Placebo hypoalgesic effects in pain: Potential applications in dental and orofacial pain management

Role of Photobiomodulation Therapy in Modulating Oxidative Stress in Temporomandibular Disorders. A Systematic Review and Meta-Analysis of Human Randomised Controlled Trials

This systematic review and meta-analysis (PROSPERO registration; ref CRD 42020198921) aimed to govern photobiomodulation therapy (PBMT) efficacy in temporomandibular disorder (TMD). PRISMA guidelines and Cochrane Collaboration recommendations were followed. Differences in pain reduction assessment by qualitative measurement with visual analogue scale pain (VAS), pressure threshold (PPT) and maximum mouth opening (MMO) were calculated with 95% confidence intervals and pooled in a random effects model with a subgroup analysis, evaluating the role of follow-up duration. Heterogeneity was analysed using Q and I² tests. Publication bias was assessed by visual examination of funnel plot symmetry. Qualitative analysis revealed 46% of the 44 included studies showed a high risk of bias. Meta-analysis on 32 out of 44 studies revealed statistically significant intergroup differences (SSID) for VAS (SMD = -0.55; 95% CI = -0.82 to -0.27; Z = 3.90 (p < 0.001)), PPT (SMD = -0.45; 95% CI = -0.89 to 0.00; Z = 1.97 (p = 0.05)) and MMO (SMD = -0.45; 95% CI = -0.89 to 0.00; Z = 1.97 (p = 0.05)), favouring PBMT compared to control treatment strategies. Sensitivity analysis revealed SSID (SMD = -0.53; 95% CI = -0.73 to -0.32; Z = 5.02 (p < 0.0001)) with low heterogeneity (Τ² = 0.02; χ² = 16.03 (p = 0.31); I² = 13%). Hence, this review, for first time, proposed suggested recommendations for PBMT protocols and methodology for future extensive TMD research.

Effectiveness of Antimicrobial Photodynamic Therapy in the Treatment of Periodontitis: A Systematic Review and Meta-Analysis of In Vivo Human Randomized Controlled Clinical Trials

This systematic review and meta-analysis evaluated antimicrobial photodynamic therapy (aPDT) efficacy in periodontitis. The review protocol was conducted in accordance with PRISMA statements, Cochrane Collaboration recommendations and is registered in PROSPERO (CRD 42020161516). Electronic and hand search strategies were undertaken to gather data on in vivo human RCTs followed by qualitative analysis. Differences in probing pocket depth (PPD) and clinical attachment level (CAL) were calculated with 95% confidence intervals and pooled in random effects model at three and six months. Heterogeneity was analyzed, using Q and I² tests. Publication bias was assessed by visual examination of the funnel plot symmetry. Sixty percent of 31 eligible studies showed a high risk of bias. Meta-analysis on 18 studies showed no additional benefit in split mouth studies in terms of PPD reduction (SMD 0.166; 95% CI −0.278 to 0.611; P = 0.463) and CAL gain (SMD 0.092; 95% CI −0.013 to 0.198; P = 0.088). Similar findings noted for parallel group studies; PPD reduction (SMD 0.076; 95% CI −0.420 to 0.573; P = 0.763) and CAL gain (SMD 0.056; 95% CI −0.408 to 0.552; P = 0.745). Sensitivity analysis minimized heterogeneity for both outcome variables; however, intergroup differences were not statistically significant. Future research should aim for well-designed RCTs in order to determine the effectiveness of aPDT.

The whitening effect of single brushing with blue-covarine containing toothpaste-A randomized controlled trial

OBJECTIVE

To evaluate whether a blue covarine containing silica-based toothpaste promotes a whitening effect immediately after tooth brushing.

METHODS

A triple-blind, parallel group, randomized design was used to compare the tooth color before and after brushing. Two silica-based toothpastes were chosen, one of them containing blue covarine (BCT) and the other one without pigment to serve as control (CT). Tooth color was measured using a spectrophotometer and expressed as CIEDE 2000 ΔE, CIELAB values, WIO index, WI_D index and VITA scale tooth shade. In addition, the participants' satisfaction with and perception of their own tooth color were registered using an aesthetic numeric analogue scale.

RESULTS

No significant changes in color components or dimensions measured using CIEDE 2000 ΔE (CT: mean = 1.3, 95% CI 0.8, 1.7; BCT: mean = 1.6, 95% CI 1.2, 2.1), WIO, WI_D, VITA scale or CIELAB values were detected for the CT and BCT groups, comparing the results before and after brushing. Likewise, the participants' satisfaction with the treatment results (P = 0.31) and the participants' evaluation of tooth color (P = 0.71) did not differ significantly between groups.

CONCLUSION

After a single application, no significant improvement in tooth whiteness by the presence of blue covarine in a silica-based toothpaste was detected in color dimensions or by assessing the participants' satisfaction and perception.

CLINICAL SIGNIFICANCE

The present study does not show a clinically relevant increase in tooth whiteness after a single brushing with a blue covarine containing toothpaste, nor could the study participants observe a difference between treatment with blue covarine containing toothpaste and control treatment.

Placebo effects in pain

Placebo effects influence symptom perceptions and treatment outcomes. Placebo effects can be explored in laboratory settings controlling for natural history and expectations. Such a mechanistic approach to neurological disorders has been implemented in the domain of chronic clinical pain and other neurological disorders. This article therefore focuses on definitions and historical notes related to placebo effects and mechanisms of placebo effects in chronic pain. Knowledge on mechanisms of placebo effects could inform current clinical practice for the treatment of neurological disorders by focusing on patients (and providers) expectations for outcome optimization.