Abstract Objectives To evaluate the efficacy of experimental proposals of desensitizing agents during tooth bleaching. Methods 140 participants without tooth sensitivity (TS) received 16% carbamide ...peroxide (14 days-04 h each) (T1) or 35% hydrogen peroxide (single session-45 min) (T2). Participants used concomitantly (10 per group): desensitizing dentifrices (D1-experimental bioactive glass-ceramic; D2-commercial potassium nitrate; D3-commercial calcium and sodium phosphosilicate) in-home, daily and, desensitizing pastes (D4-experimental bioactive glass-ceramic; D5-experimental Bioglass type 45S5; D6-commercial calcium phosphate), in-office, immediately after the treatment and more 4 times. Participants in the control group did not use any desensitizing agent. We assessed TS with Visual Analogue Scale. Assessment point 1 was immediately after the first participant’s exposure to the treatments; and points 2, 3, 4, and 5 were every 72 h along the period of the study. Two-way ANOVA (considering time and desensitizing as factors) and post-hoc Tukey test ( α = 0.05) analyzed the data. Results In the control group treated with 35% hydrogen peroxide, TS increased significantly on assessment points 1 and 2. The participants who used a 5% potassium nitrate dentifrice and in-office experimental pastes did not experience TS because of the 35% in-office bleaching treatment. Conclusions TS caused by 35% hydrogen peroxide in-office tooth bleaching was controlled by experimental products prepared as pastes D4-experimental bioactive glass-ceramic and D5-experimental Bioglass type 45S5, but not by D1-experimental dentifrice containing bioactive glass-ceramic. Clinical significance There is no a gold standard protocol for TS caused by tooth bleaching. The study of novel desensitizing agents that can obliterate the dentinal tubules in a faster-acting and long-lasting way may help meet this clinical need.
Introduction
Competitive swimmers spend considerable time practicing their sport. Prolonged exposure to chlorinated water can alter salivary parameters and might compromise oral health. This study ...aimed to determine erosive tooth wear status and its related risk factors among competitive swimmers as compared to non-swimmers.
Materials and methods
A cross-sectional study consisting of 180 athletes (90 competitive swimmers versus 90 competitive rowers “non-swimmers”) was conducted. Participants were interviewed on the common erosion risk factors. The Basic Erosive Wear Examination system was used to assess the status of erosive tooth wear. Stimulated saliva sample was collected before and after a training session and pool pH was evaluated using pH strips for 7 days. Data were analyzed using descriptive statistics and multivariable analysis.
Results
The prevalence of dental erosion was significantly higher among competitive swimmers (60%) with higher BEWE scores compared to non-swimmers (25.6%). The salivary flow rate was reduced significantly after training sessions in both groups while salivary pH increased among swimmers. Evaluation of pool water revealed a continuous reduction in the pH level, reaching a very acidic pH level of 3.24.
Conclusion
Erosive tooth wear is more prevalent among competitive swimmers. Years of practice and regular consumption of acidic drinks increase the odds of developing erosive lesions. A high incidence of erosive lesions may be attributed to a reduction in swimming pool pH level. Salivary parameters showed variations between groups after training sessions.
Objective
To verify whether ridge preservation is effective in the reduction of dimensional loss and in bone formation compared to spontaneous healing in extraction sockets of periodontally ...compromised teeth.
Methods
Twenty‐six subjects requiring tooth extraction for stage III/IV periodontitis were randomly assigned to one of two interventions: alveolar ridge preservation using collagenated bovine bone mineral and a resorbable collagen membrane (test, RP) or spontaneous healing (control, SH). Six months later, postoperative cone‐beam computed tomography (CBCT) was performed to measure the linear and volumetric changes of the sockets compared to baseline scans. Biopsies were retrieved at the implant site for histomorphometric calculations. Nonparametric tests were applied for statistical analysis.
Results
Significantly less shrinkage occurred in RP compared to SH, mainly in the crestal zone. The width loss difference between groups was 3.3 mm and 2.2 mm at 1 mm and 3 mm below the crest, respectively (p < .05). RP yielded a gain in socket height of 0.25 mm, whereas a loss of −0.39 mm was observed in SH (p < .05). The percentage of volume loss recorded in RP was also less than that recorded in SH (−26.53% vs −50.34, p < .05). Significantly less bone proportion was detected in biopsies from RP (30.1%) compared with SH (53.9%). A positive association between baseline bone loss and ridge shrinkage was found in SH but not in RP.
Conclusion
Ridge preservation in extraction sockets of periodontally compromised teeth was effective in reducing the amount of ridge resorption.
This study determined the optimum gamma irradiation dosage to sterilize sodium hyaluronate (HY), single-walled carbon nanotubes (SWCNT), multi-walled carbon nanotubes (MWCNT) and CNT functionalized ...with HY (HY-SWCNT and HY-MWCNT), evaluated the structural integrity of the materials and assessed whether sterilized materials kept biological properties without affecting renal function.
Materials were submitted to dosages of 100 gγ to 30 Kgγ and plated onto agar mediums for colony forming units (CFUs) counting. Sterilized samples were inoculated with 107Bacillus clausii, submitted again to gamma irradiation, and plated in agar mediums for CFUs counting. Scanning electron microscope was used for structural evaluation of sterilized materials. Tooth sockets of rats were treated with sterilized materials for bone formation assessment and renal function of the animals was analyzed.
The optimum gamma dosage for sterilization was 250 gγ for HY and 2.5 Kgγ for the other materials without meaningful structural changes. Sterilized materials significantly increased bone formation (p < 0.05) and they did not compromise renal function and structure.
Gamma irradiation efficiently sterilized HY, SWCNT, MWCNT, HY-SWCNT and HY-MWCNT without affecting structural aspects while maintaining their desirable biological properties.
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Background: Different approaches were advocated to preserve or improve the dimension and contour of the ridge following tooth extraction. In some of studies, socket ‘flapless extraction’ apparently ...had a successful outcome.
Aim: The objective of the present experiment was to compare hard tissue healing following tooth extraction with or without the prior elevation of mucosal full‐thickness flaps.
Material and methods: Five mongrel dogs were used. The two second mandibular premolars (2P2) were hemi‐sected. The mesial roots were retained. By random selection the distal root in one side was removed after the elevation of full‐thickness flaps while on the contralateral side, root extraction was performed in a flapless procedure. The soft tissue wound was closed with interrupted sutures. After 6 months of healing, the dogs were euthanized and biopsies were sampled. From each experimental site, four ground sections – two from the mesial root and two from the healed socket – were prepared, stained and examined in the microscope.
Results: The data showed that the removal of a single tooth (root) during healing caused a marked change in the edentulous ridge. In the apical and middle portions of the socket site minor dimensional alterations occurred while in the coronal portion of the ridge the reduction of the hard tissue volume was substantial. Similar amounts of hard tissue loss occurred during healing irrespective of the procedure used to remove the tooth was, i.e. flapless or following flap elevation.
Conclusion: Tooth loss (extraction) resulted in marked alterations of the ridge. The size of the alveolar process was reduced. The procedure used for tooth extraction – flapless or following flap elevation – apparently did not influence the more long‐term outcome of healing.
Abstract Introduction Complex root canal systems appear regularly on fused roots. The aim of this observational study was to evaluate the prevalence of fused roots and root canal merging in the first ...and second upper and lower permanent molars by using cone-beam computed tomography technology. Methods A large sample of cone-beam computed tomography examinations was accessed. Maxillary and mandibular molars were classified according to number of roots, root fusions, types of root canal system configurations, merging positions, and merging levels. The Z test for proportions was used to analyze the differences in independent groups. A value of P < .05 was considered significant. Results This study included 4120 molars. The prevalence of root fusions was 7.1% and 25.2% for the first and second upper molars, respectively; for the first and second lower molars, the prevalence was 0.7% and 12.6%, respectively. In addition, 8.6% and 10.1% of the second upper and lower molars, respectively, had fused roots with canal merging; moreover, 7.1% and 2.1% of the second upper and lower molars had single or 2 non-merging root canals, respectively. The most usual merging position for the first upper molars is between the distobuccal root and palatal root canals; for the second upper molars, the most usual merging position is between the mesiobuccal root and distobuccal root canals. Merging appears more commonly at the apical level. Significant differences were found between the teeth and gender groups. Conclusions When approaching the second upper and lower molars, the clinician should be aware of uncommon morphologies. In our sample, 15.7% and 12.2% of the second upper and lower molars, respectively, had fused roots, which did not present the usual configurations with independent root canals.
This paper aims to create a "bridge" between research and practice by developing a practical, extensive, and clinically relevant study that translates evidence-based findings on soft tissue root ...coverage (RC) of recession-type defects to daily clinical practice.
This review is prepared in accordance with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement based on the proposed focused questions. A literature search with no restrictions regarding status or the language of publication was performed for MEDLINE and EMBASE databases up to and including June 2013. Systematic reviews (SRs), randomized clinical trials, controlled clinical trials, case series, and case reports evaluating recession areas that were treated by means of RC procedures were considered eligible for inclusion through the three parts of the study (part I, an overview of the base of SRs; part II, an alternative random-effects meta-analyses on mean percentage of RC and sites exhibiting complete RC; and part III, an SR of non-randomized trials exploring other conditions not extensively evaluated by previous SRs). Data on Class I, II, III, and IV recessions, type of histologic attachment achieved with treatment, recipient- and donor-site anatomic characteristics, smoking-related outcomes, root surface conditions, tooth type and location, long-term effectiveness outcomes, unusual conditions that may be reported during conventional daily practice, and patient-centered outcomes were assessed as well.
Of the 2,456 potentially eligible trials, 234 were included. Data on Class I, II, III, and IV gingival recessions, histologic attachment achieved after treatment, recipient- and donor-site anatomic characteristics, smoking-related outcomes, root surface conditions/biomodification, tooth type and location, long-term effectiveness outcomes and unusual conditions that may be reported during conventional daily practice, and patient-centered outcomes (i.e., esthetic, visual analog scale, complications, hypersensitivity, patients perceptions) were assessed. Subepithelial connective tissue (CT)-based procedures and coronally advanced flap plus acellular dermal matrix grafts, enamel matrix derivative, or collagen matrix led to the best improvements of recession depth, clinical attachment level (CAL) gain, and keratinized tissue (KT). Some conditions, such as smoking and use of magnification, may affect RC outcomes.
All RC procedures can provide significant reduction in recession depth and CAL gain for Miller Class I and II recession-type defects. Subepithelial CT graft-based procedures provided the best outcomes for clinical practice because of their superior percentages of mean and complete RC, as well as significant increase of KT.
To evaluate retrospectively at 10 years the marginal bone levels around implants located in healed ridges or in extraction sockets and loaded immediately with provisional crowns fixed in ...prefabricated abutments.
Forty-two implants were placed in 36 patients needing single tooth replacement. Implants were inserted either in healed ridges (group 1) or in extraction sockets (group 2) and loaded immediately with prefabricated abutments. Two implants were lost during the healing period from group 2. The bone level around the implant shoulder was calculated mesially and distally on each implant using intraoral radiographs after crown cementation and 1, 3, 5, and 10 years following loading.
On the 10-year follow-up report, 36 implants were available for the clinical and radiologic evaluation. Besides the two implants lost during the osseointegration period, no implant loss was documented over the 5- to 10-year observation period. The average bone loss after implant and crown cementation was 0.266 ± 0.176 mm for 1 year, 0.194 ± 0.172 mm for 5 years, and 0.198 ± 0.165 mm for 10 years in healed ridges and 0.267 ± 0.161 mm for 1 year, 0.213 ± 0.185 mm for 5 years, and 0.287 ± 0.194 mm for 10 years in extraction sockets. Three crowns (in group 1) and one crown (in group 2) were replaced for esthetic reasons.
The outcome of this study revealed that in both groups, the responses of marginal bone were similar. Immediate placement of the definitive prefabricated abutment in an immediate loading protocol appears to conserve marginal bone around the implant neck.
Fatigue and fracture behavior at tooth root during gear meshing are critical to the gear transmission performance. This paper presents a study of the coupling behavior of spur gear meshing and tooth ...root crack propagation. A standard and an extended finite element model were developed for gear pair meshing and crack propagation, respectively. The crack morphology in the meshing analysis was updated by extracting the signed distance function value from crack propagation analysis. The time-varying moving load obtained from meshing analysis was then applied as the boundary condition of crack propagation. The existence of tooth root crack causes the reduction of meshing stiffness and the variation of contact load on cracked tooth. The load carried by the cracked tooth during the double-tooth engagement is found to decrease with crack growth. The variation of meshing load results in longer fatigue life prediction compared to conventional non-coupling analysis. The prediction of crack propagation path shows the tooth fracture in our case study and is consistent with the experimental results in the literature.
Introduction Primary failure of eruption (PFE) is characterized by nonsyndromic eruption failure of permanent teeth in the absence of mechanical obstruction. Recent studies support that this dental ...phenotype is inherited and that mutations in PTH1R genes explain several familial cases of PFE. The objective of our study was to investigate how genetic analysis can be used with clinical diagnostic information for improved orthodontic management of PFE. Methods We evaluated a family (n = 12) that segregated an autosomal dominant form of PFE with 5 affected and 7 unaffected persons. Nine available family members (5 male, 4 female) were enrolled and subsequently characterized clinically and genetically. Results In this family, PFE segregated with a novel mutation in the PTH1R gene. A heterozygous c.1353-1 G>A sequence alteration caused a putative splice-site mutation and skipping of exon 15 that segregated with the PFE phenotype in all affected family members. Conclusions A PTH1R mutation is strongly associated with failure of orthodontically assisted eruption or tooth movement and should therefore alert clinicians to treat PFE and ankylosed teeth with similar caution—ie, avoid orthodontic treatment with a continuous archwire.
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