OBJECTIVES: The aim of this study was to evaluate the bond strength of a low fusing veneering porcelain fired on Titanium grade V with different surface treatments. MATERIALS & METHODS: One hundred and twenty bars of Titanium grade V (25±1x 3±0.5x 0.5±0.05mm) were divided randomly into twelve groups: group 1 no surface treatment, group 2 Gold sputter coating, group 3 TiN sputter coating, group 4 Sandblasting Al2O3 125μm, group 5 Sandblasting Al2O3 180μm, group 6 Sandblasting Al2O3 250μm, group 7 Sandblasting Al2O3 125μm then gold sputter coating, group 8 Sandblasting Al2O3 180μm then gold sputter coating, group 9 Sandblasting Al2O3 250μm then gold sputter coating, group 10 Sandblasting Al2O3 125μm then TiN sputter coating, group 11 Sandblasting Al2O3 180μm then TiN sputter coating, group 12 Sandblasting Al2O3 250μm then TiN sputter coating. Vita Titankeramik porcelain was applied for all groups and built up manually with dimensions limited to 8x3x1mm and fired on Ti bars following the manufacturer’s instructions and ISO 9693 recommendations, and tested for bond strength by Schwickerath crack initiation test (ISO 9693) using an Instron universal testing machine (Model: 5566A). The mode of failure and bond interface were evaluated by SEM / EDS. RESULTS: The mean bond strength values of groups 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, and 12 were 2.31MPa (±0.2), 24.3MPa (±0.78), 46.94MPa (±1.29), 6.18MPa (±0.98), 9.46MPa (±1.08), 15.14MPa (±0.74), 24.84MPa (±1.73), 36.24MPa (±1.43), 41.49MPa (±2.13), 49.45MPa (±0.96), 69.36MPa (±0.96), 94.45MPa (±1.51), respectively. Two-way ANOVA with Tukey multiple comparisons test was performed to determine the groups that are statistically different. All tested groups (1-12) showed statistically significant difference except groups 2, and 7, P< 0.05. CONCLUSIONS: Within the limitations of this study, the following conclusions can be drawn: 1- Surface finish significantly affects the bond strength of low fusing porcelain to Ti grade V. 2- Larger Al2O3 particle size corresponded to higher bond strengths. 3- Sandblasting in combination with Au or TiN coatings produced the highest bond strength values. 4- Groups 1, 4, 5, & 6 showed Adhesive failure at the ceramic – metal interface; for groups 3, 10, 11, & 12 were found to be Cohesive failure within the porcelain layers; and for groups 2, 7, 8, & 9 were found to be mixed Adhesive / Cohesive failure. / 2018-09-28T00:00:00Z

New CAD/CAM materials are becoming more accepted in veneer restoration. The objective is to investigate the margin integrity of CAD/CAM veneer, their color masking over dark backgrounds and shear bond strength (SBS) to resin cements. Materials and Methods: Four types of CAD/CAM materials shaded A2: Lava Ultimate (LU); IPS Empress CAD (IPS); Vita Enamic (VE); and Vitablocs Mark II (VMII) were sectioned into tiles of different thicknesses: 0.3mm, 0.5mm and 0.7mm (n=7). The color (CIE - L*a*b*) of each specimen was measured against grey background, then against each tooth-shaded background: A3, A4, B3 and C2 acrylic (Coldpac, Motloid). Color differences (ΔE) were calculated. Specimens were measured against black then white background to calculate translucency. Two-way ANOVA was used to compare the differences in ΔE among the groups (a=0.05). SBS values of 2mm thick tile specimens of the same CAD/CAM materials to resin cements, RelyX Ultimate and Varilonik Veneer, were measured using Instron Universal Testing Machine. (n=10). Statistical analysis was performed by ANOVA with Tukey-Kramer HSD multiple comparison test (a=0.05). Qualitative evaluation of margin integrity of the veneers milled from the same CAD/CAM materials in three thicknesses 0.3, 0.5 and 0.7mm were observed under the optical microscope. Results: Significant differences in masking capabilities were found among the tested material for all three thicknesses. In comparison of ΔE values of the tested materials over tooth-shaded backgrounds, specimens over shade A3 background showed the highest color masking ability. LU and VE exhibited better color masking than IPS and VMII. IPS showed significantly higher in translucency than the other groups. IPS showed the highest SBS to resin cements and LU showed lowest SBS. Materials cemented with RelyX showed significantly higher SBS values than those with Variolink. CAD/CAM milled LU and VE veneers show smoother margins when compared to IPS and VMII. Conclusion: LU and VE exhibited higher color masking, lower translucency, lower SBS values, and better margin integrity than IPS and VMI. / 2019-09-26T00:00:00Z

BACKGROUND: Dental implants have been successful for the restoration of edentulous areas, but current techniques are inadequate in areas lacking sufficient bone volume. Piezoelectric surgery has shown encouraging effects on both osseous healing. A new wedge-shaped titanium PiezoImplant requires piezoelectric osteotomy. This study compares PiezoImplants to conventional threaded cylindrical shaped implants by microcomputed tomography and histology to assess osseointegration, tissue response, and alveolar ridge changes. METHODS: After 3 months post-extraction, 18 conventional cylindrical implants and 18 wedge-shaped PiezoImplants were placed using a split-mouth design in 3 adult mini pigs. The cylindrical implant sites were prepared for osteotomy with rotary instrumentation while the PiezoImplant sites were prepared with piezoelectric surgical inserts. One animal was sacrificed at 4, 8, and 12 weeks post operation. Quantitative µCT and histological analysis evaluated bone volume, osseointegration, and post-operative cellular events. RESULTS: The results of a multivariable linear regression model demonstrated that the PiezoImplants, arch location, and time were significant factors on higher BV/TV percentage. Bone to implant contact (BIC) analysis by high resolution microscopy and histomorphometry indicated osseointegration though intimate contact between implants and adjacent alveolar bone in both groups. The tissue response displayed no evidence of abnormal healing and the PiezoImplant was classified as a non-irritant. CONCLUSION: The combination of piezoelectric osteotomy and newly designed PiezoImplants had favorable effects on wound healing and osseointegration compared to conventional cylindrical implants. These novel wedge-shaped implants may be beneficial for narrow ridge spaces without additional ridge augmentation. Further research is needed to establish clinical validity.

Introduction: Recent studies have utilised cone beam computed tomography (CBCT) for the assessment of the volume of the nasopharyngeal airway space (Guijarro-Martínez and Swennen, 2013, Lenza et al., 2010, Woodside and Linder-Aronson, 1979, Chang et al., 2013). Some of these investigations are based on the analysis of slice data obtained from three dimensional (3D) radiographic images. The usage of a CBCT scan to measure the nasopharyngeal airway volume has drawbacks which include the effect of respiration and tongue position (Abbott et al., 2004), the impact of head posture, lordosis (cranio-cervical inclination) and mandibular morphology on the accuracy of measuring air oro-pharyngeal airways. In addition, published figures to date has not considered the detailed anatomical boundaries of the nasal cavity space, paranasal airway space and other pharyngeal sections collectively (Chang et al., 2013). Aims and objectives: The aim of the study was to assess the validity of the free access software package like ITK Snap in measuring the airways spaces, investigate, using CBCT, the three-dimensional effect of rapid maxillary expansion on the maxillary sinus, the lower part of the nasal cavity, the upper nasopharynx and the upper oropharynx (upper and lower retropalatal spaces), and to correlate the changes in these anatomical spaces with the measured RME appliance split, the dentoalveolar expansion and the gender of the subjects. Materials and methods: This study was carried out on seventeen patients (8 boys, 9 girls; mean age 12.6 + 1.8 years) who required maxillary expansion for the management of narrow upper dental arch. Sample size was calculated using the Researcher’s Toolkit calculator and this indicated that a sample size of 14 patients would produce an Alpha error level or confidence level at 95% and a Beta error level at 20%. Therefore, it was decided to recruit 17 subjects to overcome potential exclusion due to irreproducibility in the head orientation and lordosis. Pretreatment (T1) and immediate post-RME (T2) CBCT images were taken for all the patients. In all CBCT images, head orientation and lordosis were measured using OnDemand 3D software packages. Cases were excluded from the study if the difference in the head orientation and lordosis between the CBCT of T1 and CBCT of T2 was more than 5 degrees. The two scans, T1, T2, were orientated according to a specific protocol and superimposed on the cranial base to standarise the volumteric segemtation and measurements. The impact of RME was assessed by measuring, using ITK snap and OnDemand 3D software packages, the changes in the distance between the intermolar dentoalveolar width at level of molar alveolar crest (IMD), the magnitude of appliance expansion (AE), the volume of respiratory region or the lower part of the nasal cavity (LNC), the volume of the right and left maxillary sinus (RMS and LMS), the volume of the upper nasopharynx (UNP), the subdivisions of the upper oropharynx including the upper and lower retropalatal space (URP and LRP) at T1 and T2. Segmentation of the oro-naso-pharyngeal spaces into multiple segments allows a deailed localisation of the changes and aids in exclusion of any potential masking change of one airway space on adjacent or remote airway space as each segment is associated anatomically and physiologically to different function and/or disorder. The normality of the data was tested using Kolmogorov–Smirnov test. The reproducibility of meaurements was analysed using Paired t-test and interclass correlation coefficient. The volumteric and linear changes was assessed using Student t-test (P < 0.05) and Pearson correlation coefficients was used to test the correlation of these changes. Results: Bonded RME has an effective dentoalveolar expansion effect in growing patients (P=0.001) and produced a significant increase in UNP (P=0.045). There was a statistically significant reduction on the URP space (P=0.042), especially in males. There was strong correlation between the increase of the volume of the right and left maxillary sinuses (PCC=0.86) and between appliance expansion and dentolavelar expansion (PCC=0.75). Conclusions: ITK-SNAP software is a reliable package and a single threshold value (-450 grey) is an accurate value. Additionally, this software can be used to measure the size of bony defect in patient with cleft palate before secondary alveolar bone grafting. Bonded RME was an effective dentoalveolar expander in growing patients and the immediate expansion of LNC and UNP might be associated with a reduction in nasal resistance, improvement in the nasal breathing and it can be considered as an option for treatment of Paediatric Obstructive Sleep Apnea Syndrome. Findings of this dtudy showed that there is a sexual dysmorphisim secondary to RME but did not reach the statistical significance. Generally, the effect of the RME on the upper naso-oro-pharyngeal airway spaces followed a mushroom like pattern with the upper parts expanded, the middle part was significantly narrowed while the lower part was mildly, but insignificantly statistically, reduced. However, it is essential to consider that regardless of the benefit of the increase nasal patency of this orthopeadic procedure, it should not done merely for the above purposes solely but only when it is linked to a right indication for RME. A future studies could include a colour mapping for detailed assessment of changes in different part of the oro-naso-pharyngeal space, as the shape changes of the airway space is as important as volumetric changes. Finally, a further randomised clinical trial or comparative study with larger sample size and long term follow up would be beneficial in estimating the real impact of the RME on the airway confirm the findings of this study.

Periodontal disease is a chronic inflammatory disease affecting the structures supporting the teeth. It results from the interaction between a microbial biofilm on the tooth surface and a de‐regulated host response in the periodontal tissues of a genetically susceptible host. There are strong correlations between specific ‘red complex’ micro‐organisms within the subgingival biofilm and disease. Dysbiosis, a deleterious shift in the relative abundance of components of the microbiota in disease, is a recognised property of microbiomes at other sites of the GI tract in chronic diseases. Exploring dysbiosis in the oral commensal microbiota using a mouse model of periodontitis, we have shown that a ‘red complex’ organism (Porphyromonas gingivalis) caused significantly more periodontal bone loss in specific pathogen free (SPF) mice than controls and no bone loss in germ free (GF) mice. This confirms the oral commensal microbiota is fundamentally required for periodontal bone loss. In addition, low level colonisation of SPF mice with P. gingivalis led to qualitative and quantitative changes to the microbiota; dysbiosis. The oral commensal microbiota of the SPF mice was stable for our aging population of SPF mice and this led to increased alveolar bone loss with age. Through a series of co‐caging experiments we have shown that the oral commensal microbiota of different strains of mice was transmissible into GF mice and led to periodontal bone loss. We have also demonstrated that a dysbiotic oral commensal microbiota was transmissible into GF mice and led to increased periodontal bone loss. In conclusion, the oral commensal microbiota is fundamental in the pathogenesis of periodontal disease in this mouse model. Moreover, it is dysbiosis of this oral commensal microbiota, brought about by P. gingivalis, that drives accelerated alveolar bone loss. We propose that P. gingivalis be considered as a keystone species.

The complex microstructure and properties of dental enamel have been studied for decades using a variety of quantitative and qualitative techniques in order to gain a greater depth of understanding behind the chemical and physical processes that are associated with the formation and destruction of this biological apatite. Dental enamel is composed of highly ordered carbonated hydroxyapatite crystals which, together with its small organic component, are responsible for its mechanical strength, allowing it to serve its functional purpose. Environmental changes at any stage of the biomineralisation process or post eruption can disrupt the orientation and alter the structure and function, which can have detrimental clinical effects. The aim of this study is to understand and characterise the structural and crystallographic properties of disrupted enamel, and compare this to healthy unaffected tissue. Enamel affected by the genetic disorder, Amelogenesis Imperfecta, alongside enamel disrupted by dissolution and caries were studied using Synchrotron X-ray diffraction, 3D X-ray Microtomography, and Scanning Electron Microscopy techniques to relate these features to the clinically observed characteristics; to the chemistry; and to the known genetics of the tooth. Synchrotron radiation was used to map changes in preferred orientation, while the corresponding mineral density distributions were seen by using an in house developed, non-destructive microtomography system. Structural information on dental enamel at the crystallographic and micron length scales can benefit a variety of different disciplines. This project has the potential to inform early diagnosis, develop a tool for an early recognition of progressive or highly variable medical conditions, and design potential treatment regimes. The comparison of affected enamel to that of healthy enamel will provide a unique opportunity to identify the developmental pathways required for normal tooth development and give insights into the basic principles underlying mammalian biomineralisation.

The purpose of this study was to investigate the stigma of mental and physical handicap and its affects on the provision of dental care. Three groups of mentally and physically handicapped children, 4 year olds (n = 309), 14 year olds (n = 174) and 25 to 35 year olds (n = 265), were randomly selected from institutions in Hong Kong. The sample was dentally examined and dental status and treatment need assessed Their parents were also interviewed. Two psychometric scales, the Scale to Determine Attitudes Toward Disabled Persons (SADP), and the Parental Attitude Scale, a scale derived for this study, were used to assess attitude towards disabled persons in general, and specifically towards their own child. A questionnaire was also developed investigating parental experiences and feelings towards their handicapped child. Socioeconomic data was also collected and Information on the dental care delivery pattern experienced by their child. Dental practitioner members of the Hong Kong Dental Association were circulated with the SADP, the Dental Practitioner Attitude Scale, a scale derived for this study, and a questionnaire relating to qualifications and practice. A 62.5% response rate was achieved Canes experience was comparable to the non handicapped in the 4 year old group, lower in the other age groups, but with a high D component m the 25 to 35 year olds. Dental utilisation was low, the main reasons being financial, transport problems and a belief that the dentist would not treat. There was a gradation of parental attitude towards handicapped persons corresponding to education, age and socioeconomic factors. Dentists were not enthusiastic about treating handicapped patients for mainly financial reasons. Both parents and dentists felt strongly that government should provide facilities and be responsible for the treatment of handicapped individuals. The hypothesis of the study was mainly fulfilled. The stigma of handicap is a barrier to dental care, but is more socioeconomic than the way that handicapped persons present themselves.

Desmosomes and adherens junctions are intercellular junctions crucial for epithelial cell-cell adhesion and maintenance of normal tissue architecture. Desmoglein 3 (Dsg3), a member of the desmoglein sub-family, serves as an adhesion molecule in desmosomes. Its importance in cell-cell adhesion has been highlighted by the autoimmune blistering disease pemphigus vulgaris, where autoimmune antibodies directed against Dsg3 trigger a cascade of intracellular events, resulting in structural defects and blister formation in the skin and oral mucosa. In addition to its adhesive function, Dsg3 is also acknowledged to have other important roles in the regulation of cell proliferation and differentiation. Our group suggested that Dsg3 is involved in the regulation of keratinocyte stem cell differentiation, but the underlying mechanism(s) were unclear (Wan et al, 2003; Wan et al, 2007). We hypothesise that Dsg3 may be involved in the regulation of the E-cadherin-mediated cell adhesion and the reorganisation of actin cytoskeleton, which in turn contributes to differentiation programs and tissue morphogenesis. Thus, the aim of this study was to examine the interactions between Dsg3, E-cadherin and actin and to explore the underlying signalling pathways that are associated with these intercellular junctions. Using both a gain and loss of Dsg3 functional approaches, I demonstrate that Dsg3 is capable of interacting with E-cadherin and involved in the regulation of calcium-induced E-cadherin junction assembly and the activation of Src signalling pathway. Overexpression of Dsg3 increased E-cadherin/Src signalling with enhanced levels of Src and pSrc co-purified with E-cadherin. Knockdown of Dsg3 inhibited this pathway with reversed effect, suggesting that Dsg3 acts as an upstream regulator of Src signalling in the regulation of E-cadherin-mediated adherens junction formation. In addition, I show another novel function of Dsg3 in promoting actin dynamics through regulating Rac1 and Cdc42-GTPase activities, resulting in pronounced membrane protrusions and enhanced rate of actin turnover. Taken together, my work suggests that Dsg3 play an important signalling role in the assembly of E-cadherin-mediated cell adhesion and the dynamic of actin cytoskeleton.

Background: This study assumes that while all families are unique, families share common tasks that must be fulfilled as part of their functioning and the definition of whether the family process is functional or not is specific and may be unique to the family and is dependent upon what the family perceives as being normal, while considering cycle demands, resources and socio cultural influences. Objectives: To explore the role of family functioning in chronic periodontitis. Methods: The Outer North East London (ONEL) Oral Health Needs Assessments collected data in a representative sample of 2,343 adults aged16-65 and 1,174 children 3-4 years old in 2009-10. Data were collected through home visits by trained dentists and interviewers, and included dental clinical examinations and answers to questionnaires. Family function in the domains general functioning, problem solving, communication, roles, affective responsiveness, affective involvement and behaviour control was assessed using the Family Assessment Device (FAD) Epstein et al., 1983). Chronic periodontitis was defined as having at least one interproximal site with pocket depth of 4 mm or more. Results: Chronic periodontitis was associated with family functioning in the domains general functioning (odds ratio:0.45; 95%CI: 0.25-0.84), communication (odds ratio: 0.55 95%CI: 0.30-0.98), affective involvement (odds ratio:0.56; 95%CI: 0.34-0.94), affective responsiveness (odds ratio:0.47; 95%CI: 0.26-0.81) and behaviour control (odds ratio:0.40 95%CI: 0.22-0.74) after adjustment for ethnicity and socioeconomic position (NS-SEC). However, after adjusting for oral health related behaviour (tobacco consumption and plaque score) only the domain of general functioning (odds ratio: 0.51 6 95%CI: 0.27-0.97) affective responsiveness (odds ratio 0.52; 95%CI: 0.29-0.92) and behaviour control (odds ratio 0.46; 95 CI: 0.25-0.83) remained significantly associated with chronic periodontitis. Family functioning domains general functioning, communication, affective involvement, affective responsiveness and behaviour control also potentially partially mediates the relationship between socioeconomic position and chronic periodontitis experience. Conclusion: Efficient family functioning in the domains of general functioning, affective responsiveness and behaviour control may act as protective factors against chronic periodontitis.

The primary etiologic factor of periodontitis is bacterial plaque biofilm. Nevertheless, the factors that determine the progression of periodontitis are complex and poorly understood. Hence, the potential involvement of autoimmunity in the pathogenesis of periodontitis has been considered intermittently for years. The basic hypothesis for this PhD was that autoimmunity to native and/or posttranslationally modified periodontal extracellular matrix proteins is involved in the progression of periodontitis. Objectives The main objective of the study was to extend the understanding of periodontal disease pathogenesis beyond the common bacterial etiology and to address the hypothesis that periodontal disease is an auto-immune disease. This research will try to identify the exact neoepitope. Specific aims (i). To investigate the involvement of autoimmune reactivity towards native collagen type I (CI) and collagen type III (CIII), as well as CI and CIII posttranslationally modified by reactive oxygen specious (ROS) known to present in the inflamed tissue, ROS-CI and ROS-CIII, respectively. (ii). Develop human antibody fragment(s) specific to CI, ROS-CI, CIII and ROSCIII for diagnostic application. Methods Modification of CI or CIII was confirmed by SGS-PAGE, Capillary Electrophoresis and 3D-fluorescence. The presence of autoantibodies to ROS-CI and ROS-CIII in sera and saliva were then studied by ELISA and Western blotting using sera and saliva from individuals with Aggressive Periodontitis (AgP), Chronic Periodontitis (CP) and Gingivitis (G). Antibodies specific to ROS-CI and ROS-CIII were developed using phage display semi-synthetic human single chain fragment variable (scFv) libraries. Results Autoantibodies to native CI, native CIII, ROS-CI and ROS-CIII were observed exclusively in patients with AgP. Human antibody fragments specific to native and ROS-CI were developed and evaluated. Conclusions A. Autoimmune reactions to native and post-translationally modified self antigens may play a role specifically in the pathogenesis of AgP. B. Anti-ROS scFv specific to ROS-CI and ROS-CIII may have diagnostic future applications.