Hua xi kou qiang yi xue za zhi = Huaxi kouqiang yixue zazhi = West China journal of stomatology最新文献

Dental invagination is an abnormality of the crown or root development induced during tooth germ development when the enamel-forming apparatus or epithelial root sheath overpopulates and folds into the papilla. In severe cases, the invaginated channels are connected to the pulp and periodontal tissues, often causing endodontic and periapical diseases. The complex anatomical pattern of this disease adds difficulty in its preoperative diagnosis and clinical operation. In this paper, we report a case of non-surgical treatment assisted by cone beam CT and microscopy for maxillary lateral incisor double dens invaginatus type Ⅲ (Ⅲa and Ⅲb) with apical periapical infection. After 1-year follow-up, the affected tooth was asymptomatic and the periapical lesion was significantly reduced.

Objectives: This study aims to analyze the clinical epidemiology, diagnostic and treatment characteristics of minor patients with maxillofacial fracture and provide a reference for the prevention and treatment.

Methods: The clinical data of minor patients with maxillofacial fracture in Departmentof Traumatic and Plastic Surgery, West China Hospital of Stomatology, Sichuan University, from January 1, 2015 to December 31, 2020 were retrospectively studied and statistically analyzed in terms of age, gender, etiology, anatomic sites and treatment modalities.

Results: The mean age of the patients was (10.65±5.15) years, and the male-to-female ratio was 1.91∶1. High fall was the primary cause of maxillofacial fractures in minors aged 0-6 years. Traffic accident injuries were the main cause of maxillofacial fractures in minors aged 7-12 and 13-17 years. About 65.13% of the midface and 83.08% non-condylar fractures were mainly treated by surgery, and condylar fractures were treated conservatively in 74.73% and by surgical treatment in 25.27%.

Conclusions: The etiology of maxillofacial fractures in minors differs at different ages, so prevention strategies should be adjusted according to age. Surgical treatment has become the preferred treatment modality for midface and non-condylar fractures. Conservative treatment is still the main treatment method for condylar fractures, but the proportion of surgical treatment increases.

Objectives: This study aimed to investigate the temporal and spatial changes in the expression of periostin during periodontal inflammation in mice.

Methods: A periodontitis model was constructed using silk thread ligation. Mice were randomly divided into five groups including control group, 4-day ligation group, 7-day ligation group, 14-day ligation group, and self-healing group (thread removal for 14 days after 14-day ligation). Micro-CT and histological staining were performed to characterize the dynamic changes in the mouse periodontal tissue in each group. RNAscope and immunohistochemical staining were used to analyze the pattern of changes in periostin at various stages of periodontitis. The cell experiment was divided into three groups: control group, lipopolysaccharide (LPS) stimulation group (treated with LPS for 12 h), and LPS stimulation removal group (treated with LPS for 3 h followed by incubation with medium for 9 h). Quantitative real-time polymerase chain reaction (qRT-PCR) was used to detect the expression of periostin, transforming growth factor-β1 (TGF-β1), and matrix metalloproteinase 2 (MMP2).

Results: Significant alveolar bone resorption was observed 7 days after ligation. With increasing duration of ligation, the damage to the mouse periodontal tissue was aggravated, which manifested as increased osteoclasts, widening of the periodontal membrane space, and decreased alveolar bone height. Some degree of periodontal tissue repair was observed in the self-healing group. Periostin expression decreased at 4 and 7 days compared with the control group and increased at 14 days compared with 4 and 7 days. A significant recovery was found in the self-healing group. The qRT-PCR results showed that the expression of periostin and TGF-β1 in the LPS stimulation group decreased compared with that in the control group but significantly recovered in the LPS removal group.

Conclusions: Periostin expression in the PDL of mice showed a downward and upward trend with inflammation progression. The significant recovery of periostin expression after removing inflammatory stimuli may be related to TGF-β1, which is crucial to maintain the integrity of the PDL.

Most of the maxillary impacted third molars are located in the maxillary tuberosity, where the vision and operation space are limited. This paper reports a case of surgical extraction of the left maxillary horizontal superhigh impacted third molar, which is located between the roots of the adjacent teeth and is closely related to the maxillary sinus. The digital simulation technology was used to reconstruct a three-dimensional visual image of the patient's maxilla, related teeth, and other adjacent anatomical structures to assist in finding the optimal surgical method accurately. Root dislocation before the crown not only protects the roots of the adjacent tooth, but also reduces the risk of maxillary sinus lining damage or perforation during operative procedures, improves the efficiency of the operation, and reduces surgical trauma, which conforms to the concept of minimally invasive surgery and provides a new idea and experience for the clinical extraction of such maxillary impacted third molars.

Objectives: This study aims to investigate bond strength between zirconia and resin cement through surface treatments with Er: YAG laser, Nd: YAG laser, and Si-Zr coating.

Methods: Seventy-five round pre-sintered zirconia discs with a diameter of 18 mm and a thickness of 1.5 mm were prepared by a powder compactor. Fifty discs were randomly divided into five groups of 10 discs each and were subjected to five surface treatments: no treatment (control group), sandblasting with alumina particles (sandblasting group), Er: YAG laser treatment (Er: YAG laser group), Nd:YAG laser treatment (Nd: YAG laser group), and Si-Zr coating treatment (Si-Zr coating group). The discs were then bonded to composite resin columns with resin cement. The shear bond strength of each group was tested with a universal tester. Roughness tester, scanning electron microscope (SEM), and energy dispersive spectroscopy were used to analyze surface performance.

Results: The bond strength of the Si-Zr coating group was higher than that of the remaining groups (P<0.05). The difference in bond strength between the sandblasting group and the Er: YAG laser group was not statistically significant (P>0.05), but both of them had higher bond strength than the Nd: YAG laser group (P<0.05). The Si-Zr coating group had the highest surface roughness (P<0.05). The surface roughness of the sandblasting, Er: YAG laser, and Nd: YAG laser groups was higher than that of the control group (P<0.05), but the difference among the three groups was not statistically significant (P>0.05). SEM observations showed irregular scratches on the surface of the sandblasting group and large pits with holes on the surface of the Er: YAG and Nd: YAG laser groups. In the Er: YAG laser group, the crystal structure was replaced by a smooth surface with a large amount of microcracks due to partial melting. Complex porous structures that comprised "island-like" structures and mass pores among the grains were observed on the surface of the Si-Zr coating. Only Zr, O, and Y were detected on the surfaces of the control, Er: YAG laser, and Nd: YAG laser groups. Al was found on the surface of the sandblasted group, and a higher proportion of Si was detected on the surface of the Si-Zr coating group.

Conclusions: Er: YAG laser and Nd: YAG laser treatment on the zirconia ceramic surface could increase roughness and improve the bond strength to resin cement. Si-Zr coating treatment is an effective alternative for increasing the roughness and bond strength of zirconia surface and is superior to sandblasting and laser treatments.

Objectives: This study aimed to systematically compare the effects of flapless and flapped implantations on the surrounding soft tissues of dental implants.

Methods: Nine databases were searched, including PubMed, Embase, Cochrane Library, Web of Science, Clinical Trials, OpenGrey, OpenDoar, Scopus, and Ovid, from January 1, 2013, to August 27, 2023. Randomized controlled trials comparing flapless implantation with flapped implantation for restoration of missing teeth were included. Meta-analysis was conducted on studies that met the inclusion criteria by using RevMan 5.3 and Stata 14.0.

Results: A total of 1 245 articles were retrieved, and 17 studies were ultimately included. The results of Meta-analysis showed that flapless implantation resulted in better healing of the soft tissues around the dental implants than flapped implantation. Moreover, flapless implantation showed superior changes in implant success rate [mean difference (MD)=1.06, 95% confidence interval (CI) (1.02, 1.10), P=0.004], the width of keratinized gingival changes [MD=0.10, 95%CI (0.00, 0.20), P=0.04], and probing depth [MD=-0.60, 95%CI (-0.67, -0.53), P<0.000 01], with statistically significant differences. The final combined results of modified plaque index [standardized mean difference (SMD)=-0.41, 95%CI (-0.81, 0.00), P=0.05] and modified sulcus bleeding index [SMD=-0.44, 95%CI (-0.78, -0.10), P=0.01] showed superiority over flapped implantation. The papillary presence index was higher in the flapless implantation group than in the flapped implantation group. No statistically significant differences were observed in plaque index and gingival indices changes between the two groups.

Conclusions: Flapless implantation can achieve higher implant success rate, smaller changes in the width of keratinized gingival, and smaller probing depths than flapped implantation. It also has advantages in terms of modified plaque index, modified sulcus bleeding index, and papillary presence index.

Objectives: This study aims to investigate the influence of glucose regulated protein (GRP) 78 on osteoblast differentiation in periodontal ligament fibroblasts (PDLFs) under cyclic mechanical stretch and determine the underlying mechanism.

Methods: FlexCell 5000 cell mechanical device was applied to simulate the stress environment of orthodontic teeth. GRP78High and GRP78Low subpopulation were obtained by flow sorting. Gene transfection was performed to knockdown GRP78 and c-Src expression and overexpress c-Src. Western blot analysis was used to detect the protein expression of Runt-related gene 2 (RUNX2), Osterix, osteocalcin (OCN), and osteopontin (OPN). Immunoprecipitation assay was used to determine the interaction of GRP78 with c-Src. The formation of cellular mineralized nodules was determined by alizarin red staining.

Results: GRP78 was heterogeneously expressed in PDLFs, and GRP78High and GRP78Low subpopulations were obtained by flow sorting. The osteogenic differentiation ability and phosphorylation level of c-Src kinase in the GRP78High subpopulation were significantly increased compared with those in GRP78Low subpopulation after cyclic mechanical stretch (P<0.05). GRP78 interacted with c-Src in PDLFs. The overexpression c-Src group showed significantly increased osteogenic differentiation ability than the vector group (P<0.05), and the sic-Src group showed significantly decreased osteogenic differentiation ability (P<0.05) after cyclic mechanical stretch.

Conclusions: GRP78 upregulates c-Src expression by interacting with c-Src kinase and promotes osteogenic differentiation under cyclic mechanical stretch in PDLFs.

Objectives: This work aimed to evaluate the effect of artificial aging on the translucency and color difference (ΔE) of ultra-translucent zirconia and provide a reference for clinical application.

Methods: The discs of ultra-translucent zirconia from six brands (Wieland, 3M ESPE, Amann Girrbach, Kuraray Noritake, Upcera, and Besmile) were cut and sintered according to each manufacturer's product instructions; the experimental groups were named ZNT, LVP, AG, KAT, UPC, and BSM, respectively. IPS e.max Press was used as the control group (PLT). The specimens (n=6) were prepared with a diameter of 14 mm and a thickness of 1 mm. The specimens were subjected to artificial aging treatment according to the following conditions: in an autoclave at 134 ℃ at 0.2 MPa for 4, 8, and 12 h. According to the CIE1976Lab system, the CIE L*, a*, and b* values of the specimens before and after aging were measured by a co-lorimeter. The translucency parameter (TP) and ΔE were calculated.

Results: The mean TP values of each group before aging inorder were PLT>KAT>AG>ZNT>BSM>UPC>LVP. We found no significant difference in translucency in all experimental groups after aging for 4 and 8 h compared with those before aging. After 12 h of aging, the TP values of the KAT and ZNT groups were not significantly different from those before aging, but the TP values of the AG, BSM, LVP, and UPC groups were significantly lower than those before aging (P<0.05). The TP value of the control group was significantly higher than that of the other experimental groups at different stages (P<0.05). ΔE=3.3 was considered the visible color difference, and ΔE was less than 3.3 in all groups after 4 h of aging. After aging for 8 h, ΔE of the UPC group was slightly higher than 3.3. ΔE of the BSM and UPC groups was greater than 3.3 after 12 h of aging.

Conclusions: The TP and ΔE of different brands of ultra-translucent zirconia may change after various aging times. The translucency of some zirconia showed a decreasing trend and the color difference showed an increasing trend with the aging time.

Objectives: This test aimed to investigate the factors affecting the locking force between the implant and abutment and the amount of abutment subsidence in pure Morse taper connection implant systems.

Methods: With reference to the Bicon implant abutment connection design, different types of implant specimens and their corresponding types of abutments were fabricated. The implant-abutment locking taper was uniformly 1.5°. The locking depths were 1.0, 2.0, and 3.0 mm. The diameters of the locking column were 2.5, 3.0, and 3.5 mm. The thicknesses of the outer wall of the implant were 0.15 and 0.30 mm. The loading forces of the testing machine were 200, 300, and 400 N. At least 10 specimens of each group of implant-abutment were used. All specimens were loaded in the same manner using a universal testing machine (finger pressure + specified loading force, five times). The total height of the implant-abutment was measured before finger pressure, after finger pressure, and after the testing machine was loaded for five times to calculate the amount of sinking of the abutment. Finally, the implant and abutment were pulled apart using the universal testing machine, and the subluxation force was observed and recorded.

Results: The test loading force, locking depth, and locking post diameter had an effect on the implant-abutment locking force and abutment subsidence. The implant-abutment locking force increased with the increase in the test loading force, locking depth, and locking post diameter (R=0.963, 0.607, and 0.372, respectively), with the test loading force having the most significant effect. Abutment subsidence increased with the increase in test loading force (R=0.645) and decreased with the increase in locking depth and locking post diameter (R=-0.807 and -0.280, respectively), with locking depth having the most significant effect on abutment subsidence. No significant correlation was found between the thickness of the outer wall of the implant and the change in the magnitude of the implant-abutment locking force. However, an increase in the thickness of the outer wall of the implant decreased the amount of abutment subsidence, which was inversely correlated.

Conclusions: The locking force of the implant-abutment can be increased by adjusting the design of the pure Morse taper connection implant⁃abutment connection, increasing the locking depth and locking post diameter, and increasing the amount and number of times the abutment is loaded during seating. Problems, such as loosening or detachment of the abutment, can be reduced. The recommended abutment to be loaded should be no less than five times during seating to prevent the abutment from sinking and causing changes in the occlusal relationship in the later stages. Preliminary occlusal adjustments should only be conducted in the early stages of the use of temporary restorations, and

Objectives: This study aims to compare the accuracy of self-developed universal implant guide (SDG), 3D printed digital guide (DG), and free hand (FH) simulated implantation in the posterior tooth area of dental models.

Methods: Ten junior dentists were selected to place three implants in the 35, 37, and 46 tooth sites of the mandibular models (35, 36, 37, and 46 missing teeth) by using SDG, DG, and FH, and the process was repeated again to take the average value. Cone beam computed tomography (CBCT) was used to evaluate the global coronal deviation, global apical deviation, depth deviation, and angular deviation between the actual position and preoperative planned position.

Results: The coronal deviation and apical deviation of the three implant sites in the SDG group were not significantly different from those in the two other groups (P>0.05). The depth deviation and angular deviation in the SDG group were smaller than those in the DG group (P<0.05) and FH group (P<0.05), respectively. All deviations at site 37 in the SDG group were not different from those at site 35 (P>0.05), while the depth and angular deviation at site 37 in the DG group were higher than those at site 35 (P<0.05).

Conclusions: The precision of the self-developed universal dental implant guide can meet the requirements of clinical posterior implantation.