and methods: Four scanning methods were used: cone beam computed tomography (CBCT), Straumann desktop scanner (DS), Trios intraoral scanner (TIO), and Virtuo Vivo intraoral scanner (VVIO). Each method was used to duplicate all the surfaces of a printed complete denture. The denture was scanned 10 times in each group. The trueness (in root mean square, RMS) and precision (in standard deviation, SD) were calculated by comparing the combined dentition, denture extension, and intaglio surfaces with the reference file. One-way analysis of variance and F-tests were used to test statistical differences (α = 0.05).

Results: For the scanning accuracy of the whole denture, CBCT showed the highest RMS (0.249 ± 0.020 mm) and lowest trueness than DS (0.124 ± 0.014 mm p < 0.001), TIO (0.131 ± 0.006 mm p < 0.001), and VVIO (0.227 ± 0.020 mm p = 0.017), while DS and TIO showed smaller RMS than VVIO (p < 0.001). For the trueness of dentition, denture extension, and intaglio surfaces, CBCT also showed the highest mean RMS and lowest trueness among all groups (p < 0.001). DS and TIO had smaller mean RMS and higher trueness among all groups in all surfaces (p < 0.001, except VVIO in intaglio surface, p > 0.05). TIO had significantly lower within-group variability of RMS and highest precision compared to DS (p = 0.013), CBCT (p = 0.001), and VVIO (p < 0.001) in the combined surface. For dentition and denture extension surfaces, TIO showed similar within-group variability of RMS with the DS group (p > 0.05) and lower than CBCT and VVIO (p < 0.001).

Conclusion: The 7 Series desktop scanner and Trios 4 intraoral scanner can duplicate dentures in higher trueness than CBCT and the Virtuo Vivo intraoral scanner. The Trios 4 intraoral scanner was more precise in the combined surfaces than other scanning methods, while the 7 Series desktop scanner and Trios 4 intraoral scanner were more precise in the denture extension surface.

Same-day ablative and reconstructive surgeries for the treatment of head and neck pathologies are gaining in popularity with the recognition that single-day surgeries reduce morbidity and increase quality of life. Implant-borne prosthetics on the donor graft provide immediate dental reconstruction. This report describes a novel technique for extraoral pickup of a full arch immediate prosthesis from the donor site free flap. This technique minimizes intraoperative occlusal adjustments, saves intraoperative time, prevents undesirable "rolling" of a fibula segment, and immediately rehabilitates patients with dental prosthetics.