Systematic review on effects of experimental orthodontic tooth displacement on brain activation assessed by fMRI.

BACKGROUND: Orthodontic treatment is often accompanied by discomfort and pain in patients, which are believed to be a result of orthodontic tooth displacement caused by the mechanical forces exerted by the orthodontic appliances on the periodontal tissues. These lead to change blood oxygen level dependent response in related brain regions. OBJECTIVE: This systematic review aims to assess the impact of experimental orthodontic tooth displacement on alterations in central nervous system activation assessed by tasked based and resting state fMRI. MATERIALS AND METHODS: A literature search was conducted using online databases, following PRISMA guidelines and the PICO framework. Selected studies utilized magnetic resonance imaging to examine the brain activity changes in healthy participants after the insertion of orthodontic appliances. RESULTS: The initial database screening resulted in 791 studies. Of these, 234 were duplicates and 547 were deemed irrelevant considering the inclusion and exclusion criteria. Of the ten remaining potential relevant studies, two were excluded during full-text screening. Eight prospective articles were eligible for further analysis. The included studies provided evidence of the intricate interplay between orthodontic treatment, pain perception, and brain function. All of the participants in the included studies employed orthodontic separators in short-term experiments to induce tooth displacement during the early stage of orthodontic treatment. Alterations in brain activation were observed in brain regions, functional connectivity and brain networks, predominantly affecting regions implicated in nociception (thalamus, insula), emotion (insula, frontal areas), and cognition (frontal areas, cerebellum, default mode network). CONCLUSIONS: The results suggest that orthodontic treatment influences beyond the pain matrix and affects other brain regions including the limbic system. Furthermore, understanding the orthodontically induced brain activation can aid in development of targeted pain management strategies that do not adversely affect orthodontic tooth movement. Due to the moderate to serious risk of bias and the heterogeneity among the included studies, further clinical trials on this subject are recommended.

Effect of an endodontic e-learning application on students' performance during their first root canal treatment on real patients: a pilot study.

BACKGROUND: E-learning has found its way into dental teaching in general and endodontic teaching in particular. The present study aimed to implement a newly developed multimedia learning application and assess its effect on students' first root canal treatment on real patients. With the COVID-19 outbreak, the application's performance was investigated during the pandemic. METHODS: A total of 138 students in the initial clinical endodontic course participated in this study. The control group (n = 49) followed the traditional curriculum, including practice on artificial teeth and face-to-face teaching events. In addition to the traditional curriculum, test group 1 (n = 54) had access to an endodontic e-learning application containing videos demonstrating artificial teeth and patient cases. With the COVID-19 outbreak, test group 2 (n = 35) had no face-to-face teaching; however, endodontic patient treatments were included. The quality of students' first root canal treatment on real patients was compared using performance and radiographic assessment items. Statistical analysis was done using Kruskal-Wallis and chi-squared tests. Test groups received a questionnaire to assess the learning application. Test group 2 also completed a COVID-19-specific survey to measure students' perceptions of how the pandemic affected their endodontic education. RESULTS: The results of endodontic treatments were significantly better for test group 1 (P < 0.001) and 2 (P < 0.001) than for the control group. Likewise, there were significantly fewer treatment errors in test group 1 (P < 0.001) and 2 (P < 0.001). No significant differences were found between test groups 1 and 2. Students of the test groups positively evaluated the e-learning application. Students of test group 2 expressed their fear of negative impacts on their course performance. CONCLUSION: The e-learning application was well-received and seemed to improve endodontic education. The results imply that the quality of education may be maintained by implementing e-learning to compensate for face-to-face teaching. As no difference was found between online and face-to-face teaching, students' and lecturers' concerns that endodontic education is suffering because of the pandemic may be eased.

Expertise Modulates Students' Perception of Pain From a Self-Perspective: Quasi-Experimental Study.

BACKGROUND: Perception of stimuli presented in a virtual dentistry environment affects regions of the brain that are related to pain perception. OBJECTIVE: We investigated whether neural correlates of virtual pain perception are affected by education in dentistry. METHODS: In this functional magnetic resonance imaging study, a sample of 20 dental students and 20 age-matched controls viewed and listened to video clips presenting a dental treatment from the first-person perspective. An anxiety questionnaire was used to assess the level of dental anxiety. Neural correlates of pain perception were investigated through classic general linear model analysis and in-house classification methods. RESULTS: Dental students and naïve controls exhibited similar anxiety levels for invasive stimuli. Invasive dentistry scenes evoked a less affective component of pain in dental students compared with naïve controls (P<.001). Reduced affective pain perception went along with suppressed brain activity in pain matrix regions including the insula, anterior cingulate cortex, and basal ganglia. Furthermore, a substantial reduction of brain activity was observed in motor-related regions, particularly the supplementary motor area, premotor cortex, and basal ganglia. Within this context, a classifier analysis based on neural activity in the nucleus lentiformis could identify dental students and controls on the individual subject level in 85% of the cases (34 out of 40 participants, sensitivity=90%, specificity=80%). CONCLUSIONS: Virtual dental treatment activates pain-related brain regions in controls. By contrast, dental students suppress affective and motor-related aspects of pain. We speculate that dental students learn to control motoric aspects of pain perception during their education because it is a prerequisite for the professional manual treatment of patients. We discuss that a specific set of learning mechanisms might affect perceived self-efficacy of dental students, which in turn might reduce their affective component of pain perception.

Combination of Ultrasonic Decontamination, Soft Tissue Curettage and Submucosal Air Polishing With Povidone-Iodine Application for Non-Surgical Therapy of Peri-Implantitis: 12 Months Clinical Outcomes.

BACKGROUND: The aim of this study was to evaluate the clinical outcomes of a concept for non-surgical peri-implantitis combining stepwise mechanical debridement measures with adjuvant Povidone-iodine application with and without systemic antibiotics. METHODS: 45 patients with chronic periodontitis comprising 164 screw-typed implants with peri-implantitis were included. Peri-implantitis was defined as radiographic bone loss of >2 mm, probing pocket depth (PD) ≥5 mm with bleeding on probing (BOP). Stepwise treatment of implants was performed with ultrasonic debridement, soft tissue curettage (STC), glycine powder air polishing (GPAP) and a repeated submucosal application of Povidone-iodine. Teeth with PD >4mm were treated simultaneously according to the same concept except STC. In cases with severe periodontitis (N = 24), amoxicillin and metronidazole (AM) were prescribed for 7 days. RESULTS: After 12 months, implants treated without AM showed significant reductions (p<0.05) of mean PD (1.4 ± 0.7 mm), CAL (1.3 ± 0.8 mm) and BOP (33.4 ± 17.2%). In deep pockets (PD >6mm) changes of mean PD (2.3 ± 1.3 mm), CAL (2.0 ± 1.6 mm) and BOP (44.0 ± 41.7%) were more pronounced. Intake of AM did not significantly influence the changes of these parameters. However, the reduction of implant sites with PD >4 mm and BOP was significantly higher in patients with AM than in those without AM (31.8 ± 12.6% vs. 20.8 ± 14.7%; p<0.05). CONCLUSIONS: The combination of ultrasonic debridement, STC and GPAP with adjuvant Povidone-iodine led to significant clinical improvements at implants. Systemic antibiotics had limited effects on the reduction of persisting implant sites with treatment need.

Assessment of lingual nerve functions after smoking cessation.

OBJECTIVE: Cigarette smoking is associated with a variety of oral diseases. A previous study showed a reduction of thermal sensitivity in the innervation area of the lingual nerve in smokers possibly caused by a degeneration of thermosensitive receptors as a consequence of smoking. The current study investigates somatosensory changes in ex-smokers. MATERIALS AND METHODS: Sensory functions in innervation areas of lingual nerve were investigated in 40 ex-smokers by psychophysical means. Functions of lingual nerve in 40 ex-smokers were compared to those in 40 smokers and 40 non-smokers. Subjects were investigated using quantitative sensory testing (QST, cold and warm detection, thermal sensory limen, heat and cold pain, and mechanical detection). RESULTS: Significant differences were found in both groups, ex-smokers and smokers compared to non-smokers. Cold (p < .001), warm (ex-smokers: p < .01; smokers: p < .001) detection thresholds and thermal sensory limen (p < .001) showed significantly lower sensitivity in ex-smokers and smokers in comparison to non-smokers. CONCLUSIONS: The lower temperature sensitivity of ex-smokers compared to that in non-smokers indicates a reduction of somatosensory function of the tongue, possibly caused by irreversible nerve degeneration associated with smoking. Influencing factors leading to sensory changes could be modulation of thermo-receptors, demyelination as well as a change of the epithelial structure.

Evaluation of the anesthetic effect of epinephrine-free articaine and mepivacaine through quantitative sensory testing.

INTRODUCTION: Long lasting anesthesia of the soft tissue beyond the dental treatment affects patients in daily routine. Therefore a sophisticated local anesthesia is needed. The purpose of this study was an evaluation of the clinical use of epinephrine-free local anesthetic solutions in routine short-time dental treatments. MATERIALS AND METHODS: In a prospective, single-blind, non-randomized and controlled clinical trial, 31 patients (16 male, 15 female patients) undergoing short-time dental treatment under local anesthesia (plain solutions of articaine 4% and mepivacaine 3%) in area of maxillary canine were tested with quantitative sensory testing QST. Paired-Wilcoxon-testing (signed-rank-test) and Mc Nemar tests have been used for statistical results. RESULTS: Significant differences in all tested parameters to the time of measurements were found. Mepivacaine showed a significantly stronger impact for the whole period of measurement (128 min) on thermal and mechanical test parameters and to the associated nerve fibers. CONCLUSION: Plain articaine shows a faster onset of action associated with a shorter time of activity in comparison to plain mepivacaine. In addition to this articaine shows a significant low-graded effect on the tested nerve-fibers and therefore a least affected anesthesia to the patient. The clinical use of an epinephrine-free anesthetic solution can be stated as possible option in short dental routine treatments to the frequently used vasoconstrictor containing local anesthetics. Patients may benefit from shorter numbness.