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The aims of this paper were to evaluate the relation between the preoperative primary tumour maximum standardised uptake value (SUVmax, tSUVmax) and clinicopathological features, including depth of invasion (DOI), recurrence factors, and survival outcomes, and to compare the prognostic value of tSUVmax with that of other factors associated with the recurrence of early-stage oral squamous cell carcinoma (OSCC) of the tongue. We retrospectively analysed data from 155 patients. All patients were treated and regularly monitored at the Changhua Christian Hospital (CCH). Only those who had undergone

This study aimed to investigate the risk of stroke incidence in patients with periodontitis.Data on patients diagnosed with periodontitis were collected from Taiwan's National Health Insurance Research Database and were matched (1:1) with patients without periodontitis between 2001 and 2010. A multivariable Cox survival model was used to predict stroke between patients with and without periodontitis, and the possibility of confounders. Hazard ratios (HRs) with 95% confidence intervals (CIs) were used to explore the risk of stroke in the case and control groups. Diseases found during the follow-up period were analyzed to determine possible effects on the study. A total of 282 560 periodontitis and nonperiodontitis patients were enrolled, with most subjects aged 40 to 59 years.The overall cumulative incidence of stroke was 2.14 times higher in periodontitis than in nonperiodontitis, and the highest HR was in the more than 80 years age group (HR = 9.30; 95% CI, 7.06-12.26). The multivariate Cox model indicated that the adjusted HR (aHR) between the case and control was 2.03 (95% CI, 1.99-2.08), and a higher aHR was associated with hypertension. Atherosclerosis, atrial fibrillation, obesity, kidney disease, anxiety, and gout discovered during follow-up also showed a potential risk of stroke in patients with periodontitis.Therefore, this study suggests a high risk of stroke in patients with periodontitis.

Reconstruction plates are frequently used to treat mandibular segmental defects. The aim of this study is to compare the biomechanical performance of a 3-dimensional-printed self-designed titanium alloy reconstruction plate with that of the traditional reconstruction plate in mandible reconstruction. The analyzed parameters of the self-designed reconstruction plate, including plate length (100 mm and 125 mm), plate thickness (2.1, 2.4, and 2.7 mm), and bone mass (100, 75, and 50%), were also evaluated.An artificial mandible with anatomical geometry was used to develop the self-designed reconstructed plate. Both in vitro experiments and finite element simulations were performed for the biomechanical comparison of the self-designed and traditional reconstruction plates. In finite element analysis, 3 major muscle forces of mandible movement were set as the loading condition, and the displacement of the condyle was fixed in all directions as the boundary condition.The biomechanical performances (stresses in the plate and strains in bone) of the self-designed reconstruction plate were superior to those of the traditional plate. Factorial analysis indicated that plate length and thickness had significant effects on decreasing stresses of the plate and mandibular bone.The self-designed reconstruction plate might have a benefit to reduce the stresses/strains in plate itself and surrounding bone.

Background Menopause-induced decline in estrogen levels in women is a main factor leading to osteoporosis. The objective of this study was to investigate the effect of intermittent parathyroid hormone (PTH) on bone structural parameters of the femoral neck in ovariectomized rats, in addition to correlations of maximum fracture force. Methods Fifteen female Wister rats were divided into three groups: (1) control group; (2) ovariectomized (OVX) group; and (3) OVX + PTH group. All rats were then killed and the femurs extracted for microcomputed tomography scanning to measure volumetric bone mineral density (vBMD) and bone structural parameters of the femoral neck. Furthermore, the fracture forces of femoral neck were measured using a material testing system. Results Compared with the control and OVX + PTH groups, the OVX group had significantly lower aBMD, bone parameter, and mechanical strength values. A comparison between OVX and OVX + PTH groups indicated that PTH treatment increased several bone parameters. However, the OVX + PTH groups did not significantly differ with the control group with respect to the bone structural parameters, except for trabecular bone thickness of cancellous bone, which was greater. In addition, among the bone structural parameters, the CSA and BSI of cortical bone were significantly correlated with the maximum fracture force of the femoral neck, with correlations of, respectively, 0.682 (p = 0.005) and 0.700 (p = 0.004). Conclusion Intermittent PTH helped treat ovariectomy-induced osteoporosis of cancellous bone and cortical bone in the femoral necks of rats. The ability of the femoral neck to resist fracture was highly correlated with the two parameters, namely cross-sectional area (CSA) and bone strength index (= vBMD × CSA), of cortical bone in the femoral neck and was less correlated with aBMD or other bone structural parameters.

Background Many types of titanium plates were used to treat subcondylar fracture clinically. However, the efficacy of fixation in different implant positions and lengths of the bone plate has not been thoroughly investigated. Therefore, the primary purpose of this study was to use finite element analysis (FEA) to analyze the biomechanical effects of subcondylar fracture fixation with miniplates at different positions and lengths so that clinicians were able to find a better strategy of fixation to improve the efficacy and outcome of treatment. Methods The CAD software was used to combine the mandible, miniplate, and screw to create seven different FEA computer models. These models with subcondylar fracture were fixed with miniplates at different positions and of different lengths. The right unilateral molar clench occlusal mode was applied. The observational indicators were the reaction force at the temporomandibular joint, von Mises stress of the mandibular bone, miniplate and screw, and the sliding distance on the oblique surface of the fracture site at the mandibular condyle. Results The results showed the efficacy of fixation was better when two miniplates were used comparing to only one miniplates. Moreover, using longer miniplates for fixation had better results than the short one. Furthermore, fixing miniplates at the posterior portion of subcondylar region would have a better fixation efficacy and less sliding distance (5.46–5.76 μm) than fixing at the anterolateral surface of subcondylar region (6.10–7.00 μm). Conclusion Miniplate fixation, which was placed closer to the posterior margin, could effectively reduce the amount of sliding distance in the fracture site, thereby achieving greater stability. Furthermore, fixation efficiency was improved when an additional miniplate was placed at the anterior margin. Our study suggested that the placement of miniplates at the posterior surface and the additional plate could effectively improve stability.

Objective To investigate differences in the effectiveness of two lag screws, a regular bone plate, and locking bone plate fixation in treating horizontal oblique metacarpal shaft fractures. Materials and methods Horizontal oblique metacarpal shaft fractures were created in 21 artificial metacarpal bones and fixed using one of the three methods: (1) two lag screws, (2) a regular plate, and (3) a locking plate. All the specimens were subjected to the cantilever bending test performed using a material testing machine to enable recording of the force–displacement data of the specimens before failure. The Kruskal–Wallis test was used to compare failure force and stiffness values among the three fixation methods. Results The mean failure force of the two lag screw group (78.5 ± 6.6 N, mean + SD) was higher than those of the regular plate group (69.3 ± 17.6 N) and locking plate group (68.2 ± 14.2 N). However, the mean failure force did not significantly differ among the three groups. The mean stiffness value of the two lag screw group (17.8 ± 2.6 N/mm) was lower than those of the regular plate group (20.2 ± 10.5 N/mm) and locking plate group (21.8 ± 3.8 N/mm). However, the mean stiffness value did not significantly differ among the three groups. Conclusion The fixation strength of two lag screw fixation did not significantly differ from that of regular and locking bone plate fixation, as indicated by the measurement of the ability to sustain force and stiffness.

The objective of this study was to evaluate the effect of bone–miniscrew contact percentage (BMC%) and bone quality and quantity on orthodontic miniscrew stability and the maximum insertion torque value (ITV). Orthodontic miniscrews of five different dimensions and several bovine iliac bone specimens were used in the evaluation. Miniscrews of each dimension group were inserted into 20 positions in bovine iliac bone specimens. The experiment was divided into three parts: (1) Bone quality and quantity were evaluated using cone-beam computed tomography (CBCT) and microcomputed tomography. (2) The 3D BMC% was calculated. (3) The ITVs during miniscrew insertion were recorded to evaluate the stability of the orthodontic miniscrews. The results indicated that longer and thicker miniscrews enabled higher ITVs. CBCT was used to accurately measure cortical bone thickness (r = 0.939, P P

Background For oblique metacarpal shaft fracture, if anatomical reduction is achieved through conservative cast immobilization rather than stable fixation, bone malrotation can easily occur, resulting in severe loss in hand prehensile function. However, whether bone plate fixation or only lag screw fixation is more preferable remains unclear. Few studies have evaluated whether screw fixation can provide biomechanical fixation strength similar to bone plate fixation. Objective We assessed the difference in fixation strength between fixtation with two lag screws and bone plate for oblique metacarpal shaft fractures. Materials and methods We created oblique metacarpal shaft fractures on 21 artificial bones and fixated them using (1) double lag screw (2LS group), (2) regular plate (RP group), or (3) locked plate (LP group). To obtain the force–displacement data, a cantilever bending test was conducted for each specimen through a material testing machine. One-way analysis of variance and a Tukey test were conducted to compare the maximum fracture force and stiffness of the three fixation methods. Results The maximum fracture force of the 2LS group (mean + SD: 153.6 ± 26.5 N) was significantly lower than that of the RP (211.6 ± 18.5 N) and LP (227.5 ± 10.0 N) groups (p Conclusion Compared with bone plate fixation, double lag screw fixation yielded slightly lower maximum bearable fracture force but similar stiffness. Therefore, this technique could be used for treating oblique metacarpal shaft fractures. However, using double lag screw fixation alone is technically demanding and requires considerable surgical experiences to produce consistent results.

The information on the outpatient expenditure of patients with oromaxillofacial cancer is minimal. This study aimed to compare the average annual expenditure on dental treatment for these patients 5 years before and 5 years after oromaxillofacial cancer diagnosis. In this study, 7731 patients who received oromaxillofacial cancer diagnosis in 2005 were selected from the Registry of Catastrophic Illness Database as the case-cohort. In the control cohort, 38,655 people without cancer were selected from the National Health Insurance Research Database, with the case–control ratio being 1:5. All participants were observed for 5 years before diagnosis and 5 years after diagnosis. The conditional logistic regression model was used to determine the odds ratios of annual expenditures incurred by participants in the case-cohort. The measurement results indicated that in the oromaxillofacial cancer cohort, the average annual dental expenditure levels at 1, 2, 3, 4, and 5 years after diagnosis were US $97.34, US $77.23, US $109.65, US $128.43, and US $128.03 and those at these years before diagnosis were US $37.52, US $32.10, US $31.86, US $29.14, and US $29.35, respectively. In conclusion, the average annual expenditure on the dental treatment of oromaxillofacial cancer patients after five years of diagnosis was increased compared to five years before diagnosis.

Primary surgical treatment for oral squamous cell carcinoma (OSCC) is reserved for T1 to T4a tumors, but not for T4b tumors, according to the present National Comprehensive Cancer Network clinical practice guidelines. In this retrospective study, we aimed to determine the association between the clinicopathological characteristics and different treatment modalities for T4b OSCC based on whether patients received primary surgical treatment. Therefore, we conducted a survival analysis based on different treatment modalities.This retrospective cohort study enrolled 125 patients with clinical stage T4b OSCC who received treatment and were followed up at Changhua Christian Hospital between January 1, 2008 and December 31, 2018.Overall, 81 patients received primary surgical treatment and 44 received primary nonsurgical treatment. Comparison of the clinicopathological characteristics between those who did and did not undergo surgery revealed no significant differences in age at tumor diagnosis, tumor location, clinical N stage, and involved tumor area based on computed tomography or magnetic resonance imaging, or stratified Charlson Comorbidity Index scores. In the survival analysis, Kaplan-Meier curves revealed that patients who received treatment modalities including surgery exhibited better survival than those who received treatment modalities that did not include surgery.In the present study, patients with T4b OSCC treated with primary surgery had a better overall survival rate than those who received nonsurgical treatment. In the future, it will be necessary for clinicians worldwide to report the treatment outcomes of patients with T4b OSCC based on the common criteria.

Background/purpose Incisor liability is the discrepancy in the sum of the mesiodistal crown width between the primary and permanent incisors. Incisor liability affects the integrity and eruption of the permanent incisors during the transition from the primary to permanent dentition. This study investigated the incisor liability in the primary dentition of Taiwanese children. Methods The digital periapical films of 203 upper arches of 105 boys and 98 girls and 195 lower arches of 119 boys and 76 girls aged between 3 and 6 years were selected in this retrospective study. The mesiodistal crown widths of the primary and permanent incisors were measured using the medical imaging software for both arches. Differences in incisor liability values were statistically analyzed. Results The mean ± standard deviation of the incisor liability values were 8.32 ± 1.88 and 6.91 ± 1.13 mm for the upper and lower arches, respectively, in all children. The incisor liability was closely related with the total crown widths of the permanent incisors for upper and lower arches. The incisor liability values were higher among boys than girls for the upper but not lower arch. Conclusion Incisor liability differs depending on ethnicity. In Taiwanese children, incisor liability was closely related with the crown widths of the permanent incisors. The incisor liability values of boys were higher than those of girls in the upper arch but not the lower arch.

The incidence of oral cavity squamous cell carcinoma (OSCC) is particularly high in South Asia. According to the National Comprehensive Cancer Network, OSCC can arise in several subsites. We investigated survival rates and the clinical and pathological characteristics of OSCC in different anatomical subsites in the Taiwanese population. We retrospectively analyzed data for 3010 patients with OSCC treated at the Changhua Christian Hospital. Subsequently, we compared clinical and pathological features of OSCC in different subsites. Pathological T4 stage OSCCs occurred in the alveolar ridge and retromolar trigone in 56.4% and 43.7% of cases, respectively. More than 25% of patients with tongue OSCC and 23.4% of those with retromolar OSCC had lymph node metastasis. The prognosis was worst for hard palate OSCC (hazard ratio 1.848; p p = 0.017). Retromolar OSCC recurred most often and tongue OSCC second most often. The risk for cancer-related mortality was highest for hard palate OSCC, followed by alveolar ridge and retromolar OSCC. We found distinct differences in survival among the different subsites of OSCC. Our findings may also help prompt future investigations of OSCC in different subsites in Taiwanese patients.

18F-fluorodeoxyglucose-positron emission tomography (FDG-PET) is widely used for tumor staging. This study sought to determine the relationship of preoperative primary tumor SUVmax (tSUVmax) with the clinicopathological features of patients with OSCC and to compare the prognostic ability of tSUVmax with that of other recurrence factors. Data of 340 patients with OSCC who were diagnosed, treated, and followed up at the Changhua Christian Hospital were retrospectively analyzed. Only patients with OSCC arising from gingiva, palate, floor of the mouth, and retromolar trigone and those who had received preoperative FDG-PET within 2 weeks before surgery were included. tSUVmax value > 9.2 was the strong predictor of bone invasion (area under the receiver operating characteristic curve, 0.844). tSUVmax value > 7.2 showed a strong association with advanced pathological T stage and recurrence factors and was associated with poor survival; tSUVmax > 7.2 showed stronger predictive power for poor disease-free survival (DFS) than pT stage and the other recurrence factors related to primary tumor. FDG-PET can be a useful supplement to contrast-enhanced computed tomography or contrast-enhanced magnetic resonance imaging for diagnosing bone invasion by OSCC. The tSUVmax value was an independent predictor of DFS in this study.

Background Metacarpal shaft fractures are a common hand trauma. The current surgical fixation options for such fractures include percutaneous Kirschner wire pinning and nonlocking and locking plate fixation. Although bone plate fixation, compared with Kirschner wire pinning, has superior fixation ability, a consensus has not been reached on whether the bone plate is better placed on the dorsal or lateral side. Objective The purpose of this study was to evaluate the fixation of locking and regular bone plates on the dorsal and lateral sides of a metacarpal shaft fracture. Materials and methods Thirty-five artificial metacarpal bones were used in the experiment. Metacarpal shaft fractures were created using a saw blade, which were then treated with four types of fixation as follows: (1) a locking plate with four locking bicortical screws on the dorsal side (LP_D); (2) a locking plate with four locking bicortical screws on the lateral side (LP_L); (3) a regular plate with four regular bicortical screws on the dorsal side (RP_D); (4) a regular plate with four regular bicortical screws on the lateral side (RP_D); and (5) two K-wires (KWs). All specimens were tested through cantilever bending tests on a material testing system. The maximum fracture force and stiffness of the five fixation types were determined based on the force–displacement data. The maximum fracture force and stiffness of the specimens with metacarpal shaft fractures were first analyzed using one-way analysis of variance and Tukey’s test. Results The maximum fracture force results of the five types of metacarpal shaft fracture were as follows: LP_D group (230.1 ± 22.8 N, mean ± SD) ≅ RP_D group (228.2 ± 13.4 N) > KW group (94.0 ± 17.4 N) > LP_L group (59.0 ± 7.9 N) ≅ RP_L group (44.5 ± 3.4 N). In addition, the stiffness results of the five types of metacarpal shaft fracture were as follows: LP_D group (68.7 ± 14.0 N/mm) > RP_D group (54.9 ± 3.2 N/mm) > KW group (20.7 ± 5.8 N/mm) ≅ LP_L group (10.6 ± 1.7 N/mm) ≅ RP_L group (9.4 ± 1.2 N/mm). Conclusion According to our results, the mechanical strength offered by lateral plate fixation of a metacarpal shaft fracture is so low that even KW fixation can offer relatively superior mechanical strength; this is regardless of whether a locking or nonlocking plate is used for lateral plate fixation. Such fixation can reduce the probability of extensor tendon adhesion. Nevertheless, our results indicated that when lateral plate fixation is used for fixating a metacarpal shaft fracture in a clinical setting, whether the mechanical strength offered by such fixation would be strong enough to support bone union remains questionable.

Metacarpal shaft fractures are common hand fractures. Although bone plates possess strong fixation ability, they have several limitations. The use of headless compression screws for fracture repair has been reported, but their fixation ability has not been understood clearly. This study aimed to compare the fixation ability of locked plate with that of headless compression screw for metacarpal fracture repair. A total of 14 artificial metacarpal bones (Sawbones, Vashon, WA, USA) were subjected to transverse metacarpal shaft fractures and divided into 2 groups. The first group of bones was fixed using locked plates (LP group), whereas the second group was fixed using headless compression screws (HC group). A material testing machine was used to perform cantilever bending tests, whereby maximum fracture force and stiffness were measured. The fixation methods were compared by conducting a Mann–Whitney U test. The maximum fracture force of the HC group (285.6 ± 57.3 N, median + interquartile range) was significantly higher than that of the LP group (227.8 ± 37.5 N; P .05) was observed between the HC (65.2 ± 24.6 N/mm) and LP (61.7 ± 19.7 N/mm) groups. Headless compression screws exhibited greater fixability than did locked plates, particularly in its resistance to maximum fracture force.

Background Metacarpal shaft fractures are a common type of hand fracture. Despite providing strong fixation strength, plate fixation has numerous shortcomings. Concerning internal fixation with Kirschner wires (K-wires), although this approach is frequently used to treat metacarpal shaft fractures, the lack of functional stability may result in fixation failure. Objective To evaluate the effect of figure-of-eight cerclage wire on fixation for transverse metacarpal shaft fractures using two K-wires. Materials and methods We used a saw blade to create transverse metacarpal shaft fractures in 14 fourth-generation artificial third metacarpal bones (Sawbones, Vashon, WA, USA), which were assigned to groups undergoing fixation with two K-wires (KP) or with two K-wires and figure-of-eight cerclage wire (KP&F8). All specimens were subjected to material testing, specifically cantilever bending tests. The maximum fracture force and stiffness of the two fixation types were determined on the basis of the force–displacement data. The Mann–Whitney U test was used to compare between-group differences in maximum fracture force and stiffness. Results The maximum fracture force of the KP group (median ± interquartile range = 97.30 ± 29.70 N) was significantly lower than that of the KP&F8 group (153.2 ± 69.50 N, p p Conclusion The incorporation of a figure-of-eight cerclage wire increased the maximum fracture force and stiffness by 57.5 and 110.9%, respectively, compared with those achieved in standard two K-wire fixation. Therefore, hand surgeons are advised to consider the proposed approach to increase fixation strength.

The retromolar canal is an anatomical variation that occurs in the mandibular bone. The retromolar canal typically originates in the mandibular canal on the distal side of the third molar and extends forward and upward to the retromolar foramen (RMF), which contains the neurovascular bundle. Accidentally damaging the neurovascular bundle in the retromolar canal during the extraction of the third molar, dental implant surgery, or maxillofacial orthognathic surgery may lead to subsequent complications such as incomplete local anesthesia, paresthesia, and bleeding during operation. The objective of this study was to investigate the prevalence of the RMF in the Taiwanese population in a medical center by using dental cone-beam computed tomography (CBCT) and to identify the position of the RMF in the mandibular bone. The dental CBCT images for the mandibular bone of 68 hemi-mandible were uploaded to the medical imaging software Mimics 15.1 to determine the prevalence of the RMF in the Taiwanese population and the three positional parameters of the RMF in the mandibular bone: (1) The diameter of the RMF, (2) the horizontal distance from the midpoint of the RMF to the distal cementoenamel junction of the second molar, and (3) the vertical distance from the midpoint of the RMF to the upper border of the mandibular canal. Seven RMFs were observed in the 68 hemi-mandibles. Thus, the RMF prevalence was 10.3%. In addition, the diameter of the RMF was 1.41 ± 0.30 mm (mean ± standard deviation), the horizontal distance from the midpoint of the RMF to the distal cementoenamel junction of the the second molar was 12.93 ± 2.87 mm, and the vertical distance from the midpoint of the RMF to the upper border of the mandibular canal below second molar was 13.62 ± 1.3487 mm. This study determined the prevalence of the RMF in the Taiwanese population in a medical center and its relative position in the mandibular bone. This information can provide clinicians with a reference for posterior mandible anesthesia and surgery to ensure medical safety.

Background/purpose: Type 1 diabetes mellitus (T1DM) is a chronic autoimmune disease affecting oral health. Evidence shows possible association between T1DM and periodontal diseases (PDs). We conducted a nationwide population-based study in Taiwan, with a 14-year follow-up to investigate the risk of PDs in T1DM patients. Methods: We used data from the National Health Insurance Research Database in Taiwan. The T1DM cohort was identified with newly diagnosed T1DM from 1998 to 2011. The non-T1DM cohort was frequency matched with the T1DM cohort. Participants comprised 4248 patients in the T1DM cohort and 16992 persons in the non-T1DM cohort. Results: The T1DM patients showed an increased risk of PDs compared to non-T1DM individuals [adjusted hazard ratio (aHR) = 1.45]. T1DM patients who visited the emergency room more than twice per year had a higher aHR of 13.0 for developing PDs. The aHR for PDs was 13.2 in the T1DM patients who had been hospitalized more than twice per year. Conclusion: T1DM patients are at higher risk of developing PDs than non-T1DM individuals. Our results further showed that the number of T1DM interventions; that is, annual emergency visits and hospitalizations were associated with increased the risk of developing PDs. Keywords: Diabetes, Type 1 diabetes mellitus (T1DM), Periodontal disease, Cohort study

Dental implants are among the most common treatments for missing teeth. The thickness of the crestal cortical bone at the potential dental implant site is a critical factor affecting the success rate of dental implant surgery. However, previous studies have predominantly focused on female patients, who are at a high risk of osteoporosis, for the discussion of bone quality and quantity at the dental implant site. This study aimed to investigate the effect of male patients’ age on the crestal cortical bone of the jaw at the dental implant site by using dental cone-beam computed tomography (CBCT). This study performed dental CBCT on 84 male patients of various ages to obtain tomograms of 288 dental implant sites at the jawbone (41 sites in the anterior maxilla, 95 in the posterior maxilla, 59 in the anterior mandible, and 93 in the posterior mandible) for measuring the cortical bone thickness. A one-way analysis of variance and Scheffe’s test were performed on the measurement results to compare the cortical bone thickness at implant sites in the four jaw areas. The correlation between male patient age and cortical bone thickness at the dental implant site was determined. The four jaw areas in order of the cortical bone thickness were as follows: posterior mandible (1.07 ± 0.44 mm), anterior mandible (0.99 ± 0.30 mm), anterior maxilla (0.82 ± 0.32 mm), and posterior maxilla (0.71 ± 0.27 mm). Apart from dental implant sites in the anterior and posterior mandibles, no significant correlation was observed between male patients’ age and the cortical bone thickness at the dental implant site.

Background and Objectives: Hepatitis C virus (HCV) is a major cause of liver disease worldwide. People who inject drugs (PWIDs) constitute the majority of patients with HCV infection in the United States and Central Asia. There are several obstacles to treating HCV infection in PWIDs because PWIDs are often accompanied by concurrent infection, low compliance, substance abuse, and risky behavior. The aim of the study is to compare the efficacies of direct-acting antiviral (DAA) therapy for HCV infection in PWIDs and those without opioid injection. Materials and Methods: In this retrospective cohort study, we included 53 PWIDs with HCV infections treated on site in a methadone program and 106 age- and sex-matched patients with HCV infections who had no history of opioid injection (ratio of 1:2). All eligible subjects received anti-HCV treatment by DAA agents in our hospital from March 2018 to December 2020. The charts of these patients were carefully reviewed for demographic data, types of DAA agents, and treatment outcomes. The primary outcome measure was sustained virological response (SVR). Results: PWIDs and non-drug users had different HCV genotype profiles (p = 0.013). The former had higher proportions of genotype 3 (18.9% vs. 7.5%) and genotype 6 (24.5% vs. 14.2%) than the latter. The two patient groups had comparable rates of complete drug refilling (100.0% vs. 91.1%) and frequency of loss to follow-up (3.8% vs. 0.9%). However, PWIDs had a lower SVR rate of DAA treatment than non-drug users (92.2% vs. 99.0%; p = 0.04). Further analysis showed that both human immunodeficiency virus (HIV) coinfection and history of PWID were risk factors associated with treatment failure. The subjects with coinfection with HIV had lower SVR rates than those without HIV infection (50.0% vs. 96.5%; p = 0.021). Conclusions: PWIDs with HCV infections have higher proportions of HCV genotype 3 and genotype 6 than non-drug users with infections. DAA therapy can achieve a high cure rate (>90%) for HCV infection in PWID, but its efficacy in PWID is lower than that in non-drug users.

There is a distinct male predominance in head and neck cancers. The present study aimed to investigate the clinical and pathological features of male and female patients with oral squamous cell carcinoma (OSCC), and to simultaneously conduct a survival analysis. Patients (n = 2573) were identified between January 2008 and December 2018, and subsequently analyzed for characteristics such as age at squamous cell carcinoma diagnosis, lifestyle factors (smoking habit, betel nut chewing and alcohol consumption), pathological American Joint Committee on Cancer (AJCC) anatomic site, AJCC TNM stage, pathological recurrence factor and interval from first diagnosis to recurrence. A case-matched comparison between female (n = 122) and male (n = 2451) patients was conducted. Significant gender differences were noted in age at diagnosis, anatomic site of the tumor, smoking habit, betel nut chewing and alcohol consumption (p &lt, 0.001). There were no significant gender differences in the other clinical and pathological characteristics and survival conditions. In conclusion, female patients with OSCC were older than male patients with OSCC, and mostly had tumors of the oral tongue. Once patients develop OSCC, there was no difference in survival between men and women in a Taiwanese population.

Background The influences of potential bone-to-implant contact (BIC) area (pBICA), BIC area (BICA), and three dimensional (3D) BIC percentage (3D BIC%; defined as BICA divided by pBICA) in relation to the implant length on initial implant stability were studied. Correlations between these parameters were also evaluated. Methods Implants with lengths of 8.5, 10, 11.5, and 13 mm were placed in artificial bone specimens to measure three indexes of the initial implant stability: insertion torque value (ITV), Periotest value (PTV), and implant stability quotient (ISQ). The implants and bone specimens were also scanned by microcomputed tomography, and the obtained images were imported into Mimics software to reconstruct the 3D models and calculate the parameters of 3D bone-to-implant contact including pBICA, BICA, and 3D BIC%. The Kruskal-Wallis test, Wilcoxon rank-sum test with Bonferroni adjustment, and Spearman correlations were applied for statistical and correlation analyses. Results The implant length affected ITV more than PTV and ISQ, and significantly affected pBICA, BICA, and 3D BIC%. A longer implant increased pBICA and BICA but decreased 3D BIC%. The Spearman coefficients were high (>0.78) for the correlations between the three 3D BIC parameters and the three indexes of the initial implant stability. Conclusions pBICA, BICA, and 3D BIC% are useful when deciding on treatment plans related to various implant lengths, since these 3D BIC parameters are predictive of the initial implant stability.

Background/Purpose This study investigated the effects of three three-dimensional (3D) bone-to-implant contact (BIC) parameters—potential BIC area (pBICA), BIC area (BICA), and 3D BIC percentage (3D BIC%; defined as BICA divided by pBICA)—in relation to the implant diameter on primary implant stability, as well as their correlations were also evaluated. Methods Dental implants with diameters of 3.75, 4, 5, and 6 mm and artificial bone specimens were scanned by microcomputed tomography to construct 3D models for calculating pBICA, BICA, and 3D BIC%. Indexes of the primary implant stability including the insertion torque value (ITV), Periotest value (PTV), and implant stability quotient (ISQ) were measured after implants with various diameters were placed into bone specimens. The Kruskal–Wallis test, Wilcoxon rank-sum test with Bonferroni adjustment, and Spearman correlations were all performed as statistical and correlation analyses. Results The implant diameter significantly influenced pBICA and BICA, but not 3D BIC%. ITV and PTV were more sensitive to implant diameter than was ISQ. The coefficients of determination were high (>0.92) for the correlations between pBICA (or BICA) and indexes of the primary implant stability. Conclusion This study revealed how the implant diameter and the three-dimensional (3D) BIC influence the primary stabilities of dental implant. ITV and PTV were more sensitively influenced by the implant diameter than ISQ. The pBICA and BICA seem to be more important than 3D BIC % for using wider implant in treatment plan, since those two parameters are highly predictive of variations in the primary stability of dental implant.

Background Dental implants have become reliable and predictable tools for treating missing teeth. The survival rate of dental implants is markedly influenced by the host bone quality and quantity of the jawbone. A better host bone provides higher initial stability of the dental implant, resulting in better osseointegration and a higher success rate. Host bone quality and quantity are determined by the crestal cortical bone thickness and inner cancellous bone density. Objective The purpose of this study was to determine the crestal cortical bone thickness at dental implant sites in different regions of the jawbone through the use of dental cone-beam computed tomographic (CBCT) images. Materials and Methods A total of 661 dental implant sites (81 in the anterior mandible, 122 in the anterior maxilla, 224 in the posterior mandible, and 234 in the posterior maxilla) were obtained from the jawbones of 173 humans. The data were subjected to statistical analysis to determine any correlation between crestal cortical bone thicknesses and jawbone regions using one-way analysis of variance with Tukey's post-test. Results The crestal cortical bone thicknesses at dental implant sites in the four regions decreased in the following order: posterior mandible (1.07 ± 0.47 mm, mean ± SD) >anterior mandible (0.99 ± 0.36 mm) >anterior maxilla (0.82 ± 0.30 mm) >posterior maxilla (0.75 ± 0.35 mm). Conclusion The dental CBCT data demonstrate that crestal cortical bone thickness varies markedly between dental implant sites in the four regions of the jawbone.

Background/Purpose: Impact of the implant shape on the biomechanical performance of all-on-four treatment of dental implant is still unclear. This study evaluated the all-on-four treatment with four osseointegrated implants in terms of the biomechanical effects of implant design and loading position on the implant and surrounding bone by using both in vitro strain gauge tests and three-dimensional (3D) finite element (FE) analyses. Methods: Both in vitro and 3D FE models were constructed with placing NobelSpeedy and NobelActive implants as well as a titanium framework in an edentulous jawbone based on the concept of all-on-four treatment. Three types of loads were applied: at the central incisor area (loading position 1) and at the molar regions with (loading position 2) and without (loading position 3) the denture cantilever. For the in vitro tests, the principal bone strains were recorded by rosette strain gauges and statistically evaluated using Wilcoxon's rank-sum test. The 3D FE simulations analyzed the peak von-Mises stresses in the implant and surrounding cortical bone. Results: The peak stress and strain in the surrounding bone were typically 36–62% (3D FE analysis) and 47–57% (in vitro test) (p

Objectives The evaluation of neck lymph node metastasis is critical for predicting survival after head and neck cancer treatment. However, traditional pathological N staging does not completely correlate with survival; the total number of lymph nodes resected during surgery affects staging, and a minimal number of nodes must be resected to achieve a superior outcome. Thus, the prognostic abilities of various lymph node staging systems for oral cavity squamous cell carcinoma (OSCC)-positive lymph nodes were compared. Materials and Methods Data for 639 patients with OSCC-positive nodes who were treated and monitored at the Changhua Christian Hospital were retrospectively analyzed. The different N staging systems were compared to evaluate their disease-free survival (DFS) predictability. Results The areas under the receiver operating characteristic curve were as follows: 0.551 for the traditional American Joint Committee on Cancer (AJCC) N staging, 0.60 for lymph node density (LND), 0.596 for log odds of positive lymph nodes (LODDS), and 0.597 for the number of metastatic lymph nodes (nmLN). The LND, LODDS, and nmLN systems could predict DFS better than AJCC N staging. Multivariable analysis for DFS revealed that extranodal spread, level IV or V positive nodes, and tumor invasion deeper than 13 mm were independent prognostic factors in these four models. LND and LODDS predicted DFS better than pathological N staging. Conclusion LND and LODDS staging predicted DFS better than AJCC N staging for OSCC-positive nodes. In the future, the prognostic ability of AJCC staging may be strengthened by LND or LODDS staging.

The TNM staging system for oral squamous cell carcinoma (OSCC) provides clinicians a dependable foundation for patient prognosis and management decisions, but in clinical practice, treatment outcomes of patients with OSCC are sometimes unsatisfactory. This retrospective study investigated the association between survival and clinicopathological characteristics and histological grades of 2535 patients with OSCC. Additionally, the present study aimed to compare the predictive abilities of histological grades with other common prognostic factors. The enrolled patients were divided into three groups by two experienced pathologists into well-differentiated, moderately differentiated, and poorly differentiated groups, according to the WHO classification. Finally, we designed an observational, retrospective study based on the histological grading of tumors to compare their clinicopathological characteristics and conducted survival analysis among the three groups. Advanced tumor stage was diagnosed in 23.9%, 44.0%, and 55.1% of patients with grades 1–3 OSCC, respectively. By T status, T3 or T4 tumors were found in approximately 22%, 34%, and 40% of patients with grades 1–3 OSCC, respectively. By N status, lymph node metastases were found in 6.1%, 29.3%, and 45.9% of patients with grades 1–3 OSCC, respectively. Thus, significant survival differences were observed based on different OSCC histological grades. Meanwhile, in the multivariate (adjusted) analysis, N1 and N2 stages, extranodal spread, and poor differentiation were associated with a higher recurrence risk than the other common prognostic factors. In conclusion, 5% of patients in our study presented with poorly differentiated OSCC at diagnosis. Furthermore, grade 3 OSCC has worse prognosis and is more aggressive than grades 1 and 2 OSCC. In the future, we should focus on modifying individual therapy for poorly differentiated OSCC to achieve improved outcomes.

This study used available or purchased equipment and an image reconstruction system developed by the college of dentistry to establish a basic self-assembled micro-computed tomography (micro-CT) system. Such a system would be suitable for teaching dental radiology to dental students. Specifically, it could help students to understand the principles governing dental cone-beam computed tomography (CBCT) and provide graduate students with a system for scanning small samples (e.g., individual teeth) during the early stages of research. The self-assembled micro-CT system was constructed using a portable dental X-ray tube, an intraoral digital X-ray detector, a high-precision rotation stage, related bracket accessories, and a notebook computer. Reconstructed images and three-dimensional models of the maxillary right third molar were produced using the self-assembled micro-CT system and an advanced commercially available micro-CT system (Skyscan 2211). Subsequently, the reconstructed images and 3D models produced using the two systems were compared by two senior dentists to determine whether considerable visual differences could be observed. Finally, the signal-to-noise ratio (SNR) was used for quantitative analysis and to compare the systems. Although the self-assembled micro-CT system produced image boundaries that were not as sharp as those of Skyscan 2211, the images were nonetheless remarkably similar. In addition, the two micro-CT systems produced 3D models that were almost identical in appearance and root canal shape. Quantitative analysis revealed that Skyscan 2211 had produced a SNR that was superior to that of the self-assembled micro-CT system, with the difference ranging from 36.77% to 136.22%; enamel, which has a higher density, exhibited lower SNR differences, whereas dentin, which has a lower density, exhibited higher SNR differences. The self-assembled micro-CT system with a resolution of 36 μm was created using a portable dental X-ray tube and an intraoral digital X-ray detector. Although the scanning time was relatively long (~30 min to scan images of a tooth), the images were adequate in the preliminary stage of experiments. More importantly, students were afforded the opportunity to observe the process of assembling and disassembling each component of a micro-CT scanner and thereby achieve a more comprehensive understanding of the principles governing micro-CT and dental CBCT.

Background Fifth metacarpal neck fracture, also known as boxer’s fracture, is the most common metacarpal fracture. Percutaneous Kirschner-wire (K-wire) pinning has been shown to produce favorable clinical results. However, the fixation power of K-wires is a major concern. Plate fixation is also a surgical option, but it has the disadvantages of tendon adhesion, requirement of secondary surgery for removal of the implant, and postoperative joint stiffness. A fixation method that causes little soft tissue damage and provides high biomechanical stability is required for patients with fifth metacarpal neck fracture for whom surgical intervention is indicated. The present study proposed fixation using K-wires and a cerclage wire to treat fifth metacarpal neck fracture. The fixation power of this new method was compared with that of K-wires alone and plates. Methods We used a saw blade to create transverse metacarpal neck fractures in 16 artificial metacarpal bone specimens, which were then treated with four types of fixation as follows: (1) locking plate with five locking bicortical screws (LP group), (2) regular plate with five bicortical screws (RP group), (3) two K-wires (K group), and (4) two K-wires and a figure-of-eight cerclage wire (KW group). The specimens were tested by using cantilever bending testing on a material testing system. The stiffness of the four fixation types was determined by observing force–displacement curves. Finally, the Kruskal–Wallis test was adopted to process the data, and the Mann–Whitney exact test was performed to conduct paired comparison between the fixation types. Results The fixation strength levels of the four fixation approaches for treating fifth metacarpal neck fracture were ranked in a descending order of LP group (24.6 ± 5.1 N/mm, median ± interquartile range) > RP group (22.2 ± 5.8 N/mm) ≅ KW group (20.1 ± 3.2 N/mm) > K group (16.9 ± 3.0 N/mm). Conclusion The fixation strength of two K-wires was significantly higher when reinforcement was provided using a figure-of-eight cerclage wire. The strength of the proposed approach is similar to that of a regular plate with five bicortical screws but weaker than that of a locking plate with the same amount of bicortical screws. Cerclage wire-integrated K-wires can be an alternative method that avoids the excessive soft tissue dissection required for plating in open reduction internal fixation for fifth metacarpal neck fracture.

Objectives. Dual-energy X-ray absorptiometry (DXA) is frequently used to measure the areal bone mineral density (aBMD) in clinical practice. However, DXA measurements are affected by the bone thickness and the body size and are unable to indicate nonosseous areas within the trabecular bone. This study aims to quantify the volumetric bone mineral density (vBMD) using computed tomography (CT) images and the two-compartment model (TCM) methods. Methods. The TCM method was proposed and validated by dipotassium phosphate (K2HPO4) phantoms and a standard forearm phantom. 28 cases with DXA scans and pelvic CT scans acquired within six months were retrospectively collected. The vBMD calculated by TCM was compared with the aBMD obtained from DXA. Results. For the K2HPO4 phantoms with vBMD ranging from 0.135 to 0.467 g/cm3, the average difference between the real and calculated vBMD was 0.009 g/cm3 and the maximum difference was 0.019 g/cm3. For the standard forearm phantom with vBMD of 0.194, 0.103, and 0.054 g/cm3, the average differences between the real and calculated vBMD were 0.017, 0.014, and 0.011 g/cm3. In the clinical CT image validation, a good linear relationship between vBMD and aBMD was observed with the Pearson correlation coefficient of 0.920 (p<0.01). Conclusions. The proposed TCM method in combination with the homemade cortical bone equivalent phantom provides accurate quantification and spatial distribution of bone mineral content.

Background/Purpose: Spaced primary dentition plays a critical role in the eruption of permanent teeth and the establishment of ideal occlusion. A lack of these spaces in deciduous dentition may result in disproportionate jaw and tooth sizes. Additionally, spaced primary dentition is significantly affected by ethnic factors. However, few of these studies have been conducted in Asia. The purpose of this study was to investigate the prevalence of spaced primary dentition in Taiwan. Methods: One hundred and forty-seven 3- to 6-year-old Taiwanese children (58 girls and 89 boys) were recruited for a cross-sectional study. Primate and interdental spaces were recorded by intraoral photos. The prevalence of spaced dentition was evaluated. The interpersonal agreement of spaced dentition between the upper and lower arches was also assessed. Results: Most of the subjects had spaced primary dentition. The prevalence of primate space was 83.7% in the upper arch and 61.2% in the lower arch, whereas the prevalence of interdental space was 44.2% in the upper arch and 53.1% in the lower arch. The prevalence rates of interdental space and upper primate space were significantly higher in boys than in girls. Interdental spaces of the lower arch increased with age. Conclusion: Ethnic factors can affect the ratio of spaced dentition. Most of the 3- to 6-year-old Taiwanese children have spaced dentition. The boys have higher incidence of spaced dentition than the girls. Furthermore, primate space is more frequently found in the upper arch than in the lower arch, whereas interdental space is reversed. Keywords: Spaced dentition, Primary dentition, Interdental space, Primate space, Dental arch

Reference phantoms are widely applied to evaluate the radiation dose for external exposure. However, the frequently used reference phantoms are based on Caucasians. Dose estimation for Asians using a Caucasian phantom can result in significant errors. This study recruited 40 volunteers whose body sizes are close to the average Taiwanese population. Magnetic resonance imaging was performed to obtain the organ volume for construction of the Taiwanese reference man (TRM) and Taiwanese reference woman (TRW). The dose conversion coefficients (DCC) resulting from photo beams in anterior-posterior, posterior-anterior, right-lateral, left-lateral, and isotropic irradiation geometries were estimated. In the anterior-posterior geometry, the mean DCC differences among organs between the TRM and ORNL phantom at 0.1, 1, and 10 MeV were 7.3%, 5.8%, and 5.2%, respectively. For the TRW, the mean differences from the ORNL phantom at the three energies were 10.6%, 7.4%, and 8.3%. The DCCs of the Taiwanese reference phantoms and the ORNL phantom presented similar trends in other geometries. The torso size of the phantom and the mass and geometric location of the organ have a significant influence on the DCC. The Taiwanese reference phantoms can be used to establish dose guidelines and regulations for radiation protection from external exposure.

This study compared the effects of external hex, internal octagon, and internal Morse taper implant–abutment connections on the peri-implant bone level before and after the occlusal loading of dental implants. Periapical radiographs of 103 implants (63 patients) placed between 2002 and 2010 were collected, digitized, standardized, and classified into groups based on the type of implant–abutment connection. These radiographs were then analyzed with image-processing software to measure the peri-implant crestal bone change during the healing phase (4 months after implant placement) and at loading phases 1 and 2 (3 and 6 months after occlusal loading, respectively). A generalized estimating equation method was employed for statistical analysis. The amount of peri-implant crestal bone change differed significantly among all time–phase pairs for all 3 types of implant–abutment connection, being greater in the healing phase than in loading phase 1 or 2. However, the peri-implant crestal bone change did not differ significantly among the 3 types of implant–abutment connections during the healing phase, loading phase 1, or loading phase 2. This retrospective clinical study reveals that the design of the implant–abutment connection appears to have no significant impact on short-term peri-implant crestal bone change.

This study compared the capabilities of micro-computed tomography (micro-CT) and dental cone-beam computed tomography (CBCT) in assessing trabecular bone parameters and cortical bone strength. Micro-CT and CBCT scans were applied to 28 femurs from 14 rats to obtain independent measurements of the volumetric cancellous bone mineral density (vCanBMD) in the femoral head, volumetric cortical bone mineral density (vCtBMD) in the femoral diaphysis, cross-sectional moment of inertia (CSMI), and bone strength index (BSI) (=CSMI×vCtBMD). Five structural parameters of the trabecular bone of the femoral head were calculated from micro-CT images. A three-point bending test was then conducted to measure the fracture load of each femur. Bivariate linear Pearson analysis was conducted to calculate the correlation coefficients (r values) of the micro-CT, dental CBCT, and three-point bending measurements. The statistical analyses showed a strong correlation between vCanBMD values obtained using micro-CT and dental CBCT (r=0.830). There were strong or moderate correlation between vCanBMD measured using dental CBCT and five parameters of trabecular structure measured using micro-CT. Additionally, the results were satisfactory regardless of whether micro-CT or dental CBCT was used to measure the femoral diaphysis vCtBMD (r=0.733 and 0.680, respectively), CSMI (r=0.756 and 0.726, respectively), or BSI (r=0.846 and 0.847, respectively) to predict fracture loads. This study has yielded a new method for using dental CBCT to evaluate bone parameters and bone strength; however, further studies are necessary to validate the use of dental CBCT on humans.

Purpose Bone stress and interfacial sliding at the bone-implant interface (BII) were analyzed in zirconia and titanium implants with various thread designs and interface conditions (bonded BII and contact BIIs with different frictional coefficients) for both conventional and immediately loaded treatments. Materials and methods A total of 18 finite element models comprising two implant materials (zirconia and titanium), three thread designs (different shapes and pitches), and three interface conditions (bonded and contact BIIs) were analyzed to assess the effects on bone stresses and on sliding at the BII. The material properties of the bone model were anisotropic, and a lateral force of 130 N was applied as the loading condition. Results In the immediately loaded implant, the stress was highly concentrated at one site of the peri-implant bone. The peak bone stress was more than 20% lower in zirconia implants than in titanium implants for a bonded BII and 14% to 20% lower for a contact BII. The bone stresses did not differ significantly between implants with V-shaped threads and square threads. However, sliding at the BII was more than 25% lower with square-thread implants than with V-shaped-thread implants for titanium implants and 36% lower for zirconia implants. Reducing the thread size and pitch in cortical bone (via two V-shaped threads with different pitches) decreased the bone stress by 13%. Increasing the frictional coefficient reduced sliding at the BII in both zirconia and titanium implants. Conclusions As an implant material, zirconia can reduce the bone stress in the crestal cortical region. Bone stress and sliding at the BII are heavily dependent on the thread design and the frictional coefficient at the BII of immediately loaded implants.

Few studies involving human participants have been conducted to investigate the effect of orthodontic treatment on alveolar bone density around the teeth. Our previous study revealed that patients who received 6 months of active orthodontic treatment exhibited an ∼24% decrease in alveolar bone density around the teeth. However, after an extensive retention period following orthodontic treatment, whether the bone density around the teeth can recover to its original state from before the treatment remains unclear, thus warranting further investigation. The purpose of this study was to assess the bone density changes around the teeth before, during, and after orthodontic treatment. Dental cone-beam computed tomography (CBCT) was used to measure the changes in bone density around 6 teeth in the anterior maxilla (maxilla central incisors, lateral incisors, and canines) of 8 patients before and after orthodontic treatment. Each patient underwent 3 dental CBCT scans: before treatment (T0); at the end of 7 months of active orthodontic treatment (T1); after several months (20–22 months) of retention (T2). The Friedman test was applied to evaluate the changes in the alveolar bone density around the teeth according to the 3 dental CBCT scans. From T0 to T1, a significant reduction in bone density was observed around the teeth (23.36 ± 10.33%); by contrast, a significant increase was observed from T1 to T2 (31.81 ± 23.80%). From the perspective of the overall orthodontic treatment, comparing the T0 and T2 scans revealed that the bone density around the teeth was relatively constant (a reduction of only 0.75 ± 19.85%). The results of the statistical test also confirmed that the difference in bone density between T0 and T2 was nonsignificant. During orthodontic tooth movement, the alveolar bone density around the teeth was reduced. However, after a period of bone recovery, the reduced bone density recovered to its previous state from before the orthodontic treatment. However, the bone density around ∼10% of the teeth in this region could not recover to 80% of its state from before the orthodontic treatment.

This study investigated the effects of gender on the three-dimensional (3D) bone mineral density (BMD) and micromorphology of the trabeculae of matured autogenous bone grafts after sinus floor augmentation, and compared them to those of adjacent native bone. Ten bone biopsy samples were removed from the implant placement areas of patients who had received second-stage sinus floor augmentation, and analyzed by microcomputed tomography. BMD phantoms with two calcium hydroxyapatite densities (0.25 and 0.75 g/cm3) were used to determine the BMD of the grafted and native bone samples. The 3D structural parameters of the trabeculae, including percentage of bone volume (bone volume/tissue volume, BV/TV), trabecular thickness (Tb.Th), trabecular number, trabecular separation, trabecular pattern factor (Tb.Pf), and structure model index, were analyzed between males and females and between grafted bone and native bone. No significant gender-specific differences in BMD and 3D trabecular structure of either native or grafted bone were found (P > 0.05). Compared to the adjacent native bone, the autogenous grafted bone exhibited lower BV/TV and Tb.Th as well as a higher Tb.Pf (P

The purpose of this study was to determine the correlation between the peak insertion torque value (ITV) of a dental implant and the bone-implant contact percentage (BIC%).Dental implants were inserted into specimens comprising a 2-mm-thick artificial cortical shell representing cortical bone and artificial foam bone representing cancellous bone with four densities (groups 1 to 4--0.32, 0.20, 0.16, and 0.12 g/cm(3)). Each specimen with an inserted implant was subjected to micro-computed tomography (micro-CT) scanning, from which the 3D BIC% values were calculated. Pearson's correlation coefficients (r) between the ITV and BIC% were calculated.The ITVs in groups 1 to 4 were 56.2 ± 4.6 (mean±standard deviation), 45.6 ± 0.9, 43.3 ± 4.3, and 38.5 ± 3.4 N cm, respectively, and the corresponding BIC% values were 41.5 ± 0.5%, 39.0 ± 1.0%, 30.8 ± 1.1%, and 26.2 ± 1.6%. Pearson's correlation coefficient between the ITV and BIC% was r = 0.797 (P 0.0001).The initial implant stability, quantified as the ITV, was strongly positively correlated with the 3D BIC% obtained from micro-CT images.The ITV of a dental implant can be used to predict the initial BIC%; this information may provide the clinician with important information on the optimal loading time.

The aim of this study is to determine the effects of various designs of internal tapered abutment joints on the stress induced in peri-implant crestal bone by using the three-dimensional finite element method and statistical analyses.Thirty-six models with various internal tapered abutment-implant interface designs including different abutment diameters (3.0, 3.5, and 4.0 mm), connection depths (4, 6, and 8 mm), and tapers (2°, 4°, 6°, and 8°) were constructed. A force of 170 N was applied to the top surface of the abutment either vertically or 45° obliquely. The maximum von Mises bone-stress values in the crestal bone surrounding the implant were statistically analyzed using analysis of variance. In addition, patterns of bone stress around the implant were examined.The results demonstrate that a smaller abutment diameter and a longer abutment connection significantly reduced the bone stresses (P0.0001) in vertical and oblique loading conditions. Moreover, when the tapered abutment-implant interfaced connection was more parallel, bone stresses under vertical loading were less (P = 0.0002), whereas the abutment taper did not show significant effects on bone stresses under oblique loading (P = 0.83). Bone stresses were mainly influenced by the abutment diameter, followed by the abutment connection depth and the abutment taper.For an internal tapered abutment design, it was suggested that a narrower and deeper abutment-implant interface produced the biomechanical advantage of reducing the stress concentration in the crestal region around an implant.

Background Before extracting impacted lower third molars, dentists must first identify the spatial relationship between the inferior alveolar nerve (IAN) and an impacted lower third molar to prevent nerve injury from the extraction. Nevertheless, the current method for describing the spatial relationship between the IAN and an impacted lower third molar is deficient. Therefore, the objectives of this study were to: (1) evaluate the relative position between impacted lower third molars and the IAN; and (2) investigate the relative position between impacted lower third molars and the IAN by using a cylindrical coordinate system. Methods From the radiology department’s database, we selected computed tomography images of 137 lower third molars (from 75 patients) requiring removal and applied a Cartesian coordinate system by using Mimics, a medical imaging software application, to measure the distribution between impacted mandibular third molars and the IAN. In addition, the orientation of the lower third molar to the IAN was also measured, but by using a cylindrical coordinate system with the IAN as the origin. Results According to the Cartesian coordinate system, most of the IAN runs through the inferior side of the third molar (78.6 %), followed by the lingual side (11.8 %), and the buccal side (8.9 %); only 0.7 % is positioned between the roots. Unlike the Cartesian coordinate system, the cylindrical coordinate system clearly identified the relative position, r and θ, between the IAN and lower third molar. Conclusions Using the cylindrical coordinate system to present the relationship between the IAN and lower third molar as (r, θ) might provide clinical practitioners with a more explicit and objective description of the relative position of both sites. However, comprehensive research and cautious application of this system remain necessary.

Objective The purpose of this study was to determine the relationships and differences in three-dimensional (3D) bone mineral density (BMD) and microtrabecular structures between autogenous bone grafts and their adjacent native bone after a healing period following maxillary sinus augmentation. Materials and methods Nine rod-shaped human bone biopsy samples were taken from patients receiving two-stage sinus augmentation therapy in implantation areas and analyzed using microcomputed tomography (micro-CT). Before micro-CT scanning, two BMD phantoms were placed near to the bone biopsy samples for executing BMD calculations of the grafted and native bone samples. In addition, 3D structural parameters of the trabeculae were analyzed for both the grafted and native bone, including percentage of bone volume [bone volume (BV)/tissue volume (TV)], bone-specific surface [bone surface (BS)/BV], trabecular thickness (Tb.Th), trabecular number (Tb.N), trabecular separation (Tb.Sp), trabecular pattern factor (Tb.Pf), and structure model index (SMI). Results No significant correlations with regard to BMD and trabecular-structure parameters were found between native bone and grafted bone; however, BS/BV and Tb.Pf were higher and Tb.Th and Tb.Sp were 37.35% and 12.74% lower in grafted bone than in native bone. For grafted bone, there were significant correlations (P

The object of this study was to evaluate the relationship between changes in the alveolar bone density around the teeth and the direction of tooth movement by using cone-beam computed tomography (CBCT). CBCT was used to measure the bone densities around six maxilla anterior teeth before and after 7 months of orthodontic treatment in eight patients. Each root was divided into three levels (cervical, intermediate, and apical) to determine whether the bone density change varied with the tooth level. Moreover, each level was divided into four regions (palatal, distal, mesial, and buccal sides). Three-dimensional computer models of the maxilla before and after orthodontic treatment were created to detect the direction of tooth movement. The percentage for all 144 samples [8 (patients) × 6 (teeth) × 3 (levels)] in which the side (palatal, distal, mesial, or buccal sides) of maximum bone density reduction (before and after orthodontic treatment) coincided with the direction of tooth movement was calculated; this was referred to as the "coincidence percentage". The bone density around the teeth reduced by 24.3 ± 9.5%. The average coincidence percentage for the eight patients was 59.0%. The coincidence percentages for the eight patients were 62.5%, 62.5%, and 52.1% at the cervical, intermediate, and apical levels, respectively. The obtained results demonstrate that the direction of tooth movement is associated with the side of maximum bone density reduction, and that CBCT is a useful approach for evaluating bone density changes around teeth induced by orthodontic treatment.

This study aims to evaluate the inclinations of right and left sides the mandibular fossa in Asian population using computed tomography (CT) images and determine its effects according to the parameters of gender, age, and asymmetry. CT images of the heads of 198 Asian subjects [95 females aged 44.2 ± 20.7 years, range 11-88 years; and 103 males aged 44.5 ± 19.7 years, range 15-98 years] were selected. The following eight parameters characterizing the inclinations of the mandibular fossa were measured by medical imaging software: anterior and posterior inclinations on the left and right sides on a sagittal view, and medial and lateral inclinations on the left and right sides on a coronal view. The anterior inclination was significant steeper in males than in females on both the left and right sides. A moderate positive correlation was found between age and anterior inclinations on the left and right sides. None of the other parameters were significantly affected by age or gender. None of the parameters differed significantly between the right and left sides of the mandibular fossa in males, females, or all subjects. The anterior inclination of the mandibular fossa was affected by aging and gender becoming steeper in Asians males than females. Besides, there were no asymmetry in the right and left side inclinations of the mandibular fossa.

The survival rate of dental implants is markedly influenced by the quality of the bone into which they are placed. The purpose of this study was to determine the trabecular bone density at potential dental implant sites in different regions of the Chinese jawbone using computed tomography (CT) images. One hundred and fifty-four potential implant sites (15 in the anterior mandible, 47 in the anterior maxilla, 55 in the posterior mandible, and 37 in the posterior maxilla) were selected from the jawbones of 62 humans. The data were subjected to statistical analysis to determine any correlation between bone density (in Hounsfield units, HU) and jawbone region using the Kruskal-Wallis test. The bone densities in the four regions decreased in the following order: anterior mandible (530 +/- 161 HU, mean +/- s.d.) approximately equal anterior maxilla (516 +/- 132 HU) > posterior mandible (359 +/- 150 HU) approximately equal posterior maxilla (332 +/- 136 HU). The CT data demonstrate that trabecular bone density varies markedly with potential implant site in the anterior and posterior regions of the maxilla and mandible. These findings may provide the clinician with guidelines for dental implant surgical procedures (i.e., to determine whether a one-stage or a two-stage protocol is required).

Background/Purpose Knowledge of root canal anatomy is important for dental practice and for identifying features of anthropological significance. Three-rooted permanent mandibular molars are considered an anatomical variant of the Mongoloid race. This study aimed to determine the prevalence of three-rooted primary mandibular first molars in Taiwanese subjects. Methods Vertical bite-wing radiographs of 227 subjects, which had been obtained previously in the Department of Pediatric Dentistry, Taichung Veterans General Hospital, Taichung, Taiwan, from January 2004 to December 2007, were screened retrospectively. Images of 121 subjects [54 boys and 67 girls; mean age (range), 5.8 (2.4–10.4) years] who had bilateral primary mandibular first molars were studied. The sex, symmetry and frequency of occurrence of three-rooted primary mandibular first molars were recorded and statistically analyzed. Results The overall prevalence of subjects with three-rooted primary mandibular first molars was 5.0% (6/121), and 83.0% of the molars were unilateral. The prevalence of teeth that showed an extra root among all teeth examined was 2.9% (7/242). Such prevalence did not differ significantly between the right and left sides of the mandible, bilateral and unilateral, or with sex. Conclusion The data presented here indicate that approximately 5% of Taiwanese subjects had a three-rooted mandibular primary first molar and 80% of such teeth occurred unilaterally. Dentists should take into account the prevalence of these three-rooted variants in primary mandibular first molars among Taiwanese patients during their daily endodontic and exodontic procedures.

Acetabular cup loosening is one of the major failure models of total hip replacement (THR), which is mostly due to insufficient initial stability of the cup. Previous studies have demonstrated that cup stability is affected by the quality of the host bone and the surgical skill when inserting screws. The purpose of this study was to determine the effects on the initial stability of the acetabular cup of eccentric screws in bone of different qualities. In this study, hemispherical cups were fixed into bone specimens constructed from artificial foam with three elastic moduli using one to three screws. The effects of two types of screw eccentricity (offset and angular) on the stability of the acetabular cup were also evaluated. The experimental results indicate that in the presence of ideal screwing, the cup was stable in bone specimens constructed from foam with the highest elastic modulus. In addition, increasing the number of ideal screws enhanced the cup stability, especially in bone specimens constructed from soft foam. Moreover, the cup stability was most affected by offset eccentric screw(s) in the hard-foam bone specimens and by angular eccentric screw(s) in the soft-foam bone specimens. The reported results indicate that the presence of screw eccentricity affects the initial stability of the acetabular cup. Surgeons should keep this in mind when performing screw insertions in THR. However, care is necessary when translating these results to the intraoperative situation due to the experiments being conducted under laboratory conditions, and hence, future studies should attempt to replicate the results reported here in vivo.

This study investigated the effects of the stiffness of a maxillary sinus graft and the surface roughness of an immediately loaded implant using a non-linear three-dimensional finite element (FE) analysis (3D). Six FE models were created, including two stiffness values of grafted bone (345 and 3450 MPa of elastic modulus) and three conditions of implant-bone interfaces (Frictional coefficient of 0.3 for machined surface, 0.45 for rough implant surface and a bonded implant-bone interface for an osseointegrated implant). Computer tomographic images of a human skull were used to construct a posterior maxillary model. All implants were designed via the computer aided design software with a spiral threaded configuration. Three loading scenarios were investigated for each of the six models; axial loading and lateral loadings at 30 degrees and 60 degrees . The results showed that a 60 degrees lateral loading has scored the highest level of bone stresses among the three loading conditions. Immediately loaded implants with 0.3 frictional coefficient have suffered the highest bone stresses which were higher than those with bonded interface by about 57%. Increasing the frictional coeffecient to 0.45, however, did not show any benefits in reducing the peak bone stress. Raising the stiffness of grafted bone diminished the bone stress by about 10% in both the immediately loaded and the osseointegrated implants. It was also noted that increasing graft stiffness and implant surface roughness reduced the sliding at the implant-bone interface which may improve the implant stability and long-term survival.

One of the major causes of loosening of cementless acetabular cup implants is insufficient initial stability. This study used three-dimensional finite element models of the pelvis and acetabular components to investigate the effects of the number of screws, bone quality, and friction coefficient of the acetabular cup on the initial stability under normal walking. A commercially available hemispherical acetabular cup with five screw holes was used as the default model. The stiffness of the pelvis and the friction coefficient of the cup were systematically varied, within a realistic range, to assess the initial stability of the acetabular cup. The simulations showed that the inserted screws provide only a localized reduction in the relative micromotion between the cup and pelvis therefore inserting several screw closed together might not be useful. Changes in the pelvic stiffness have a non-linear effect on the initial stability of acetabular cup and the subchondral bone provides good support for fixation of the cementless cup. The friction coefficient of the acetabular cup plays a limited role, comparing with the factor of bone quality, in resisting relative micromotion in the cup-pelvis interface.

One of the major failure modes of cementless acetabular components is the loosening of the acetabular cup, which is mostly attributable to insufficient initial stability. A hemispherical cup with a porous coating which is inserted with press-fit fixation and secured with several screws is one of the most widely used approaches. Many studies have found that bone screws are very helpful aids for cup fixation, but the optimal surgical technique for inserting screws has not been clearly reported. In this study, hemispherical cups were fixed into blocks of foam bone with zero to three screws. The effects of three types of screw eccentricity (a 1-mm offset and angular eccentricities of 15 degrees and 25 degrees ) on the initial stability of the acetabular cup were evaluated. The experimental results indicate that increasing the number of screws enhances the cup stability in the case of ideal screwing (i.e., with no eccentricity). An angular eccentricity of 15 degrees did not affect the cup stability for fixation with one or two screws. However, the presence of 25 degrees of angular eccentricity significantly reduced the stability of the cup, while 1 mm of offset eccentricity produced an even greater impact.

The objective of this study was to evaluate the effect of clenching tasks on the stress and stability of a temporomandibular joint (TMJ) condylar prosthesis, as well as on the stress and strain in the whole mandible and bone surrounding three screws. Three-dimensional finite element models of the mandible and a TMJ condylar prosthesis using three screws were established. Six static clenching tasks were simulated in this study: incisal clench (INC), intercuspal position (ICP), right unilateral molar clench (RMOL), left unilateral molar clench (LMOL), right group function (RGF), and left group function (LGF). Based on the simulation of the six clenching tasks, none of the inserted screws or the TMJ condylar prosthesis were broken. In addition, the stability of the TMJ condylar prosthesis was sufficiently high for bone ongrowth. For the whole mandibular bone, the maximum von Mises stress and von Mises strain observed in the cortical bone and cancellous bone were yielded by the ICP and RMOL, respectively. For the bone surrounding the inserted screws, the maximum von Mises stress and von Mises strain in both the cortical bone and cancellous bone were yielded by the LMOL. Clenching tasks had significant effects on the stress distribution of the TMJ condylar prosthesis, as well as on the stress and strain distribution of the whole mandible and the bone surrounding the inserted screws.