The accuracy of a partially guided system using an in-office 3D-printed surgical guide for implant placement.

AIM: To conduct an observational study evaluating the efficacy of a partially guided system for implant surgery. MATERIALS AND METHODS: The study included 48 implant placements in 24 patients. Following virtual implant planning with designated software, a surgical guide was fabricated using a 3D desktop printer. Each surgically placed implant was compared with its planned position in the software. The coronal and apical distance and angular errors of the implants were evaluated. The correlation between the errors and the variables (residual bone height, surgeon, implant placement site, guide support type, implant diameter) was analyzed using multiple regression analysis. RESULTS: The coronal and apical mean distance errors were 1.28 ± 0.85 and 1.8 ± 0.97 mm, respectively. The mean angular error was 3.66 ± 3.37 degrees. The correlation coefficients (coronal: 0.285; apical: 0.308) indicated a significant linear correlation between the anterior and posterior implant placement positions (P < 0.05). CONCLUSION: A partially guided system with in-office guide fabrication using a 3D desktop printer is a useful option for implant placement.

Decompression of Large Cyst Invading the Mandibular Canal Leading to Reduced Cyst Volume and Increased Mandibular Canal Length.

PURPOSE: The mandibular canal is damaged by the growth of cysts, and remodeling of the mandibular canal is observed as the size of the cyst decreases after decompression procedures. This study aimed to estimate changes in cyst volume and mandibular canal length using cone-beam computed tomography (CBCT) before and after decompression surgery. MATERIALS AND METHODS: A retrospective cohort study was conducted in patients with a diagnosis of mandibular cyst invading the mandibular canal between 2012 and 2018. All patients underwent CBCT at the initial visit and after decompression. The predictor variable was the period before decompression and before enucleation surgery. The outcome variables were changes in cyst volume and mandibular canal length, which were evaluated 3-dimensionally. The initial volume of the cyst, initial length of the mandibular canal, and patient's age were set as variables of interest that affected the outcome. RESULTS: Decompression was performed in 20 patients (18 male and 2 female patients), and the mean decompression duration was 8.81 ± 2.94 months. The average volume reduction rate after decompression was 60.23%, with an average volume reduction speed of 0.72 mL/month. The average length increase rate after decompression was 50.88%, and the average speed of length increase was 2.68 mm/month. The initial volume of the cyst and initial length of the mandibular canal were the important variables affecting the results. Complete separation of the mandibular canal from the cyst was observed in 11 cases, and incomplete separation was found in 9. CONCLUSIONS: Separation from the cyst and regeneration of the mandibular canal using decompression were observed using 3-dimensional CBCT analysis. The results of this study suggest that decompression is effective in separating and preserving important anatomic structures invaded by the cyst.

Exploring dental students' knowledge of HIV and attitudes towards saliva screening for HIV.

INTRODUCTION: Early detection of human immunodeficiency virus (HIV) allows antiretroviral therapy to commence, improving patient outcomes. Screening for HIV with saliva can be undertaken by dental practitioners. Research has found the procedure to be better accepted by patients than traditional blood testing. However, lack of knowledge and time constraints were identified as barriers to implementation for dental practitioners. This study aimed to explore dental students' knowledge of HIV and their attitudes towards implementing saliva screening for HIV in a dental setting. METHODS: Convenience sampling was used to recruit four focus groups of six to nine dentistry students from the University of Queensland. Participants also completed a questionnaire prior to the focus group. RESULTS: Thirty-three students participated in the focus groups. Students recognised their knowledge of HIV was limited, and 46% (n = 15) reported having treated a HIV-positive patient in the last year. Three key themes emerged from discussions; knowledge and experience of HIV; barriers and enablers; and scope of practice. Students identified stigma, lack of training, cost and time restraints as barriers to implementing saliva screening for HIV. Opinions varied on if screening was within a dental practitioner's scope of practice. CONCLUSIONS: Whilst students were open to conducting saliva screening for HIV, they identified prominent barriers limiting its implementation within a dental setting. Education on saliva screening for HIV, patient counselling and referral pathways could be integrated into dentistry curriculums to reduce these barriers. Further investigation is needed into the cost-effectiveness of implementing screening for HIV in a dental setting.

Porous SnO2 nanostructure with a high specific surface area for improved electrochemical performance.

Tin oxide (SnO2) has been attractive as an alternative to carbon-based anode materials because of its fairly high theoretical capacity during cycling. However, SnO2 has critical drawbacks, such as poor cycle stability caused by a large volumetric variation during the alloying/de-alloying reaction and low capacity at a high current density due to its low electrical conductivity. In this study, we synthesized a porous SnO2 nanostructure (n-SnO2) that has a high specific surface area as an anode active material using the Adams fusion method. From the Brunauer-Emmett-Teller analysis and transmission electron microscopy, the as-prepared SnO2 sample was found to have a mesoporous structure with a fairly high surface area of 122 m2 g-1 consisting of highly-crystalline nanoparticles with an average particle size of 5.5 nm. Compared to a commercial SnO2, n-SnO2 showed significantly improved electrochemical performance because of its increased specific surface area and short Li+ ion pathway. Furthermore, during 50 cycles at a high current density of 800 mA g-1, n-SnO2 exhibited a high initial capacity of 1024 mA h g-1 and enhanced retention of 53.6% compared to c-SnO2 (496 mA h g-1 and 23.5%).

Erratum: Text in Figure 1A. Factors affecting treatment outcomes in patients with oral lichen planus lesions: a retrospective study of 113 cases.

[This corrects the article on p. 213 in vol. 48, PMID: 30202605.].

Factors affecting treatment outcomes in patients with oral lichen planus lesions: a retrospective study of 113 cases.

PURPOSE: Oral lichen planus (OLP) is a chronic oral mucosal disease that has been recognized as an immune condition. The purpose of this study was to evaluate factors affecting the clinical outcomes of topical corticosteroid application on OLP lesions using dexamethasone gargle and ointment. METHODS: The charts of patients who were clinically diagnosed with OLP and treated with dexamethasone from July 2003 to August 2017 at the Section of Dentistry of Seoul National University Bundang Hospital were thoroughly evaluated to identify subjects who were suitable for this retrospective study. For each patient, age at the index date, gender, medical history, and dental records related to OLP lesions and dexamethasone treatment were reviewed. RESULTS: In total, 113 of the 225 patients were included in the present study. Among them, 79 patients were female (69.9%) and 34 were male (30.1%), with a mean age of 57.6 years. The average duration of dexamethasone treatment was 4.7 months and the mean follow-up period was 2.24 years. Improvements were observed within 1 year after dexamethasone treatment in most cases, and 17.7% of patients had a new OLP lesion after treatment. New OLP lesions were more frequently gingival than mucosal, although mucosal OLP lesions were more common than gingival OLP lesions in all age groups. In age- and gender-adjusted multivariate logistic regression, a history of malignant disease was found to be a significant factor affecting the formation of new lesions. Gingival OLP lesions and intermittent use of dexamethasone showed near-significant associations. In Kaplan-Meier failure analysis, history of malignancy, menopausal status, age, and the site of the OLP lesion were significant factors affecting clinical outcomes. CONCLUSIONS: The treatment outcomes of OLP were significantly influenced by age, history of malignancy, menopausal status, and the site of the OLP lesion, but not by factors related to dexamethasone treatment.

One-Year Prospective Study of 7-mm-Long Implants in the Mandible: Installation Technique and Crown/Implant Ratio of 1.5 or Less.

This study prospectively evaluated the clinical prognoses of short implants (7-mm long) in the mandible. We investigated the clinical prognosis of short implants in 20 patients (46 implants) according to the installation technique (submerged or nonsubmerged), installation depth (5.5-mm depth, 7-mm depth), and crown/implant ratio. We investigated the marginal bone loss and peri-implant soft-tissue index 12 months after the final prosthetic delivery. Twelve months after prosthetic delivery, no statistically significant differences were observed in bone loss in relation to the type of installation technique, installation depth, or crown/implant ratio. The plaque index and pocket depth indexes were not influenced by the installation technique, installation depth, or crown/implant ratio. We observed marginal bone loss of 3.3 mm in 1 implant from the nonsubmerged group. The total 1-year success rate was 97.83%. Based on this 1-year success rate, short implants had a good clinical prognosis, regardless of the installation technique, installation depth, or crown/implant ratio.

Comparative Study of the Early Loading of Resorbable Blasting Media and Sandblasting with Large-grit and Acid-etching Surface Implants: A Retrospective Cohort Study.

PURPOSE: This study compares the prognosis (the survival rate and marginal bone loss) of resorbable blasting media (RBM) surface implants and sandblasting with large-grit and acid-etching (SLA) surface implants in the early loading. METHODS: This study targeted 123 patients treated by implants installation from January 2008 to March 2010. The loading was initiated in the maxilla within three to four months and in the mandible within one to two months. The types of restoration were single crown and fixed partial prosthesis. Those functioned over one year. The implants were classified by the surface of implants as Group 1: RBM surface (GS III; OSSTEM, Busan, Korea) and, Group 2: SLA surface (Superline; Dentium, Seoul, Korea). The groups were categorized by maxilla and mandible and compared by survival rate, marginal bone loss through clinical records evaluation, and radiographic measurements. RESULTS: The marginal bone loss in the maxilla was 0.14±0.34 mm (Group 1) and 0.30±0.37 mm (Group 2), a statistically significant difference (P <0.05). In the mandible those were 0.28±0.54 mm (Group 1) and 0.20±0.33 mm (Group 2), not significant (P >0.05). There was no significant difference of marginal bone loss between maxilla and mandible by groups. During observation there was no implant failure, a survival rate of 100%. CONCLUSION: Both surfaces showed an excellent survival rate, and the marginal bone loss was not substantial.

A pharmacodynamic comparison study of different botulinum toxin type A preparations.

BACKGROUND: Because more botulinum toxin (BoNT) preparations have become available worldwide, there is a clinical need to compare the pharmacologic profiles of these products. OBJECTIVE: We compared three different preparations: onabotulinumtoxinA (ona-BoNT/A), abobotulinumtoxinA (abo-BoNT/A), and Neuronox (neu-BoNT/A), in a mouse model using a digit abduction scoring (DAS) assay. METHODS: The efficacy, duration of effect, and safety margin of each preparation was determined after delivering a single injection to the right gastrocnemius (0-240 U/kg body weight of neu-BoNT/A or ona-BoNT/A; 0-600 Speywood Units/kg body weight of abo-BoNT/A). RESULTS: Neu-BoNT/A (intramuscular (IM) median effective dose (ED(50) ) 11.2 ± 2.7 U/kg) and ona-BoNT/A (IM ED(50) 11.9 ± 2.4 U/kg) had similar effects in terms of muscle weakness at significantly lower doses than abo-BoNT/A (IM ED(50) 41.2 ± 2.4 U/kg; p < .001). The safety margin (ratio between IM ED(50) and IM median lethal dose (LD(50) )) of neu-BoNT/A (10.7 ± 2.6 U/kg) was also similar to that of ona-BoNT/A (10.3 ± 1.3 U/kg) but significantly higher than that of abo-BoNT/A (5.9 ± 0.4 U/kg; p < .02). Neu-BoNT/A and ona-BoNT/A also produced comparable patterns of DAS response and body weight recovery by day 29. CONCLUSION: Neu-BoNT/A and ona-BoNT/A may be interchangeable based on a simple dose ratio.

Mouse compound muscle action potential assay: an alternative method to conduct the LD50 botulinum toxin type A potency test.

PURPOSE: We performed a prevalidation of the compound muscle action potential (CMAP) assay to determine the potency of botulinum neurotoxin type A (BoNT/A) with the aim of substituting for the mouse lethality test (LD50), which is used for quality control. METHODS: Prevalidation experiments were performed to demonstrate the specificity, linearity, accuracy, precision, range, limit of quantitation (LOQ), and robustness of the assay. For specificity, toxin detection ability was determined in the presence of neutralizing antibodies (0.8 and 8 IU/mL). Linearity of this assay was determined by measuring CMAP amplitude using nine concentrations (n = 3) in the range of 1-100 U/mL (n = 3). Accuracy was assessed using five concentrations (n = 3) in the range of 4-40 U/mL. Intermediate precision was confirmed by analyzing individually prepared reagents on multiple days by one operator (n = 3). Different body weights (23-25 and 25-27 g) and measurement times (3-5 and 5-7 min) after anesthetic induction were tested to assess robustness. RESULTS: This assay might have BoNT/A specificity, based on the CMAP amplitude recovery using a concentration of neutralizing antibodies. The calibration curves were linear over the range of 2-40 U/mL (R² = 0.982). The accuracy of 14 determinations was within the range of 89.8-118.6% compared to the theoretical values among 15 determinations, except one (131.3%). Assay variability was acceptable with coefficients of variation of 4.3-14.4%. The range of quantification and the LOQ were 4-40 U/mL and 4 U/mL, respectively. Different body weights and measurement times after inducing anesthesia had no effect on CMAP amplitude. CONCLUSIONS: These results suggest that the mouse CMAP assay is an alternative method to the standard LD50 potency test and meets the requirement of the three Rs (particularly refinement and reduction).