Kelvin I Afrashtehfar

Bio: Kelvin I Afrashtehfar is an academic researcher from University of Bern. The author has contributed to research in topics: Medicine & Dentistry. The author has an hindex of 11, co-authored 64 publications receiving 429 citations. Previous affiliations of Kelvin I Afrashtehfar include McGill University & Jewish General Hospital.

Computerized occlusal analysis as an alternative occlusal indicator

Abstract: Background: All disciplines of dentistry require that clinicians assess the articulation of the teeth/prosthesis with respect to simultaneous contacts, bite force and timing.Aims: This article intends to describe the advantages and limitations of the data acquired when using a computerized occlusal analysis as a dynamic occlusal indicator.Methodology: A search of the literature was completed (Medline, PubMed) using the keywords occlusion, occlusal registration, computerized occlusal analysis and T-Scan for dental.Results: According to the evidence available, the computerized occlusal analysis system is the only occlusal indicator that demonstrates the ability to provide quantifiable force and time variance in a real-time window from the initial tooth contact into maximum intercuspation.Conclusion: The reported advantages to accurately indicate occlusal contacts make the computerized occlusal analysis system a better occlusal indicator when compared with other non-digital convention indicator mater...

Clinical performance of zirconia implants: A meta-review.

Abstract: Statement of problem The clinical effectiveness of zirconia implants as an alternative to titanium implants is still controversial. Purpose The purpose of this analysis was to identify and evaluate systematic reviews reporting on the clinical outcomes of zirconia implants for oral rehabilitation. Material and methods An electronic search was undertaken on MEDLINE, Embase, and the Cochrane Oral Health Reviews databases up to December 24, 2018, without language restriction. Eligible reviews were screened and assessed. The eligibility criteria were systematic reviews or meta-analyses, implant survival rate, implant success, marginal bone loss, peri-implant soft tissue status, and biologic and functional complications of zirconia implants. Two review authors independently evaluated the quality assessment of the secondary studies by applying the Assessing the Methodological Quality of Systematic Reviews (AMSTAR) tool. Results Nine reviews fulfilled the inclusion criteria and were evaluated. Seven reviews were classified as moderate and 2 as high quality. The overall AMSTAR's quality of these reports was moderate. In the primary studies contained in these reviews, zirconia implant clinical outcomes were found to be similar or inferior to those for titanium implants. The few primary clinical studies contained in these reviews were not homogeneous among each other, presented poor methodology, and only offered promising short-term outcomes due to the lack of long-term follow-ups. Conclusions Based on this meta-review, in spite of short-term promising results of zirconia implants, evidence with long term is lacking.

Lay preferences for dentogingival esthetic parameters: A systematic review

Abstract: Statement of problem An objective definition of the characteristics that render a smile esthetically acceptable in the eye of laypeople is lacking. Purpose The purpose of this systematic review was to identify, appraise, and synthesize the available evidence on the opinion of laypeople regarding the dentogingival characteristics that render a smile esthetically acceptable. The evidence was collected by surveying with standardized digitally modified smile images. Material and methods Four databases were used to search English language studies published between January 1996 and December 2015. This was complemented by a manual search of 8 dental journals. Following the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines, 2 independent reviewers extracted the relevant characteristics of lay evaluators, the images evaluated, and the outcomes measure. Included studies were assessed in agreement with the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) statement. Outcomes were treated as a continuous variable, and when more than 1 article provided information on a parameter, the weighted arithmetic mean was calculated. Results After 8851 articles were screened, 20 studies were included. Those studies addressed 20 different dentogingival esthetic parameters. The total number of participants interviewed was 3107. According to the Olmos classification, 6 studies had a high level of quality, and 14 studies had a moderate level of quality. The 2 reviewers agreed on all the quality assessments. In the articles reviewed, central incisors clearly played a key role in smile esthetics. Almost all dental, gingival, and occlusal parameters are related to the proportion, shape, and position of central incisors and their relation to the adjacent dental structures. Conclusions The present review provides the estimated thresholds of tolerability and ideal values of smile parameters determined by laypeople. This may guide clinicians in evidence-based diagnosis and the planning of dental esthetic treatments.

Marginal and internal adaptation of single crowns and fixed dental prostheses by using digital and conventional workflows: A systematic review and meta-analysis.

Abstract: Statement of problem Digital and conventional options for definitive impressions and for the fabrication of fixed dental prostheses (FDPs) have been compared in previous studies. However, a comprehensive review with concluding data that determined which method provided the minimal internal and marginal adaptation is lacking. Purpose The purpose of this systematic review and meta-analysis of in vivo and in vitro studies was to compare the marginal and internal adaptation of complete-coverage single-unit crowns and multiunit FDPs resulting from digital and conventional impression and fabrication methods. Material and methods The review protocol was registered in International Prospective Register of Systematic Reviews (PROSPERO) and followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. PubMed, Cochrane Trials, Scopus, and Open Grey databases were used to identify relevant articles. Based on fixed prostheses impression and fabrication methods, groups from each study were categorized into 4 groups: conventional impression and fabrication (CC), conventional impression and digital fabrication (CD), digital scanning and conventional fabrication (DC), and digital scanning and fabrication (DD). The risk of bias was assessed by using the Cochrane Collaboration tool for clinical trials and the modified Methodological Index for Non-Randomized Studies (MINORS) for in vitro studies. Heterogeneity was evaluated among studies, and meta-analysis was performed with random-effect models (α=.05). Subgroup analysis was conducted when possible. Results Eight clinical trials and 21 in vitro studies were eligible for analysis. There was no significant difference between the CD and DD clinical groups for marginal adaptation (P=.149); However, the DD group had significantly less internal discrepancy than the CD group (P=.009). The in vitro studies found no significant difference in marginal adaptation among the CC-CD, CC-DC, and CC-DD pairs (P=.437, P=.387, P=.587), but in the comparison CD versus DD group, a significantly better marginal adaptation was observed for the DD group (P=.001). All the compared in vitro groups were similar in terms of internal adaptation. Conclusions Impression and fabrication techniques may affect the accuracy of fit of complete-coverage fixed restorations. A completely digital workflow yielded restorations with comparable or better marginal adaptation than the other methods.

Osteoporosis: a still increasing prevalence

Abstract: It is estimated that over 200 million people worldwide have osteoporosis. The prevalence of osteoporosis is continuing to escalate with the increasingly elderly population. The major complication of osteoporosis is an increase in fragility fractures leading to morbidity, mortality, and decreased quality of life. In the European Union, in 2000, the number of osteoporotic fractures was estimated at 3.79 million. A baseline fracture is a very strong predictor of further fractures with 20% of patients experiencing a second fracture within the first year. The costs to health care services are already considerable and, on current trends, are predicted to double by 2050. The direct costs of osteoporotic fractures to the health services in the European Union in the year 2000 were estimated at 32 billion Euros. Guidelines for the diagnosis and treatment of osteoporosis are available in many countries; however, implementation is generally poor despite the availability of treatments with proven efficacy. Programs to increase awareness of osteoporosis and its outcomes are necessary for healthcare specialists and the general public. Earlier diagnosis and intervention prior to the first fracture are highly desirable.

Should my composite restorations last forever? Why are they failing?

Abstract: Composites resins have become the first choice for direct anterior and posterior restorations. The great popularity is related to their esthetic appearance and reduced need of sound tissue removal as compared with former treatments. Several studies have demonstrated that composite restorations may last long in clinical service. In this review we discuss the factors playing a role on the long-term longevity. Composite restorations have demonstrated a good clinical performance with annual failure rates varying from 1% to 3% in posterior teeth and 1% to 5% in anterior teeth. Factors related to the patients such as caries risk and occlusal stress risk, in addition to socioeconomic factors, may affect the survival significantly. Characteristics of the clinical operators, particularly their decision making when it comes to observing or approaching an existing restoration, are decisive for longevity. Cavity features such as the number of restored walls, composite volume, and presence of endodontic treatment are of major importance and may dictate the service time of the restorative approach. The choice of restorative composite seems to have a minor effect on longevity provided that appropriate technical procedures are used. The main reasons for failure in posterior teeth are secondary caries and fracture (restoration or tooth/restoration), while in anterior teeth esthetic concerns are the main reasons leading to restoration failures. Composite resin restorations can be considered a reliable treatment as long as both the professional and the patient are aware of the factors involved in restoration failures.

Zirconia in biomedical applications

Abstract: Introduction: The use of zirconia in medicine and dentistry has rapidly expanded over the past decade, driven by its advantageous physical, biological, esthetic, and corrosion properties. Zirconia orthopedic hip replacements have shown superior wear-resistance over other systems; however, risk of catastrophic fracture remains a concern. In dentistry, zirconia has been widely adopted for endosseous implants, implant abutments, and all-ceramic crowns. Because of an increasing demand for esthetically pleasing dental restorations, zirconia-based ceramic restorations have become one of the dominant restorative choices.Areas covered: This review provides an updated overview of the applications of zirconia in medicine and dentistry with a focus on dental applications. The MEDLINE electronic database (via PubMed) was searched, and relevant original and review articles from 2010 to 2016 were included.Expert commentary: Recent data suggest that zirconia performs favorably in both orthopedic and dental appli...

The etiology of hard- and soft-tissue deficiencies at dental implants: A narrative review

Abstract: Objective The objective of the present paper was to review factors and conditions that are associated with hard and soft-tissue deficiencies at implant sites. Importance Hard- and soft-tissue deficiencies at dental implants are common clinical findings. They can lead to complications and compromise implant survival and, hence, may require therapeutic interventions. It is, therefore, important to understand the etiology of hard and soft-tissue deficiencies. Based on this understanding, strategies should be developed to correct hard and soft-tissue deficiencies with the aim of improving clinical outcomes of implant therapy. Findings A large number of etiological factors have been identified that may lead to hard and soft-tissue deficiencies. These factors include: 1) systemic diseases and conditions of the patients; 2) systemic medications; 3) processes of tissue healing; 4) tissue turnover and tissue response to clinical interventions; 5) trauma to orofacial structures; 6) local diseases affecting the teeth, the periodontium, the bone and the mucosa; 7) biomechanical factors; 8) tissue morphology and tissue phenotype; and 9) iatrogenic factors. These factors may appear as an isolated cause of hard and soft-tissue defects or may appear in conjunction with other factors. Conclusions Hard- and soft-tissue deficiencies at implant sites may result from a multitude of factors. They encompass natural resorption processes following tooth extraction, trauma, infectious diseases such as periodontitis, peri-implantitis, endodontic infections, growth and development, expansion of the sinus floor, anatomical preconditions, mechanical overload, thin soft tissues, lack of keratinized mucosa, malpositioning of implants, migration of teeth, lifelong growth, and systemic diseases. When more than one factor leading to hard and/or soft-tissue deficiencies appear together, the severity of the resulting condition may increase. Efforts should be made to better identify the relative importance of these etiological factors, and to develop strategies to counteract their negative effects on our patient's wellbeing.