METHODS: HA having nanorods structure were synthetized using ultrasonication with precipitation method. HA nanorods were characterized by TEM for average-size/shape. Following phosphoric acid demineralization, dentine specimens were treated with HA-nanorods with/without subsequent HIFU exposure for 5 s, 10 s and 20 s then stored in artificial saliva for 1-month. Dentine specimens were characterized using different SEM and Raman spectroscopic techniques. In addition, the biochemical stability and HA-nanorods were examined using ATR-FTIR to observe attachment of nanoparticles. Also, surface nanoindentation properties were evaluated using AFM in tapping-mode.
RESULTS: HA-nanorods displayed well-defined, homogenous plate-like nanostructure. TEM revealed intact collagen-fibrils network structure with high density due to obliteration of interfibrillar spaces with clear evidence of remineralization in combined HA/HIFU treatment. With HA-nanorods treatment collagen-network structure was visible, consisting of fibrils interlaced into a compact pattern with evidence of minerals deposition. AFM investigation revealed clear mineral formation with the increase of HIFU exposure time. Bands associated with inorganic phase dominate well in HIFU exposed specimens with PO stretching within dentine mineral identified at 960 cm-1. Characteristic dentine structure for control and HIFU 20 s specimens is reflected as oscillatory mean Amide-I intensity with measurement giving a precise sinusoidal response of polarization angle β within dentinal tissue. Nanoindentation testing showed a gradual significant increase in elastic-modulus with the increase in HIFU exposure time after 1-month storage. FTIR spectrum of the HIFU exposed dentine displayed bands at 1650 cm-1, 1580 cm-1 and 1510 cm-1 that can be attributed to Amide-I, II and III.
SIGNIFICANCE: The synergetic effect of HIFU exposure on remineralization potential of demineralized dentine-matrix following nano-hydroxyapatite treatment was revealed. This synergetic effect is dependent on HIFU exposure time.
METHODS: 75 human mandibular molars were randomly divided into five equal groups. Teeth were standardized, endodontically-treated and restored according the assigned group as follows: amalgam core only, prefabricated titanium post in the distal canal and amalgam core, composite core only; fiber post in the distal canal and composite core. One group of untreated sound teeth was used as a control. Non-precious metal crowns were fabricated and cemented on the prepared specimens with Rely X U200 resin cement. All specimens were subjected to a compressive load at crosshead speed 0.5 mm/minute, 25° to the long axis of the tooth. Failure loads and modes were recorded.
RESULTS: Mean failure loads among the groups were significantly different (P= 0.035). Post-hoc multiple pair-wise comparisons revealed the amalgam core and composite core groups produced significantly lower fracture resistance than the control group (P= 0.041 and P= 0.025, respectively) and no significant differences among the different intra-radicular techniques (P> 0.05). The composite core with fiber post and amalgam core with titanium posts showed the highest percentage of favorable failures (67%) and non-favorable failures (87%) respectively.
CLINICAL SIGNIFICANCE: The composite core with fiber post is the most appropriate intraradicular restoration in cases of severely compromised molars.
OBJECTIVES: To evaluate the effects of sealants compared to no sealant or a different sealant in preventing pit and fissure caries on the occlusal surfaces of primary molars in children and to report the adverse effects and the retention of different types of sealants.
SEARCH METHODS: An information specialist searched four bibliographic databases up to 11 February 2021 and used additional search methods to identify published, unpublished and ongoing studies. Review authors scanned the reference lists of included studies and relevant systematic reviews for further studies.
SELECTION CRITERIA: We included parallel-group and split-mouth randomised controlled trials (RCTs) that compared a sealant with no sealant, or different types of sealants, for the prevention of caries in primary molars, with no restriction on follow-up duration. We included studies in which co-interventions such as oral health preventive measures, oral health education or tooth brushing demonstrations were used, provided that the same adjunct was used with the intervention and comparator. We excluded studies with complex interventions for the prevention of dental caries in primary teeth such as preventive resin restorations, or studies that used sealants in cavitated carious lesions.
DATA COLLECTION AND ANALYSIS: Two review authors independently screened search results, extracted data and assessed risk of bias of included studies. We presented outcomes for the development of new carious lesions on occlusal surfaces of primary molars as odds ratios (OR) with 95% confidence intervals (CIs). Where studies were similar in clinical and methodological characteristics, we planned to pool effect estimates using a random-effects model where appropriate. We used GRADE methodology to assess the certainty of the evidence.
MAIN RESULTS: We included nine studies that randomised 1120 children who ranged in age from 18 months to eight years at the start of the study. One study compared fluoride-releasing resin-based sealant with no sealant (139 tooth pairs in 90 children); two studies compared glass ionomer-based sealant with no sealant (619 children); two studies compared glass ionomer-based sealant with resin-based sealant (278 tooth pairs in 200 children); two studies compared fluoride-releasing resin-based sealant with resin-based sealant (113 tooth pairs in 69 children); one study compared composite with fluoride-releasing resin-based sealant (40 tooth pairs in 40 children); and one study compared autopolymerised sealant with light polymerised sealant (52 tooth pairs in 52 children). Three studies evaluated the effects of sealants versus no sealant and provided data for our primary outcome. Due to differences in study design such as age of participants and duration of follow-up, we elected not to pool the data. At 24 months, there was insufficient evidence of a difference in the development of new caries lesions for the fluoride-releasing sealants or no treatment groups (Becker Balagtas odds ratio (BB OR) 0.76, 95% CI 0.41 to 1.42; 1 study, 85 children, 255 tooth surfaces). For glass ionomer-based sealants, the evidence was equivocal; one study found insufficient evidence of a difference at follow-up between 12 and 30 months (OR 0.97, 95% CI 0.63 to 1.49; 449 children), while another with 12-month follow-up found a large, beneficial effect of sealants (OR 0.03, 95% CI 0.01 to 0.15; 107 children). We judged the certainty of the evidence to be low, downgrading two levels in total for study limitations, imprecision and inconsistency. We included six trials randomising 411 children that directly compared different sealant materials, four of which (221 children) provided data for our primary outcome. Differences in age of the participants and duration of follow-up precluded pooling of the data. The incidence of development of new caries lesions was typically low across the different sealant types evaluated. We judged the certainty of the evidence to be low or very low for the outcome of caries incidence. Only one study assessed and reported adverse events, the nature of which was gag reflex while placing the sealant material.
AUTHORS' CONCLUSIONS: The certainty of the evidence for the comparisons and outcomes in this review was low or very low, reflecting the fragility and uncertainty of the evidence base. The volume of evidence for this review was limited, which typically included small studies where the number of events was low. The majority of studies in this review were of split-mouth design, an efficient study design for this research question; however, there were often shortcomings in the analysis and reporting of results that made synthesising the evidence difficult. An important omission from the included studies was the reporting of adverse events. Given the importance of prevention for maintaining good oral health, there exists an important evidence gap pertaining to the caries-preventive effect and retention of sealants in the primary dentition, which should be addressed through robust RCTs.
OBJECTIVES: To evaluate the effects of home-based tooth whitening products with chemical bleaching action, dispensed by a dentist or over-the-counter.
SEARCH METHODS: Cochrane Oral Health's Information Specialist searched the following databases: Cochrane Oral Health's Trials Register (to 12 June 2018), the Cochrane Central Register of Controlled Trials (CENTRAL; 2018, Issue 6) in the Cochrane Library (searched 12 June 2018), MEDLINE Ovid (1946 to 12 June 2018), and Embase Ovid (1980 to 12 June 2018). The US National Institutes of Health Ongoing Trials Register ClinicalTrials.gov (12 June 2018) and the World Health Organization International Clinical Trials Registry Platform (12 June 2018) were searched for ongoing trials. No restrictions were placed on the language or date of publication when searching the electronic databases.
SELECTION CRITERIA: We included in our review randomised controlled trials (RCTs) which involved adults who were 18 years and above, and compared dentist-dispensed or over-the-counter tooth whitening (bleaching) products with placebo or other comparable products.Quasi-randomised trials, combination of in-office and home-based treatments, and home-based products having physical removal of stains were excluded.
DATA COLLECTION AND ANALYSIS: Two review authors independently selected trials. Two pairs of review authors independently extracted data and assessed risk of bias. We estimated risk ratios (RRs) for dichotomous data, and mean differences (MDs) or standardised mean difference (SMD) for continuous data, with 95% confidence intervals (CIs). We assessed the certainty of the evidence using the GRADE approach.
MAIN RESULTS: We included 71 trials in the review with 26 studies (1398 participants) comparing a bleaching agent to placebo and 51 studies (2382 participants) comparing a bleaching agent to another bleaching agent. Two studies were at low overall risk of bias; two at high overall risk of bias; and the remaining 67 at unclear overall risk of bias.The bleaching agents (carbamide peroxide (CP) gel in tray, hydrogen peroxide (HP) gel in tray, HP strips, CP paint-on gel, HP paint-on gel, sodium hexametaphosphate (SHMP) chewing gum, sodium tripolyphosphate (STPP) chewing gum, and HP mouthwash) at different concentrations with varying application times whitened teeth compared to placebo over a short time period (from 2 weeks to 6 months), however the certainty of the evidence is low to very low.In trials comparing one bleaching agent to another, concentrations, application method and application times, and duration of use varied widely. Most of the comparisons were reported in single trials with small sample sizes and event rates and certainty of the evidence was assessed as low to very low. Therefore the evidence currently available is insufficient to draw reliable conclusions regarding the superiority of home-based bleaching compositions or any particular method of application or concentration or application time or duration of use.Tooth sensitivity and oral irritation were the most common side effects which were more prevalent with higher concentrations of active agents though the effects were mild and transient. Tooth whitening did not have any effect on oral health-related quality of life.
AUTHORS' CONCLUSIONS: We found low to very low-certainty evidence over short time periods to support the effectiveness of home-based chemically-induced bleaching methods compared to placebo for all the outcomes tested.We were unable to draw any conclusions regarding the superiority of home-based bleaching compositions or any particular method of application or concentration or application time or duration of use, as the overall evidence generated was of very low certainty. Well-planned RCTs need to be conducted by standardising methods of application, concentrations, application times, and duration of treatment.
OBJECTIVES: To evaluate the sensitivity of QLF and OCT in detecting initial dental erosion in vitro.
METHODS: 12 human incisors were embedded in resin except for a window on the buccal surface. Bonding agent was applied to half of the window, creating an exposed and non-exposed area. Baseline measurements were taken with QLF, OCT and surface microhardness. Samples were immersed in orange juice for 60 min and measurements taken stepwise every 10 min. QLF was used to compare the loss of fluorescence between the two areas. The OCT system, OCS1300SS (Thorlabs Ltd.), was used to record the intensity of backscattered light of both areas. Multiple linear regression and paired t test were used to compare the change of the outcome measures.
RESULTS: All 3 instruments demonstrated significant dose responses with the erosive challenge interval (p < 0.05) and a detection threshold of 10 min from baseline. Thereafter, surface microhardness demonstrated significant changes after every 10 min of erosion, QLF at 4 erosive intervals (20, 40, 50 and 60 min) while OCT at only 2 (50 and 60 min).
CONCLUSION: It can be concluded that OCT and QLF were able to detect demineralization after 10 min of erosive challenge and could be used to monitor the progression of demineralization of initial enamel erosion in vitro.