Long-term outcome of primary non-surgical root canal treatment

Aim: The aim of this study is to examine the survival distributions of primary root canal treatment using interval-censored data and to assess the factors affecting the outcome of primary root canal treatment, in terms of periapical healing and tooth survival. Materials and methods: About one tenth of primary root canal treatment performed between January 1981 and December 1994 in a dental teaching hospital were systematically sampled for inclusion in this study. Information about the patients' personal particulars, medical history, pre-operative status, treatment details, and previous review status of the treated teeth, were obtained from dental records. Patients were recalled for examination clinically and radiographically. Treatment outcomes were categorized according to the status for periapical healing and tooth survival. The event time was interval-censored and subjected to survival analysis using the Weibull accelerated failure time model. Results: A total of 889 teeth were suitable for analysis. Survival curves of both outcome measures (periapical healing and tooth survival) declined in a non-linear fashion with time. Median survival of the treated teeth was 119 months (periapical healing) and 252 months (tooth survival). Age, tooth type, pre-operative periapical status, occlusion, type of final restoration, and condition of the tooth/restoration margin were significant factors affecting both periapical healing and tooth survival. Apical extent and homogeneity of root canal fillings had a significant impact towards periapical healing (p < 0.05), but not tooth survival. Conclusion: The longevity of treated teeth based on tooth survival was considerably greater than that of periapical healing. Both outcome measures were affected by a number of socio-demographic, pre-, intra-, and post-operative factors. Clinical relevance: Root canal-treated teeth may continue to function for a considerable period of time even though there may be radiographic periapical lesion present. Decision for extraction may be due to reasons other than a failure of the periapical tissues to heal. © 2011 The Author(s).published_or_final_versionSpringer Open Choice, 28 May 201

Perceived oral health condition and self-satisfaction with oral health

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The applications of stereolithography in facial reconstructive surgery

The development of rapid prototyping has evolved from the crude milled models to the laser polymerised stereolithographic models of excellent accuracy. The technology was advanced further with the recent introduction of fused deposition modelling and the 3-dimensional ink-jet printing technique in stereo-model fabrication. The concept of using a 3-dimensional model in planning the operation has amazed the maxillofacial surgeons since its first application in grafting a skull defect in 1995. It was followed by many bright ideas of applications in the field of facial reconstructive surgery. The stereo-model may assist in the diagnosis of facial fractures, joint ankylosis and even impacted teeth. The surgery can be simulated prior to the operation of complex craniofacial syndromes, facial asymmetry and distraction osteogenesis. The stereo-model can be used for preparation of reconstructive plate or joint prosthesis. It has an enormous value as an educational teaching and patient information tool for obtaining the consent for surgery. The aims of the paper are to present the modern manufacturing methods of the stereo-model and to illustrate the clinical applications of the stereomodel in facial reconstruction.published_or_final_versio

Filtering of false positive microRNA candidates by a clustering-based approach

B M C BioinformaticsBackground: MicroRNAs are small non-coding RNA gene products that play diversified roles from species to species. The explosive growth of microRNA researches in recent years proves the importance of microRNAs in the biological system and it is believed that microRNAs have valuable therapeutic potentials in human diseases. Continual efforts are therefore required to locate and verify the unknown microRNAs in various genomes. As many miRNAs are found to be arranged in clusters, meaning that they are in close proximity with their neighboring miRNAs, we are interested in utilizing the concept of microRNA clustering and applying it in microRNA computational prediction. Results: We first validate the microRNA clustering phenomenon in the human, mouse and rat genomes. There are 45.45%, 51.86% and 48.67% of the total miRNAs that are clustered in the three genomes, respectively. We then conduct sequence and secondary structure similarity analyses among clustered miRNAs, non-clustered miRNAs, neighboring sequences of clustered miRNAs and random sequences, and find that clustered miRNAs are structurally more similar to one another, and the RNAdistance score can be used to assess the structural similarity between two sequences. We therefore design a clustering-based approach which utilizes this observation to filter false positives from a list of candidates generated by a selected microRNA prediction program, and successfully raise the positive predictive value by a considerable amount ranging from 15.23% to 23.19% in the human, mouse and rat genomes, while keeping a reasonably high sensitivity. Conclusion: Our clustering-based approach is able to increase the effectiveness of currently available microRNA prediction program by raising the positive predictive value while maintaining a high sensitivity, and hence can serve as a filtering step. We believe that it is worthwhile to carry out further experiments and tests with our approach using data from other genomes and other prediction software tools. Better results may be achieved with fine-tuning of parameters. © 2008 Leung et al; licensee BioMed Central Ltd.published_or_final_versio

Incidence of neurosensory deficits and recovery after lower third molar surgery: a prospective clinical study of 4338 cases

A prospective study of all lower third molar surgery performed in the outpatient extraction clinic of a teaching dental hospital was conducted from January 1998 through October 2005 to determine the incidence of subsequent neurosensory deficit due to inferior alveolar nerve (IAN) and lingual nerve (LN) injury, to examine possible contributing risk factors and to describe the pattern of recovery. 3595 patients were included (61% female, 39% male; age range, 14-82 years). Of the 4338 lower third molar extractions performed by various grades of operators, 0.35% developed IAN deficit and 0.69% developed LN deficit. Distoangular impaction was found to increase the risk of LN deficit significantly (p < 0.001). Depth of impaction was related to the risk of IAN deficit (p < 0.001). Undergraduates caused more LN deficits (p < 0.001). Sex, age, raising of a lingual flap, protection of LN with a retractor, removal of distolingual cortex, tooth sectioning and difficulty in tooth elevation were not significantly related to IAN or LN injury. Postoperative recovery from IAN and LN deficits was noted most significantly at 3 and 6 months, respectively. By the end of the follow-up period, 67% of IAN deficits and 72% of LN deficits had recovered completely. © 2009 International Association of Oral and Maxillofacial Surgeons.postprin

Effect of WeiJia on carbon tetrachloride induced chronic liver injury

Aim: To study the effect of WeiJia on chronic liver injury using carbon tetrachloride (CCl 4) induced liver injury animal model. Methods: Wista r rats weighing 180-220g were randomly divided into three groups: normal control group (Group A), CCl 4 induced liver injury control group (Group B) and CCl 4 induction with WeiJia treatment group (Group C). Each group consisted of 14 rats. Liver damage and fibrosis was induced by subcutaneous injection with 40% CCl 4 in olive oil at 3 mL/kg body weight twice a week for eight weeks for Groups B and C rats whereas olive oil was used for Group A rats. Starting from the third week, Group C rats also received daily intraperitoneal injection of WeiJia at a dose of 1.25 μg/kg body weight. Animals were sacrificed at the fifth week (4 male, 3 female), and eighth week (4 male, 3 female) respectively. Degree of fibrosis were measured and serological markers for liver fibrosis and function including hyaluronic acid (HA), type IV collagen (CIV), γ-glutamyl transferase (γ-GT), alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were determined. Alpha smooth muscle actin (α-SMA) and proliferating cell nuclear antigen (PCNA) immunohistochemistry were also performed. Results: CCl 4 induction led to the damage of liver and development of fibrosis in Group B and Group C rats when compared to Group A rats. The treatment of WeiJia in Group C rats could reduce the fibrosis condition significantly compared to Group B rats. The effect could be observed after three weeks of treatment and was more obvious after eight weeks of treatment. Serum HA, CIV, ALT, AST and γ-GT levels after eight weeks of treatment for Group C rats were 58±22 μg/L (P 0.05) respectively, similar to normal control group (Group A), but significantly different from CCl 4 induced liver injury control group (Group B). An increase in PCNA and decrease in α-SMA expression level was also observed. Conclusion: WeiJia could improve liver function and reduce liver fibrosis which might be through the inhibition of stellate cell activity. © 2006 The WJG Press. All rights reserved.published_or_final_versio

Oral health education for visually impaired children in Hong Kong

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Structural equation modeling in oral health-related quality of life data

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A metaphyseal fracture rat model for mechanistic studies of osteoporotic bone healing

Most osteoporotic fractures occur at metaphyseal regions of long bones. The present study proposed a clinically relevant animal model that satisfied: i) induction of osteoporosis, ii) unilateral complete osteotomy at metaphysis, iii) internal fixation. 6 months old female Sprague-Dawley rats (n = 64) were randomly divided into the ovariectomised-metaphyseal osteotomy (OVX, n = 32) and metaphyseal osteotomy (SHAM, n = 32) groups. The metaphyseal-osteotomy model was created with a plate-fixation of the osteotomy and assessed by X-ray, micro-computed tomography, histomorphometry and mechanical testing at weeks 1, 3 and 6. X-ray results showed complete healing of metaphyseal osteotomy at week 6. Histology showed 3 stages of metaphyseal healing. Stage 1 was characterised by fibrous tissue, consisting of disorganised orientation of collagen fibres, and infiltration of immune cells. At stage 2, a transitional zone consisting of maturing fibrous tissue and differentiating mesenchymal cells with early trabecular bone formation and disorganised woven bone were observed. During stage 3, cortical bone ends unified and woven bone underwent transformation to lamellar bone. OVX group healing was significantly delayed when compared to SHAM samples. The study demonstrated that healing of osteoporotic osteotomy at the metaphyseal region was delayed in terms of radiography, histomorphometry and mechanical strength. These quantitative evaluations, along with histological features, may provide key references for future studies. The animal model may provide additional clinical relevance as most osteoporotic fracture in humans occurs at metaphyseal regions

Exploiting solar visible-range observations by inversion techniques: from flows in the solar subsurface to a flaring atmosphere

Observations of the Sun in the visible spectral range belong to standard measurements obtained by instruments both on the ground and in the space. Nowadays, both nearly continuous full-disc observations with medium resolution and dedicated campaigns of high spatial, spectral and/or temporal resolution constitute a holy grail for studies that can capture (both) the long- and short-term changes in the dynamics and energetics of the solar atmosphere. Observations of photospheric spectral lines allow us to estimate not only the intensity at small regions, but also various derived data products, such as the Doppler velocity and/or the components of the magnetic field vector. We show that these measurements contain not only direct information about the dynamics of solar plasmas at the surface of the Sun but also imprints of regions below and above it. Here, we discuss two examples: First, the local time-distance helioseismology as a tool for plasma dynamic diagnostics in the near subsurface and second, the determination of the solar atmosphere structure during flares. The methodology in both cases involves the technique of inverse modelling.Comment: 29 pages, 15 figures. Accepted for publication in the book "Reviews in Frontiers of Modern Astrophysics: From Space Debris to Cosmology" (eds Kabath, Jones and Skarka; publisher Springer Nature) funded by the European Union Erasmus+ Strategic Partnership grant "Per Aspera Ad Astra Simul" 2017-1-CZ01-KA203-03556