Dissemination and publication of research findings: an updated review of related biases

OBJECTIVES

To identify and appraise empirical studies on publication and related biases published since 1998; to assess methods to deal with publication and related biases; and to examine, in a random sample of published systematic reviews, measures taken to prevent, reduce and detect dissemination bias.

DATA SOURCES

The main literature search, in August 2008, covered the Cochrane Methodology Register Database, MEDLINE, EMBASE, AMED and CINAHL. In May 2009, PubMed, PsycINFO and OpenSIGLE were also searched. Reference lists of retrieved studies were also examined.

REVIEW METHODS

In Part I, studies were classified as evidence or method studies and data were extracted according to types of dissemination bias or methods for dealing with it. Evidence from empirical studies was summarised narratively. In Part II, 300 systematic reviews were randomly selected from MEDLINE and the methods used to deal with publication and related biases were assessed.

RESULTS

Studies with significant or positive results were more likely to be published than those with non-significant or negative results, thereby confirming findings from a previous HTA report. There was convincing evidence that outcome reporting bias exists and has an impact on the pooled summary in systematic reviews. Studies with significant results tended to be published earlier than studies with non-significant results, and empirical evidence suggests that published studies tended to report a greater treatment effect than those from the grey literature. Exclusion of non-English-language studies appeared to result in a high risk of bias in some areas of research such as complementary and alternative medicine. In a few cases, publication and related biases had a potentially detrimental impact on patients or resource use. Publication bias can be prevented before a literature review (e.g. by prospective registration of trials), or detected during a literature review (e.g. by locating unpublished studies, funnel plot and related tests, sensitivity analysis modelling), or its impact can be minimised after a literature review (e.g. by confirmatory large-scale trials, updating the systematic review). The interpretation of funnel plot and related statistical tests, often used to assess publication bias, was often too simplistic and likely misleading. More sophisticated modelling methods have not been widely used. Compared with systematic reviews published in 1996, recent reviews of health-care interventions were more likely to locate and include non-English-language studies and grey literature or unpublished studies, and to test for publication bias.

CONCLUSIONS

Dissemination of research findings is likely to be a biased process, although the actual impact of such bias depends on specific circumstances. The prospective registration of clinical trials and the endorsement of reporting guidelines may reduce research dissemination bias in clinical research. In systematic reviews, measures can be taken to minimise the impact of dissemination bias by systematically searching for and including relevant studies that are difficult to access. Statistical methods can be useful for sensitivity analyses. Further research is needed to develop methods for qualitatively assessing the risk of publication bias in systematic reviews, and to evaluate the effect of prospective registration of studies, open access policy and improved publication guidelines.

Improvement of microbial strains and fermentation processes

Improvement of microbial strains for the overproduction of industrial products has been the hallmark of all commercial fermentation processes. Conventionally, strain improvement has been achieved through mutation, selection, or genetic recombination. Overproduction of primary or secondary metabolites is a complex process, and successful development of improved strains requires a knowledge of physiology, pathway regulation and control, and the design of creative screening procedures. In addition, it requires mastery of the fermentation process for each new strain, as well as sound engineering know-how for mediaoptimization and the fine-tuning of process conditions. This review focuses on the various options that may be employed to improve microbial strains and addresses the complex problems of screening, the tools and technology behind the selection of targeted organisms, and the importance of process optimization. Furthermore, this review discusses new and emerging technologies and designing optimized media for tracking mutants with enhanced productivity or other desired attributes.

A systematic review of the public's knowledge and beliefs about antibiotic resistance

OBJECTIVES

The objective of this study was to systematically review quantitative and qualitative studies on the public's knowledge and beliefs about antibiotic resistance.

METHODS

We searched four databases to July 2014, with no language or study design restrictions. Two reviewers independently extracted data. We calculated the median (IQR) of the proportion of participants who agreed with each statement and synthesized qualitative data by identifying emergent themes.

RESULTS

Of 3537 articles screened, 54 studies (41 quantitative, 3 mixed methods and 10 qualitative) were included (55 225 participants). Most studied adults (50; 93% studies) and were conducted in Europe (23; 43%), Asia (14; 26%) or North America (12; 22%). Some participants [median 70% (IQR 50%-84%); n = 8 studies] had heard of antibiotic resistance, but most [median 88% (IQR 86%-89%); n = 2 studies] believed it referred to changes in the human body. Many believed excessive antibiotic use [median 70% (IQR 59%-77%); n = 11 studies] and not completing antibiotic courses [median 62% (IQR 47%-77%); n = 8 studies] caused resistance. Most participants nominated reducing antibiotic use [median 74% (IQR 72%-85%); n = 4 studies] and discussing antibiotic resistance with their clinician (84%, n = 1 study) as strategies to reduce resistance. Qualitative data supported these findings and additionally identified that: participants believed they were at low risk from antibiotic resistance participants; largely attributed its development to the actions of others; and strategies to minimize resistance should be primarily aimed at clinicians.

CONCLUSIONS

The public have an incomplete understanding of antibiotic resistance and misperceptions about it and its causes and do not believe they contribute to its development. These data can be used to inform interventions to change the public's beliefs about how they can contribute to tackling this global issue.

Not in my backyard: a systematic review of clinicians' knowledge and beliefs about antibiotic resistance

OBJECTIVES

To systematically review clinicians' knowledge and beliefs about the importance and causes of antibiotic resistance, and strategies to reduce resistance.

METHODS

Four databases were searched (until July 2014), without restrictions on language, setting or study design. Fixed responses (from surveys) were grouped into categories. The proportion of participants who agreed with each category was expressed as median, percentage and IQR. Qualitative data were coded into emergent themes. Quantitative categories and qualitative themes were grouped into four overarching categories that emerged from the data.

RESULTS

There were 57 included studies (38 quantitative, 14 qualitative, 5 mixed methods) of 11593 clinicians. Most clinicians (69%, IQR 63%-72%, n=5 studies) had heard of antibiotic resistance and 98% (IQR 93%-99%, n=5 studies) believed it was serious. The proportion who believed it was a problem for their practice (67%, IQR 65%-74%, n=13 studies) was smaller than the proportion who believed it was a problem globally (89%, IQR 85%-97%, n=5 studies) or nationally (92%, IQR 88%-95%, n=21 studies). Most believed excessive antibiotic use (97%, IQR 91%-98%, n=12 studies) and patient non-adherence (90%, IQR 82%-92%, n=7 studies) caused resistance. Most knew of strategies to reduce resistance (e.g. clinician education, 90%, IQR 85%-96%, n=7 studies). Qualitative findings support these data: they attributed responsibility for antibiotic resistance to patients, other countries and healthcare settings; resistance was considered a low priority and a distant consequence of antibiotic prescribing.

CONCLUSIONS

Clinicians believe antibiotic resistance is a serious problem, but think it is caused by others. This needs to be accommodated in interventions to reduce antibiotic resistance.

A phase I study of a combination of anti-CD19 and anti-CD22 immunotoxins (Combotox) in adult patients with refractory B-lineage acute lymphoblastic leukaemia

Novel agents are needed for patients with refractory and relapsed acute lymphoblastic leukaemia (ALL). Combotox is a 1:1 mixture of two immunotoxins (ITs), prepared by coupling deglycosylated ricin A chain (dgRTA) to monoclonal antibodies directed against CD22 (RFB4-dgRTA) and CD19 (HD37-dgRTA). Pre-clinical data demonstrated that Combotox was effective in killing both pre-B-ALL cell lines and cells from patients with pre-B ALL. A clinical study of paediatric patients in which 3 of 17 patients with ALL experienced complete remission, supported the preclinical work and motivated this study. This study was a Phase I, dose-escalation trial using Combotox in adults with refractory or relapsed B-lineage-ALL. A cycle consisted of three doses, with one dose given every other day. Dose levels were 3, 5, 6, 7 and 8 mg/m(2) per dose. Seventeen patients, aged 19-72 years, were enrolled in this multi-institution study. The maximum tolerated dose was 7 mg/m(2) /dose (21 mg/m(2) /cycle) and vascular leak syndrome was the dose-limiting toxicity. Two patients developed reversible grade 3 elevations in liver function tests. One patient achieved partial remission and proceeded to allogeneic stem cell transplantation. All patients with peripheral blasts experienced decreased blast counts following the administration of Combotox. Thus, Combotox can be safely administered to adults with refractory leukaemia.

The acceptability of variations in smile arc and buccal corridor space

OBJECTIVES

To evaluate the esthetic acceptability range of computer-generated variations in smile arc and buccal corridor.

DESIGN

Web-based descriptive study using available subjects.

SETTING AND SAMPLE POPULATION

The World Wide Web. Subjects for the main study included 115 lay and 131 orthodontist raters.

EXPERIMENTAL VARIABLES

Buccal corridors and smile arcs, each presented for a female and a male image. Buccal corridors were presented as none, ideal and excessive. The smile arc was presented as flat, ideal and excessive. The nine male and female variations, as combinations of the above variables, were each presented twice to evaluate reliability.

OUTCOME MEASURE

Acceptability of buccal corridors and smile arcs using the web-based instrument. An arbitrary super majority threshold of acceptability was set at 67% approval.

RESULTS

Both laypersons and orthodontists showed good reliability (k >or= 0.70). There was a broad range of acceptability, but laypersons and orthodontists showed no significant differences on the two variables tested. While orthodontists and laypersons both found smiles with excessive buccal corridors to be significantly less acceptable than those with ideal or absent buccal corridors, they were still acceptable over 70% of the time. Flat smile arcs were only acceptable 50-60% of the time, while smiles with ideal and excessive smile arcs were significantly more acceptable 84-95% of the time. When examining buccal corridors and smile arcs together, excessive buccal corridors were significantly less acceptable than ideal or absent buccal corridors regardless of the smile arc. A flat smile arc significantly reduced the acceptability of any buccal corridor to below the threshold of acceptability.

CONCLUSIONS

Laypersons and orthodontists have similar preferences when acceptability of buccal corridors and smile arcs are considered. Flat smile arcs are more detrimental to smile esthetics than variations in buccal corridors. Clinicians must realize that although attractiveness may be reduced by variations in buccal corridors and smile arcs, the result may still be acceptable to a majority of people.

High-resolution chromatin immunoprecipitation (ChIP) sequencing reveals novel binding targets and prognostic role for SOX11 in mantle cell lymphoma

Sex determining region Y-box 11 (SOX11) expression is specific for mantle cell lymphoma (MCL) as compared with other non-Hodgkin's lymphomas. However, the function and direct-binding targets of SOX11 in MCL are largely unknown. We used high-resolution chromatin immunoprecipitation sequencing to identify the direct target genes of SOX11 in a genome-wide, unbiased manner and elucidate its functional significance. Pathway analysis identified WNT, PKA and TGF-beta signaling pathways as significantly enriched by SOX11-target genes. Quantitative chromatin immunoprecipitation sequencing and promoter reporter assays confirmed that SOX11 directly binds to individual genes and modulates their transcription activities in these pathways in MCL. Functional studies using RNA interference demonstrate that SOX11 directly regulates WNT in MCL. We analyzed SOX11 expression in three independent well-annotated tissue microarrays from the University of Wisconsin (UW), Karolinska Institute and British Columbia Cancer Agency. Our findings suggest that high SOX11 expression is associated with improved survival in a subset of MCL patients, particularly those treated with intensive chemotherapy. Transcriptional regulation of WNT and other biological pathways affected by SOX11-target genes may help explain the impact of SOX11 expression on patient outcomes.

The cleavage site for the restriction endonuclease EcoRV is 5'-GAT/ATC-3'

The cleavage site for the restriction endonuclease EcoRV has been found to be 5'-GAT/ATC-3', rather than 5'- GATAT /C-3' as reported earlier by Kholmina et al. [ Dokl . Akad . Nauk . 253 (1980) 495-497].

Assessment of the quality of reporting of randomized clinical trials in paediatric dentistry journals

INTRODUCTION

Reporting of randomized controlled trials (RCTs) should be of high quality to support the conclusions reached by the authors. Poor-quality reporting has been associated with an overestimation in intervention efficacy. Within the field of paediatric dentistry, no study has assessed the quality of reporting.

OBJECTIVE

The aim of this study was to assess published RCTs in paediatric dental journals between 1985 and 2006 for: (i) whether quality of reporting allows readers to assess the validity of trials; and (ii) whether quality of reporting has improved since the introduction of the Consolidated Standards of Reporting Trials (CONSORT) guidelines.

METHODS

Hand search of the main paediatric dentistry journals; inclusion criteria were: the trial was performed on children, and RCT. CONSORT guidelines were made into an operational checklist. Trials published between 1985 and 1997, and between 1998 and 2006 were compared to determine any improvement since the publication of the CONSORT guidelines.

RESULTS

One hundred and seventy-three of 5635 articles met the inclusion criteria. Reporting quality was poor overall and showed heterogeneity. It had improved slightly since the publication of CONSORT. Few trials were reported adequately.

CONCLUSION

The quality of reporting of clinical trials is poor, and often not adequate to allow readers to assess trial validity. Overall quality of reporting has not substantially improved since the publication of CONSORT.

Peyronie's disease is associated with Paget's disease of bone

Peyronie's disease is an idiopathic disorder in which an inflammatory fibrosis occurs in the tunica albuginea of the corpora cavernosa which causes the erect penis to become deformed. Peyronie's disease has a prevalence of 1% in men over age 50 years. Paget's disease of bone is a chronic skeletal disease with areas of increased bone turnover leading to pain, deformity, and in some cases arthritis. Because of a high rate of Peyronie's disease in subjects in a Paget's disease industry-sponsored drug trial, we asked whether there was an association between Peyronie's disease and Paget's disease of bone. We evaluated 61 men with Paget's disease attending our clinic for metabolic bone disease in a tertiary referral hospital, reviewed hospital records of all men discharged from our three hospitals with the diagnosis of Peyronie's disease, and mailed a validated questionnaire about shape of the erect penis to 1500 male members of the Paget Foundation. In the clinic population of men with Paget's disease of bone, 51 of 61 (83.6%) reported having normal erections; 10 patients (16.4%) were impotent. Sixteen of the 51 men (31.4%) had developed a bend or deformity in their erect penis which was confirmed by a urologist's examination to be Peyronie's disease. When the men with Paget's disease with and without Peyronie's disease were compared, there was no difference in their ages, years with Paget's disease, or serum alkaline phosphatase level. Upon medical record review, 1 patient of 262 (0.4%) with Peyronie's disease was found to have Paget's disease of bone. The men with Paget's disease returned their questionnaires for a response rate of 44.8% and reported Peyronie's disease with a prevalence of 14.5%. We suggest that Peyronie's disease is associated with Paget's disease of bone. Furthermore, we suggest that Peyronie's disease may be a previously unrecognized complication of Paget's disease of bone.

How do children with amelogenesis imperfecta feel about their teeth?

BACKGROUND

Amelogenesis imperfecta (AI) is an inherited dental condition affecting enamel, which can result in significant tooth discolouration and enamel breakdown, requiring lifelong dental care. The possible impact of this condition on children and adolescents from their perspectives is not fully understood.

AIMS

The aim of the study was to explore the impact of AI on children and adolescents through in-depth interviewing. The information derived from this was then used to construct a questionnaire to distribute to a larger cohort of AI patients.

DESIGN

This research involved semistructured in-depth interviews with seven AI patients, and common themes and concepts were then identified using framework analysis. A questionnaire was developed based on the themes and subthemes identified, and completed by 40 AI patients at various stages of treatment.

RESULTS

Children and adolescents with AI exhibited concerns regarding aesthetics and function. Patients also expressed a high level of concern regarding comments by other people and self-consciousness associated with this. A small number of AI patients highlighted the effect of their dental treatment and health on their personal life.

CONCLUSION

The results indicate that there are marked impacts on children and adolescents as a result of AI, including aesthetics, function, and psychosocial.

Knowledge of dental trauma first aid (DTFA): the example of avulsed incisors in casualty departments and schools in London

OBJECTIVE

To investigate awareness and practices of dental trauma first aid (DTFA) in hospital emergency settings and in primary and secondary schools in London.

DESIGN

A cross-sectional study using self-administered questionnaires and semi-structured interviews.

SETTING

Primary and secondary schools and casualty/emergency and walk-in casualty centres in London in 2005.

SUBJECTS AND METHODS

A randomly selected sample of 125 schools and a total of 31 walk-in casualty centres, providing services for five randomly selected London boroughs. A person responsible for emergency care of children represented each of these study sites.

RESULTS

Response rates of 81.6% and 87% were achieved for schools and casualty/emergency centres respectively. The school respondents who had previously received advice on DTFA were three times more likely to be willing to replant an avulsed tooth compared to those who had not. A third of casualty personnel showed gaps in knowledge in DTFA. Results from schools showed an unwillingness to start emergency action mainly due to perceived inadequacy in knowledge/skills and also for legal reasons.

CONCLUSION

There is the need for further studies focused on the barriers resulting in unwillingness to provide DTFA among school personnel and clarification regarding issues of responsibility and acceptable levels of competence of professionals other than dentists.

Best clinical practice guidance for treating deep carious lesions in primary teeth: an EAPD policy document

Purpose

The European Academy of Paediatric Dentistry (EAPD) has developed this best clinical practice guidance to help clinicians manage deep carious lesions in primary teeth.

Methods

Three expert groups conducted systematic reviews of the relevant literature. The topics were: (1) conventional techniques (2) Minimal Intervention Dentistry (MID) and (3) materials. Workshops were held during the corresponding EAPD interim seminar in Oslo in April 2021. Several clinical based recommendations and statements were agreed upon, and gaps in our knowledge were identified.

Results

There is strong evidence that indirect pulp capping and pulpotomy techniques, and 38% Silver Diamine Fluoride are shown to be effective for the management of caries in the primary dentition. Due to the strict criteria, it is not possible to give clear recommendations on which materials are most appropriate for restoring primary teeth with deep carious lesions. Atraumatic Restorative Technique (ART) is not suitable for multi-surface caries, and Pre-formed Metal Crowns (PMCs) using the Hall technique reduce patient discomfort. GIC and RMGIC seem to be more favourable given the lower annual failure rate compared to HVGIC and MRGIC. Glass carbomer cannot be recommended due to inferior marginal adaptation and fractures. Compomers, hybrid composite resins and bulk-fill composite resins demonstrated similar values for annual failure rates.

Conclusion

The management of deep carious lesions in primary teeth can be challenging and must consider the patient’s compliance, operator skills, materials and costs. There is a clear need to increase the use of MID techniques in managing carious primary teeth as a mainstream rather than a compromise option.

Paraneoplastic pemphigus presenting as an unusual bullous eruption

We describe a patient with a widespread annular bullous eruption on the trunk and extremities and involvement of the conjunctivae, oral mucous membranes, and esophagus. Findings of a biopsy specimen of an intraabdominal mass revealed nodular and diffuse well-differentiated lymphoma. Histologic examination of a skin lesion showed acantholysis with bulla formation and keratinocyte necrosis. Direct immunofluorescence testing of a skin lesion showed intercellular deposition of IgG. The patient's serum contained autoantibodies with broad specificity for skin and other epithelia and identified the characteristic bands of paraneoplastic pemphigus at 250, 230, 210, and 190 kd on immunoprecipitation. The patient died despite therapy.

Hypnosis for children undergoing dental treatment

BACKGROUND

Managing children is a challenge that many dentists face. Many non-pharmacological techniques have been developed to manage anxiety and behavioural problems in children, such us: 'tell, show & do', positive reinforcement, modelling and hypnosis. The use of hypnosis is generally an overlooked area, hence the need for this review.

OBJECTIVES

This systematic review attempted to answer the question: What is the effectiveness of hypnosis (with or without sedation) for behaviour management of children who are receiving dental care in order to allow successful completion of treatment?

NULL HYPOTHESIS

Hypnosis has no effect on the outcome of dental treatment of children.

SEARCH STRATEGY

We searched the Cochrane Oral Health Group's Trials Register, CENTRAL, MEDLINE (OVID), EMBASE (OVID), and PsycINFO. Electronic and manual searches were performed using controlled vocabulary and free text terms with no language restrictions. Date of last search: 11th June 2010.

SELECTION CRITERIA

All children and adolescents aged up to 16 years of age. Children having any dental treatment, such as: simple restorative treatment with or without local anaesthetic, simple extractions or management of dental trauma.

DATA COLLECTION AND ANALYSIS

Information regarding methods, participants, interventions, outcome measures and results were independently extracted, in duplicate, by two review authors. Authors of trials were contacted for details of randomisation and withdrawals and a quality assessment was carried out. The methodological quality of randomised controlled trials (RCTs) was assessed using the criteria described in the Cochrane Handbook for Systematic Reviews of Interventions 5.0.2.

MAIN RESULTS

Only three RCTs (with 69 participants) fulfilled the inclusion criteria. Statistical analysis and meta-analysis were not possible due to insufficient number of studies.

AUTHORS' CONCLUSIONS

Although there are a considerable number of anecdotal accounts indicating the benefits of using hypnosis in paediatric dentistry, on the basis of the three studies meeting the inclusion criteria for this review there is not yet enough evidence to suggest its beneficial effects.

A survey of attitudes, knowledge and practice of dentists in London towards child protection. Are children receiving dental treatment at the Eastman Dental Hospital likely to be on the child protection register?

OBJECTIVE

To investigate the attitudes, knowledge and practices of general dental practitioners (GDPs), specialists and consultants in paediatric dentistry in London, towards child protection. Additionally, to determine if children attending paediatric dental casualty at the Eastman Dental Hospital (EDH) and those who need treatment of caries under general anaesthesia (GA) are on the child protection register (CPR).

DESIGN

The survey was conducted by postal questionnaires with 14 closed questions. A total of 228 dentists were invited to participate in the study. Children who attended EDH and required treatment under GA or at paediatric dental casualty were checked against the CPR.

RESULTS

The respond rate was 46% (105/228). Overall 15% (16/105) of dentists had seen at least one patient with suspected child abuse in the last six months, but only 7% (7/105) referred or reported cases to child protection services. Reasons for dentists not referring included: fear of impact on practice (10%; 11/105); fear of violence to child (66%; 69/105); fear of litigation (28%; 29/105); fear of family violence against them (26%; 27/105); fear of consequences to the child (56%; 59/105); lack of knowledge regarding the procedures for referral (68%; 71/105); and lack of certainty about the diagnosis (86%; 90/105). Of the 220 children attending for dental GA and casualty from October 2004 to March 2005, one child was found to be on the CPR.

CONCLUSION

More information and training is required to raise awareness of the potential importance of the role of dentists in child protection. Improved communication between dental and medical departments is important for safeguarding children.

Hypomineralisation or hypoplasia?

Enamel hypomineralisation is a qualitative defect, with reduced mineralisation resulting in discoloured enamel in a tooth of normal shape and size. Because the enamel is weaker, teeth can undergo post eruptive breakdown, resulting in missing enamel. Enamel hypoplasia is a quantitative defect of the enamel presenting as pits, grooves, missing enamel or smaller teeth. It can sometimes be difficult to differentiate between the two. In this review paper, we aim to explain the importance of differentiating between the two conditions, and how to manage patients presenting with enamel defects.

Phenotypic Properties of Collagen in Dentinogenesis Imperfecta Associated with Osteogenesis Imperfecta

Introduction

Dentinogenesis imperfecta type 1 (OIDI) is considered a relatively rare genetic disorder (1:5000 to 1:45,000) associated with osteogenesis imperfecta. OIDI impacts the formation of collagen fibrils in dentin, leading to morphological and structural changes that affect the strength and appearance of teeth. However, there is still a lack of understanding regarding the nanoscale characterization of the disease, in terms of collagen ultrastructure and mechanical properties. Therefore, this research presents a qualitative and quantitative report into the phenotype and characterization of OIDI in dentin, by using a combination of imaging, nanomechanical approaches.

Methods

For this study, 8 primary molars from OIDI patients and 8 primary control molars were collected, embedded in acrylic resin and cut into longitudinal sections. Sections were then demineralized in 37% phosphoric acid using a protocol developed in-house. Initial experiments demonstrated the effectiveness of the demineralization protocol, as the ATR-FTIR spectral fingerprints showed an increase in the amide bands together with a decrease in phosphate content. Structural and mechanical analyses were performed directly on both the mineralized and demineralized samples using a combination of scanning electron microscopy, atomic force microscopy, and Wallace indentation.

Results

Mesoscale imaging showed alterations in dentinal tubule morphology in OIDI patients, with a reduced number of tubules and a decreased tubule diameter compared to healthy controls. Nanoscale collagen ultrastructure presented a similar D-banding periodicity between OIDI and controls. Reduced collagen fibrils diameter was also recorded for the OIDI group. The hardness of the (mineralized) control dentin was found to be significantly higher (p<0.05) than that of the OIDI (mineralized) dentine. Both the exposed peri- and intratubular dentinal collagen presented bimodal elastic behaviors (Young’s moduli). The control samples presented a stiffening of the intratubular collagen when compared to the peritubular collagen. In case of the OIDI, this stiffening in the collagen between peri- and intratubular dentinal collagen was not observed and the exposed collagen presented overall a lower elasticity than the control samples.

Conclusion

This study presents a systematic approach to the characterization of collagen structure and properties in OIDI as diagnosed in dentin. Structural markers for OIDI at the mesoscale and nanoscale were found and correlated with an observed lack of increased elastic moduli of the collagen fibrils in the intratubular OIDI dentin. These findings offer an explanation of how structural changes in the dentin could be responsible for the failure of some adhesive restorative materials as observed in patients affected by OIDI.

Multiple pulp stones and shortened roots of unknown etiology

An unusual case of generalised pulpal calcifications (pulp stones) with normal clinical crowns is reported in a 13-year-old boy. Radiographic examination revealed pulp stones in the single rooted and premolar teeth, situated at the midroot level, with the roots bulging around them. The apical portion of the roots, periodontal ligament space, and surrounding bone had a normal radiographic appearance, apart from the upper premolars, and no periapical pathology was discernible. The upper premolars exhibited considerably shortened roots. No medical, dental, or family history was found to be contributory. Reviewing the literature revealed similar cases, but with differing diagnoses including dentine dysplasia (DD) or idiopathic cases. This report suggests either a variation of DD or possibly a new nonsyndromic dentine defect, and highlights the difficulties in establishing a definitive diagnosis by traditional methods. The recent discovery that mutation of the bicistronic dentine sialophosphoprotein gene (DSPP) is involved in DD may provide solutions to this problem.

Optical coherence tomography use in the diagnosis of enamel defects

Molar incisor hypomineralization (MIH) affects the permanent incisors and molars, whose undermineralized matrix is evidenced by lesions ranging from white to yellow/brown opacities to crumbling enamel lesions incapable of withstanding normal occlusal forces and function. Diagnosing the condition involves clinical and radiographic examination of these teeth, with known limitations in determining the depth extent of the enamel defects in particular. Optical coherence tomography (OCT) is an emerging hard and soft tissue imaging technique, which was investigated as a new potential diagnostic method in dentistry. A comparison between the diagnostic potential of the conventional methods and OCT was conducted. Compared to conventional imaging methods, OCT gave more information on the structure of the enamel defects as well as the depth extent of the defects into the enamel structure. Different types of enamel defects were compared, each type presenting a unique identifiable pattern when imaged using OCT. Additionally, advanced methods of OCT image analysis including backscattered light intensity profile analysis and enface reconstruction were performed. Both methods confirmed the potential of OCT in enamel defects diagnosis. In conclusion, OCT imaging enabled the identification of the type of enamel defect and the determination of the extent of the enamel defects in MIH with the advantage of being a radiation free diagnostic technique.

Treatment of HCV infection in liver transplant recipients with ledipasvir and sofosbuvir without ribavirin

BACKGROUND

Ledipasvir and sofosbuvir is a well-tolerated regimen with high sustained virological response (SVR) rates in pre-liver transplant patients infected with chronic hepatitis C virus (HCV), but data in liver transplant recipients outside of clinical trials is limited.

AIM

To address this knowledge gap and assess SVR rates without the use of ribavirin in liver transplant recipients METHODS: This is a retrospective study examining the treatment of 75 post-liver transplant recipients with ledipasvir and sofosbuvir without ribavirin. Differences between SVR cohorts and predictors of SVR were analysed in an intention-to-treat (ITT) fashion.

RESULTS

A total of 408 genotype 1, HCV patients were treated with ledipasvir/sofosbuvir from October 2014 to August 2015 at our centre. Seventy-three patients were post-liver transplant and were treated with a median of 2.9 years from transplant. Ledipasvir/sofosbuvir achieved an SVR12 of 95.9%. African Americans made up 28.8% of the cohort. Sixty-three per cent of patients were treated previously, including 13.7% of patients previously treated with direct-acting antivirals. Only 2.7% had recurrent allograft cirrhosis, and the majority (90.4%) was on calcineurin inhibitor based immunosuppressive therapy. Approximately 82% of patients had chronic kidney disease (CKD) stage 2 or 3. In univariate logistic regression, only detectable week 8 viral load was predictive of failure to achieve SVR.

CONCLUSION

Our data confirm excellent SVR outcomes and favourable safety and tolerability profiles with ledipasvir/sofosbuvir without ribavirin in post-liver transplant recipients infected with HCV, despite treatment guidelines to use ribavirin.