Effect of thread depth and thread pitch on the primary stability of miniscrews receiving a torque load : A finite element analysis.

PURPOSE: We have been developing a new type of miniscrew to specifically withstand orthodontic torque load. This study aimed to investigate the effect of thread depth and thread pitch on the primary stability of these miniscrews if stressed with torque load. METHODS: Finite element analysis (FEA) was used to evaluate the primary stability of the miniscrews. For thread depth analysis, the thread depth was set to 0.1-0.4 mm to construct 7 models. For thread pitch analysis, the thread pitch was set to 0.4-1.0 mm to construct another 7 models. A torque load of 6 Nmm was applied to the miniscrew, and the other parameters were kept constant for the analyses. Maximum equivalent stress (Max EQV) of cortical bone and maximum displacement of the miniscrews (Max DM) were the indicators for primary stability of the miniscrew in the 14 models. RESULTS: In the thread depth analysis, Max DM increased as the miniscrew thread depth increased, while Max EQV was smallest in model 3 (thread depth = 0.2, Max EQV = 8.91 MPa). In the pitch analysis, with an increase of the thread pitch, Max DM generally exhibited a trend to increase, while Max EQV of cortical bone showed a general trend to decrease. CONCLUSION: Considering the data of Max DM and Max EQV, the most appropriate thread depth and thread pitch of the miniscrews in our model was 0.2 and 0.7 mm, respectively. This knowledge may effectively improve the primary stability of newly developed miniscrews.

Optimization Analysis of Two-Factor Continuous Variable between Thread Depth and Pitch of Microimplant under Toque Force.

Microimplant, an anchorage device, is widely applied in clinical orthodontic treatment. Since tooth torque is required to be controlled during orthodontic tooth movement, a novel microimplant needs to be developed to apply better torque force during orthodontic. In this study, the optimal value ranges of thread depth and pitch under toque force were studied for choosing microimplant with relevant value ranges in clinical design from biomechanical perspective. Finite element analysis (FEA) and optimization design technology were used for accessing the optimal value ranges of thread depth and pitch under toque force. Thread depth (D) (0.1 mm to 0.4 mm) and pitch (P) (0.4 mm to 1 mm) were used as continuous variables, with the other parameters as constant, and the optimal value ranges were obtained by analyzing the tangent slope and sensitivity of the response curve. When a torque force of 6 Nmm was applied on the microimplant, the maximum equivalent stress (Max EQV) of cortical bone and maximum displacements (Max DM) of microimplant were analysis indexes. When 0.55 mm ≤ P ≤ 1 mm, the Max EQV of cortical bone was relatively smaller with less variation range. When 0.1 mm ≤ D ≤ 0.35 mm, the Max DM of microimplant was relatively smaller with less variation range. So in conclusion, the initial stability of microimplants with pitch 0.55 mm ≤ P ≤ 1 mm and thread depth 0.1 mm ≤ D ≤ 0.35 mm was better with the torque force applied.

Application of an L-shaped anterolateral thigh flap in reconstruction after hemiglossectomy.

OBJECTIVE: Tongue defect reconstruction is one of the key components of tongue cancer surgery. In this study, we used an L-shaped flap design adopted as a simple and efficient method to repair tongue defects after hemiglossectomy. Furthermore, we evaluated and contrasted the clinical effects of two methods, the L-shaped and traditional methods. STUDY DESIGN: Fifteen patients in the L-shaped group and 20 patients in the traditional group were evaluated and compared in terms of postoperative complications, dysphagia, language function and appearance satisfaction. RESULTS: The results (Table 1) showed that there were 2 cases of donor area invalid traumas, and 2 patients had scar hyperplasia in the traditional group. The degree of global and functional dysphagia of the L-shaped group (2.60 ± 0.29 and 11.47 ± 1.38) was lower than that of the traditional group (3.55 ± 0.29 and 15.75 ± 1.22) (P < 0.05). In the language evaluation, the traditional group (3.20 ± 0.26) had lower scores than the L-shaped group (4.13 ± 0.30) (P < 0.05). CONCLUSION: The L-shaped ALTP flap is a simple and efficient modification of ALTP, that can be used for half-tongue repair after radical operations for tongue cancer. It has better performance in the recovery of dysphagia and language function than the traditional ALTP flap.

A Novel Prognostic Model for Oral Squamous Cell Carcinoma: The Functions and Prognostic Values of RNA-Binding Proteins.

PURPOSE: The biological roles and clinical significance of RNA-binding proteins (RBPs) in oral squamous cell carcinoma (OSCC) are not fully understood. We investigated the prognostic value of RBPs in OSCC using several bioinformatic strategies. MATERIALS AND METHODS: OSCC data were obtained from a public online database, the Limma R package was used to identify differentially expressed RBPs, and functional enrichment analysis was performed to elucidate the biological functions of the above RBPs in OSCC. We performed protein-protein interaction (PPI) network and Cox regression analyses to extract prognosis-related hub RBPs. Next, we established and validated a prognostic model based on the hub RBPs using Cox regression and risk score analyses. RESULTS: We found that the differentially expressed RBPs were closely related to the defense response to viruses and multiple RNA processes. We identified 10 prognosis-related hub RBPs (ZC3H12D, OAS2, INTS10, ACO1, PCBP4, RNASE3, PTGES3L-AARSD1, RNASE13, DDX4, and PCF11) and effectively predicted the overall survival of OSCC patients. The area under the receiver operating characteristic (ROC) curve (AUC) of the risk score model was 0.781, suggesting that our model exhibited excellent prognostic performance. Finally, we built a nomogram integrating the 10 RBPs. The internal validation cohort results showed a reliable predictive capability of the nomogram for OSCC. CONCLUSION: We established a novel 10-RBP-based model for OSCC that could enable precise individual treatment and follow-up management strategies in the future.

Treatment of donor site wounds using facial skin remaining in the scar area.

Reconstruction of cheek skin defects is surgically challenging. We evaluated the outcomes of using cheek skin remaining in the scar area for treating donor site wounds following the repair of cheek skin defects using full-thickness skin. We conducted a retrospective case series study that included 12 patients with a scar of the cheek. The patients included seven females and five males. The donor site was treated using the cheek skin remaining in the scar area following repair of the cheek skin defect with a full-thickness skin graft from the inner side of the upper arm. Minor flap necrosis of the full-thickness skin graft in the cheek developed in one patient. The postoperative esthetic results were excellent and satisfactory in 11 and 1 patient, respectively. Patients were followed up for 18-32 months; no lagophthalmos or ectropion was noted. However, there were two cases of hyperpigmentation in cheek grafts, and two of graft hypertrophy in the arm. The facial skin remaining in the scar area can be used to treat donor site wounds following a full-thickness skin graft from the inner side of the upper arm to repair a large cheek skin defect.

Vermilionectomy followed by reconstruction of the vermilion mucosa using allograft dermal matrix in patients with actinic cheilitis of the lower lip.

BACKGROUND: When treating actinic cheilitis (AC), it is essential to minimize the risk of malignant transformation (MT) and maintain lip functionality and cosmesis. AIMS: We evaluated the outcomes of vermilionectomy followed by reconstruction of the vermilion mucosa using allograft dermal matrix (ADM) in patients with AC of the lower lip. MATERIALS AND METHODS: We evaluated eight patients with lower lip AC who underwent vermilion mucosa reconstruction using ADM after vermilionectomy. We enrolled five males and three females ranging in age from 55 to 70 years (mean, 62.1 years). The ADM ranged in area from 1.3 × 5.0 to 1.7 × 5.8 cm (median, 1.6 × 5.5 cm). All patients were followed up for at least 3 months postoperatively by a panel of three surgeons who assessed the esthetic results, and orbicularis oris and speech functions. RESULTS: All patients underwent successful reconstruction of the vermilion mucosa using ADM after vermilionectomy, without complications. The postoperative esthetic results, and the orbicularis oris and speech functions, were satisfactory to excellent in all patients. Patients were followed up for 18-38 months (median, 26.1 months). No MT or recurrence was noted. CONCLUSIONS: Vermilionectomy followed by reconstruction of the vermilion mucosa with ADM is safe and feasible for AC patients.

Thread shape affects the stress distribution of torque force on miniscrews: a finite element analysis.

This study aimed to investigate the effect of miniscrews thread shape on the stress distribution receiving a torque load. Seven thread shapes (S,V1,V2,B1,B2,R1,R2) models were constructed and a 6 Nmm-torque load was applied. The order of maximum equivalent stress (EQV) value was V1 > V2 > B1 > R1 > R2 > B2 > S. The order of maximum displacement of miniscrew (Max DM) value was S > B2 > R1 = V1 > B1 > V2 > R2. Model R2 may be the most appropriate thread shape affording a torque force.

Endoscopic-assisted enucleation of large mandibular odontogenic cysts.

OBJECTIVE: Traditional enucleation of large mandibular odontogenic cysts is an invasive method, which might be associated with several complications. The purpose of this study was to evaluate the clinical outcome of endoscope-assisted enucleation of large mandibular cysts. STUDY DESIGN: Fifty-seven patients with large mandibular odontogenic cysts were enrolled in this study. Patients were divided into 2 groups as follows: (1) 25 patients who were treated with traditional enucleation and (2) 32 who underwent endoscope-assisted enucleation. Allogeneic bone grafting was applied in all cases. RESULTS: All patients successfully underwent the operation. The follow-up period ranged from 16 to 28 months. Recurrence was found in 2 patients (8%) in the traditional enucleation group; no recurrence was observed in patients in the endoscope-assisted enucleation group. Permanent mandibular nerve palsy was found in 2 patients in the traditional enucleation group; only 2 cases of temporary mandibular nerve palsy were observed in the endoscope-assisted enucleation group. CONCLUSIONS: Endoscope-assisted enucleation of large mandibular odontogenic cysts proved to be an effective treatment method, providing complete enucleation of the cystic lesion while preserving surrounding tissue.

Clinical application of painless oral anesthesia instrument combined with piezosurgery in the orthodontic traction of impacted maxillary anterior teeth / 口腔疾病防治

Objective @#To investigate the clinical efficacy of painless oral anesthesia combined with piezosurgery compared with ordinary cassette syringe combined with high speed turbine handpiece in the Fenestration operation of orthodontic traction of impacted maxillary anterior teeth.@*Methods @#A total of 128 cases of impacted maxillary anterior teeth were treated with Fenestration operation and orthodontic traction, and the patients were randomly divided into two groups. Group A (64 patients) received painless oral anesthesia combined with piezosurgery. Group B (64 patients) received ordinary cassette syringe combined with high speed turbine handpiece. The cooperation of fenestration and the swelling and pain after operation were compared between the 2 groups.@*Results @#The proportion of 0 and Ⅰ in the anesthesia group was 45.3% and 31.3% respectively, and the conventional group 0 and I accounted for 32.8% and 20.3% respectively. The difference between the two groups was statistically significant (Z=-2.676, P < 0.05). The pateints' cooperative degree in group A was better than that in group B (P < 0.05). The ratio of pain and swelling in the anesthesia instrument combined with Piezosurgery group was 81.2%, the conventional group had a grade I ratio of 59.4%, and the anesthesia instrument combined with Piezosurgery group was lighter than the conventional group, The difference was statistically significant (Z=-2.777, P < 0.05); anesthesia combined with Piezosurgery group after surgery accounted for 81.2% of the swelling, the conventional group of pain accounted for 71.9%, There was significant difference between the two groups (Z=-2.097, P < 0.05). Symptoms and signs as swelling and pain degree in group A were relatively minor than those in group B (P < 0.05). @*Conclusion @#It is worthy clinical promotion to use Painless oral anesthesia combined with piezosurgery in the fenestration and orthodontic traction of impacted maxillary anterior teeth, for its better cooperation and minor post-surgery reaction.

Effect of silica coating on the bond strength of milled pure titanium to dental porcelain.

The creation of a high bond strength between machined computer-manufactured pure titanium and porcelain remains problematic, and the effects of a silica coating on the bond strength of milled pure titanium bonded to dental porcelain require further investigation. The objective of this study was to evaluate the bond strength of machined pure titanium, with an intermediate coating of silica, to dental porcelain. In this work, 24 specimens of milled pure titanium were prepared and randomly divided into test and control groups, in which the test group was coated with silica using the sol-gel dipping technique. The metal-ceramic bond strength was evaluated, according to ISO 9693 standards, using the three-point bending test, and scanning electron microscopy and energy-dispersive spectroscopy were used to study the microstructure and elemental composition of the specimens. The bonding strength of the silica-coated group was significantly higher than that of the control group, and more residual porcelain on the metal surface could be observed in the silica-coated group. Therefore, the application of a silica intermediate coating produced using the sol-gel method could significantly improve the bond strength between machined pure titanium and porcelain.

Finite Element Analysis of Bone Stress around Micro-Implants of Different Diameters and Lengths with Application of a Single or Composite Torque Force.

BACKGROUND: Stress on the bone surrounding dental micro-implants affects implant success. PURPOSE: To compare the stress on the bone surrounding a micro-implant after application of a single force (SF) of 200 g or a composite force (CF) of 200 g and 6 N.mm torque. MATERIALS AND METHODS: Finite element models were developed for micro-implant diameters of 1.2, 1.6, and 2.0 mm, and lengths of 6, 8, 10, and 12 mm and either a SF or CF was applied. The maximum equivalent stress (Max EQS) of the bone surrounding the micro-implant was determined, and the relationships among type of force, diameter, and length were evaluated. RESULTS: The Max EQS of the CF exceeded that of the SF (P< 0.05). The effect of force on stress was related to implant diameter, but not to implant length. The larger CF led to greater instability of the micro-implant and the effect was most pronounced at an implant diameter of 1.2 mm. The use of implant diameters of 1.6 mm and 2.0 mm produced no significant difference in implant stability when either a CF or SF was applied. CONCLUSION: When considering the use of an implant to perform three-dimensional control on the teeth, the implant diameter chosen should be > 1.2 mm.

Analysis on the stress of the bone surrounding mini-implant with different diameters and lengths under torque.

The purpose of this study is to compare the stress of the bone around the mini-implant under the two kinds of force: the composite force which contains torque and traditional single force. There were 96 finite element models formed by the combination of mini-implant and bone, with diameters of 1.2 mm, 1.6 mm, 2.0 mm and corresponding length being 6 mm, 8 mm, 10 mm, 12 mm, respectively. Each size corresponded to 8 models. Group SF (each size n=4) was loaded with 200 g single force, while Group CF (each size n=4) was loaded with composite force which contained 6N mm torque and 200 g single force. The maximum equivalent stress (Max EQS) of the bone surrounding mini implant with different loading directions was calculated, and the relationship of force direction, diameter and length was also evaluated. The Max EQS of Group CF was higher than that of Group SF. The effect of force direction on the stress was related to the diameter of mini implant, but had nothing to do with its length. The Max EQS of the cortical bone around mini implant in Group CF was higher (P<0.05) than that in Group SF. In contrast, there was no significant difference (P>0.05) between Group SF and Group CF in terms of bone stress when the diameter of mini implant was 1.6 mm or 2.0 mm. In our study, it is demonstrated that the diameter of mini-implant is better to be larger than 1.2 mm when a mini-implant is used in a torque control of tooth. The impact of this feature in the clinical setting needs to be verified.

Effect of heating palladium-silver alloys on ceramic bond strength.

STATEMENT OF PROBLEM: The effects of different heat treatments on the internal oxidation and metal-ceramic bond in Pd-Ag alloys with different trace elements require further documentation. PURPOSE: The purpose of this in vitro study was to determine whether heat treatment affects the metal-ceramic bond strength of 2 Pd-Ag alloys containing different trace elements. MATERIAL AND METHODS: Thirteen cast specimens (25×3×0.5 mm) from each of 2 Pd-Ag alloy groups (W-1 and Argelite 61+3) were allocated to heat treatments before porcelain application: heating under reduced atmospheric pressure of 0.0014 MPa and 0.0026 MPa and heating under normal atmospheric pressure. Bond strengths were evaluated using a 3-point bending test according to ISO9693. Results were analyzed using 2-way ANOVA and Tukey HSD test (α=.05). Visual observation was used to determine the failure types of the fractured specimens. Scanning electron microscopy and energy dispersive spectroscopy were used to study morphologies, elemental compositions, and distributions in the specimens. RESULTS: The W-1 group had a mean bond strength significantly higher than that of Argelite 61+3 (P<.001). Heating under reduced atmospheric pressures of 0.0014 MPa and 0.0026 MPa resulted in similar bond strengths (P=.331), and both pressures had significantly higher bond strengths than that of heating under normal atmospheric pressure (P=.002, P<.001). Heating under different air pressures resulted in Pd-Ag alloys that contained either Sn or In and Ga, with various degrees of internal oxidation and different quantities of metallic nodules. CONCLUSIONS: Heating under reduced atmospheric pressure effectively improved the bond strength of the ceramic-to-Pd-Ag alloys.

[Selection of optimal length and diameter of mini implant in two different forces: a three-dimensional finite element analysis].

OBJECTIVE: To investigate the effect of different length and diameters on the stability of mini implant and to select optimal length and diameter using continuous variation of parameters. METHODS: To perform 3-dimensional finite element analysis, finite element models of a maxilla, and mini implants with length of 6-12 mm and diameters of 1.2-2.0 mm were generated. Load of two different forces were applied to the head of mini implant. One type was horizontal force (HF), the other was composite force (CF). The maximum equivalent stress (Max EQV) in maxilla and the maximum displacement (Max DM) of mini implant were evaluated. RESULTS: The Max EQV in maxilla and Max DM of mini implant decreased as length and diameter increased. When length was more than 9 mm, the evaluation indexes were small and had a less change. Datas indicated that diameter played a more important role in reducing target, and was a more effective parameter in reducing Max EQV when CF was loaded. CONCLUSION: From biomechanical point of view, the choice of the length should not be more than 9 mm. When CF is loaded using the mini implant, diameter exceeding 1.2 mm are optimal design for mini implant.

[Influence of the diameter and length of the mini-implant on the primary stability after loading with composite forces].

OBJECTIVE: To investigate the influence of the diameter and length of the mini-implant on the primary stability after loading with composite forces (CF) which contained torque and horizontal forces (HF). METHODS: Ninety-six finite element models were established by the combination of mini-implant and bone, diameters (1.2 mm, 1.6 mm, 2.0 mm) and length (6 mm, 8 mm, 10 mm, 12 mm). There were 12 sizes, each size corresponded with 8 models. Group HF (each size n = 4) was loaded with 1.96 N horizontal force and Group CF (each size n = 4) was loaded with composite force which contained 6 N·mm torque and 1.96 N horizontal force. The maximum displacement of mini-implant with different force directions, implant diameters and lengths were evaluated. RESULTS: The effect of force direction on the displacement related to diameter of mini-implant. The maximum displacement under load with HF respectively was changed with the changing of diameter[1.2 mm: (7.71 ± 0.49) µm; 1.6 mm: (3.94 ± 0.31) µm; 2.0 mm: (2.32 ± 0.43) µm], which were smaller than the maximum displacement of Group CF [1.2 mm: (9.22 ± 0.63) µm; 1.6 mm: (4.62 ± 0.52) µm; 2.0 mm: (2.69 ± 0.49) µm] (P < 0.05). When diameter was 1.2 mm, the difference of the maximum displacement [(1.61 ± 0.22) µm] between Group HF and CF was more obvious than that when the diameter was 1.6 mm or 2.0 mm [(0.64 ± 0.12), (0.49 ± 0.06) µm] (P < 0.05). CONCLUSIONS: The composite force had unfavorable effect on the primary stability of the mini-implant. The diameter of the mini-implant had better be larger than 1.2 mm when the composite forces were applied.

Expression of Cyr61 in primary salivary adenoid cystic carcinoma and its relation to Ki-67 and prognosis.

Cysteine-rich protein 61 (Cyr61) selectively binds heparin and insulin-like growth factors and mediates a variety of biological actions, including cell adhesion, differentiation, proliferation, migration, angiogenesis, and tumorigenesis. Cyr61 is also a prognostic factor for tumor progression and survival of individuals with various types of tumors. This study investigated the relationship between the expression level of Cyr61 and clinicopathological features, as well as the prognostic significance of Cyr61 expression in human salivary adenoid cystic carcinoma (SACC). The expression of Cyr61 and Ki-67, a cell-proliferation marker, was examined immunohistochemically in paraffin embedded tissue specimens from 60 SACC patients who underwent radical surgery between 1995 and 2004. A chi-square test was used to investigate the relationship between Cyr61 and Ki-67 expression and clinicopathological features. Survival analysis was performed to determine the prognostic significance of Cyr61 expression. Cyr61 expression was observed in 39 cases (39/60, 65%) of SACC, and Cyr61 expression was positively correlated with Ki-67 expression (P=0.002). A high expression of Cyr61 was significantly associated with solid subtype, perineural invasion, vascular invasion or cancer embolus, advanced stage, recurrence, and metastasis (P<0.05). The survival rate of patients with high expression of Cyr61 or Ki67 was significantly lower than that of patients with low expression. Multivariate Cox's proportional hazards analysis showed that vascular invasion, TNM stage, recurrence, distant metastasis, Ki-67 expression, and Cyr61 expression were independent prognostic factors of overall survival (P<0.05). Cyr61 expression is significantly correlated with Ki-67 expression and may have potential value in screening high-risk cases for recurrence and metastasis, as well as identifying poor prognosis in SACC patients.