DO ORAL CARE AND REHABILITATION IMPROVE COGNITIVE FUNCTION? A SYSTEMATIC REVIEW OF CLINICAL STUDIES.

OBJECTIVES: An increasing number of studies have identified an association between oral health status and cognitive function. However, the effect of oral interventions, including oral health care, dental treatment and oral motor exercises, on cognitive function remains unclear. This systematic review examined whether oral interventions contribute to the long-term improvement of cognitive status. METHODS: Four databases were searched (MEDLINE, Web of Science, Cochrane Library, and ICHUSHI Web) to identify randomized and nonrandomized controlled trial studies and prospective cohort studies from inception until 1 September 2023, published in English or Japanese. The Cochrane risk of bias tool for randomized controlled trials and the risk of bias assessment tool for nonrandomized studies were used to assess bias risk. RESULTS: A total of 20 articles were included in the qualitative analysis; 13 articles were published in English, and 7 were published in Japanese. The implemented interventions were oral care in 8 studies, dental treatment in 8 studies, and oral motor exercise in 4 studies. One study found a significant effect on attention following oral care intervention. Some dental treatments influenced cognitive function, although a clear positive effect was not determined. In 1 study, attention and working memory improved in the chewing exercise group. CONCLUSIONS: Several studies verified the improvement effects of oral interventions, such as oral care, dental treatment, and oral motor exercise, on cognitive function or impairment. However, there was still a lack of conclusive evidence that such an intervention clearly improved cognitive function. To clarify the effects of oral interventions on cognitive function, it is necessary to examine participants, interventions, and outcome measures in detail.

Clinical application of robots in dentistry: A scoping review.

PURPOSE: The surge in digitalization and artificial intelligence has led to the wide application of robots in various fields, but their application in dentistry started relatively late. This scoping review aimed to comprehensively explore and map the current status of the clinical application of robots in dentistry. STUDY SELECTION: An iterative approach was used to gather as much evidence as possible from four online databases, including PubMed, the China National Knowledge Infrastructure, the Japan Science and Technology Information Aggregator, Electronic, and the Institute of Electrical and Electronics Engineers, from January 1980 to December 2022. RESULTS: A total of 113 eligible articles were selected from the search results, and it was found that most of the robots were developed and applied in the United States (n = 56; 50%). Robots were clinically applied in oral and maxillofacial surgery, oral implantology, prosthodontics, orthodontics, endodontics, and oral medicine. The development of robots in oral and maxillofacial surgery and oral implantology is relatively fast and comprehensive. About 51% (n = 58) of the systems had reached clinical application, while 49% (n = 55) were at the pre-clinical stage. Most of these are hard robots (90%; n = 103), and their invention and development were mainly focused on university research groups with long research periods and diverse components. CONCLUSIONS: There are still limitations and gaps between research and application in dental robots. While robotics is threatening to replace clinical decision-making, combining it with dentistry to gain maximum benefit remains a challenge for the future.

Knowledge acquisition efficacy of a remote flipped classroom on learning about removable partial dentures.

PURPOSE: Coronavirus disease 2019 has forced the use of remote education worldwide. In 2020, the authors conducted a fully digitized, remote flipped (RF) classroom focusing on removable partial dentures. This study aimed to evaluate the learning outcomes of the RF classroom and compare these with those of the on-site classroom. METHODS: The fourth-year dental students in 2017-2019 attended on-site flipped classroom (OF; n=70) or on-site lecture classroom (OL; n=67), and those in 2020 (n=58) attended the RF classroom. Lecture videos and text were provided online in the OF and RF groups, while only the text was given to the OL group. Individual and group tests were conducted to assess knowledge acquisition one week after all the classes ended. A one-way analysis of variance following Tukey's test was performed to compare individual/group test scores among the OF, OL, and RF groups. Multilevel linear regression analysis was performed to identify the factors associated with an increase in each test score. RESULTS: The mean individual test scores in the RF and OF groups were significantly higher than in the OL group (P<0.01). The mean group test score in the RF group was significantly higher than in the OF and OL groups (P<0.001). The multilevel analysis identified remote and flipped classroom styles in the individual test, and the remote style in the group test, as significant effective factors in learning (P<0.05). CONCLUSIONS: These results suggest that the RF classroom is more effective than the on-site lecture in knowledge acquisition in undergraduate prosthodontic education.

Short-term effect of thermoplastic resin removable partial dentures on periodontal health: A randomized cross-over trial.

PURPOSE: This study aimed to compare the short-term effects of thermoplastic resin removable partial dentures (TR-RPDs), referred to as non-metal clasp dentures, with those of metal-clasp-retained RPDs (MC-RPDs) on the periodontal health of abutment teeth. METHODS: A randomized cross-over trial was conducted in 28 partially dentate patients. Participants were randomized into two groups and received MC-RPDs followed by TR-RPDs, or vice versa, for 3 months. Periodontal clinical parameters, such as the plaque index, gingival index, probing pocket depth, tooth mobility, and microbiological status of the abutment teeth, were evaluated at the delivery and 3 months after using each RPD. RESULTS: Of the 28 patients enrolled, 24 (mean age, 67.3 years) completed the trial, and 55 abutment teeth were evaluated. The periodontal condition of the abutment teeth did not deteriorate after 3 months of using both types of RPDs. There was no statistically significant difference in the plaque index, gingival index, probing pocket depth, tooth mobility, and the red complex bacteria between TR- and MC-RPDs (p >0.05). The Periotest value for TR-RPDs was significantly lower than that for MC-RPDs (p <0.05). However, this difference was not clinically significant. CONCLUSIONS: These results suggest that the influence of TR-RPDs on the periodontal health of abutment teeth was limited within 3 months of use.

A systematic review of digital removable partial dentures. Part I: Clinical evidence, digital impression, and maxillomandibular relationship record.

PURPOSE: This study comprehensively reviewed the current status of digital workflows in fabricating removable partial dentures (RPDs) using evidence from clinical trials and case reports. STUDY SELECTION: We performed a systematic review of the literature on the materials and fabrication of RPDs using digital technologies published in online databases from 1980 to 2020. We selected eligible articles from the search results, retrieved information on digital RPDs from these, and conducted a qualitative analysis. We report evidence from clinical papers and case reports, digital impression-taking methods, and maxillomandibular relationship (MMR) records. RESULTS: A case report electronically published in 2019 introduced a clasp-retained RPD fabricated via a full-digital workflow without a gypsum definitive cast. Computer-aided design and computer-aided manufacturing of double-crown-retained RPDs with nonmetal materials were described in some case reports. Intraoral scanners were used to obtain digital impressions and MMR records in the fabrication of digital RPDs, which have potential advantages for reducing the number of clinical appointments and simplifying laboratory procedures. Evidence from clinical trials is scarce; a randomized controlled trial reported higher patient satisfaction with digital clasp-retained RPDs than with conventional RPDs. CONCLUSIONS: Full-digital RPDs can be fabricated without a gypsum definitive cast. However, the indication for full-digital RPDs is limited to cases with Kennedy Class III/IV partially edentulous arches with several missing teeth. Challenges in digital impression-taking and MMR recording remain to be solved to extend these indications. More evidence from clinical trials is required to evaluate the efficacy and usefulness of digital RPDs.

A systematic review of digital removable partial dentures. Part II: CAD/CAM framework, artificial teeth, and denture base.

PURPOSE: This study comprehensively reviewed the current status of the digital workflow of removable partial dentures (RPDs) and summarized information about the fabrication methods and material properties of the dental framework, artificial teeth, and denture base. STUDY SELECTION: We performed a systematic review of the literature published in online databases from January 1980 to April 2020 regarding RPD fabrication and materials used in the related digital technology. We selected eligible articles, retrieved information regarding digital RPDs, and conducted qualitative/quantitative analyses. In this paper, the computer-aided design/computer-aided manufacturing (CAD/CAM) framework, artificial teeth, and denture base materials are reported. RESULTS: A variety of materials, such as cobalt-chromium alloy, titanium, zirconia, and polyether ether ketone, are used for dental CAD/CAM frameworks. The mechanical strength of the metal materials used for the CAD/CAM framework was superior to that of the cast framework. However, the fitness and surface roughness of the framework and clasp fabricated using a selective laser melting (SLM) method were not superior to those obtained via cast fabrication. Most material properties and the surface roughness of poly methyl methacrylate (PMMA) discs used for digital RPDs were superior to those of heat-cured PMMA. CONCLUSION: The use of a CAD/CAM framework and PMMA disc for digital RPDs offers numerous advantages over conventional RPDs. However, technical challenges regarding the accuracy and durability of adhesion between the framework and denture base remain to be solved. In digital fabrication, human technical factors influence the quality of the framework.

Multilevel factor analysis of flipped classroom in dental education: A 3-year randomized controlled trial.

PURPOSE: Previous studies have rarely attempted to test the confounding factors that may affect learning outcomes of the flipped classroom. The purpose of this study was to assess how flipped classrooms affect the acquisition of knowledge in clinical dental education based on multilevel factor analysis. METHOD: The authors conducted a 3-year (2017, 2018, and 2019) randomized controlled trial in a series of introductory prosthodontics courses in dental education. A total of 137 participants were randomly assigned to flipped classroom (n = 70, 51%) or lecture (n = 67, 49%) formats. The flipped group was instructed to self-learn knowledge-based content through online preparation materials, including videos and text, while the lecture group was given text only. Both groups were provided with the same study content and opportunities for different styles of learning. The session attendance rate and number of times the materials were accessed were monitored. Individual and team readiness assurance tests (IRAT/TRAT) were conducted to evaluate knowledge acquisition. A multilevel linear regression analysis was conducted on both instructional styles (flipped vs. lecture) as an intervention factor, and confounding factors that could affect the outcomes were implemented. RESULTS: The average number of online accesses was 2.5 times per session in the flipped group and 1.2 in the lecture group, with a significant difference (p < .05). The average IRAT score was significantly higher in the flipped than in the lecture group (effect size [ES] 0.58, p < .001). The number of online accesses was significantly and positively correlated with IRAT scores (0.6 [0.4, 0.8]). The instructional style was significantly and positively correlated with TRAT scores (coefficient [95% confidence interval]: 4.6 [2.0, 7.3]), but it was not correlated with IRAT (4.3 [-0.45, 9.0]). CONCLUSIONS: The flipped classroom was more effective than the lecture format regarding knowledge acquisition; however, the decisive factor was not the instructional style but the number of individual learning occasions. The employment of the flipped classroom was the decisive factor for team-based learning outcomes.

Adaptive brain activity changes during tongue movement with palatal coverage from fMRI data.

Successful adaptation to wearing dentures with palatal coverage may be associated with cortical activity changes related to tongue motor control. The purpose was to investigate the brain activity changes during tongue movement in response to a new oral environment. Twenty-eight fully dentate subjects (mean age: 28.6-years-old) who had no experience with removable dentures wore experimental palatal plates for 7 days. We measured tongue motor dexterity, difficulty with tongue movement, and brain activity using functional magnetic resonance imaging during tongue movement at pre-insertion (Day 0), as well as immediately (Day 1), 3 days (Day 3), and 7 days (Day 7) post-insertion. Difficulty with tongue movement was significantly higher on Day 1 than on Days 0, 3, and 7. In the subtraction analysis of brain activity across each day, activations in the angular gyrus and right precuneus on Day 1 were significantly higher than on Day 7. Tongue motor impairment induced activation of the angular gyrus, which was associated with monitoring of the tongue's spatial information, as well as the activation of the precuneus, which was associated with constructing the tongue motor imagery. As the tongue regained the smoothness in its motor functions, the activation of the angular gyrus and precuneus decreased.

A new masticatory performance scale to integrate food biting, comminution and mixing ability in removable partial denture wearers.

BACKGROUND: The existing masticatory performance (MP) tests cannot comprehensively evaluate objective masticatory function. OBJECTIVES: We aimed to examine the construct validity and responsiveness and determine the clinically minimum important difference (MID) and related factors of a newly developed MP scale to integrate food biting, comminution and mixing ability in patients with removable partial dentures (RPDs). METHODS: Masticatory performance tests using gummy jelly, peanuts and colour-changeable gum were performed before and 3 months after RPD treatment in 248 partially dentate patients. A 10-point ordinal subscale was created for each MP test based on the distributions of MP values, and the three subscales were integrated into a single scale (iMP scale). We analysed the correlations between MP values and iMP scores and determined the effect size for RPD treatments and the MID on the basis of patient perception of chewing ability. RESULTS: iMP scores exhibited moderate correlations with the three MP values (|ρ| = 0.73-0.79, p < .001) and with the change scores (|ρ| =0.61-0.64, p < .001). The mean iMP score significantly increased after RPD treatment (p < .001), and the effect size was 0.35. Of the 248 patients, 55 (22%) reported a slight improvement in chewing ability with a mean iMP score change of 2.1 points. Sex and the number of missing teeth were significantly associated with iMP scores (p < .05). CONCLUSIONS: The iMP scale comprehensively evaluated objective masticatory function, including food biting, comminution and mixing ability in RPD wearers, and an increase of two points on the iMP scale was considered to be the MID in RPD treatments.

Responsiveness of methods to evaluate objective masticatory function in removable partial denture treatments.

Purpose The aim of this study was to examine the responsiveness of chewing tests after removable partial denture (RPD) treatment in this prospective cohort study.Methods Pre- and post-RPD treatment, objective masticatory function was evaluated in 248 patients via chewing tests involving peanuts, a gummy jelly, and a color-changeable gum. A statistical comparison was performed between the pre- and post-treatment scores, and the standardized response mean (SRM) was determined as the treatment effect size (ES).Results After RPD treatment, the median particle size in the sieving method using peanuts significantly decreased, and the glucose concentration in the gummy jelly method significantly increased (P < 0.001). The ESs of the sieving and gummy jelly methods were larger (|SRM| = 0.3-0.4) than that of the gum method (|SRM| = 0.1). In the subgroup analysis, the sieving and gummy jelly methods resulted in a broader effective range (|SRM| ≥ 0.3) than the gum method. In patients without pre-treatment dentures, the ES was medium in the sieving method (|SRM| = 0.6) and weak in the gummy jelly and gum methods (|SRM| = 0.3-0.4). The pre-treatment level of masticatory function was significantly correlated with ES (ρ = 0.93, P < 0.001).Conclusions These results suggest that the sieving and gummy jelly methods are more responsive than the gum method for RPD treatment and that the pre-treatment scores affect the responsiveness.

Cost-effectiveness analysis of prosthetic treatment with thermoplastic resin removable partial dentures.

PURPOSE: The aim of this study was to compare the cost-effectiveness of thermoplastic resin removable partial dentures (TR-RPDs) with metal clasp-retained removable partial dentures (MC-RPDs), from the patients' perspective. METHODS: Patient-reported outcome measures (Oral health-related quality of life [OHRQoL], patient satisfaction, oral appearance) were assessed among 24 partially dentate subjects who completed a randomized crossover trial comparing TR-RPDs and MC-RPDs. The prosthetic treatment fee for patients was used as the direct cost. The cost of achieving a clinically minimum important difference (MID) in Oral Health Impact Profile (OHIP) summary score, and the incremental cost-effectiveness ratio (ICE R) for each outcome measure were determined. RESULTS: OHRQoL, patient satisfaction, and oral appearance was rated higher with TR-RPDs compared to MC-RPDs. The median cost of achieving a MID in OHRQoL with TR-RPDs ($698) was 6.5 times higher than that with MC-RPDs ($107). The ICER was $67 for the OHIP summary score, $195 for the satisfaction score, and $1,169 for the oral appearance rating. CONCLUSIONS: Although TR-RPDs provide better OHRQoL, patient satisfaction, and oral appearance than MC-RPDs, the cost-effectiveness of TR-RPDs was inferior to MC-RPDs from the patients' perspective.

Responsiveness of methods to evaluate chewing ability after removable partial denture treatments.

BACKGROUND: The ability of an instrument to detect a clinically important change in patient-reported outcomes following prosthetic treatment is critical for its use in clinical practice and research settings. OBJECTIVES: This study aimed to examine the responsiveness of instruments in evaluating patient perception of chewing ability after removable partial denture (RPD) treatment in a prospective cohort. METHODS: A single 100-mm visual analogue scale (VAS), 20-item food intake questionnaire (FIQ) and 6-point chewing difficulty scale (CDS) were administered to 248 partially edentulous patients to evaluate chewing ability pre- and post-RPD treatment. We conducted a statistical comparison between the pre- and post-treatment scores and determined the effect size (r) of RPD treatment for the instruments. RESULTS: A significant improvement in chewing ability after RPD treatment was identified by VAS and CDS (P < .05), but not by FIQ (P = .16), which identified an improvement after controlling for sex, age, the number of missing teeth and presence/absence of existing removable dentures. The effect size was medium for VAS (r = .54), weak for CDS (r = .14-.17) and absent for FIQ (r = -.09). The increase in r was significantly associated with impaired chewing ability before treatment (ρ = -0.87, P < .001). CONCLUSIONS: These results suggest that the 100-mm VAS, followed by CDS, is the most responsive instrument to detect an improvement in chewing ability after RPD treatment. Pre-treatment impairment of chewing ability was associated with better responsiveness of the instruments.

Pre-treatment impairment of oral health-related quality of life is associated with variations in minimal clinically important differences among patients with removable partial denture treatment.

BACKGROUND: The minimal clinically important differences (MID) of the Oral Health-related Quality of Life (OHRQoL) are the benchmark to meaningfully interpret treatment outcomes. However, there is no available information regarding the factors impact the MID variations after removable partial denture (RPD) treatment. OBJECTIVE: The purpose of this study was to determine the influence of the pre-treatment OHRQoL impairment on the MID in the oral health impact profile (OHIP) after RPD treatment. METHODS: In this prospective study, OHIP and Self-reported Oral Health (SROH) questionnaires were administered to patients before and 3 months after RPD treatment. The MID in each OHIP version (OHIP-49, OHIP-20, OHIP-14 and OHIP-5) was the mean score of patients who showed a minimum SROH improvement. Multiple linear regression analysis was conducted to determine the influence of the pre-treatment OHIP summary score on the MID score. RESULTS: Among 248 participants who completed both evaluations, 85 (34%) patients had minimum SROH improvements after RPD treatment. Multiple regression analysis indicated that each 10-point increase in the pre-treatment summary OHIP score was associated with an increase in the MID score of three points for OHIP-49 and four points for OHIP-20, OHIP-14 and OHIP-5 (P < .05), after controlling for age, sex and the number of missing teeth. Therefore, the MID increased as the pre-treatment OHRQoL was impaired. CONCLUSIONS: The MID was accounted for by approximately one-third of the pre-treatment summary score, independent of the OHIP version, in the interpretation of the effects of RPD treatment on patients' OHRQoL.

Patient satisfaction and preference with thermoplastic resin removable partial dentures: a randomised cross-over trial.

PURPOSE: This randomised cross-over trial aimed to comparatively investigate patient preference and satisfaction with thermoplastic resin removable partial dentures (TR-RPDs) and conventional metal clasp-retained removable partial dentures (MC-RPDs). METHODS: Twenty-eight partially dentate subjects were enrolled and randomised to receive MC-RPDs followed by TR-RPDs or vice versa (n=14, each group). The subjects were asked to score overall satisfaction and denture-related parameters 3 months after delivery of each denture. Additionally, they were asked to choose their preferred denture type at the end of the trial. RESULTS: Of the 28 subjects, 24 (86%; mean age, 67.3 years) completed the trial. The overall satisfaction scores and ratings for oral appearance with TR-RPDs were significantly higher than those with MC-RPDs (P<0.05). Moreover, 75% (18/24) and 83% (20/24) of the subjects reported greater overall satisfaction and better oral appearance with TR-RPDs than with MC-RPDs (P<0.001, both). Scores for mucosal pain and food impaction were significantly better with TR-RPDs than with MC-RPDs (P<0.05). Relative to MC-RPDs, TR-RPDs provided slightly better oral comfort and speech, although the differences were not statistically significant (P>0.05). Scores for chewing ability, denture stability, and ease of denture cleaning were almost identical for both types of dentures. CONCLUSIONS: These results suggest that TR-RPDs hold an advantage over MC-RPDs in terms of oral appearance and can offer greater satisfaction than MC-RPDs in partially dentate arches with at least an occluding pair in the posterior region. CLINICAL TRIAL REGISTRATION: UMIN Clinical Trials Registry (UMIN000007310).

Minimal clinically important differences of oral health-related quality of life after removable partial denture treatments.

OBJECTIVES: This study aimed to determine the minimal clinically important difference (MID) of the oral health-related quality of life (OHRQoL) in removable partial dentures (RPDs) wearers, using the oral health impact profile (OHIP). METHODS: In this study, RPD patients were asked to complete the OHIP and self-reported oral health (SROH) questionnaires before the treatment and 3 months after the RPD treatment. The Wilcoxon signed ranked test compared the pre- and post-treatment status and the Spearman correlation analysis evaluated the relationship between the pre- and post- treatment change scores of the OHIP and SROH. The median OHIP change score in a subgroup that showed minimum SROH improvement was determined as the MID. RESULTS: Of the 277 participants, 248 (89.5 %) completed the pre-and post- treatment evaluations. SROH and OHIP scores showed significant improvements after RPD treatment (P < 0.05). The OHIP change scores showed significant moderate correlations with the SROH change scores (P < 0.05). The MIDs for the summary scores of OHIP-49, 20, 14, and 5 versions were 14, 7, 3, and 2 points, respectively. An additional 2-3 points were assigned to the four dimensions (oral function, orofacial pain, orofacial appearance, and psychological impact). CONCLUSIONS: An OHIP change of more than 14 points (OHIP-49), 7 points (OHIP-20), 3 points (OHIP-14), 2 points (OHIP-5) and 2-3 points (4 dimensions) was considered clinically meaningful in RPD treatments. CLINICAL SIGNIFICANCE: The proposed MID scores could be used as a benchmark for clinical decision making, interpretation of RPD treatment effects on OHRQoL, and sample size calculations in clinical trials.

Does oral dryness influence pressure pain sensitivity in the oral mucosa of removable denture wearers?

OBJECTIVE: This study aimed to determine if oral dryness is associated with oral pain sensitivity in removable denture wearers. MATERIALS AND METHODS: The pressure pain threshold (PPT) in the mucosa at the midline between the central incisors in the maxilla and mandible was evaluated in 333 removable denture wearers (mean age 71.2 years, male 33.3%). The frequency of oral dryness and severity of anxiety were evaluated using self-reported questionnaires. Multilevel analyses considering the correlated data structure (jaws nested within individual) adjusted for age, sex, number of missing teeth, anxiety level, smoking status, and systemic diseases were performed to examine the association between PPT and oral dryness. Further subgroup analysis stratified by number of missing teeth was performed. RESULTS: Oral dryness was present in 122 (21.6%) of 566 jaws in 73 (21.9%) of the 333 subjects. The mean (standard deviation) of the log PPT was 2.00 (0.26) in the subjects who perceived oral dryness and 2.04 (0.22) in those who did not. Oral dryness was associated with a lower log PPT, but the relationship was not significant (coefficient - 0.017; 95% confidence interval - 0.071, 0.038). Subjects with oral dryness and edentulous oral mucosa had a significantly lower PPT (coefficient - 0.145; 95% confidence interval - 0.283, - 0.006) than their partially dentate counterparts. CONCLUSION: There was a significant association of oral dryness with increased pressure pain sensitivity in the oral mucosa only in jaws with complete dentures. CLINICAL RELEVANCE: The approach to oral dryness could contribute to reduction of oral pain sensitivity.

The association between mucosal pain and subjective masticatory function in patients with partial removable dental prostheses.

BACKGROUND: Improvement of masticatory function is critical in prosthetic treatment. Multiple factors are related to patients' perception of chewing ability in denture wearers. However, the associations between such factors and chewing ability have not yet been fully elucidated. OBJECTIVE: To investigate the association between mucosal pain and subjective masticatory function in patients with partial removable dental prostheses (PRDPs). METHODS: This cross-sectional study included 333 consecutive patients with PRDPs (mean age 71.2 years, male 33.3%) who were recruited from the prosthetic clinic of a dental hospital in Japan. Patients' perception of chewing ability was evaluated using a food intake questionnaire consisting of 20 items, and chewing difficulty was rated by patients using an 11-point numerical scale. Participants rated the pain intensity of the denture-supporting mucosa and oral dryness while chewing. In addition, the bilateral maximal biting force (MBF) was recorded. A structural equation model was used to identify the factors associated with chewing ability and chewing difficulty. RESULTS: The model indicated that mucosal pain, oral dryness, the number of occluding pairs, the denture type (interim/definitive PRDPs) and the MBF were significant independent predictors of chewing ability and chewing difficulty (P < 0.01). CONCLUSIONS: Our findings suggest that mucosal pain is a risk factor for impairment of subjective masticatory function in patients with PRDPs. It is clinically important to consider the denture design and to select denture base materials with regard to the prevention of mucosal pain.