Effect of low-level laser therapy on orthodontic dental alignment: a systematic review and meta-analysis.

The aim of this study is to systematically summarize the available evidence regarding low-level laser therapy (LLLT) speed-up effect on dental alignment in comprehensive orthodontic treatment. An extensive electronic search was conducted in PubMed, ScienceDirect, Cochrane, Web of Science, and Scopus up to February 20, 2023. The Cochrane risk of bias tool and the Newcastle-Ottawa Quality Assessment Form were used by two authors independently to assess the risk of bias (RoB). Statistical analysis was performed by Review Manager 5.3. The eight eligible trials were reviewed and included in qualitative synthesis. Four studies reported the overall time of leveling and alignment (OLAT, days), enabling a synthesizing of the data. The meta-analysis results showed that LLLT significantly reduced the overall time of leveling and alignment compared to control group (MD=-30.36, 95% CI range -41.50 to -19.22, P<0.0001), with moderate heterogeneity (χ2=4.10, P=0.25, I2=27%). Based on the data available, statistically significant evidence with moderate risk of bias suggests that LLLT may have a positive effect on accelerating dental alignment. However, due to the differences in intervention strategy and evaluating method, the conclusions should be interpreted with caution.

Effects of low-level laser therapy on orthodontic miniscrew stability: a systematic review.

BACKGROUND: Miniscrews as auxiliary anchorage devices in orthodontic treatment have definite advantages and efficacy. The aim of the present study was to investigate the scientific evidence including randomized controlled trials (RCTs) or controlled clinical trials (CCTs) to support the application of low-level laser therapy to improve miniscrews stability in orthodontic treatment. METHODS: An extensive literature research was conducted with the Cochrane Library, PubMed, EMBASE, Web of Science and ScienceDirect without language limitations. All searches were inclusive until June 2020. The Cochrane Risk of Bias Tool was used to assess the risk of bias (RoB) in the included RCTs. RESULTS: Through the electronic searches, 428 titles and abstracts were identified. From these, 4 articles were retrieved for review, and 3 of these met the inclusion criteria. Two RCTs reported increased miniscrews stability with low-intensity laser therapy, but the other one reported no difference. Except one study assessed as "high risk of bias" the other two were rated as "low risk of bias". CONCLUSION: There is insufficient evidence to support or refute the effectiveness of LLLT for improvement of miniscrew stability. Further studies with a better study design, reliable evaluation method, comprehensive evaluation intervals and appropriate loading protocol are required to provide more reliable evidence for the clinical application of LLLT.

[Study on the changes of soft and hard tissue before and after early treatment of Classâ ¡skeletal malocclusion with Twin-block appliance].

PURPOSE: To investigate the effect of early correction with Twin-block appliance on soft and hard tissues of patients with Class Ⅱ skeletal malocclusion. METHODS: Sixty patients with Angle Class Ⅱ skeletal malocclusion were prospectively selected. The patients were divided into 2 groups, 30 cases in each group, by random number table method. Patients in the experimental group were treated with a Twin-block appliance combined with straight wire appliance, while patients in the control group were treated with a straight wire appliance. The soft and hard tissue indexes(SNA, SNB, ANB, U1-NA angle, U1-NA distance, L1-NB distance, L1-NB angle, U1-L1) before, and 12 months after treatment were measured. Soft tissue measurement indicators included UL-U1, LL-L1, over jet, overbite, E-upper-lip from the upper lip to the E-line, and the lower lip to the E-line, changes in the vertical distance (E-lower-lip), the dip angle of the sulcus, and the thickness of the soft tissue. SPSS 25.0 software package was used for statistical analysis of the data. RESULTS: U1-NA, U1-NA, L1-NB, L1-NB, overjet, overbite, E-upper-lip, and E-lower-lip were significantly less than the control group at 12 months and 36 months after treatment in the experimental group(P<0.05). U1-L1, nasolabial angle, sulcus angle, and soft tissue thickness of the experimental group were significantly greater than those of the control group(P<0.05). CONCLUSIONS: Twin-block appliance combined with straight wire appliance can significantly improve the relationship between the jaw and the soft and hard tissues of patients with Class Ⅱ skeletal malocclusion, and the long-term effect is good.

[An experimental study on the penetration abilities of resin infiltration into proximal caries lesions in primary molars].

OBJECTIVE: To compare the penetration abilities of resin infiltration into proximal lesions in primary molars with those of adhesive in vitro. METHODS: Thirty-two extracted or exfoliated primary molars showing proximal white spot lesions were selected. Roots of the teeth were removed, and the crowns were cut across the white spot lesions perpendicular to the surface. Cut surfaces were examined (by stereo microscopy) and classified with respect to histological lesion extension (C1-C4): lesions confined to the outer half on enamel (C1), lesions confined to the inner half on enamel (C2), lesions confined to the outer half on dentin (C3), lesions extending into the inner half of dentin (C4). Corresponding lesion halves were etched for 120 s with 15% hydrochloric acid gel and were subsequently treated with either adhesive or resin infiltration. Specimens were observed with laser scanning confocal microscope (LSCM) in dual fluorescence mode. In confocal microscopic images, lesion depth and penetration depth of the resin infiltration or the adhesive in corresponding halves were measured, and penetration percentages were calculated respectively. Differences of the data between two groups were analyzed by Wilcoxon signed rank test. Variations of histological caries extensions were detected with Kruskal-Wallis H test. RESULTS: At the same grading level (C1-C3) in histological caries extension, penetration depths of the resin infiltration group and the adhesive group were 240 (230, 260) µm vs 190 (150, 210) µm, 405 (300, 523) µm vs 180 (160, 200) µm, and 590 (430, 640) µm vs 180 (160, 200) µm respectively. There was significant statistical difference in the data between two groups (P < 0.05). Statistically significant difference in penetration depths of the resin infiltration group (at C1-C3) were found (P < 0.01). At the same grading level (C1-C3) in histological caries extension, percentage penetrations of the resin infiltration group and the adhesive group were [100.0% (96.2%, 100.0%)], [99.1% (95.7%, 100.0%)], [82.0% (81.1%, 92.2%)] and [79.2% (68.4%, 87.5%)], [41.8% (29.1%, 74.5%)], [30.2% (29.2%, 39.6%)], respectively. The difference between the above data was also significant (P < 0.05). Percentage penetrations of the resin infiltration group at C1 and C2 level was higher than those at C3 level (P < 0.05). CONCLUSIONS: The resin infiltration is capable of penetrating almost completely into proximal lesions in primary molars.