The Effect of Removable Partial Dentures on Alveolar Bone Resorption: A Retrospective Study with Cone‐Beam Computed Tomography

Purpose: The aim of this study was to compare vertical and horizontal mandibular alveolar bone resorption by measuring bone morphological variation in Kennedy Class II removable partial denture (RPD) wearers and non‐wearers using cone‐beam computed tomography (CBCT). Materials and Methods: In total, 124 sites in the CBCT scans of 62 (29 RPD non‐wearers, 33 RPD wearers) Kennedy Class II patients were analyzed retrospectively. Three‐dimensional representations of the mandible with superimposed cross‐sectional slices were developed with the CBCT scans to evaluate the mandibular alveolar height and width by measuring distances between the mandibular canal, mylohyoid ridge, alveolar crest, and lower border of the mandible in four regions (eight sites) of Kennedy Class II non‐wearers and wearers of RPDs. Results: Mandibular alveolar bone height and width were significantly lower in edentulous sites when compared with dentate sites in both Kennedy Class II non‐wearers and wearers of RPDs (p < 0.05). Additionally, mean vertical and horizontal mandibular bone resorption was significantly higher in RPD wearers than in non‐wearers (p < 0.05). Conclusions: Vertical and horizontal alveolar bone resorption was found to be higher in the RPD wearing patients when comparing the dentate and edentulous sites.     

Probiotic <Emphasis Type="Italic">Lactobacillus paracasei</Emphasis> effect on cariogenic bacterial flora

Lactobacillus paracasei has been demonstrated to inhibit the growth of many pathogenic microbes such as Streptococcus mutans, in vitro. However, its clinical application remains unclear. Here, we examined whether a novel probiotic L. paracasei GMNL-33 may reduce the caries-associated salivary microbial counts in healthy adults. Seventy-eight subjects (aged 20 to 26) had completed this double-blinded, randomized, placebo-controlled study. A probiotic/test (n = 42) and a control group (n = 36) took a L. paracasei GMNL-33 and a placebo oral tablet three times per day for 2 weeks, respectively. Bacterial counts of salivary S. mutans, lactobacilli, and salivary buffer capacity were measured with chair-side kits at the beginning (T1), the completion (T2) of medication, and 2 weeks after medication (T3). The results did not show differences in the counts of S. mutans and lactobacilli between probiotic and control groups at T1, T2, and T3. Nevertheless, within the probiotic group, an interesting probiotic effect was noticed. Between T1 and T2, no inhibitory effect against S. mutans was observed. However, a significant count reduction in the salivary S. mutans was detected between T2 and T3 (p = 0.016). Thus, a 2-week period of medication via oral administration route may be needed for L. paracasei GMNL-33 to be effective in the probiotic action.     

A fast Look–Locker method for <Emphasis Type="Italic">T</Emphasis><Subscript>1</Subscript> mapping of the head and neck region

Objective  A sequence for T ₁ relaxation time measurements that allows a high-resolution image to be obtained within a short acquisition time is described. Its application to the orofacial region is investigated. Methods  The sequence is based on the Look–Locker (LL) method and employs a magnetization-preparation pulse prior to data acquisition, with either a turbo-field echo (TFE) or turbo-field echo echo-planar imaging (TFEPI) sequence. We applied the multiple LL sequence by synchronizing the data acquisition with the virtual electrocardiogram. T ₁ results from the LL sequence were compared with those from the inversion recovery (IR) sequence. In an in vitro study, we evaluated the T ₁ maps of contrast medium at different concentrations. In an in vivo study, we evaluated the T ₁ maps in seven volunteers. Results  In the in vitro study, the correlation between the T ₁ values obtained from the LL sequence and those from the IR sequence was high, with an R ² of more than 0.99. For T ₁ values between 200 and 1,500 ms, the difference between the two methods was less than 7%. In the in vivo study, a high correlation was observed between the T ₁ values from the IR sequence and those from the LL sequence. The scan duration for the LL sequence was less than 3 min. Conclusion  Our method, based on the LL sequence, was found to be clinically useful for producing a T ₁ map.     

Short‐term antimicrobial properties of mineral trioxide aggregate with incorporated silver‐zeolite

Abstract – The purpose of this in vitro study was to determine whether adding silver‐zeolite (SZ) to mineral trioxide aggregate (MTA) would enhance the antimicrobial activity of MTA against Staphylococcus aureus (ATCC #25923), Enterococcus faecalis (ATCC #29212), Escherichia coli (ATCC#25922), Pseudomonas aeruginosa (ATCC #27853), Candida albicans (ATCC #90028), Porphyromonas gingivalis (ATCC #33277), Actinomyces israelii (ATCC #12102), and Prevotella intermedia (ATCC# 15032). SZ was added at 0.2% and 2% mass fraction concentration to MTA powder. The control group was MTA powder with no SZ. The antimicrobial effect test was accomplished by placing freshly mixed MTA specimens on agar plates inoculated with microorganisms and comparing the zones of inhibition at 24, 48, and 72 h. The amounts of silver ion release from MTA specimens were measured with atomic absorption spectrophotometry at 10‐min, 24‐, 48‐, and 72‐h periods. The pH of MTA specimens was measured with a pH meter at 10‐min, 24‐, 48‐, and 72‐h periods. MTA with 2% and 0.2% SZ specimens showed inhibitory effects on some microorganisms at all time periods, whereas no antimicrobial activity showed for P. intermedia and A. israelii. MTA without SZ inhibited C. albicans, E. Coli, and P. intermedia. The highest silver release was detected in 2% SZ MTA at 24 h. The incorporation of SZ may enhance the antimicrobial activity of MTA.     

Analysis of brain and muscle activity during low‐level tooth clenching – a feasibility study with a novel biting device

In electromyographic (EMG) and functional magnetic resonance imaging (fMRI) studies, muscle and brain activity was compared during low levels of tooth clenching using a novel biting device to control bite force. A total of 21 healthy subjects performed motor tasks, comprising tooth clenching at 5, 10 and 20 N. During all measurements, subjects kept the novel bite device between the anterior teeth during tooth clenching. The EMG study (n = 15) characterised jaw muscle activity for the three motor tasks and demonstrated significant differences in root mean square (RMS) EMG amplitude between 5‐, 10‐ and 20‐N tooth clenching (F = 46·21, P < 0·001). There were no differences in variability of muscle activity between the three tooth‐clenching levels. In an fMRI pilot study (n = 6), statistical comparisons were used to identify brain regions with significant activation in the subtraction of baseline from 5‐ or 20‐N tooth‐clenching activity. 5‐ and 20‐N tooth clenching significantly and bilaterally activated the sensorimotor cortex, supplementary motor area, cerebellum and basal ganglia (P < 0·05, corrected for multiple comparisons). However, activation of each brain region did not differ significantly between two tooth‐clenching tasks. Based on these preliminary findings, we propose that the novel biting device may be useful in further fMRI studies on controlled jaw muscle activation patterns in different craniofacial pain conditions. In addition, our fMRI result suggests that there are no significant differences in brain activity within low levels of tooth clenching with controlled force.     

Dental caries experience in relation to salivary findings and molecular identification of <Emphasis Type="Italic">S. mutans</Emphasis> and <Emphasis Type="Italic">S. sobrinus</Emphasis> in subjects with Down syndrome

This study investigated the association between clinical and salivary or molecular parameters in Down syndrome subjects. Sixty individuals (1- to 48-year old) were clinically examined using DMFT/DMFS. Stimulated saliva was collected; salivary flow was calculated (mL/min), buffering capacity was measured using a standard pH tape. In addition, 25 μL of saliva was diluted using 10-fold-dilution method and then placed on Mitis-Salivarius-Bacitracin agar to count colony forming units (CFU/mL) of mutans streptococci. Polymerase chain reaction analysis identified species. Caries indexes were 0.65–13.5 (DMFT) and 0.65–26.0 (DMFS) according to groups. Ninety-four percent of subjects had low flow rate (0.7–1.0 mL/min) and 44% had low buffering capacity (pH < 4). Besides, 60% had more than 1 × 10⁶ CFU/mL, 60% had S. mutans, and 41.4% had S. sobrinus. Caries indexes did not significantly correlate with flow rate, buffering capacity, CFU/mL by Pearson’s correlation (p > 0.05), and showed no significant association with prevalence of species by Chi-square (p > 0.05). There is no association between clinical picture and salivary or molecular parameters in Down syndrome subjects.     

Efficacy of denture cleansers on denture liners contaminated with Candida species

As poor denture hygiene is related to Candida colonisation, disinfectant solutions have been proposed as an effective method of preventing denture stomatitis. This study assessed the efficacy of denture cleansers on Candida albicans and Candida glabrata adherence on denture liners. Another aim was to correlate materials’ surface roughness (Ra) to Candida adherence. Specimens of three denture liners (soft and hard polymethyl methacrylate (PMMA)-based and soft silicone-based) were prepared and had their Ra measured. Specimens were randomly divided to adherence assays with C. albicans or C. glabrata. After contamination with the fungi, specimens were treated with an enzymatic cleanser solution, a cleanser solution or a 0.5% NaOCl solution by soaking for 3, 15 or 10 min, respectively. Control group specimens were soaked in distilled water for 15 min. Number of remaining Candida cells after treatment was determined by light microscopy (×400). Analysis of variance (α = 0.05) showed that Ra of the silicone-based liner was lower than that of the PMMA-based liners (p < 0.05). The overall results showed high C. glabrata adherence (p < 0.001), while the lowest levels of remaining Candida cells were found for the treatment with 0.5% NaOCl (p = 0.0019). No difference among denture cleansers and control was found (p = 0.19). There was no correlation between Ra and C. albicans or C. glabrata adherence in all materials tested. The only treatment able to reduce both Candida species adherence on all materials tested was 0.5% NaOCl solution.     

Assessment of occlusion after placement of stainless steel crowns in children – a pilot study

Many stainless steel crowns (SSCs) disrupt the occlusion in children, but stabilisation appears to occur within a short period post‐placement. The extent and mechanism of these short‐term occlusal changes in children are unknown. This study sought to determine whether placement of a SSC changes the maximum intercuspation position (MIP) in children, whether the MIP returns to normal within 4 weeks and whether local anaesthesia had an effect on the child's ability to achieve MIP. The T‐Scan^® III was used for the measurement of occlusal contacts. Reliability and reproducibility of the system was determined using a calibration exercise where MIP recordings were taken of eleven children not undergoing any dental treatment. For the main study, the percentage of total occlusal force on each tooth was recorded in 20 children preoperatively, after local anaesthesia, after SSC placement and 4 weeks postoperatively. There was no significant difference in MIP (P = 0·435) preoperatively and post‐administration of local anaesthesia. There was a significant difference between the preoperative force on a tooth and the reading after crown placement (P = 0·0013, Wilcoxon test). By 4 weeks, there was no significant difference overall between post‐SSC placement and the preoperative value for the tooth (P = 0·3). Administration of local anaesthesia did not affect the ability of a child to attain MIP. Maximum intercuspation position was disturbed by the placement of a SSC in seven of 20 cases. When MIP was disturbed, in most cases, it returned to preoperative status within 4 weeks of crown placement.     

Association between patient satisfaction with complete dentures and oral health-related quality of life: two-year longitudinal assessment

The objective was to evaluate the development of oral health-related quality of life (OHRQoL) in patients with complete dentures and the association between OHRQoL and patient satisfaction. Fifty-two patients (mean age, 66.3, 48.1% male) received dentures in at least one jaw. The analysis was conducted on participants with dentures in both jaws (CD-Both; n = 22) or in the upper jaw only (CD-Max; n = 28). Data were collected 4 weeks, 6 months, and 1 and 2 years after insertion. OHRQoL was measured by use of the OHIP-EDENT. Self-rated patient satisfaction was assessed on a scale of 0–10. To prove the hypothesis that patient satisfaction would be a meaningful predictor of OHRQoL, and not vice versa, multilevel analysis and cross-lagged correlation analysis were performed for both groups separately. OHRQoL improved from 22.9 (SD, 20.7) to 12.1 (SD, 14.5) for CD-Both and from 20.3 (SD, 17.2) to 14.7 (SD, 15.1) for CD-Max. Multilevel analysis revealed that patient satisfaction and OHRQoL were significantly associated (p < 0.0001) for both groups. Differences between the groups were found with regard to the effect of time after insertion and the interaction between time and satisfaction with OHRQoL which were significant only for the group CD-Both; however, no evidence was found for the causality of this association in the cross-lagged analysis for both groups (ZPF test, p > 0.016). Patient satisfaction and OHRQoL were associated for wearers of complete dentures. Within the limitations of the study, however, the causality that patient satisfaction predicts OHRQoL, and not vice versa, could not be proven.     

In vitro models of cranial neural crest development toward toxicity tests: frog,mouse, and human

During craniofacial development, cranial neural crest (NC)‐derived mesenchymal cells migrate to pharyngeal arches and contribute extensively to neurons, Schwann cells, smooth muscle cells, osteoblasts, chondrocytes, and odontoblasts, forming maxillofacial structures. In vitro models using model organism cells, such as African clawed frog (Xenopus Laevis) and mouse (Mus Musculus), were developed to understand cellular and molecular mechanisms of cranial NC development. Recent studies using human embryonic stem cells (hESCs) and human‐induced pluripotent stem cells (hiPSCs) have enabled the generation of human NC cells (NCCs) in vitro to provide insight into human NC development. Understanding molecular mechanisms underlying craniofacial development will contribute to develop novel embryotoxicity tests and to decrease the incidence of drug‐induced congenital anomalies in the craniofacial region, such as cleft lip or cleft palate. Here, we review culture methods to derive NCCs in vitro from Xenopus presumptive ectoderm (animal caps), mouse embryonic stem cells (mESCs), and human pluripotent stem cells (hPSCs) and discuss how these in vitro models can be used to help clarify the mechanisms underlying craniofacial development and for developing embryotoxicity tests predicting drug‐induced congenital anomalies in the craniofacial region.     

Differences between salivary and blood neutrophils from elderly and young denture wearers

Summary We previously showed that neutrophils from patients with Candida‐related denture stomatitis exhibited damaged function, and the advance in age intensified this condition. Because such alterations had been determined in elderly people that were not denture wearers, the purpose of this study was to clarify functional and phenotypic characteristics of neutrophils from elderly denture wearers (EDW) and young denture wearers (YDW) without oral lesion. We enrolled 20 denture wearers (12 EDW and 8 YDW) and determined the positivity of Candida species on maxillary prosthesis and palate. Additionally, blood and salivary neutrophils were evaluated. Furthermore, cytokines and chemokines salivary levels were detected. YDW presented higher positivity of Candida albicans than elderly ones. However, blood neutrophils from EDW expressed less CXCR1, CD62L and CD11b and had lower C. albicans phagocytosis than YDW. Although myeloperoxidase and elastase activity was significantly higher in C. albicans‐stimulated blood neutrophils from elderly, they produced high levels of IL‐10 and low levels of Granulocyte macrophage‐colony stimulating factor (GM‐CSF). Despite apoptosis rate of salivary neutrophils was enhanced, these cells were at a high number in YDW. GM‐CSF and IL10 were lower in saliva from elderly group. These data confirmed that ageing affects blood and salivary neutrophils and could predispose elderly to persistent oral infections.     

Panoramic radiograph, computed tomography or magnetic resonance imaging. Which imaging technique should be preferred in bisphosphonate-associated osteonecrosis of the jaw? A prospective clinical study

It was the aim of the present study to find out which radiological imaging techniques allow assessing the extent of bisphosphonate-associated osteonecrosis of the jaw (BONJ) in an adequate way. Twenty-four patients suffering from BONJ were included in the study. Before surgery, each patient was examined with panoramic radiograph, contrast-enhanced magnetic resonance imaging (MRI) and non-enhanced computed tomography. The detectability of BONJ was assessed for the three imaging techniques. The extent of the jaw region affected by BONJ was determined in MRI and CT scans and compared to the intra-operative situation. The detectability of BONJ lesions was 54% for panoramic radiographs, 92% for MRI scans and 96% for computed tomography (CT) scans. The intra-operatively assessed extent of BONJ correlated significantly with the measurements on CT scans (p = 0.0004) but did not correlate significantly with the measurements in MRI scans (p = 0.241). The intra-operatively measured extent of BONJ differed significantly from the CT measurements (p = 0.00003) but not from the MRI data (p = 0.137). Although MRI as well as CT have a high detectability for BONJ lesions that exceeds that of panoramic radiographs by far, both techniques show problems with the exact assessment of the extent of BONJ lesions in the individual patients. Therefore, the relevance of MRI and CT for the preoperative assessment of the extent of BONJ lesions is limited. Future research should focus on the identification of imaging techniques that allow assessing the extent of BONJ lesions with a higher accuracy.     

Effect of complete and partial removable dentures on chewing movements

Partial or complete edentulism impairs mastication. However, it is unclear how the chewing cycle is affected by prosthetics. We evaluated the chewing movements of patients fitted with complete (CD) or removable partial denture (RPD). A total of 29 subjects were kinesiographically evaluated during chewing of peanuts and Optocal portions in a random sequence. The subjects were divided into two groups according to prosthesis type. Group RPD was composed of 14 partially edentulous patients using a lower distal extension RPD (mean age 61 ± 8 years), and group CD contained 15 completely edentulous patients using CD (mean age 65·9 ± 7·9 years) in both jaws. Opening, closing, occlusal and masticatory cycle times, movement angle (opening and closing), maximum velocity (opening and closing), total area and chewing cycle amplitudes were evaluated. The results were subjected to anova and Tukey's HSD test at a significance level of 5%. The RPD group exhibited shorter opening and closing phases and masticatory cycle time (P < 0·05). Maximum velocities were also higher in the RPD group, irrespective of the test material (P < 0·05). The area and amplitude of the chewing envelope was smaller in the CD group (P < 0·0001). The test material did not influence chewing cycles in any of the parameters evaluated (P > 0·05). RPD wearers use a faster chewing sequence with greater vertical and lateral jaw excursions compared with CD wearers.     

Multilevel modeling of gingival bleeding on probing in young adult carriers of non-JP2-like strains of Aggregatibacter actinomycetemcomitans

The influence of Aggregatibacter actinomycetemcomitans on inflammation in subjects with gingivitis has not been studied in great detail. Seventeen healthy young adults with plaque-induced gingivitis or localized mild chronic periodontitis harboring cultivable numbers of A. actinomycetemcomitans were thoroughly examined. Samples of subgingival plaque were obtained from mesial surfaces of all teeth present. In addition, 12 oral mucosal surfaces and unstimulated saliva were sampled. Species identity, presence of the leukotoxin gene, and absence of a specific 530 b deletion in the leukotoxin promoter region indicating non-JP2-like strains were assessed by polymerase chain reaction. Based on a multilevel random intercept model adjusted for probing depth, age, and smoking status, the odds of bleeding on probing was increased by a factor of 1.89 (1.09–3.29, p = 0.024) if, in addition to plaque, A. actinomycetemcomitans could be recovered from the site. At a site without visible supragingival plaque but with cultivable numbers of subgingival A. actinomycetemcomitans the odds ratio of bleeding on probing was 3.37 (0.86–13.2, p = 0.081). Simulating variance partition coefficients revealed that between 1–2% (a clean, shallow site without A. actinomycetemcomitans; a deep site covered by plaque containing A. actinomycetemcomitans) and 6–7% (a moderately deep site with neither visible plaque nor cultivable A. actinomycetemcomitans) of the residual variance was attributable to differences between subjects. The present cross-sectional study indicates that non-JP2-like strains of A. actinomycetemcomitans may enhance gingival bleeding tendency even in the absence of clinically visible supragingival plaque.     

Identification of key determinants in Porphyromonas gingivalis host‐cell invasion assays

The periodontal pathogen Porphyromonas gingivalis can invade host cells, a virulence trait which may contribute to the persistence of infection at subgingival sites. Whilst the antibiotic protection assay has been commonly employed to investigate and quantify P. gingivalis invasion, data obtained have varied widely and a thorough investigation of the factors influencing this is lacking. We investigated the role of a number of bacterial and host‐cell factors and report that the growth phase of P. gingivalis, source (laboratory strain vs. clinical strain), host‐cell identity (cell line vs. primary), host‐cell lysis method, and host‐cell passage number had no significant effect on bacterial invasion. However, incubation time, host‐cell seeding density, method of quantification (viable count vs. DNA), and whether host cells were plated or in suspension, were shown to influence invasion. Also, cells isolated by rapid adhesion to fibronectin exhibited higher levels of P. gingivalis invasion, possibly as a result of increased levels of active α5β1 integrin. Interestingly, this may represent a population of cells with stem cell‐like properties. This study provides important new information by identifying the most important factors that influence P. gingivalis invasion assays and may help to explain variations in the levels previously reported.     

Narrow‐ and regular‐diameter implants in the posterior region of the jaws to support single crowns: A 3‐year split‐mouth randomized clinical trial

Objectives

The objective of this 3‐year split‐mouth randomized controlled clinical study was to compare narrow‐diameter implants (NDIs) to regular‐diameter implants (RDIs) in the posterior region of the jaws (premolars and molars) in regards to (i) the marginal bone level (MBL) and (ii) implant and prosthesis survival and success rates.

Material and Methods

A total of 22 patients were included in the study. Each patient received at least one implant of each diameter (Ø3.3 and Ø4.1 mm), placed either in the maxilla or mandible to support single crowns. A total 44 implants (22 NDIs and 22 RDIs) were placed and included in the study. Twenty‐one implants were placed in the premolar, whereas 23 were placed in molar areas. Radiographic evaluations to access the MBL were performed immediately after implant placement, 1 and 3 years after implant loading. Peri‐implant clinical variables including probing pocket depth (PPD) and bleeding on probing (BoP) were obtained after crown delivery, 1 and 3 years after loading. Furthermore, the survival and success rates of the implants and prosthesis were also evaluated.

Results

Twenty patients were able to complete the study. There was no statistically significant difference regarding MBL between groups at implant placement (p = .084), 1‐year (p = .794) and 3‐year (p = .598) time intervals. The mean peri‐implant bone loss at 3‐year follow‐up was ?0.58 ± 0.39 mm (95% CI: ?0.751 to ?0.409) and ?0.53 ± 0.46 mm (95% CI: ?0.731 to ?0.329) for NDIs and RDIs, respectively. BoP was present at 15% and 10% of NDIs and RDIs, respectively, at 3‐year follow‐up. PPD >5 mm was observed in 5% and 0% of the implants of NDIs and RDIs, respectively, at 3‐year follow‐up. At the 3‐year examination, the implant success rates were in the NDIs and RDIs sites, respectively, 95% and 100%. The corresponding values for prosthesis success rates were 90% for NDIs and 95% for RDIs.

Conclusion

The present study demonstrated that NDIs placed to support single crowns in the posterior region did not differ to RDIs in regards to MBL, implant survival, and success rates.     

Impact of a triclosan‐containing toothpaste during the progression of experimental peri‐implant mucositis: Clinical parameters and local pattern of osteo‐immunoinflammatory mediators in peri‐implant fluid

1 Background

This study evaluated the influence of a triclosan‐containing toothpaste in the profile of osteo‐immunoinflammatory mediators in peri‐implant crevicular fluid (PICF) and in clinical parameters during progression of peri‐implant mucositis.

2 Methods

Twenty‐two clinically healthy patients with an implant‐supported single‐unit crown were enrolled in this double‐blind, randomized, crossover study carried out in two phases of 21 days each. During an experimental 3‐week period of undisturbed plaque accumulation in the implants, patients were randomly assigned to use three times/day: triclosan (n = 11), triclosan/copolymer/fluoride toothpaste; or placebo (n = 11), fluoride toothpaste. After a professional prophylaxis, a washout period of 30 days was established. Clinical parameters and 15 osteo‐immunoinflammatory mediators in the PICF were evaluated at baseline and at 3, 7, 14, and 21 days.

3 Results

Both groups showed increase in plaque index at implant sites from the 3rd until the 21st day (P < 0.05). Only triclosan treatment was able to avoid an increase in bleeding on probing (BOP) throughout the follow‐ups (P > 0.05), whereas a significant intensification in BOP was observed from the 14th day in the placebo‐treated sites (P < 0.05). Lower interleukin (IL)‐10 concentrations were detected in the placebo group at the 21st day when compared with triclosan‐treated implant sites (P < 0.05). IL‐10 levels were reduced and IL‐1β concentrations were increased at 21 days when compared with baseline only in placebo‐treated sites (P < 0.05). Osteoprotegerin levels significantly increased from the 14th until the 21st day only in triclosan‐treated sites (P < 0.05).

4 Conclusion

Triclosan‐containing toothpaste controls clinical inflammation and interferes positively in the profile of osteo‐immunoinflammatory mediators during progression of experimental peri‐implant mucositis.     

Adherence of <Emphasis Type="Italic">Candida albicans</Emphasis> to denture base acrylics and silicone-based resilient liner materials with different surface finishes

This study evaluated the surface roughness and Candida albicans adherence on denture base acrylic resins and silicone-based resilient liners with different surface finishes. Four commercial denture base acrylic resins (three heat polymerized and one room temperature polymerized) and five silicone-based liner materials (two heat polymerized and three room temperature polymerized) (10 × 10 × 2 mm) were tested in this study. The materials were processed against glass or plaster or finished with a tungsten carbide bur. Surface roughness measurements were made using a profilometer with an optical scanner probe. All specimens were ultrasonically cleaned in water for 15 s, autoclave sterilized, and contaminated with C. albicans solution for adherence assay evaluation. The materials processed against the glass surface showed significantly lower surface roughness values (0.11 ± 0.1–1.66 ± 1.1 μm) than those of the materials processed against the dental plaster (2.61 ± 0.2–6.12 ± 2.8 μm) or roughening with a bur (1.48 ± 0.2–7.05 ± 1.2 μm; p < 0.05, one- or two-way analysis of variance). Also, the materials processed against the glass surface showed lower C. albicans adhesion (mean ranks 120.36) than those of the materials processed against the dental plaster (mean ranks 139.77) or roughening with a bur (mean ranks 143.06), but the differences were not statistically significant (p > 0.05, Kruskal–Wallis and Mann–Whitney). In all types of surface finishes, C. albicans adhesion on denture base acrylics was significantly less (mean ranks 90.18–90.40) than those of silicone liners (mean ranks 119.38–205.18; p < 0.01, Kruskal–Wallis).     

Assessment of changes in the oral tactile function of the soft tissues by implant placement in the anterior maxilla: a prospective study

The aim of the present study was to assess the somatosensory function in the peri-implant soft tissues in the anterior jaw bone by means of two psychophysical tests. Light-touch sensation (LTS) and two-point discrimination (2PD) were performed before, and at planned intervals until 18 months after the placement of one or two implants in the anterior maxilla. The same tests were used on the contralateral control sites. The psychophysical threshold was determined by performing the staircase method. The mean values and standard deviation of LTS and 2PD, pooled over the four sessions at each test area, were calculated. Despite a large intersubject variation in both the LTS and 2PD, significantly high intra-individual correlations were found (P < 0.005). For LTS, the thresholds were not significantly affected over time (P > 0.05) on both implant and control sites. The 2PD increased significantly after surgery and maintained the higher discriminatory sense for 1 year (P-value 0.005). The control sites remained stable over time. However, no correlation was revealed between LTS and 2PD perception (Pearson correlation test). In this prospective study, no major differences between the different sites and testing sessions were reported; except for the 2PD thresholds which were lowered after implant surgery. These findings suggest that the regenerated nerves may be responsible for the increased 2PD sensitivity in the peri-implant soft tissue. The unchanged LTS thresholds did not allow confirming this hypothesis.     

Oral health‐related quality of life in patients with tooth wear

The aim of this study was to investigate the impact of tooth wear (TW) on patients' oral health‐related quality of life. A total of 198 participants were included in the study. They belonged to the following four different diagnostic categories: 51 patients with TW, 46 patients with painful temporomandibular disorders (TMD), 43 complete denture wearers and 58 healthy controls. The Dutch version of the Oral Health Impact Profile (OHIP‐NL) was used to assess the patients' oral health‐related quality of life. The results of the study show that patients with TW have an impaired oral health‐related quality of life compared with healthy controls (P < 0·001). Furthermore, the impact of TW and of edentulousness do not differ significantly, while both of these oral conditions seem to have a lower impact on quality of life compared with painful TMD (P < 0·05). It was concluded that TW has a negative impact on patients' quality of life. This impact is comparable with that of edentulousness.