Hygienic maintenance in patients with maxillae atrophy and in oncological patients with maxillary resection rehabilitated with zygomatic implants: A nested monocentric prospective cohort study.

OBJECTIVE: To assess peri-implant soft tissues condition, comparing clinical parameters of implants placed in patients with atrophic upper jaws and patients who underwent maxillary resection for oncological reasons. BACKGROUND: Zygomatic implants (ZIs) in oncologic patients could be affected by more complications compared to implants placed in atrophic maxillae. The soft tissue condition is an essential requirement for implant success, but few studies have investigated this topic. METHODS: A nested monocentric prospective parallel cohort (atrophic vs. oncological patients) study was performed. Clinical visits and professional hygiene sessions were performed every three months, and bleeding on probing (BOP), probing pocket depth (PPD), gingival index (GI), plaque index (PI) and implant mobility were recorded by a blind outcome assessor. RESULTS: In total, 77 ZIs placed in 21 patients were evaluated: 54 (70.1%) ZIs were inserted in patients belonging to the atrophic cohort (PAM) and 23 (29.9%) ZIs in the oncologic cohort (OP). The probability of having BOP at the considered mean follow-up (27 months) was 24.8% (95% CI 19.0-31.9) for PAM and 22.9% (95% CI 15.1-33.9) OP. The mean PPD values were 2.78 ± 1.28 (range 1-8) in PAM and 2.91 ± 1.98 (range 0-10) in OP. None of the implants showed mobility. No associations between group belongingness and the entity of PPD, PI, GI and the risk of BOP were found, adjusting for the considered confounding factors (age, smoking and implant position). CONCLUSIONS: Under a strict supportive hygiene therapy protocol ZIs in oncologic patients showed similar peri-implant tissue conditions to that of patients with maxillary atrophy.

Oral and throat microbiological changes after orthodontic debonding.

As already known, orthodontic treatment presents a factor of plaque retention, promoting an increase of bacterial growth in the oral cavity. Nevertheless, after orthodontic debonding an alteration of the previous microbiological status may occur. The present study was designed to assess variations among six bacterial species in the oral cavity and the status of oral health after orthodontic debonding. At the end of the fixed orthodontic treatment, 30 patients were divided into three groups based on the type of retention: I - 10 patients were treated with upper and lower fixed retention devices, II - 10 with upper and lower removable retention devices, and III - 10 with lower fixed and upper removable retention devices. To assess the alterations of oral microbiota after orthodontic debonding, two salivary swabs were collected for each individual: the first immediately after debonding (T0) and the other one 6 weeks later (T1). Six species, the ones most correlated with the development of caries and periodontal disease, were selected for microbiological analysis with Real-time PCR: Streptococcus mutans, Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Tannerella forsythia, Treponema denticola, and Fusobacterium nucleatum. Furthermore, in order to correlate the microbiological outcomes with the clinical condition, oral health indexes at T0 and T1 were assessed for all patients. Six weeks after debonding, the salivary levels of the bacteria investigated tend to decrease and the values of the oral health indexes tend to improve with all types of treatment considered (p<.05). Salivary bacteria levels and oral health are similarly influenced by fixed and/or removable orthodontic retentions.

Stannous Fluoride Preventive Effect on Enamel Erosion: An In Vitro Study.

The aim of this in vitro study was to evaluate the effects of a single dose application of two daily toothpastes on enamel exposed to acid attack. The research was conducted on human molars enamel fragments (n = 72). The two different toothpastes active ingredients were sodium fluoride (NaF) and stannous fluoride (SnF2). They were compared in protecting the surface of the enamel exposed to three acids: citric acid, lactic acid and hydrochloric acid. A spectrophotometer was used to measure the calcium ions and phosphate released in the solutions by the enamel specimens. Afterward, ionic concentrations were analyzed through the t-Student test, in order to estimate the significance level (p < 0.05) of the solubility differences obtained between the treatment and control groups. Finally, sample surfaces were analyzed with scanning electron microscopy and X-ray energy dispersive spectroscopy (SEM/EDX). The two analyzed toothpastes did not reveal any statistically significant variation in the release of calcium and phosphate (p > 0.05). Nevertheless, acid-resistant deposits were detected in samples treated with stannous fluoride and exposed to lactic acid, though the presence of tin ion deposits on samples treated with stannous fluoride was not shown. A single dose of a fluoride-based toothpaste before different acids attack, in simulated oral cavity conditions, did not show a significant preventive effect.

Enamel structural changes induced by hydrochloric and phosphoric acid treatment.

PURPOSE: The aim of this study was to evaluate enamel acid-induced structural changes after 2 different treatments, by means of Raman and infrared (IR) spectroscopy analyses, and to correlate these findings with permeability measured as fluid discharge from outer enamel. METHODS: Two different treatments were investigated: 10 enamel slices were etched with 15% hydrochloric acid (HCl) for 120 seconds and 10 slices with 37% phosphoric acid gel (H3PO4) for 30 seconds, rinsed for 30 seconds and then air-dried for 20 seconds. Powders of enamel treated as previously described were produced. Replicas of enamel subjected to the same treatments were obtained to evaluate the presence of fluid droplets on enamel surface. RESULTS AND CONCLUSIONS: Raman and IR spectroscopy showed that the treatment with both hydrochloric and phosphoric acids induced a decrease in the carbonate content of the enamel apatite. At the same time, both acids induced the formation of HPO42- ions. After H3PO4 treatment, the bands due to the organic component of enamel decreased in intensity, while they increased after HCl treatment. Replicas of H3PO4 treated enamel showed a strongly reduced permeability. Replicas of HCl 15% treated samples showed a maintained permeability. A decrease of the enamel organic component, as resulted after H3PO4 treatment, involves a decrease in enamel permeability, while the increase of the organic matter (achieved by HCl treatment) still maintains enamel permeability.The results suggested a correlation between organic matter and enamel permeability. Permeability was affected by etching technique and could be involved in marginal seal, gap and discoloration at the enamel interface, still causes of restoration failure.

In vivo effects of fluoride on enamel permeability.

This in vivo study evaluated the effects of topical fluoride application on enamel by repeated scanning electron microscopy analysis of replicas. Baseline fluid droplets were employed as qualitative indication of enamel permeability. CaF(2)-like globules were detected in vivo after fluoride application and were not found after professional brushing, ultrasound action, or chemical extraction. Absence of water permeability of enamel was demonstrated even after removal of CaF(2)-like globules. Droplets reappeared within 1 h in sodium fluoride-treated teeth, but they did not reappear even after 1 week following topical enamel treatment with acidulated phosphate fluoride. Teeth treated with an acidulate fluoride-free solution showed lack of CaF(2)-like globules and no droplets for at least 1 week as detected in acidulate phosphate fluoride-treated teeth. The caries-preventing action of fluoride may be due to its ability to decrease permeability and diffusion pathways. CaF(2)-like globules seem to be indirectly involved in enamel protection over time maintaining an impermeable barrier, and phosphoric acid seemed to play an unexpected fluoride-independent preventive role.

Recovery of Enterococcus faecalis in root canal lumen of patients with primary and secondary endodontic lesions.

The presence of Enterococcus faecalis in root canal teeth affected by primary and secondary periapical lesions was studied using polymerase chain reaction (PCR) assays. The association between presence of E. faecalis with clinical signs of apical lesions was assessed to evaluate a possible relationship between clinical findings. Microbial samples were obtained from healthy patients affected by different periapical lesions, 79 teeth with primary periapical lesion and 23 with secondary periapical lesion. For each tooth, clinical symptoms and X-ray appearance were examined. E. faecalis was detected in 6 of 79 samples with primary lesion (7.6%), and in 9 of 23 with secondary lesion (39.1%). Suggested association was found between E. faecalis and secondary apical lesions. As regard specific signs and symptoms E. faecalis was more associated with asymptomatic lesions (all p<0.05) than with symptomatic apical lesions. The study confirms the high presence of E. faecalis in secondary apical lesions. However, its effective role in endodontic pathogenesis such as bone periapical lesions needs to be clarified.

In vivo enamel fluid movement.

The aim of this study was to visualize fluid movement through dental enamel in vivo. Fifty permanent upper central incisors, from subjects aged 10-70 yr, and 5 permanent central just-erupted incisors, from subjects aged 6-7 yr, were included in the study. An impression was obtained by vinyl polyxiloxane, and replicas were then obtained by polyether impression material. The hydrophobic vinyl polyxiloxane material yielded a morphological image in situ of outward fluid flow through tooth enamel. The study confirmed in vivo that enamel is a permeable substrate, as shown by the presence of droplets on its surface, and demonstrated that age and enamel permeability are closely related. Samples from subjects of different ages showed a decreasing number and size of droplets with increasing age: freshly erupted permanent teeth showed many droplets covering the entire enamel surface. Droplets in permanent teeth were prominent along enamel perikymata.

The influence of smear layer in lateral channels filling.

This in vitro study evaluated the ability of a warm gutta-percha obturation system Thermafil to fill lateral channels in presence/absence of smear layer. Forty single-rooted extracted human teeth were randomly divided into two groups for which different irrigation regimens were used: group A, 5 ml of 5% NaOCl + 2.5 ml of 3.6% H(2)O(2); group B, 5 ml of 5% NaOCl 5% + 2.5 ml of 17% ethylenediamine tetraacetic acid. A conventional crown-down preparation technique was employed. Obturation was performed using epoxy resin-based cement (AH Plus) and a warm gutta-percha plastic carrier system (Thermafil). Specimens were cleared in methyl salicylate and analyzed under a stereomicroscope to evaluate the number, length, and diameter of lateral channels. Lateral channels were identified in both groups at medium and apical thirds. Additional samples were prepared for scanning electron microscopy inspection to confirm the presence of smear layer in group A, and the absence of smear layer in group B. All lateral channels resulted filled in both groups. No statistically significant differences regarding number, length, and diameter were observed between the two groups. Smear layer did not prevent the sealing of lateral channels.