Distribution of Caries in Children: Variations between and within Populations.
J Dent Res. 2012 Jan 5;
Authors: Do LG
Abstract
The rapid changes in social and economic conditions in many populations may have significant impacts on health, including child oral health. Understanding trends and variations between and within countries will assist in the development of effective preventive programs. This review aims (1) to document time-trends in child caries experience of countries with different levels of social and economic development, and (2) to compare factors affecting the caries experience of children in two contrasting countries. A time-trend analytical approach of ecological data from countries with different levels of social and economic development and individual data of the two contrasting Vietnamese and Australian child populations were used. The analysis found a significant decline in caries experience of children, mostly driven by the improvement in populations with high social and economic development. Significant variations in caries experience and in associations with risk factors between and within countries were observed. Socio-economic inequality in child oral health existed within developed countries and between countries with different levels of development. Population programs aimed at improving upstream factors are of priority in further improving child oral health in different populations.
PMID: 22223436 [PubMed - as supplied by publisher]
Chipping Resistance of Graded Zirconia Ceramics for Dental Crowns.
J Dent Res. 2012 Jan 9;
Authors: Zhang Y, Chai H, Lee JJ, Lawn BR
Abstract
A serious drawback of veneering porcelains is a pronounced susceptibility to chipping. Glass-infiltrated dense zirconia structures can now be produced with esthetic quality, making them an attractive alternative. In this study, we examined the hypothesis that such infiltrated structures are much more chip-resistant than conventional porcelains, and at least as chip-resistant as non-infiltrated zirconia. A sharp indenter was used to produce chips in flat and anatomically correct glass-infiltrated zirconia crown materials, and critical loads were measured as a function of distance from the specimen edge (flat) or side wall (crown). Control data were obtained on zirconia specimens without infiltration and on crowns veneered with porcelains. The results confirmed that the resistance to chipping in graded zirconia is more than 4 times higher than that of porcelain-veneered zirconia and is at least as high as that of non-veneered zirconia.
PMID: 22232142 [PubMed - as supplied by publisher]
This randomized split-mouth controlled clinical trial aimed at assessing the therapeutic effects of infiltration vs. sealing for controlling caries progression on proximal surfaces. Out of 90 adult students/patients assessed at university clinics and agreeing to participate, 39, each with 3 proximal lesions identified radiographically around the enamel-dentin junction to the outer third of the dentin, were included. Lesions were randomly allocated for treatment to test-A (Infiltration: ICON-pre-product; DMG), test-B (Sealing: Prime-Bond-NT; Dentsply), or control-C (Placebo). Primary outcome after 1, 2, and 3 yrs of radiographically observed lesion progression was assessed by an independent examiner blinded to groups, using pair-wise and digital-subtraction readings. No adverse events occurred. In 37 participants assessed after 3 yrs, 10 lesions (A-4; B-2; C-4) progressed deep into dentin and needed operative treatment. The 3-year therapeutic effect, based on pair-wise radiographic readings between infiltration and placebo, was 37.8% (95%CI: 20.5-55.2%) and that between sealing and placebo was 29.7% (95%CI: 20.2-35.0%). One-year follow-up digital-subtraction readings showed significant differences in lesion progression between infiltration and placebo (P = 0.0012) and between sealing and placebo (P = 0.0269). The study showed that infiltration and sealing are significantly better than placebo treatment for controlling caries progression on proximal lesions. No significant difference was seen between infiltration and sealing (ClinicalTrials.gov number CT01417832).
PMID: 22257664 [PubMed - as supplied by publisher]
Functional Properties of Tooth Pulp Neurons Responding to Thermal Stimulation.
J Dent Res. 2012 Jan 17;
Authors: Ahn DK, Doutova EA, McNaughton K, Light AR, Närhi M, Maixner W
Abstract
The response properties of tooth pulp neurons that respond to noxious thermal stimulation of the dental pulp have been not well-studied. The present study was designed to characterize the response properties of tooth pulp neurons to noxious thermal stimulation of the dental pulp. Experiments were conducted on 25 male ferrets, and heat stimulation was applied by a computer-controlled thermode. Only 15% of tooth pulp neurons (n = 39) responded to noxious thermal stimulation of the teeth. Tooth pulp neurons were found in both the superficial and deep nuclear regions of the subnucleus caudalis (Vc) and in the interface between the nucleus caudalis and interpolaris (Vc/Vi). Thirty-seven neurons had cutaneous receptive fields and were classified as either NS (16) or WDR (21) neurons. Repeated heat stimulation of the dental pulp sensitized and increased the number of electrically evoked potentials of tooth pulp neurons. These results provide evidence that both the Vc and Vc/Vi regions contain neurons that respond to noxious thermal stimulation of the dental pulp, and that these cells may contribute to the sensitization process associated with symptomatic pulpitis.
PMID: 22257665 [PubMed - as supplied by publisher]
A Photoelastic Assessment of Residual Stresses in Zirconia-Veneer Crowns.
J Dent Res. 2012 Jan 18;
Authors: Belli R, Monteiro S, Baratieri LN, Katte H, Petschelt A, Lohbauer U
Abstract
Residual stresses within the veneer are linked to the high prevalence of veneer chipping observed in clinical trials of zirconia prostheses. We hypothesized that the thermal mismatch between the zirconia infrastructure and the veneer porcelain, as well as the rate used for cooling zirconia-veneer crowns, would be directly proportional to the magnitude of residual stresses built within the veneer layer. Two porcelains with different coefficients of thermal expansion were used to veneer zirconia copings, to create high or low thermal mismatches. The crowns were cooled according to a fast- or a slow-cooling protocol. The retardation of polarized light waves was used to calculate the residual stress magnitude and distribution across the veneer, according to the photoelasticity principle, in 1.0-mm-thick crown sections. While thermal mismatch was an important factor influencing the maximum stress development in the veneer, cooling rate had a minor role. Curved surfaces were preferential sites for stress concentration regardless of thermal mismatch or cooling rate.
PMID: 22262632 [PubMed - as supplied by publisher]
Increased Atherogenesis during Streptococcus mutans Infection in ApoE-null Mice.
J Dent Res. 2012 Jan 18;
Authors: Kesavalu L, Lucas AR, Verma RK, Liu L, Dai E, Sampson E, Progulske-Fox A
Abstract
Streptococcus mutans, a dental caries pathogen, also causes endocarditis and is detected in atheroscelerotic plaque. We investigated the potential for an invasive strain of S. mutans, OMZ175, to accelerate plaque growth in apolipoprotein E deficient (ApoE(null)) mice without and with balloon angioplasty (BA) injury, a model of restenosis. ApoE(null) mice were divided into 4 groups (N = 10), 2 with and 2 without BA. One each of the BA and non-BA groups was infected with S. mutans (Sm). S. mutans DNA, plaque area, inflammatory cell invasion, and Toll-like receptor (TLR) expression were measured at 6-20 weeks post-infection. S. mutans genomic DNA was detected in the aorta, liver, spleen, and heart. Plaque growth was significantly increased in infected mice with BA (Sm+BA) vs. those in the non-infected groups (p < 0.03). Plaque size was increased after infection without BA (Sm), but did not reach significance. Aortic specimens from both S. mutans and Sm+BA groups displayed increased numbers of macrophages, and TLR4 expression was increased in BA mice. In conclusion, S. mutans infection accelerated plaque growth, macrophage invasion, and TLR4 expression after angioplasty. S. mutans may also be associated with atherosclerotic plaque growth in non-injured arteries.
PMID: 22262633 [PubMed - as supplied by publisher]
Perspectives in the effective use of fluoride in Asia.
J Dent Res. 2012 Feb;91(2):119-21
Authors: Petersen PE, Phantumvanit P
Abstract
Dental caries is the most prevalent chronic disease affecting human populations worldwide. The diverse disease patterns across and within countries are related to socio-behavioral determinants, demographic factors, environmental conditions, and the availability and accessibility of oral health services, in particular, exposure to disease prevention programs (Petersen, 2003, 2008a). Benefits of fluoride for caries prevention have been substantiated in many countries (Petersen and Lennon, 2004; Jones et al., 2005). In the second half of the 20(th) century, this focus shifted to the development and evaluation of fluoride toothpastes and rinses and, to a lesser extent, to alternatives to water fluoridation, such as salt and milk fluoridation. Most recently, efforts have been made to summarize this extensive database through systematic reviews of fluoride administration (McDonagh et al., 2000; Marinho et al., 2003; Australian Government, 2007). The Asian workshop held in Phan-Nga, Thailand, during March 22-24, 2011, aimed to discuss current information on fluoride and dental caries, as well as to try identifying barriers and opportunities that countries of Asia may have for implementing such programs. In addition, the intention was to give recommendations for including fluoride schemes within national public health programs.
Advances in tissue engineering have permitted the three-dimensional (3D) reconstruction of human oral mucosa for various in vivo and in vitro applications. Tissue-engineered oral mucosa have been further optimized in recent years for clinical applications as a suitable graft material for intra-oral and extra-oral repair and treatment of soft-tissue defects. Novel 3D in vitro models of oral diseases such as cancer, Candida, and bacterial invasion have been developed as alternatives to animal models for investigation of disease phenomena, their progression, and treatment, including evaluation of drug delivery systems. The introduction of 3D oral mucosal reconstructs has had a significant impact on the approaches to biocompatibility evaluation of dental materials and oral healthcare products as well as the study of implant-soft tissue interfaces. This review article discusses the recent advances in tissue engineering and applications of tissue-engineered human oral mucosa.
PMID: 22266525 [PubMed - as supplied by publisher]
Chlorhexidine Inhibits the Activity of Dental Cysteine Cathepsins.
J Dent Res. 2012 Jan 19;
Authors: Scaffa PM, Vidal CM, Barros N, Gesteira TF, Carmona AK, Breschi L, Pashley DH, Tjäderhane L, Tersariol IL, Nascimento FD, Carrilho MR
Abstract
The co-expression of MMPs and cysteine cathepsins in the human dentin-pulp complex indicates that both classes of enzymes can contribute to the endogenous proteolytic activity of dentin. Chlorhexidine (CHX) is an efficient inhibitor of MMP activity. This study investigated whether CHX could also inhibit cysteine cathepsins present in dentin. The inhibitory profile of CHX on the activity of dentin-extracted and recombinant cysteine cathepsins (B, K, and L) was monitored in fluorogenic substrates. The rate of substrate hydrolysis was spectrofluorimetrically measured, and inhibitory constants were calculated. Molecular docking was performed to predict the binding affinity between CHX and cysteine cathepsins. The results showed that CHX inhibited the proteolytic activity of dentin-extracted cysteine cathepsins in a dose-dependent manner. The proteolytic activity of human recombinant cathepsins was also inhibited by CHX. Molecular docking analysis suggested that CHX strongly interacts with the subsites S2 to S2′ of cysteine cathepsins B, K, and L in a very similar manner. Taken together, these results clearly showed that CHX is a potent inhibitor of the cysteine cathepsins-proteolytic enzymes present in the dentin-pulp complex.
PMID: 22266526 [PubMed - as supplied by publisher]
A Randomized Clinical Trial of Biodegradable and Titanium Fixation Systems in Maxillofacial Surgery.
J Dent Res. 2012 Jan 23;
Authors: Buijs GJ, van Bakelen NB, Jansma J, de Visscher JG, Hoppenreijs TJ, Bergsma JE, Stegenga B, Bos RR
Abstract
Biodegradable fixation systems could reduce or delete the problems associated with metallic systems, since removal is not necessary. The aim of this study was to establish the effectiveness and safety of biodegradable plates and screws as potential alternatives to metallic ones. This multi-center randomized controlled trial was conducted from December 2006 to July 2009. Included were patients who underwent mandibular and/or Le Fort I osteotomies and those with fractures of the mandible, maxilla, and zygoma. The patients were assigned to a titanium control group (KLS Martin) or to a biodegradable test group (Inion CPS). The primary outcome measure was ‘bone healing 8 weeks post-operatively’. The Intention-To-Treat (ITT) analysis of 113 patients in the titanium group and 117 patients in the biodegradable group yielded a significant difference (p < 0.001), primarily because in 25 patients (21%) who were randomized to the biodegradable group, the surgeon made the decision to switch to titanium intra-operatively. Despite this ‘inferior’ primary outcome result, biodegradable plates and screws could be safely used when it was possible to apply them. The benefits of using biodegradable systems (fewer plate removal operations) should be confirmed during a follow-up of minimally 5 years (Controlled-trials.com ISRCTN number 44212338).
PMID: 22269272 [PubMed - as supplied by publisher]
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