Prognosing post-treatment outcomes of head and neck cancer using structured data and machine learning: A systematic review.

BACKGROUND: This systematic review aimed to evaluate the performance of machine learning (ML) models in predicting post-treatment survival and disease progression outcomes, including recurrence and metastasis, in head and neck cancer (HNC) using clinicopathological structured data. METHODS: A systematic search was conducted across the Medline, Scopus, Embase, Web of Science, and Google Scholar databases. The methodological characteristics and performance metrics of studies that developed and validated ML models were assessed. The risk of bias was evaluated using the Prediction model Risk Of Bias ASsessment Tool (PROBAST). RESULTS: Out of 5,560 unique records, 34 articles were included. For survival outcome, the ML model outperformed the Cox proportional hazards model in time-to-event analyses for HNC, with a concordance index of 0.70-0.79 vs. 0.66-0.76, and for all sub-sites including oral cavity (0.73-0.89 vs. 0.69-0.77) and larynx (0.71-0.85 vs. 0.57-0.74). In binary classification analysis, the area under the receiver operating characteristics (AUROC) of ML models ranged from 0.75-0.97, with an F1-score of 0.65-0.89 for HNC; AUROC of 0.61-0.91 and F1-score of 0.58-0.86 for the oral cavity; and AUROC of 0.76-0.97 and F1-score of 0.63-0.92 for the larynx. Disease-specific survival outcomes showed higher performance than overall survival outcomes, but the performance of ML models did not differ between three- and five-year follow-up durations. For disease progression outcomes, no time-to-event metrics were reported for ML models. For binary classification of the oral cavity, the only evaluated subsite, the AUROC ranged from 0.67 to 0.97, with F1-scores between 0.53 and 0.89. CONCLUSIONS: ML models have demonstrated considerable potential in predicting post-treatment survival and disease progression, consistently outperforming traditional linear models and their derived nomograms. Future research should incorporate more comprehensive treatment features, emphasize disease progression outcomes, and establish model generalizability through external validations and the use of multicenter datasets.

Factors associated with the use of oral health care services among Canadian children and youth.

Background: This study investigates the association between dental insurance, income, and dental care access for Canadian children and youth aged 1 to 17 years. It contributes to a baseline understanding of oral health care use before the implementation of the Canadian Dental Care Plan (CDCP). Data and methods: This study used data from the 2019 Canadian Health Survey on Children and Youth (n=47,347). Descriptive statistics and logistic regression models were employed to assess the association of dental insurance, adjusted family net income, and other sociodemographic factors on oral health care visits and cost-related avoidance of oral health care. Results: A large percentage of children under the age of 5 had never visited a dentist (79.8% of 1-year-olds to 16.4% of 4-year-olds). Overall, 89.6% of Canadian children and youth aged 5 to 17 had visited a dental professional within the past 12 months: 93.1% of those who were insured and 78.5% of those who were uninsured. Insured children and youth had a 4.5% cost-related avoidance of dental care, contrasting with 23.3% for uninsured children and youth. After adjustment for sociodemographic variables, children and youth with dental insurance were nearly three times more likely (odds ratio [OR]: 2.94; 95% confidence interval [CI]: 2.60 to 3.33) to have visited a dental professional in the past 12 months than uninsured children and youth. Having dental insurance (OR: 0.19; 95% CI: 0.16 to 0.21) was protective against barriers to seeing a dental professional because of cost. There was a strong income gradient for both dental service outcomes. Interpretation: The study emphasizes the significant association of dental insurance and access to oral health care for children and youth. It highlights a significant gap between insured and uninsured children and youth and points out the influence of sociodemographic and income factors on this disparity.

Assessing the role of dental insurance in oral health care disparities in Canadian adults.

Background: This study examines the association of dental insurance with oral health care access and utilization in Canada while accounting for income and sociodemographic factors. It contributes to a baseline of oral health care disparities before the implementation of the Canadian Dental Care Plan (CDCP). Data and methods: This retrospective study of Canadians aged 18 to 64 years is based on data from the 2022 Canadian Community Health Survey. Multivariable logistic regression was employed to evaluate the association of dental insurance with the recency and frequency of dental visits, as well as avoidance of dental care because of cost. Results: Overall, 65.7% of Canadians reported visiting a dental professional in the previous year: 74.6% of those with private insurance, 62.8% with public insurance, and 49.8% uninsured. Cost-related avoidance of dental care was 16.0%, 20.9%, and 47.4% for the privately insured, publicly insured, and uninsured, respectively. After adjustment, adults with private (odds ratio [OR]=2.54; 95% confidence interval [CI]: 2.32 to 2.78) and public (OR=2.17; 95% CI: 1.75 to 2.68) insurance were more likely to have visited a dental professional in the last year compared with those without insurance. Similarly, both private (OR=0.22; 95% CI: 0.20 to 0.25) and public (OR=0.22; 95% CI: 0.17 to 0.29) insurance holders showed a significantly lower likelihood of avoiding dental visits because of cost when compared with uninsured individuals. Interpretation: This study showed the significant association of dental insurance with access to oral health care in Canada, contributing to setting a critical benchmark for assessments of the CDCP's effectiveness in addressing oral health disparities.

Non-cannulated versus cannulated cancellous screws for the internal fixation of femoral neck fractures in osteoporotic patients: A single-blind randomized clinical trial.

Background: The incidence of femoral neck fractures in osteoporotic patients is rising worldwide and is associated with significant increases in healthcare and social costs, as well as dependency. Improving minimally invasive treatment strategies, including internal fixation with screws, can result in favorable clinical outcomes and lesser incidence of complications, while preserving the hip. This study compared the outcomes of using non-cannulated cancellous screws (NCS) and cannulated cancellous screws (CS) in the internal fixation of undisplaced intracapsular femoral neck fractures (UIFNF) of osteoporotic patients of Iranian descent. Methods: This randomized clinical trial was conducted on the patients referring to an institutional tertiary hospital in northwestern Iran between March 2020 and June 2021. The patients' preoperative, perioperative, and postoperative characteristics were evaluated for at least two years. Primary endpoints were defined as the incidence of hip-related complications, while secondary endpoints were assessed based on the patients' hip function using Harris Hip Score (HHS). Results: Fifty-seven patients with osteoporosis and UIFNF were included in the final analysis, with 27 patients in the NCS group and 30 patients in the CS group. The surgical duration, the amount of intraoperative blood loss, and the frequency of C-arm were considerably lower in the CS group (p < 0.05). The incidence of implant failure was higher in the NCS group (p = 0.04). Screw migration occurred more frequently in the CS group (p = 0.03). The HHS values were significantly higher for the NCS group than those of the CS group at both the 1-year and 2-years of follow-up assessments (1 year, p = 0.007; 2 years, p = 0.001). Conclusion: Fixation using CS was accompanied by enhanced perioperative outcomes and lower implant failure rates compared to the NCS group. However, patients in the NCS group posed a reduced risk of complications, including screw migration, and experienced a long-term improvement in HHS scores.

Active learning in undergraduate classroom dental education- a scoping review.

INTRODUCTION: Previous reviews on active learning in dental education have not comprehensibly summarized the research activity on this topic as they have largely focused on specific active learning strategies. This scoping review aimed to map the breadth and depth of the research activity on active learning strategies in undergraduate classroom dental education. METHODS: The review was guided by Arksey & O'Malley's multi-step framework and followed the PRISMA Extension Scoping Reviews guidelines. MEDLINE, ERIC, EMBASE, and Scopus databases were searched from January 2005 to October 2022. Peer-reviewed, primary research articles published in English were selected. Reference lists of relevant studies were verified to improve the search. Two trained researchers independently screened titles, abstracts, and full-texts articles for eligibility and extracted the relevant data. RESULTS: In total, 93 studies were included in the review. All studies performed outcome evaluations, including reaction evaluation alone (n = 32; 34.4%), learning evaluation alone (n = 19; 20.4%), and reaction and learning evaluations combined (n = 42; 45.1%). Most studies used quantitative approaches (n = 85; 91.3%), performed post-intervention evaluations (n = 70; 75.3%), and measured student satisfaction (n = 73; 78.5%) and knowledge acquisition (n = 61; 65.6%) using direct and indirect (self-report) measures. Only 4 studies (4.3%) reported faculty data in addition to student data. Flipped learning, group discussion, problem-based learning, and team-based learning were the active learning strategies most frequently evaluated (≥6 studies). Overall, most studies found that active learning improved satisfaction and knowledge acquisition and was superior to traditional lectures based on direct and indirect outcome measures. CONCLUSION: Active learning has the potential to enhance student learning in undergraduate classroom dental education; however, robust process and outcome evaluation designs are needed to demonstrate its effectiveness in this educational context. Further research is warranted to evaluate the impact of active learning strategies on skill development and behavioral change in order to support the competency-based approach in dental education.

Detecting dental caries on oral photographs using artificial intelligence: A systematic review.

OBJECTIVES: This systematic review aimed at evaluating the performance of artificial intelligence (AI) models in detecting dental caries on oral photographs. METHODS: Methodological characteristics and performance metrics of clinical studies reporting on deep learning and other machine learning algorithms were assessed. The risk of bias was evaluated using the quality assessment of diagnostic accuracy studies 2 (QUADAS-2) tool. A systematic search was conducted in EMBASE, Medline, and Scopus. RESULTS: Out of 3410 identified records, 19 studies were included with six and seven studies having low risk of biases and applicability concerns for all the domains, respectively. Metrics varied widely and were assessed on multiple levels. F1-scores for classification and detection tasks were 68.3%-94.3% and 42.8%-95.4%, respectively. Irrespective of the task, F1-scores were 68.3%-95.4% for professional cameras, 78.8%-87.6%, for intraoral cameras, and 42.8%-80% for smartphone cameras. Limited studies allowed assessing AI performance for lesions of different severity. CONCLUSION: Automatic detection of dental caries using AI may provide objective verification of clinicians' diagnoses and facilitate patient-clinician communication and teledentistry. Future studies should consider more robust study designs, employ comparable and standardized metrics, and focus on the severity of caries lesions.

The relationship between nitrous oxide sedation and psychosocial factors in the pediatric outpatient setting.

BACKGROUND: Moderate sedation using nitrous oxide (N2 O) has become common in pediatric dentistry. However, less is known regarding the role of patients' characteristics and psychosocial factors in their cooperative behavior during dental procedures with N2 O. AIMS: This study aimed to examine pediatric dental patients' behaviors while undergoing N2 O sedation and to measure the associations between child's cooperative behavior and demographic, physiological responses, and psychosocial factors. METHODS: In this within-subject observational study, participants received 40% N2 O/O2 , by nasal hood, for non-surgical dental procedures. The main outcome measure was the extent of cooperative behaviors, as assessed by the Frankl scale at five timepoints, namely T1: pre-administration of N2 O, T2: post-administration of N2 O, T3: dental injection, T4: dental treatment, and T5: post-procedure administration of 100% O2 . Predictors included age, sex, psychosocial factors reported using the Parenting Style and Dimension Questionnaire and Spence Children Anxiety Scale, as well as pulse rate, respiratory rate, and oxygen saturation. The Wilcoxon signed-rank test and generalized estimation equation were used for data analyses. RESULTS: In 80 children with a mean age of 7.2 (2.2) years, administration of N2 O was significantly associated with cooperative behaviors (odds ratio [OR]:2.62, confidence interval [CI]: 1.46-4.70, p = .001) when adjusted for other predictors. There was no interaction between any of the predictors and N2 O sedation on behaviors. Except for the authoritative parenting style (OR: 1.96, CI: 1.16-3.31, p = .012), which predicted more cooperative behaviors, other predictors were not associated with behavioral outcomes. CONCLUSION: In children sedated with N2 O, behavior was independent of the child's demographic and psychosocial factors. While sedated, demographics, vital signs, and anxiety did not contribute to behavior management. However, screening for parenting style may help predict the child's behavioral response.

Frequency and pattern of outpatient dental visits during the COVID-19 pandemic at hospital and community clinics.

BACKGROUND: The authors aimed to measure the frequency of dental visits before and during the COVID-19 pandemic and to evaluate whether dental visits can be predicted from demographic characteristics, socioeconomic status, oral problem diagnoses, and dental service providers. METHODS: Participants for this retrospective study were patients visiting dental care providers at hospital- and community-based outpatient clinics in Alberta, Canada. Data were retrieved from electronic databases from March 12, 2020, through September 30, 2020, and from the same period for 2018 and 2019. The COVID-19 lockdown was declared for March 12 through May 14, 2020. Data were analyzed using analysis of variance test and multiple logistic regression at α = 0.05. RESULTS: From a total of 14,319 dental visits, 5,671, 5,036, and 3,612 visits occurred in 2018, 2019, and 2020, respectively. The mean (standard deviation) frequency of daily visits was 36.69 (15.64), 32.09 (15.51), and 24.24 (14.78), respectively. Despite the overall decrease, the frequency of visits for infections, salivary problems, and temporomandibular disorders increased during the COVID-19 pandemic in 2020. Dental visits during the pandemic were associated with more complicated oral diagnoses and dental services as well as higher economic status. CONCLUSIONS: During the COVID-19 pandemic, the frequency of dental visits decreased specifically during lockdown. Patients with complicated problems requiring urgent treatments mainly visited dental clinics. Reduced access to care was observed primarily among socially disadvantaged groups. PRACTICAL IMPLICATIONS: Although guidelines and related recommendations have been effective in restoring the compromised dental system during the COVID-19 pandemic, additional modifications are needed to promote in-person visits to improve the oral health status of patients.

Oral health status of individuals with obsessive-compulsive disorder considering oral hygiene habits.

AIMS: This study aimed to evaluate the oral health status of individuals with obsessive-compulsive disorder (OCD). METHODS: Ninety-two participants, aged 18 years and older from which 46 had OCD symptoms, were included in this comparative cross-sectional study. Data on age, sex, smoking habit, educational level, and potential mediators including brushing frequency (BF) and brushing duration (BD) were collected. Clinical examinations determined outcome measures including decayed-missing-filled teeth (DMFT), presence of root caries (PoRC), gingival recession (GR), plaque index (PI), and papillary bleeding index (PBI). Pathway analysis was used for data analysis. RESULTS: Individuals with OCD had significantly lower DMFT (p < .01), higher BF (p = .01), and lower PI (p = .01); however, there were no significant differences regarding BD, GR, PBI, and PoRC (p > .05). While BD did not have a mediating role, BF mediated the effect of OCD on DMFT (B = -0.31, CI = -0.60 to -0.06) and PI (B = -0.15, CI = -0.36 to -0.03). Males had less PI (B = -1.03, CI = -1.81 to -0.24) and PBI (B = -1.14, CI = -2.09 to 0.20) than females. Except for OCD and sex, other predictors were not significant. CONCLUSIONS: Individuals with OCD had lower caries experience and similar gingival health compared to controls. Part of the impact of OCD was mediated through brushing habits.

Association of Internet Addiction with Emotional and Behavioral Characteristics of Adolescents.

Objective: This study aimed to measure the prevalence of internet addiction and its impact on the psychological well-being of adolescents in Tehran, considering the sociodemographic characteristics. Method : In this cross sectional study, a total of 945 (mean age of 14.85) students (522 boys and 423 girls) were recruited by 2-stage clustering sampling method in 2017. The Chen Internet Addiction Scale (CIAS) and Youth Self-Report (YSR) were used to measure internet addiction and psychological characteristics, respectively. The data were analyzed using multiple-logistic regression analysis adjusted for internet addiction and sociodemographic variables. Results: Overall, 20% of the adolescents were internet addicts. Gender, consanguineous marriage, and father's education level were significantly associated with internet addiction. Regarding emotional and behavioral characteristics, internet addiction was significantly associated with the scores of internalizing (OR = 5.03; 95% CI: 3.05-8.28) and externalizing problems (OR = 5.84; 95% CI: 3.61-9.43), the total score of empirical scales (OR = 6.51; 95% CI: 3.71-11.6), and all DSM-oriented scales of the YSR (p < 0.001). Except for school performance, other competency scales had no correlations with internet addiction. Conclusion: Regarding the high prevalence of the internet addiction and its correlation with emotional and behavioral characteristics, students and their parents should be advised of the detrimental impacts of internet addiction and try to focus on its constructive application.

How adjustment could affect internal and marginal adaptation of CAD/CAM crowns made with different materials.

PURPOSE: Recently introduced hybrid and reinforced glass ceramic computer-aided design/computer-aided manufacturing (CAD/CAM) materials have been used for full-coverage restorations. However; the effect of adjustment and type of materials on internal and marginal adaptation are unknown. This study aimed to evaluate and compare the marginal and internal adaptations of crowns made of three different CAD/CAM materials before and after adjustment. MATERIALS AND METHODS: One acrylic resin maxillary first molar was prepared and served as the master die. Thirty-six restorations were fabricated using CAD/CAM system (CEREC Omnicam, MCXL) with three materials including lithium disilicate (IPS e.max CAD), zirconia-reinforced lithium silicate (Suprinity), and hybrid ceramic (Enamic). Internal and marginal adaptations were evaluated with the reference point matching technique before and after adjustment. The data were analyzed using mixed ANOVA considering α=.05 as the significance level. RESULTS: The effect of adjustment and its interaction with the restoration material were significant for marginal, absolute marginal, and occlusal discrepancies (P<.05). Before adjustment, Suprinity had lower marginal discrepancies than IPS e.max CAD (P=.18) and Enamic (P=.021); though no significant differences existed after adjustment. CONCLUSION: Within the limitations of this study, crowns fabricated from IPS e.max CAD and Suprinity resulted in slightly better adaptation compared with Enamic crowns before adjustment. However, marginal, axial, and occlusal discrepancies were similar among all materials after the adjustment.

Adaptation and Retention of Conventional and Digitally Fabricated Posts and Cores in Round and Oval-Shaped Canals.

PURPOSE: To compare the adaptation of conventional cast posts and cores to digitally milled counterparts in round and oval-shaped canals and to evaluate the retention of the milled posts. MATERIALS AND METHODS: One cast post and one milled post were fabricated for each of the 26 selected teeth, which had either round or oval-shaped canals. The apical gap was evaluated with radiography, and coronal adaptation was evaluated by weighing the silicon wash trapped between the post and canal wall and also by comparing the volumes of the stereolithographic models. The milled posts were cemented with self-curing glass-ionomer, and the pullout test was performed to evaluate retention. A two-way analysis of variance and independent t test were used for statistical analyses, with α = .05. RESULTS: Conventional cast posts and cores revealed significantly higher coronal adaptation and less apical gap than the milled groups (P < .001), irrespective of the type of canal. Within the milled groups, there was no significant difference between the coronal adaptation of posts in the round and oval canals. On the contrary, the apical gap of milled posts was the least in the round canals (P = .024). The pull-out test revealed no statistically significant difference between the milled posts in the round and oval canals (P = .0864). CONCLUSION: Conventional cast posts and cores revealed significantly better adaptation compared to the milled group. However, the adequate adaptation of the milled posts to the coronal portions of the canals provided tolerable retention. Nevertheless, clinicians should be cautious with the application of the scan posts, particularly in oval canals, as they could result in a large apical gap.

Effect of 5 Popular Disinfection Methods on Microflora of Laboratory: Customized Implant Abutments.

PURPOSE: To compare the efficacy of 5 different decontamination methods of titanium abutments and to assess their possible effects on surface roughness of titanium. MATERIALS AND METHODS: Micrococcus luteus, Acinetobacter baumannii, Enterococcus faecalis, and Candida albicans were cocultured to form a multispecies biofilm on 18 titanium discs. In another group, Bacillus subtilis, a spore-forming species, was cultivated on another set of 18 titanium discs. Each group was further divided into 5 test groups: high-pressure steam cleaning (4 Mpa, 5 seconds), NaOCl (1% active chlorine, 5 minutes), H2O2 (3%, 5 minutes), GaAlAs laser (810 nm, CW, 1 W, 400-µm fiber, 1-mm distance, 1 minute), Er:YAG laser (2940 nm, pulse mode, 100 mJ, 10 Hz, 230-µm noncontact handpiece, 4-mm distance, 50/50% air/water, 1 minute), and a control group of no treatment. After each decontamination procedure, the remaining microbial load was reported as colony-forming unit/disc. To evaluate the effect of each treatment on titanium discs, surface roughness parameters including Sa, Sq, Ssk, Sku, Sal, and Sdr were measured at 6 points of each disc using an atomic force microscope. RESULTS: Complete disinfection was achieved using high-pressure steam, NaOCl, H2O2, and Er:YAG laser. GaAlAs laser was able to reduce microbial count over 90%. Sa and Sq parameters were only increased significantly in diluted NaOCl group in comparison with control group, whereas Sdr was increased significantly in both absolute and diluted NaOCl groups. CONCLUSION: All the methods could decontaminate machined titanium surfaces, although complete microbial elimination was not achieved by diode laser. None of the treatments altered surface roughness significantly, except for sodium hypochlorite (NaOCl).

Mandibular Overdentures Supported by Two vs Four Endosteal Implants: A Retrospective Cohort Study.

AIM: Documentation of marginal bone resorption caused by implant-supported mandibular overdentures is scarce. This study sought to evaluate marginal bone resorption, survival rate, patient satisfaction, peri-implant soft tissue status, and prosthetic aftercare of mandibular overdentures supported by two vs four implants. MATERIALS AND METHODS: This retrospective cohort study evaluated 92 edentulous patients presented to the Implant Center of Tehran University of Medical Sciences; out of which, 46 patients received overdentures supported by two Implantium implants (group A), while the remaining 46 received overdentures supported by four Implantium implants (group B). Standard radiographic indices were assessed following the delivery of overdenture and after 2 years of functional loading. Clinical evaluation was performed after 2 years of function. Data were analyzed using the t test (for continuous variables) and the Mann-Whitney test (for ordinal variables). RESULTS: In group A, two implants were lost in one patient. The groups were not significantly different in terms of clinical or radiographic parameters (p > 0.05). Patient satisfaction and prosthetic aftercare were not significantly different in groups A and B (p > 0.05). CONCLUSIONS: During the 2-year evaluation period, the clinical and radiographic parameters were the same in patients who received overdentures supported by two or four implants. CLINICAL SIGNIFICANCE: Successful results may be obtained by the use of mandibular overdentures supported by two or four implants.

Graphene oxide incorporated polycaprolactone/chitosan/collagen electrospun scaffold: Enhanced osteogenic properties for bone tissue engineering.

This in vitro study aimed to evaluate the physicochemical and biological activity of the polycaprolactone/chitosan/collagen scaffolds incorporated with 0, 0.5, 3, and 6 wt% of graphene oxide (GO). Using standard tests and MG-63 cells, the characteristics of scaffolds were evaluated, and the behavior of osteoblasts were simulated, respectively. A non-significant decrease in nanofibers diameter was noted in scaffolds with a higher ratio of GO. The hydrophilicity and bioactivity of the scaffold surface, as well as cell attachment and proliferation, increased in correspondence to an increase in GO. The higher ratio of GO also improved the osteogenesis activity. GO increased the degradation rate, but it was negligible and seemed not enough to endanger stability. Modifying the scaffolds with GO did not make a significant change to the antibacterial effect.

Effects of air abrasive decontamination on titanium surfaces: A systematic review of in vitro studies.

BACKGROUND: Air abrasion (AA) is one of the decontamination methods that have demonstrated promising results in treating peri-implant diseases. PURPOSE: This systematic review aimed at evaluating the in vitro effect of AA on surface change, cleaning efficacy, and biocompatibility of titanium surfaces and at comparing it with other decontamination methods. MATERIALS AND METHODS: A comprehensive search was conducted up to April 2018 using PubMed, Scopus, and Google Scholar databases to identify studies on the decontamination effect of AA. All types of titanium surfaces, abrasive powders, contaminated surfaces, and measuring methods were included. RESULTS: Overall, 1502 articles were identified. After screening the titles and abstracts, and carefully reading the full-texts, 48 articles published between 1989 and 2018 were selected. AA was considered almost safe, particularly for the nonmodified surfaces. Nevertheless, harder powders such as sodium bicarbonate tended to damage the surface more than glycine. AA resulted in surface change similar to plastic curettes and Er: YAG lasers. Regarding the cleaning efficacy, there was no significant difference between glycine and sodium bicarbonate, but different mixtures of calcium phosphate, hydroxyapatite, and erythritol were superior to glycine. AA was superior or equal to all other decontamination methods in cleaning. Regarding biocompatibility, AA was more successful in preserving biocompatibility for noncontaminated surfaces compared with contaminated surfaces and when used with erythritol and osteoinductive powders. CONCLUSIONS: AA can efficiently remove contamination without serious damage to the surface. The main drawback of the AA method seems to be its limitation in restoring the biocompatibility of the surface.

The effect of conventional, half-digital, and full-digital fabrication techniques on the retention and apical gap of post and core restorations.

STATEMENT OF PROBLEM: Conventional cast metal posts and cores are fabricated using direct and indirect techniques, both of which need impression materials and considerable laboratory work. Digital techniques have the capacity to substitute for conventional methods in fabricating the posts and cores. However, the accuracy of restorations resulting from a digital workflow is unknown. PURPOSE: The purpose of this in vitro study was to compare the retention of posts and cores fabricated using full-digital, half-digital, and conventional techniques and to define the accuracy of each technique in terms of the apical gap. METHOD AND MATERIALS: Thirty newly extracted mandibular first and second premolar teeth were selected for this in vitro study. Impressions were made using direct acrylic resin patterns (conventional), indirect silicone impressions of the intracanal which scanned with a 3Shape laboratory scanner (half digital), and intracanal scan posts captured with an intraoral 3Shape scanner (full digital). Casting and milling were conducted for the conventional impression and digital scans. The obtained posts were cemented using zinc phosphate cement. A universal pullout test was used to measure retention at a crosshead speed of 0.5 mm/min. The apical gap of each post in the canals was defined with parallel digital radiography. The data were analyzed using the Kruskal-Wallis test (α=.05) and Mann-Whitney test at the adjusted α=.016. RESULTS: Significant differences were found among the conventional, full-digital, and half-digital techniques in terms of the apical gap (0.11, 0.29, and 0.66 mm; P<.001) and retention (171.6 ±1.9, 107.1 ±5.6 and 91.8 ±6.6 N; P<.001). The correlation between gap and retention in conventional (P=.43), full-digital (P=.09), and half-digital techniques (P=.06) was not statistically significantly different. CONCLUSIONS: The conventional technique was more accurate and resulted in higher retention than both the full- and half-digital techniques. However, the retention and gap of all the posts fell within clinical guidelines.

Evaluating the effect of photobiomodulation with a 940-nm diode laser on post-operative pain in periodontal flap surgery.

The aim of this study was to evaluate the efficacy of low-power of 940-nm diode laser on post-operative pain after undisplaced flap surgery. This randomized clinical trial study was conducted using a split-mouth design. The study participants comprised 30 patients who needed periodontal flap surgery for periodontal pockets on the same tooth on both sides of the mandible. One side of the mandible was subjected to undisplaced flap surgery plus treatment with a 940-nm diode laser, and on the contralateral side, the surgery was conducted without applying the laser. Patients received anti-inflammatory medication and analgesics after surgery. The patients were asked to report the number of analgesics they took and the pain they experienced each night for 1 week using a visual analogue scale. An independent-sample t test was used to compare the results between the two groups. Patients reported less pain on days 2, 3, 4, 5, 6, and 7 after surgery in the laser-treated group (p < 0.05). Furthermore, fewer analgesics were used in this group on days 3, 4, 5, 6, and 7 following the surgery (p < 0.05). The 940-nm diode laser with the settings used in this study could significantly reduce pain and the number of analgesics taken by patients after undisplaced flap surgery.

The Esthetic Crown Lengthening by Er;Cr:YSGG laser: A Case Series.

Introduction: Laser technology as a new modality in dentistry has gained special attention. Among different types of lasers, erbium lasers have gained special attention for management of oral soft and hard tissue simultaneously. This study presents series of cases of crown lengthening (CL) and restorations accomplished by erbium, chromium: yttrium-scandium-gallium-garnet (Er,Cr:YSGG). Case Reports: Seven patients were selected for this study. After complete oral examination and diagnosis, the treatment plan of each patient was designed. All cases needed esthetic CL. In some cases, frenum revision and class V cavity preparation was done by Er;Cr:YSGG laser. All patients treated with Er;Cr:YSGG laser producing a wavelength of 2780 nm (Biolase, Irvine, California, USA); Tip T4, 400 µm Diameter for soft tissue management and Tip G6, 6 mm long, 600 µm diameter for hard tissue management. Results: All patients reflected acceptable results based on clinical evaluation and patients' declaration of post-surgical status. Conclusion: Using Er;Cr:YSGG laser in class v cavity preparation and flapless CL seemed to be effective and beneficial.

Microflora of Laboratory-Customized Dental Implant Abutments.

OBJECTIVE: This study aimed to detect and categorize the microorganisms of customized abutments returned from laboratories due to probable contamination and their role in peri-implantitis. METHODS: The samples included 202 abutments from 10 laboratories. Ten µL aliquots obtained from the microbial suspension of each abutment were inoculated on sheep blood agar (as non-selective enriched media), MacConkey agar (selective media for Gram-negative bacteria), Columbia agar with colistin and nalidixic acid agar (selective media for Gram-positive bacteria) and Sabouraud Dextrose Agar with antibiotics (selective media for fungi). They were then incubated in an aerobic atmosphere at 37°C. The molecular methods based on 16S rRNA gene sequence analysis were used in the identification of isolates that did not fi t with any recognized biochemical profi les. The distribution of qualitative variables was presented numerically and according to frequency. Complex sample analysis with a 95% confidential interval was used for analysis. RESULTS: The results showed that the mean number of teeth increased in the more recent study: for the age category 35 - 44 years, this increased from 19.2 to 23.8 teeth; however, both studies described a signifi cant decrease in the number of teeth at later ages. Values for the extent and severity index were high in both studies. A larger proportion of subjects was affected by mild and generalized attachment loss in the new study, but the percentages of participants affected by moderate and severe attachment loss were similarFrom a total of 49 detected microorganisms, 44 were aerobic bacteria and 5 were fungi. Micrococcus luteus, Bacillus subtilis, Staphylococcus epidermis and Candida (the dominant genus among fungi) were the dominant species observed in samples from all 10 laboratories, and on average presented on 13.7, 6.2, 5.0 and 4.1 abutments, respectively. The most abundant Gram-positive and Gram-negative bacteria were M. luteus and Acinetobacter baumannii, respectively. B. subtilis was the most common bacillus, and M.luteus was the most common coccus. CONCLUSION: Certain decontamination protocols and regulations must be defined to eliminate bacteria and fungi, as both were present in samples from all of the laboratories.