Effect of bioceramic powder abrasion on different implant surfaces.

PURPOSE: Bioceramic coatings have been shown to promote bone repair, which aids in the early integration of implants. This study aimed to evaluate the influence of air abrasion with a bioceramic abrasive on the surface characteristics of different implant materials and surfaces. The dissolution of the applied treatment from the surfaces over 3 weeks was also assessed. MATERIALS AND METHODS: Discs of three alloys used for dental implants were studied and compared: two types of commercially pure titanium (CpTi)/ (CpTi SLActive) and titanium-zirconia (TiZr). The tested surfaces were: CpTi control (CpC), sandblasted (SB), sandblasted and acid-etched (SBE), and CpTi SLActive®, (TiZr) Roxolid®. Three discs from each group underwent air abrasion with apatite bioceramic powders, 95% hydroxyapatite (HA)/5% calcium oxide (CaO), and 90% hydroxyapatite (HA)/10% calcium oxide (CaO). The treated discs were surface characterized by optical profilometry to obtain surface roughness, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS) to compare element weight percentages of titanium, calcium, and phosphate. Dissolution was assessed using inductively coupled plasma optic emission spectrometry (ICP-OES). RESULTS: Bioceramic powders were deposited on all tested surfaces leading to changes in surface characteristics. The only statistically significant differences between the material groups for surface roughness were found with 95% HA/5% CaO powder in the Sp and Rp parameters (p = 0.03 and 0.04, respectively). There were no significant differences in the Ca and P wt% between all groups and powders 95% HA/5% CaO and 90% HA/10% CaO (p = 0.14, 0.18, and p = 0.15, 0.12, respectively). A non-uniform dispersion of the treatment on the surface layer was visible on all treated surfaces. The bioceramic powder continued to dissolute from the tested surfaces for 3 weeks. CONCLUSION: Bioceramic abrasion modifies implant surface characteristics, although the change in surface characteristics resulting from such treatment was not influenced by the implant material or surface treatment. Air abrasion with hydroxyapatite and calcium oxide bioceramics leaves powder deposits on the treated implant surfaces that could potentially influence the healing of implants affected by peri-implantitis.

The effect of water storage on nanoindentation creep of various CAD-CAM composite blocks.

BACKGROUND: To study the effect of water storage (3 months) on the creep deformation of various CAD-CAM composite structures at the nanoscale and compare it to that at the macroscale. METHODS: Seven CAD-CAM blocks were investigated: five resin-composite blocks (RCB), one polymer-infiltrated ceramic network (PICN) block, and one ceramic-filled polyetheretherketone (PEEK) block. Specimens of each material (n = 6) were separated into two groups (n = 3) according to their storage conditions (24 h dry storage at 23˚C and 3 months storage in 37˚C distilled water). Nano-indentation creep measurements were undertaken (creep depth measured in µm) using a nanoindenter (Nanovea) equipped with Berkovich three-sided pyramidal diamond tip. The machine was set for the chosen parameters: a load of 20 gf, a pause of 20 s, and the material type. Thirty indentations on 3 samples were made for each material for each test. Data were analysed using two-way ANOVA followed by one-way ANOVA and Bonferroni post hoc tests and independent t-test (< 0.05) for comparisons between the materials. RESULTS: The nanoindentation creep depth after 24 h storage ranged from 0.09 to 0.33 µm and increased after 3 months storage in distilled water to between 0.28 and 3.46 µm. There was a statistically significant difference in nanoindentation creep behaviour between the two storage conditions for each investigated material (independent t-test) and between all materials (Bonferroni post hoc). There was a non-significant negative correlation between nanoindentation creep (µm) and filler weight% at 24 h dry storage but a significant correlation at 3 months of water storage. A further non-significant positive correlation between nanoindentation creep (µm) and bulk compressive creep (%) was found. CONCLUSION: The PICN material showed superior dimensional stability in terms of nanoindentation creep depth in both storage conditions. Other composite blocks showed comparable performance at 24 h dry condition, but an increased nanoindentation creep upon water storage.

The impact of surgical guide design and bone quality on heat generation during pilot implant site preparation: an in vitro study.

BACKGROUND: Surgical guides restrict the flow of cooling agent to osteotomy site, which will lead to a temperature rise that provokes tissue injury. Few studies compared differences in the temperature changes between non-limiting 'conventional' and limiting 'guided' surgical guides during implant site preparation. The objective of this study was to investigate the difference in temperature changes during bone drilling for implant placement using non-limiting and limiting surgical guides at cortical and cancellous bone levels. METHODS: Forty-four bovine rib samples were used for implant bed preparation in this study with a minimum thickness of 11 mm was chosen for the ribs. The bone was stored in a freezer at 10 °C until it was used. On the day of the study, the bone was defrosted and soaked in water at 21 °C for three hours before embarking on drilling to make sure each sample was at the same temperature when tested. Forty-four bone specimens were prepared and randomly allocated to receive either a limiting or a non-limiting surgical guides (22 for each group). The osteotomy site was prepared by one operator following the manufacturer's instructions, using limiting and non-limiting surgical guides. Temperature changes were recorded during implant bed preparation using thermocouples that fit into 7 mm-horizontal channels at two different depths (Coronally) and (Apically) at 1 mm distance from the osteotomy site. The data were tested for homogeneity of variances using Levene's test, then data were analyzed using an Independent sample t-test and the significance level was set at P ≤ 0.05. RESULTS: The mean temperature rise for all samples was 0.55 °C. The mean temperature rises for the limiting and non-limiting surgical guides were 0.80 °C and 0.33 °C respectively. There was a statistically significant difference in temperature rise between the limiting and non-limiting surgical guides (P = 0.008). In relation to position of temperature recording (coronal vs. apical), there was no significant difference (P > 0.05). No significant difference was noted between the two groups at cancellous bone level (P = 0.68), but the difference was significant at cortical bone level (P = 0.036). CONCLUSION: Limiting surgical guides showed higher readings than non-limiting. However, for both techniques, temperature rise was not significant clinically and within a safe range.

Pattern, frequency and causes of tooth extraction among adult Syrian refugees.

AIMS OR OBJECTIVES: The Syrian crisis has resulted in a significant impact on refugee oral health status, but the scientific literature lacks information characterizing the pattern of tooth extraction in refugees. MATERIALS AND METHODS: The current study analyzed the pattern of tooth extraction and the associated sociodemographic factors among 626 (53.4% females, 46.6% males) Syrian refugees who were treated in dental clinics in the Zaatari camp. All adult Syrian refugees attending the dental unit at Zaatari camp were eligible to participate. Clinical and sociodemographic data were collected from the study sample using a validated semi-structured survey over a period of 4 months. Descriptive statistics were generated and Chi-square test, independent sample t-test, ANOVA test and Bonferroni Post Hoc test were used to examine associations between the different variables. RESULTS: More than one third of the attendees (33.9%) were young adults (18-29 years), and nearly two thirds (69.8%) had no or very basic education. The mean number of teeth that needed extraction was (1.46 ± 0.84) and was significantly higher in males, smokers, older patients, and those with no or basic education. The most common cause for tooth extraction was dental caries (54.8%), followed by tooth fracture/un-restorability (38.5%), and periodontitis (3.4%); while the least common reason was tooth extraction for orthodontic treatment (0.20%). CONCLUSIONS: Dental caries and its sequelae were the leading cause of tooth extraction in this refugee population. Molar teeth were found to be the most frequently extracted and lower anteriors were the least. Older age, smoking, patients with lower educational level, poor oral hygiene and male gender all predispose to a higher incidence of tooth extractions.

The Effect of Simulated Chewing on the Surface Roughness of Direct and Indirect Resin-Composites Opposed by Zirconia: An In Vitro Study.

Purpose: To assess the surface roughness of two different light-cured resin-composites when opposed by monolithic zirconia after simulated mastication. Materials and Methods: Materials included a direct restorative nanohybrid (n = 10) and an indirect microhybrid (n = 10) resin-composite (Tetric EvoCeram and Sinfony, respectively). The antagonist material was 3 mol% yttria-stabilized tetragonal zirconia polycrystalline ceramic. Each material was subjected to in vitro chewing against zirconia using a chewing simulator for 250,000 cycles. A 3D profilometer was used to assess the surface roughness parameters of each resin-composite before and after the simulated chewing. Independent t-test and paired sample t-test were performed to compare roughness values for both materials and to compare baseline and after chewing simulation values (p = 0.05). Results: Sinfony showed significantly greater roughness values compared to Tetric EvoCeram (p ≤ 0.025) before and after simulated chewing, except for Sa and Sv parameters after simulated chewing where the difference between the two materials was insignificant (p = 0.06 and 0.89, respectively). Surface roughness increased for both materials after simulated chewing compared to baseline values, but the difference was insignificant (p ≥ 0.065). However, Sa (p = 0.04) and Sv (p = 0.012) for Tetric EvoCeram were significantly higher after compared to before chewing simulation. Conclusion: Tetric EvoCeram had a smoother surface than Sinfony before and after simulated chewing. Surface roughness for both materials was higher after simulated chewing compared to baseline values which represent surface damage that was significant for Tetric EvoCeram while Sinfony showed better resistance.

Sociodemographic Factors and Implant Consideration by Patients Attending Removable Prosthodontics Clinics.

Objective: This study is aimed at investigating the treatment options offered to and chosen by patients attending a student prosthodontics clinic and to investigate the effect of the sociodemographic background of participants on implant consideration. Material and Methods. A cross-sectional descriptive study was conducted on 200 participants including their socioeconomic background, treatment options presented, treatment preferences, and implant consideration. Bivariate tests (unpaired t-test, chi-square, and Mann-Whitney test) and Spearman correlation were used for comparison of different socioeconomic groups according to treatment preferences (implant consideration versus conventional removable prosthesis). Results: Treatment options presented by dental students include 63.5% complete denture, 32% implants/removable dentures, and partial denture 4.5%. Conventional removable prostheses were mostly chosen due to low income. Implants were only considered by 26% of participants. Age and implant consideration had a significant negative correlation. No significant difference in gender and residency area on implant consideration was found. The chi-square test showed a significant difference between implant consideration and conventional removable prostheses in the various occupation groups. Conclusions: Low income is the main factor prohibiting patients from considering dental implants. Age and educational level may play a considerable role in considering dental implants. There should be more emphasis on dental students' treatment planning education to include and explain dental implants as a treatment option for their patients in the prosthodontics clinic.

Quantitative nano-mechanical mapping AFM-based method for elastic modulus and surface roughness measurements of model polymer infiltrated ceramics.

OBJECTIVES: The aim of this in vitro investigation was to assess and compare surface characteristics and nanomechanics of model polymer infiltrated ceramic network (PICN) materials compared to CAD/CAM resin composite blocks. MATERIAL AND METHODS: Four model PICN materials sintered at different temperatures (Exp.125, Exp.130, Exp.135 and Exp.155) were investigated along with three CAD/CAM resin composites; Lava Ultimate (LU), Cerasmart (CS) and Grandio Bloc (GB), and one commercial PICN block - Vita Enamic (VE). Forty samples were prepared with dimensions of 14 × 12 × 2 mm for resin ceramic and VE blocks and 15 × 2 mm discs for model PICN materials. All samples were scanned using atomic force microscopy (AFM) (n = 3) at multiple locations and two different scan sizes (20 ×20 µm and 3 ×3 µm). Surface optical gloss (n = 5) at 60° was also determined for all the groups. Data were analysed using one-way ANOVA, and Tukey's post hoc test (α = 0.05). RESULTS: Resin composite blocks showed smoother surfaces compared to the PICN materials. The average surface roughness values (Ra) ranged from 7.75 nm to 31.21 nm and the gloss value ranged from 56.43 GU to 91.81 GU. The highest surface roughness value was found for Exp.125 (31.21 nm) while LU showed the lowest roughness value (7.75 nm) (the difference being statistically significant: p = 0.001). Variation was noticed in terms of nanomechanical mapping within and between the groups. Images generated from the elastic modulus map values clearly indicated that all PICN materials had more than one phase and very different components. CONCLUSIONS: CAD/CAM resin composite blocks exhibited higher gloss and lower roughness values compared to PICN materials. However, both the commercial and model PICN materials showed more stiffness than resin composite with the presence of at least two different phases. Sintering temperature appears to have a significant effect on material topography and nanomechanical properties. The model PICN sintered at 1550 °C showed a comparable range of elastic modulus values to those of enamel.

Pattern, frequency and causes of dental extraction among children/adolescents Syrian refugees: an observational study.

BACKGROUND: The Syrian conflict has had a massive impact on the dental health of refugees. Dental extraction is a good indicator of socioeconomic position and degree of oral hygiene, however there is a scarcity of evidence in the scientific literature that characterizes the reasons for extraction in refugees. AIMS AND METHODS: The current study looked at the extraction causes and related sociodemographic variables of 322 Syrian refugees (46.3% females, 53.7% males) who were treated in a dental clinic in Zaatari camp (Jordan), from September to December 2019. All child Syrian refugees (aged 4-16) visiting the facility were eligible to participate. A validated semi-structured survey was used to collect clinical and sociodemographic data from the research sample. Chi-square test, Independent sample t-test, and ANOVA test were used to examine associations between the different variables. The significance level was set at P < 0.05. RESULTS: The total number of teeth extracted was 397: 25 (6.3%) permanent teeth, 371 (93.5%) primary teeth, and one mesiodens (0.2%). Overall, lower teeth were most commonly extracted (56.9%). The most common teeth that required extraction were the lower primary molars, with lower left primary second molars being the most commonly extracted (15.9%). As the level of parental education increased, the mean number of extracted teeth decreased (P = 0.035), additionally, as the frequency of toothbrushing increased extractions due to caries decreased significantly (P = 0.027). CONCLUSIONS: Dental caries and pulpal diseases were discovered to be the most prevalent causes for primary and permanent tooth extraction, with no difference between males and females. The lower left primary molar was the most commonly afflicted tooth.

Long-term hydrolytic stability of CAD/CAM composite blocks.

This study aimed to assess water sorption and solubility of CAD/CAM composite blocks compared to CAD/CAM ceramic after 8 months storage in water and artificial saliva. Eight CAD/CAM blocks were investigated: Five resin-composite blocks (RCBs), one polymer-infiltrated ceramic network (PICN) block, one ceramic-filled polyetheretherketone (PEEK) block, and one feldspathic ceramic block. One hundred and twelve specimens were prepared comprising 14 specimens of each of the eight materials. From each group of specimens, seven randomly selected specimens were immersed in 10 mL of water, while the other seven specimens were immersed in artificial saliva. All specimens were stored at 37°C and weighed at various time intervals. The data were analysed via repeat measures ANOVA, one-way ANOVA and Tukey's post hoc test (α = 0.05 for all tests). Sorption values (mean [SD]) in water were within the range -1.21 (0.4) to 39.3 (2.1) µg/mm3 and in artificial saliva between -0.7 (0.2) and 41.6 (1.3) µg/mm3 . Solubility values in water were between -0.43 (0.08) and 0.34 (0.18) µg/mm3 and in artificial saliva between -0.53 (0.07) µg/mm3 and 0.33 (0.2) µg/mm3 . CAD/CAM composite blocks were hydrolytically stable under long-term storage (according to ISO 4949:2009), although not as stable as ceramic. Water sorption of CAD/CAM composite blocks was dependent on the resin-matrix and was influenced by the filler weight %.

Oral Hygiene Awareness, Practices and Attitudes among Syrian Refugees in Zaatari Camp and Their Impact on Oral Health Status.

PURPOSE: To characterise the oral hygiene habits, attitudes, and oral health practices in relation to sociodemographic factors among refugees in Jordan and to investigate their impact on the oral health status of these refugees. MATERIALS AND METHODS: This cross-sectional study consisted of two parts. First, a face-to-face interview was conducted using a structured questionnaire including demographic and oral health-related questions. Second, clinical oral examination was performed using WHO criteria, DMFT and oral health indices (OHI-S). The participants were adults, aged 18 and older. All patients attending dental clinics and accompanying personnel in the waiting areas at Zaatari camp during the study period were invited to participate, with a sample size of 547 refugees (males = 212, females = 335). RESULTS: 547 adult refugees participated. 75.3% reported toothbrushing less than twice daily, while flossing was uncommon (9.5%). Toothbrushing habits were significantly associated with gender and smoking status. Untreated carious lesions had a high incidence (94.1%); the mean number of decayed teeth was 5.4 and was statistically significantly higher in males and smokers. The mean number of missing teeth was 3.2 and was significantly associated with males, age, smoking, and presence of chronic disease. Participants who reported conditions that had persisted 1 year or more and required ongoing medical attention or limited activities of daily living or both (e.g. diabetes mellitus, hypertension, heart diseases, thyroid disease, chronic renal disease, rheumatoid arthritis, anemia, peptic ulcer, or asthma) were recorded as having chronic disease. The mean number of filled teeth was 3.2 and was statistically significantly associated with age and presence of chronic disease. The mean DMFT was 11.8 and was statistically significantly higher in males, older people, smokers, and those with chronic disease. The OHI-S was 2.2. The most common complaint was pain (92.2%), and only 1.1% visited a dentist for a check-up. CONCLUSION: The prevalence of caries was extremely high, with poor oral hygiene practices among refugees, justifying the urgent need to develop and implement targeted oral health promotion, preventive programs and curative strategies and to enable collaboration of the oral healthcare providers and funding agencies to design the most appropriate interventions for this disadvantaged population. In addition, this information can be used as a basis upon which preventive programs can be assessed for efficacy.

Relationship between dental caries, oral hygiene and malocclusion among Syrian refugee children and adolescents: a cross-sectional study.

BACKGROUND: Little is known about the oral disease burden in refugee children and associated risk factors. This cross-sectional study aimed to explore the oral hygiene status and prevalence of caries, and to investigate their association with malocclusion characteristics in a child refugee population. METHODS: 606 Syrian refugee children and adolescents aged 7-19 years, registered as refugees in Jordan and residing in Zaatari camp, were recruited to the study. Oral hygiene and caries status were recorded using DMFT (mean of decayed, missing, and filled permanent teeth) and OHI-S (Simplified Oral Hygiene Index) according to WHO criteria. Oral health results were then cross tabulated with previously reported malocclusion traits for the same study sample (crowding, spacing, contact point deflection and IOTN) to detect any associations. Statistical analysis was conducted using chi-square test, independent sample t-test, one-way ANOVA, Welch test and Post Hoc testing (Gabriel and Games-Howell). RESULTS: Overall DMFT and OHI-S were 4.32 and 1.33 respectively with no difference between males and females. Around 40% of the sample showed ≥ 5 DMFT score. 96.1% of the sample either do not brush or brush occasionally: females showed better oral hygiene practices (P = 0.002). No significant differences in DMFT scores were noted for gender or age, other than the 7-9.9 year old group having significantly higher mean DMFT scores than all other age groups (P < 0.01);the mean of OHI-S was not significantly different between different age groups (P = 0.927). Subjects with malocclusion, specifically crowding, contact point deflection and IOTN grades 3, 4 and 5 had higher scores in both arches for OHI-S and DMFT than subjects without malocclusion traits, although this was not statistically significant for DMFT scores. Overall, patients with generalized spacing had a significantly lower OHI-S score than those without spacing (P = 0.021). Significant correlations were found between parameters of intra-arch and inter-arch relationships and oral health indices (DMFT and OHI-S). CONCLUSION: Malocclusion may increase the risk of caries and periodontal disease; the magnitude of this risk is amplified in populations with poor oral health and limited access to oral healthcare services, highlighting the need for preventive and curative oral health programs.

Knowledge and awareness of dental implants among Syrian refugees: a cross sectional study in Zaatari camp.

BACKGROUND: The popularity of implant dentistry is increasing dramatically, but the success of implant treatment depends on a patient's knowledge and expectations. METHODS: This study aimed to assess dental implant knowledge among refugees as a treatment option (n = 565), using face-to-face interviews. The frequency distribution of the responses in general and according to age, gender and education was calculated. RESULTS: 81.8% of the interviewees had missing teeth, however, only 26.2% replaced them. 16.6% of participants had never/hardly heard about implants. Females who never heard of implants were more than males (P < 0.001). 51.3% of participants described dental implants as a screw, and only 35.4% knew implants were placed in jawbones. 6.2% of respondents reported that implants required more care than a natural teeth, with 47.6% believing that diseases affect implant success. Friends were the main source of information (61.4%). Highly educated participants showed higher knowledge about implants. CONCLUSIONS: The surveyed sample revealed limited knowledge about dental implants with high cost being a major obstacle, warranting more strategies to increase awareness and to make implants more affordable for this population.

Prevalence of malocclusion and assessment of orthodontic treatment needs among Syrian refugee children and adolescents: a cross-sectional study.

BACKGROUND: There is a scarcity of data concerning the prevalence and pattern of malocclusion and orthodontic treatment needs in Syrian refugee. In this study, extra and intra-oral features of malocclusion and the dental health component of the Index of Orthodontic Treatment Need (IOTN) were reported. METHODS: Examination of 606 Syrian children/adolescents refugees attending Zaatari clinic was carried out (males = 280, females = 326, mean age = 11.84 ± 2.1 years). Subjects not within the age limit, with a history of orthodontic treatment, or with craniofacial anomalies were excluded. Both extra and intra-oral features of malocclusion were assessed. Intra-oral features included inter- and intra-arch occlusal characteristics: crowding, spacing, crossbite, overjet, overbite, molar and canine relationship, incisor relationship, and centerline shift. In addition, the dental health component (DHC) of the Index of Orthodontic Treatment Need (IOTN) was recorded. Gender and age variations in malocclusion characteristics and IOTN grading were tested using chi-square and nonparametric tests respectively (P < 0.05). RESULTS: The prevalence of malocclusion was 83.8% (52.6% class I, 24.2% class II, 7% class III). The most common features of malocclusion were crowding (71.1%) followed by centerline shift (52.1%), increased overjet (36.1%), high vertical proportions (34%) and deep overbite (31.2%); there were significant gender and age differences for a number of occlusal traits. The prevalence of moderate to severe need for orthodontic treatment was 67.7%. CONCLUSIONS: This study provides baseline data on the prevalence of malocclusion in Syrian refugee children/adolescents in Zaatari camp where data concerning oral health of this population are lacking. The prevalence of orthodontic treatment need was high warranting the need for a comprehensive interceptive orthodontic program to prevent increasing oral health problems in the future. This high burden of oral diseases has a negative financial impact on the hosting country which can be reduced through public health interventions and implementing community-based dental healthcare for this underprivileged population.

Satisfaction with healthcare services among refugees in Zaatari camp in Jordan.

BACKGROUND: Feedback on satisfaction regarding healthcare services is vital for continuous improvement of the service delivery process and outcome. AIMS AND METHODS: The objective of this study was to assess the satisfaction of refugees with the medical and dental services in Zaatari camp, under 3 domains with 20 key indicators (human and physical health resources, interaction and reactivity, and administration) using a self-administered questionnaire. RESULTS: Of the 500 participants, the satisfaction rate was 72.5%. Young participants and participants with a shorter stay in the camp showed higher overall satisfaction rates (P ≤ 0.01). Within the domains, 'interaction and reactivity' achieved the highest satisfaction score, whereas 'administration efficiency' was ranked the lowest. As for elements within the domains, the most acceptable were the sufficient number of staff and the working hours, availability of radiological services and proper care for children, reasonable waiting time and asking for medical history in every visit. Whereas difficulty to access healthcare services, difficulty to be referred to hospitals, lack of follow up and lack of dental services were the least acceptable. CONCLUSION: In conclusion, whereas refugees were generally satisfied with the provided services, this study indicates that there are areas for further service improvement. This study highlights a significant gaps in healthcare services which if not addressed have the potential to amplify oral/medical health problems.

The effect of different storage media on the monomer elution and hardness of CAD/CAM composite blocks.

OBJECTIVE: This study aimed to assess the effect of different storage media on the hardness and monomer elution of CAD/CAM composite blocks. METHODS: Five resin-composite blocks (RCB), one polymer-infiltrated ceramic network (PICN) block (Enamic (EN)), one ceramic-filled poly ether ether ketone (PEEK) block (Dentokeep (DK)), and one feldspathic ceramic block. Microhardness was measured using a Vickers indenter tester (FM-700, Future Tech Corp., Japan). In addition 4 conventional resin-composites were investigated for monomer elution using high performance liquid chromatography (HPLC) after storage in different media for 3 months. The data were analysed by three-way ANOVA, two-way ANOVA, one-way ANOVA, Tukey's post hoc test and the independent t-test (α=0.05 for all tests). RESULTS: The specimens stored in the water had a hardness reduction ranging from 0.9% to 24.4%. In artificial saliva, the specimens had a hardness reduction ranging from 2.8% to 23.2%. The hardness reduction percentage in 75% Ethanol/Water (E/W) ranged between 3.8% and 35.3%. All materials, except GR (resin-composite block) and DK (Polyetheretherketone (PEEK)), showed a variable extent of monomer elution into 75% E/W with significantly higher amounts eluted from conventional composites. GRA and GND (conventional resin-composites) eluted TEGDMA in artificial saliva and GRA eluted TEGDMA in water. SIGNIFICANCE: The hardness of CAD/CAM composite blocks was affected by different storage media, and they were not as stable as ceramic, with PICN exhibited superior hardness stability to all of the resin-composite blocks in all the storage media and was comparable to ceramic block. The hardness reduction percentage of the CAD/CAM composite blocks was influenced by the filler loading and resin-matrix composition.Minimal or no monomer elution from CAD/CAM blocks was detected.

Response of two gingival cell lines to CAD/CAM composite blocks.

OBJECTIVE: This study aimed to investigate the influence of CAD/CAM composite materials on human gingival fibroblasts (HGF) and gingival keratinocytes (HGK). METHODS: Four materials were investigated: two resin-composite blocks (RCB), Grandio Blocs (GR) and Block HC (HC); one polymer-infiltrated ceramic network (PICN) (Enamic, EN); and one conventional resin-composite, Grandioso (GND). HGF and HGK were cultured as per the supplier's protocol (ATCC, UK). Cell proliferation and cytotoxicity were evaluated at 1, 3, 5 and 10 days using LDH and Alamar Blue assays. Indirect immunostaining was used to assess the Caspase-3 activity. Data were analysed via two-way ANOVA, one-way ANOVA and Tukey's post hoc test (α = 0.05 for all tests). RESULTS: There was significant difference in cell proliferation of the HGK and HGF cells in contact with different composite materials but no significant differences in their cytotoxicity. There was a significant effect on cell proliferation and cytotoxicity with different exposure times, for each type of resin-composite. HGF cell proliferation was higher than HGK with almost all investigated materials and at all time points. No Caspase-3 activity was detected in either cell lines. SIGNIFICANCE: HGK proliferation and cytotoxicity appeared to be more influenced by composite materials compared to HGF, demonstrating EN cytotoxic effects in HGK. Different manufacturing techniques of resin-composites (photo curing versus heat/pressure curing) had no significant effect on their biocompatibility.

Initial management and long-term follow up after the rehabilitation of a patient with severe dentoalveolar trauma: A case report.

Dental trauma is common and for patients who suffer significant oral injuries, rehabilitation can be challenging to the clinical team. This case report describes the successful prosthetic replacement of multiple missing teeth lost due to severe dentoalveolar trauma, using iliac crest bone grafting, an implant-retained removable dental prosthesis and implant-supported crowns. Good functionality and aesthetic outcome were achieved.

National Student Survey: Reliability and prediction of overall satisfaction scores with special reference to UK Dental Schools.

INTRODUCTION: The aim of this study was to assess the reliability of the UK National Student Survey (NSS) (2018) and explore the predictive values of individual questions and question domains on the overall satisfaction score. METHODS: UK NSS result data (for 2018) were assessed for all those providers that award an undergraduate degree in dentistry. To analyse the correlation of each question item to the overall satisfaction question (question 27), a bivariate 2-tailed Pearson correlation test was conducted, where a P value of <.05 was considered statistically significant. The same test was used to assess such correlation at question domain level. Cronbach's alpha was used to assess the test reliability of the NSS data. RESULTS: Question 5 ("My course has provided me with opportunities to explore ideas or concepts in depth") had the highest predictive value, explaining 85% of the correlation data to the overall satisfaction question. The strongest positive correlation could be seen at the "teaching on my course" and "learning opportunities" domains, whereby 84% of the data can be explained by each of these variables. The worst predictor domain was assessment and feedback, whereby only 40% of the data could be explained by the correlation line. Cronbach's alpha was 0.952-0.976. CONCLUSIONS: The NSS is a highly reliable test, both at question and domain levels. The highest predictors of overall satisfaction are teaching, learning opportunities and academic support domains. Assessment and feedback has weak predictive value towards the overall satisfaction score. Question 5 is highly predictive of the overall outcome.

Viscoelastic stability of pre-cured resin-composite CAD/CAM structures.

OBJECTIVES: To study the effect of water storage (3 months) on the creep deformation and recovery of CAD/CAM composite materials to determine their viscoelastic stability. MATERIALS AND METHODS: Five CAD/CAM composite blocks, with increasing filler loading, and one polymer-infiltrated ceramic network (PICN) were studied. Six specimens of each material were separated into two groups (n=3) according to their storage conditions (24 h dry storage at 23°C versus 3 months storage in 37°C distilled water). A constant static compressive stress of 20 MPa was applied on each specimen via a loading pin for 2 h followed by unloading and monitoring strain recovery for a further period of 2 h. The maximum creep-strain (%) and permanent set (%) were recorded. Data were analysed via two-way ANOVA followed by one-way ANOVA and Bonferroni post hoc tests (<0.05) for comparisons between the materials. Homogeneity of variance was calculated via Levene's statistics. RESULTS: The maximum creep strain after 24 h dry ranged from 0.45% to 1.09% and increased after 3-month storage in distilled water to between 0.71% and 1.85%. The permanent set after 24 h dry storage ranged from 0.033% to 0.15% and increased after 3-month water storage to between 0.087% and 0.18%. The maximum creep strain also reduced with increasing filler loading. SIGNIFICANCE: The PICN material exhibited superior dimensional stability to all of the pre-cured resin composite blocks in both storage conditions with deformation being predominantly elastic rather than viscoelastic. Notwithstanding, two of the resin-matrix composite blocks approached the PICN performance, when dry, but less so after water storage.

Effect of the Composition of CAD/CAM Composite Blocks on Mechanical Properties.

The aim of this study was to evaluate the effect of the composition of CAD/CAM blocks on their mechanical properties. Nine different CAD/CAM blocks, enamel and dentine, were tested. Sixteen samples of each material were separated for Vickers microhardness test (n=6, 5 readings per specimen), nanohardness test (n=6, 5 readings per specimen), filler weight (n=3), and SEM imaging (n=1). Data were statistically analysed using one-way ANOVA. Vita Mark II ceramic showed significantly higher values of hardness (in both nano- and microscale) and elastic modulus (6.83 GPa, 502 kg/mm2, and 47.7 GPa), respectively, than other materials. CAD/CAM composite blocks showed comparable values of hardness and elastic modulus to those of dentine but lower than those of enamel and ceramics. SEM images highlighted different filler-matrix microstructure of CAD/CAM composite blocks. It was concluded that (1) hardness and elastic moduli are positively correlated with ceramic filler percentage and microstructure and (2) CAD/CAM composite materials have comparable hardness and elastic moduli to tooth structure.