Impact of Treatment with Unilateral Implant- Supported Fixed Partial Prosthesis on the Frequency of Masticatory Side Switches in Patients with Unilateral Posterior Missing Teeth.

This study aimed to determine the impact of treatment with an implant-supported fixed partial prosthesis (ISFPP) on the frequency of masticatory side switches in patients with unilateral posterior missing teeth. This was a prospective study of 30 patients with unilateral posterior missing teeth treated with one-, two-, or three-unit ISFPPs. Comparison was with 10 healthy individuals with complete natural dentitions. Each participant performed masticatory assays, which involved chewing pieces of silicon inside a latex bag, at baseline and at 3-months' follow-up. The frequency of masticatory side switches was reported as the masticatory side-switch index: the number of side switches divided by the maximum number of possible switches. Data were analyzed by Kruskal-Wallis, Mann-Whitney U test, or Wilcoxon test, as appropriate. At baseline, the masticatory side-switch index was lower only in patients with three missing teeth than in controls. At 3 months after treatment, a significant increase in the masticatory side-switch index was only observed in patients treated with three restorative units. Treatment with ISFPPs does not change the masticatory side-switch frequency in patients with unilateral posterior missing teeth, though it could increase it in patients with three missing teeth.

Functional limitation of the masticatory system in patients with bulbar involvement in amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS) with bulbar dysfunction affects the motor neurons responsible for controlling the muscles in the jaw, face, soft palate, pharynx, larynx and tongue. This cross-sectional study aimed to determine the functional limitation of the jaw in patients with ALS and bulbar dysfunction who had upper motor neuron (UMN), lower motor neuron (LMN) or balanced involvement. One hundred and fifty-three patients with ALS and 23 controls were included. All participants answered using the 8-item Jaw Functional Limitation Scale (JFLS-8). Patients with ALS were grouped by neurologic examination as follows: non-bulbar ALS, bulbar UMN-predominant ALS; bulbar LMN-predominant ALS; and bulbar balanced (UMN + LMN) ALS. Jaw limitation between the different groups was compared using the Kruskal-Wallis test. Patients with non-bulbar ALS had similar mandibular limitations to healthy participants. Only patients with balanced UMN and LMN bulbar manifestations reported greater difficulties in chewing soft food or in jaw mobility compared to the non-bulbar ALS group. Patients with bulbar involvement also had greater difficulties in chewing tough food or chicken and in swallowing and talking compared to the non-bulbar group, regardless of whether UMN or LMN predominant. No significant differences were found between the groups in smiling and yawning difficulties. Bulbar involvement in patients with ALS is associated with functional limitation of the masticatory system. However, balanced bulbar UMN and LMN involvement is associated with the worst impairments in chewing soft food and in opening the jaw widely.

Peripheral, functional and postural asymmetries related to the preferred chewing side in adults with natural dentition.

The aim of this cross-sectional study was to determine the preferred chewing side and whether chewing side preference is related to peripheral, functional or postural lateral preferences. One hundred and forty-six adults with natural dentition performed three masticatory assays, each consisting of five trials of chewing three pieces of silicon placed into a latex bag for 20 cycles, either freestyle or unilaterally on the right- or left-hand side. Occlusal contact area in the intercuspal position, maximum bite force, masticatory performance and cycle duration were measured and the lateral asymmetry of these variables was calculated. Laterality tests were performed to determine handedness, footedness, earedness and eyedness as functional preferences, and hand-clasping, arm-folding and leg-crossing as postural lateral preferences. The preferred chewing side was determined using three different methods: assessment of the first chewing cycle for each trial, calculation of the asymmetry index from all cycles and application of a visual analogue scale. Bivariate relationship and multiple linear regression analyses were performed. Among unilateral chewers, 77% of them preferred the right side for chewing. The factors most closely related to the preferred chewing side were asymmetry of bite force, asymmetry of masticatory performance and earedness, which explained up to 16% of the variance. Although several functional or postural lateral preferences seem to be related to the preferred chewing side, peripheral factors such as asymmetry of bite force and of masticatory performance are the most closely related to the preferred chewing side in adults with natural dentition.

[Prevalence of Helicobacter pylori detected by real-time PCR in the subgingival plaque of patients with chronic periodontitis]. / Prévalence d'helicobacter pylori détecté par PCR en temps réel dans la plaque sous-gingivale des patients atteints de parodontite chronique.

BACKGROUND: Helicobacter pylori plays a significant role in gastric disease. The aim of the present pilot study was to evaluate the prevalence of H. pylori detected by real-time polymerase chain reaction (real-time PCR) in the sub-gingival plaque of chronic periodontitis patients and to determine periodontopathogens profile of positive sites at H. pylori. METHODOLOGY: 109 subgingival samples collected from 17 subjects with chronic periodontitis were studied. The DNA was extracted from the oral samples and analyzed for the presence of H. pylori by real-time PCR (LightCycler) using 16S rRNA#120 primers which targeted the 16S rRNA gene. DNA from H. pylori DSM 4867 was used as a positive control. Seven bacteria implicated in chronic periodontitis were selected to explore the presence of these periodontopathic species in the oral positive sites for H. pylori. RESULTS: 16 of 109 samples (14.7%) were positives of H. pylori. All the positives sites were also positives to Fusobacterium nucleatum and Eikenella corrodens, 62.5% to Porphyromonas gingivalis, 31.25% to Treponema denticola, 25% to Prevotella intermedia, 12.5% to Aggregatibacter actinomycetemcomitans and 6.25% to Tannerella forsythia. CONCLUSIONS: H. pylori may be present in the subgingival plaque samples of patients with chronic periodontitis who are resident in a developing country. F. nucleatum and E. corrodens could coaggregate with H. pylori in the subgingival dental plaque.

[Comparison of four different primer sets for detection of Helicobacter pylori in gastric biopsies and oral samples by using real-time PCR]. / Comparaison de quatre paires d'amorces différentes dans la détection d'Helicobacter pylori dans les biopsies gastriques et les prélèvements oraux.

AIMS: The presence of Helicobacter pylori. in the oral cavity remains controversial and the most appropriate method for detection of oral H. pylori has yet to be established. The aim of the present study was to compare four different primer sets on the detection of H. pylori in gastric biopsies and oral samples using real-time PCR. MATERIAL AND METHODS: Gastric biopsy and oral samples were collected from eight patients with gastric symptoms. DNA from clinical samples was extracted and analyzed for the presence of H. pylori by real-time PCR (LightCycler 2.0) using four pairs of primers which targeted 16S rRNA (16S rRNA#295; 16S rRNA#120) or glmM (glmM#294; glmM#722) DNA genes. Three H. pylori strains and three clinical isolates served as reference. The specificities of the four primer pairs were examined for seven oral microorganisms and two Helicobacter non-pylori species. RESULTS: Primer pair 16S rRNA#120 showed an acceptable specificity and a high sensitivity. Primer pairs glmM#294 and glmM#722 demonstrated a high specificity but a low sensitivity and primer pair 16S rRNA#295 demonstrated a poor specificity but acceptable sensitivity. Four H. pylori positive gastric biopsies were demonstrated by culture, histology and real-time PCR with primer pairs 16S rRNA#295 or 16S rRNA#120. No H. pylori was detected in oral samples, either by culture or by real-time PCR. CONCLUSION: Of the four different primer pairs examined, 16S rRNA#120 was the most appropriate to detect H. pylori in clinical samples using real-time PCR.

Dental casting alloys behaviour during power toothbrushing with toothpastes of various abrasivities. Part II: corrosion and ion release.

The purpose of this study was to evaluate the long term effect of abrasivity of toothpastes normally used over the corrosion behavior and ion release of the different dental casting alloys. Three dental casting alloys (Ni-Cr, Co-Cr and commercially pure Ti) were studied. Four specimens of each material were immersed, brushed without paste or brushed with one of four toothpastes of different Relative Dentine Abrasivity (RDA 50, 52, 80, and 114). An electric toothbrush with a load of 250 g was used for 420 min. Corrosion behavior was determined by means a potenciostat with high sensitivity and the ion release determined by Inductively Coupled Plasma-Mass Spectrometry. Two-way ANOVA and non-parametric tests were used to detect significant differences. Titanium specimens exhibited the best corrosion behavior after and before the toothbrushed, being the worst of the three alloys the Cr-Ni. Titanium oxide produced spontaneously on the Ti surface is the main cause of the high corrosion resistance of the material. However, the eutectoid of the CrNi with chemical composition between different phases produces pitting on the phases boundaries with an important decrease of the corrosion resistance. Besides, the CrNi produces high values of the Ni and Cr release. Slight increment in roughness were observed after toothbrushing and depended on the material but not on the toothpaste used. The increase of the microhardness (residual stresses) provokes a decrease of the corrosion resistance and an increase of the ion release.

Dental casting alloys behaviour during power toothbrushing with toothpastes with various abrasivities. Part I: wear behavior.

The purpose of this study was to evaluate the long term effect of abrasivity of toothpastes normally used over the surface and mechanical properties of dental casting alloys. Three dental casting alloys (Ni-Cr, Co-Cr, c.p. Ti) and one ceramic were chosen. Four specimens of each material were immersed in artificial saliva, brushed without or with one of four toothpastes of different Relative Dentine Abrasivity (RDA 50, 52, 80, and 114). An electric toothbrush with a load of 250 g was used for 420 min. Mass loss was determined by difference in weight, microhardness and surface roughness were also measured. Two-way ANOVA and non-parametric tests were used to detect significant differences. Titanium specimens (478 microg/cm(2)) exhibited the most mass loss, whereas ceramic (282 microg/cm(2)) and Co-Cr (262 microg/cm(2)) exhibited the least. However, ceramic demonstrated the most volume loss (0.239 mm(3)). The abrasivity effect of the toothpaste correlated with the RDA values. Slight variations in microhardness were observed after toothbrushing and depended on the material but not on the toothpaste used. Material surfaces were slightly smoothed by toothbrushing but no significant differences were detected. Dental casting alloys and ceramic are susceptible to abrasion by brushing with an electric toothbrush depending on the RDA value of the toothpaste. Variations in microhardness and surface roughness were not clinically relevant.

Absence of Helicobacter pylori in the oral cavity of 10 non-dyspeptic subjects demonstrated by real-time polymerase chain reaction.

Helicobacter pylori plays a significant role in gastric disease. However, the presence of this bacterium in the oral cavity remains controversial. The aim of the present study was to detect and quantify H. pylori in 29 different sites of the oral cavity in non-dyspeptic subjects by means of real-time polymerase chain reactions (PCR). Ten subjects without gastric symptoms were studied. Samples from unstimulated saliva, three sites of the tongue, oral mucosa, and 12 sites of both supragingival and subgingival plaque were collected from each subject. DNA was extracted from the oral samples and analysed for the presence of H. pylori by real-time PCR (LightCycler) using JW23/22 primers which targeted the 16S rRNA gene. DNA from H. pylori DSM 4867 was used as a positive control. Amplification efficiency for the LightCycler 2.0 runs ranged from 1.8 to 2.4. Melting curve analysis identified all the positive control capillaries, which contained H. pylori reference DNA, as a single and narrow peak at a melting temperature between 84.5 and 84.9 degrees C. All the negative control capillaries with no template control and the 29 oral samples from each subject showed either no melting peaks or broad melting peaks below 80 degrees C, which were considered as primer dimers. Therefore, H. pylori was not detected from any of the 290 oral samples. As a conclusion, H. pylori seems not to be permanently present in the oral cavity of a non-dyspeptic population.

Reproducibility of lateral excursive tooth contact in a semi-adjustable articulator depending on the type of lateral guidance.

The purposes of this study were (i) to compare the reproducibility of lateral tooth contacts of casts mounted in a semi-adjustable articulator when condylar guidance was set by different methods and (ii) to assess the margin of error of the variations of condylar guidance without changing lateral tooth contacts, depending on the type of lateral guidance. In subjects with different types of lateral guidance, intraoral lateral tooth contacts identified with occlusal registration strips were compared with those identified by use of a semi-adjustable articulator, setting the condylar guidance in four different ways: using protrusive wax wafers, by axiography and by adding and subtracting 5 degrees from the value of condylar guidance obtained by protrusive wax wafers. Tolerance to variations of condylar guidance without changing lateral tooth contacts was determined by increasing and decreasing the value of condylar guidance until lateral tooth contacts changed. Different ways of setting condylar guidance on a semi-adjustable articulator give rise to different values of condylar guidance in the same subject. The occlusal repercussions of these variations of condylar guidance values depend on the type of lateral guidance. Canine protection had the greatest tolerance to variations in the setting of condylar guidance without changing lateral occlusal contacts.

Effects of topical application of free and liposome-encapsulated lactoferrin and lactoperoxidase on oral microbiota and dental caries in rats.

Four groups of rats were inoculated with Streptococcus sobrinus ATCC 33478 and fed a cariogenic diet for 42 days. Topical treatment with either distilled water, sodium fluoride (0.2%), a solution containing lactoferrin and lactoperoxidase, or a solution containing liposome-encapsulated lactoferrin and liposome-encapsulated lactoperoxidase was applied at intervals for 35 days. Caries incidence in groups treated with liposome-encapsulated lactoferrin and lactoperoxidase was significantly lower than in control groups. The number of viable Strep. sobrinus and the proportion of Strep. sobrinus in the total counts were significantly higher in liposome-treated groups. Free lactoferrin and lactoperoxidase did not cause a significant reduction in caries incidence.

Fluoride and pilocarpine reduce the risk of caries produced by chronic clomipramine treatment in rats.

The effects of chronic clomipramine treatment on the incidence of caries in the rat and their prevention by fluoride and pilocarpine were investigated. One hundred and twenty male Wistar rats were divided into six groups, five experimental groups, one control group and treated with 50 mg/kg/day of clomipramine, 10 ppm fluoride in drinking water, and 5 mg/kg/day of pilocarpine. All animals were infected with Streptococcus sobrinus 6715 and fed a cariogenic diet ad libitum for 42 days. Water and food consumption, weight gain, salivary flow rate, amylase activity, protein and fluoride concentration in saliva, and caries scores were determined in all animals. Whereas clomipramine significantly increased the fluoride and protein concentration in saliva, pilocarpine only decreased fluoride concentration. Animals treated with clomipramine developed 40% more sulcal caries than nontreated animals. Administration of fluoride (10 ppm) in drinking water and chronic oral administration of pilocarpine prevented the increased risk of developing caries associated with chronic treatment with clomipramine.