Dentists' knowledge of non-surgical root canal treatment, a systematic review.

OBJECTIVES: Dental practice is based upon dentists' cognitions, knowledge being foundational. Knowledge is attained through education and perception. Although knowledge is modulated by beliefs, attitudes, preferences, and behaviors, it is essential to evidence-based practice. Cross-sectional studies uniformly demonstrate that community NSRCT is of sub-optimal quality worldwide, is lack of knowledge a problem? Our purpose was to measure dentists' knowledge of root canal treatment (NSRCT). DATA: Quantitative and qualitative data were extracted: purpose, topics assessed, authors cited knowledge sources, number of dentists studied, number of questions, authors descriptors of knowledge level,% correct answers by question, authors recommendations. SOURCES: OVID Medline, EMBASE, Web of Science, and hand-searching. STUDY SELECTION: Studies which had measured dentists' knowledge of non-surgical root canal treatment that was valuable, reliable, and had practical implications which could be implemented. A total of 51 papers from 19 countries measured the knowledge of 15,580 dentists using 445 questions on 29 root canal treatment topics. CONCLUSIONS: 'Gold standards' were from literature, external bodies, or expert consensus in 47, 31, and 2 papers respectively. Levels of knowledge by percentage correct answers among studies were poor to moderate and varied considerably. The mean, for the 50 studies where overall study percentages could be calculated, was 57 %, standard deviation 17 %, and a range of 16 % to 82 %. Authors' adjectives describing knowledge levels were generally negative. Additional education was advised in 49 papers, but without evidence that education was inadequate; 6 papers recommended increased use of protocols; only 5 papers advocated research on the cause of lack of knowledge. CLINICAL SIGNIFICANCE: Dentists' root canal treatment knowledge was found to be poor to moderate, as well variable. This may constrain quality of care. However, provision of information without attention to dentists' cognitions and motivations may not be successful. Educational strategies and goals should be re-evaluated. Evidence-based practice faces many barriers.

Color- and strength-graded zirconia: Strength, light transmission, and composition.

STATEMENT OF PROBLEM: Natural teeth are graded in terms of translucency and strength. Graded zirconia materials are now available with a higher yttria content on the top or in the enamel zone to increase surface translucency and a lower yttria content on the bottom or in the dentin zone to increase strength. Such materials could provide multiple advantages over uniform materials and reduce the need for porcelain veneering in anterior artificial crowns; however, studies on the properties of these materials are lacking. PURPOSE: The purpose of this in vitro study was to measure and compare the biaxial flexural strength, percentage light transmission, elemental content, and phase content of zones within and among color graded zirconia blocks and color- and strength-graded zirconia blocks. MATERIAL AND METHODS: Disks of a color graded material (Katana STML) and a strength- and color-graded material (IPS e.max ZirCAD Prime) were fabricated (Zircom Furnace). Biaxial flexural strength was measured using a piston-on-3-ball test in a universal testing machine (n=10). Absolute light transmission was measured with a spectrophotometer. Elemental compositions were quantified for 3 zones in each of the 2 zirconia materials using X-ray fluorescence analysis. Zirconia phase fractions were quantified for 3 zones using X-ray diffraction analysis (XRD). Where appropriate, 2-way ANOVA, 1-way ANOVA, and Tukey multiple pairwise comparison testing were used to determine which of the 6 zones differed from one another (α=.05). RESULTS: The color-graded zirconia exhibited gradients in light transmission and differences in phase content in the 3 zones measured. The color- and strength-graded zirconia exhibited gradients in light transmission, biaxial flexural strength, elemental composition, and phase content in the 3 zones measured. The bottom, dentin, or intaglio layer of a strength graded zirconia material was substantially stronger than all other zones of either material (P<.05). The top, enamel, zones of both materials possessed high light transmissibility (P<.05). The 2 materials differed with respect to biaxial strength (P<.001), light transmission (P<.02), elemental composition, and phase composition overall, as well as in most zone-by zone comparisons (P<.05). The performance and composition of the color graded material was consistent with it being a 5Y material throughout. The performance and composition of the color and strength graded material was consistent with it having a 3Y bottom zone and a 5Y top zone. CONCLUSIONS: A strength-graded and color-graded zirconia material offers potential advantages in both strength and translucency.

Influence of yttria content and surface treatment on the strength of translucent zirconia materials.

STATEMENT OF PROBLEM: Newly developed translucent zirconia materials have been used for anterior monolithic complete coverage restorations. Surface treatments can improve adhesion, as well as decrease or increase the strength of ceramics. However, information on the influence of surface treatments on the strength of translucent zirconias is sparse. PURPOSE: The purpose of this in vitro study was to measure and characterize the effects of different surface treatments, including airborne-particle abrasion, on the strength of different translucent 4 mol% and 5 mol% yttria-stabilized zirconia materials. MATERIALS AND METHODS: Disks (N=160) made from 4 types of translucent yttria-stabilized zirconia materials were surface-treated in 4 ways: Control groups were hand-polished with 2000-grit silicon carbide abrasive paper; as-machined; glass bead airborne-particle abraded; and alumina airborne-particle abraded. The biaxial flexural strength was measured by using a piston-on-3-ball test in a universal testing machine. The simple main effects of material type and surface treatment and their interaction on biaxial flexural strength were evaluated with 2-way ANOVA (α=.05). A priori, 1-way ANOVA and the Tukey multiple comparisons tests were used within material and treatment types (α=.05). Surface morphology was assessed by using scanning electron microscopy. Translucency, absolute transmittance, was measured by using a spectrophotometer. RESULTS: Two-way ANOVA revealed that the effects of zirconia type, surface treatment, and their interaction all significantly affected biaxial flexural strength (P<.001). One-way ANOVA revealed that the 4Y material was stronger than all 5Y materials, regardless of surface treatment; all 5Y materials were ranked from strongest to weakest as polished; as-machined, or glass bead abraded; and alumina abraded. The 4Y material was stronger when alumina abraded than when glass bead abraded. Scanning electron microscopy showed that as-polished surfaces were smoother than all others; as-machined and glass bead abraded surfaces displayed little difference; alumina abraded was the roughest; and differences among materials were not discerned. The 1-way ANOVA and multiple comparisons testing showed that the 4Y material had less absolute transmittance, approximately 5% less, than all the 5Y materials. CONCLUSIONS: Zirconia material type and surface treatment influenced the strength of translucent zirconia materials; a 4 mol% zirconia material was stronger than 5 mol% zirconia materials for all surface treatments tested; airborne-particle abrasion using alumina had a slight strengthening effect on a 4 mol% zirconia but had a weakening effect on 5 mol% materials; airborne-particle abrasion by using alumina produced the roughest surfaces on all materials; and the 4 mol% material was slightly less translucent than the 5 mol% materials.

A simple 3-point flexural method for measuring fracture toughness of the dental porcelain to zirconia bond and other brittle bimaterial interfaces.

PURPOSE: Porcelain fused to zirconia prostheses are widely used, but porcelain chipping, fracture, spalling and delamination are common clinical problems. Conventional bond strength testing is inherently unsuited for studying interfacial failure by cracking in brittle materials. Instead, fracture toughness is a more meaningful parameter because it can assess the robustness of the interface when subjected to loading, but fracture mechanics approaches have only rarely been used. Our purpose was to develop a novel, simple, 3-point flexural methodology and mathematical analysis to measure the fracture toughness of the porcelain to zirconia interface. METHODS: Equations were derived to estimate the fracture toughness of the bond by computing the interfacial energy release rate for a novel simple 3-point flexural test model. The test was validated using two different configurations of layered zirconia/porcelain beams (n = 10), approximating the dimensions of a fixed dental prosthesis, fabricated from a tetragonal polycrystalline zirconium dioxide partially stabilized with yttria and a feldspathic dental porcelain. RESULTS: Cracking along the bimaterial interface was produced and measured as a discrete event. Fracture toughness means (standard deviations) computed from the measured energy release rate, for the porcelain to zirconia interface in two different specimen configurations were 7.9 (1.3) and 5.3 (1.6) J/m2. CONCLUSIONS: Equations were derived to measure interfacial fracture toughness of brittle materials using a novel simple 3-point flexural test method. The test was then validated; estimates for the fracture toughness for the porcelain to zirconia bond, overlapped with previously published data derived from more complex 4-point notched tests.

Effect of tooth substrate and porcelain thickness on porcelain veneer failure loads in vitro.

STATEMENT OF PROBLEM: Bonded porcelain veneers are widely used esthetic restorations. High success and survival rates have been reported, but failures do occur. Fractures are the commonest failure mode. Minimally invasive or thin veneers have gained popularity. Increased enamel and porcelain thickness improve the strength of veneers bonded to enamel, but less is known about dentin or mixed substrates. PURPOSE: The purpose of this in vitro study was to measure the influences of tooth substrate type (all-enamel, all-dentin, or half-dentin-half-enamel) and veneer thickness on the loads needed to cause initial and catastrophic porcelain veneer failure. MATERIAL AND METHODS: Model discoid porcelain veneer specimens of varying thicknesses were bonded to the flattened facial surfaces of incisors with different enamel and dentin tooth substrates, artificially aged, and loaded to failure with a small sphere. Initial and catastrophic fracture events were identified and analyzed statistically and fractographically. RESULTS: Fracture events included initial Hertzian cracks, intermediate radial cracks, and catastrophic gross failure. All specimens retained some porcelain after catastrophic failure. Cement failure occurred at the cement-porcelain interface not at the cement-tooth interface. Porcelain veneers bonded to enamel were substantially stronger and more damage-tolerant than those bonded to dentin or mixed substrates. Increased porcelain thickness substantially raised the loads to catastrophic failure on enamel substrates but only moderately raised the loads to catastrophic failure on dentin or mixed substrates. The veneers bonded to half-dentin-half-enamel behaved remarkably like those bonded wholly to dentin. CONCLUSIONS: Porcelain veneers bonded to enamel were substantially stronger and more damage-tolerant than those bonded to dentin or half-enamel-half dentin.

Influence of increased patient age on longitudinal outcomes of root canal treatment: a systematic review.

OBJECTIVES: To conduct a systematic review of longitudinal endodontic outcomes in elders. BACKGROUND: Negative opinions about the prognosis of non-surgical root canal treatment (NSRCT) in elders affect decisions made by patients and dentists. Patient, caregiver and dentist attitudes and behaviours may interact to decrease the provision of NSRCT. Critical examination of the available evidence through systematic review could provide objective data to assist patients, caregivers, healthcare providers and third-party payers in making decisions about the efficacy of NSRCT in elders and provide a robust foundation for the health promotion of NSRCT in elders. METHODS: Inclusion/exclusion criteria were used for defined searches in MEDLINE and Cochrane CENTRAL. Title lists were scanned, and abstracts read to determine utility; articles meeting inclusion/exclusion criteria were analysed. Data were extracted and compiled into a table of evidence. RESULTS: Defined searching produced 3605 titles; 24 articles were included, nine prospective and 15 retrospective. Overall study quality was good. Patient samples mostly represented modern populations from countries with very high human development indices. Over 17 430 teeth were included. Meta-analysis was not attempted due to heterogeneity in reporting. All 24 included papers demonstrated that increased patient age did not decrease the success or survival rates of NSRCT. CONCLUSIONS: This systematic review of longitudinal NSRCT outcomes demonstrated that increased patient age did not decrease the success of NSRCT. Patient age is not a prognostic factor for NSRCT. Age should not be considered by dentists or patients when making NSRCT decisions.

Anxiety Related to Nonsurgical Root Canal Treatment: A Systematic Review.

INTRODUCTION: Anxiety is an emotion characterized by feelings of tension, worried thoughts, and physical changes. Dental anxiety has been associated with pain, fear, care avoidance, and more invasive treatments including nonsurgical root canal treatment (NSRCT). The very words root canal are deeply embedded in societal consciousness. Better understanding of dental anxiety may prevent treatment avoidance. The purpose of this study was to conduct a systematic review of NSRCT-associated anxiety. METHODS: Inclusion/exclusion criteria defined MEDLINE, Cochrane Library, psychINFO, manual, and citation searches. Title lists and abstracts were read to determine utility; data were extracted, summarized, and compiled into an evidence table, and meta-analyses were performed. RESULTS: Defined searching produced 835 titles; 36 articles were included, mostly representing modern populations from countries with very high human development indices. Major sources of heterogeneity included differing study aims, outcome measures, clinical settings, locations, operators, sample selection, and sample size. Meta-analysis of 18 articles including 1989 subjects gave a pretreatment anxiety rating of 39 (standard deviation, 9) on a normalized 100-point scale. Meta-analysis of 4 articles including 232 subjects gave a post-treatment anxiety rating of 27 (standard deviation, 5) on a normalized 100-point scale, representing a 30% reduction. A L'Abbe plot of 5 studies also showed that anxiety decreased after NSRCT. Limited data indicated that gender, age, and prior NSRCT experience influenced NSRCT-associated anxiety. NSRCT-associated anxiety was ranked high among dental treatments, often close to oral surgery. CONCLUSIONS: NSRCT-associated anxiety was generally moderate. Anxiety decreased after NSRCT. Limited evidence suggested that anxiety is influenced by patient and treatment factors.

Endodontic treatment options after unsuccessful initial root canal treatment: Alternatives to single-tooth implants.

BACKGROUND AND OVERVIEW: Initial root canal treatment is highly successful, appreciated by patients, and cost-effective, but failures occur. Should a tooth with unsuccessful initial root canal treatment be treated by means of other endodontic procedures or be replaced by a single-tooth implant? RESULTS: Results from systematic reviews of the outcomes of nonsurgical retreatment, apical surgery, replantation, and autotransplantation show high tooth survival rates. Nonsurgical retreatment generally is prioritized before surgical endodontic treatment. Microsurgical endodontic treatment is superior to traditional surgical endodontic treatment and has high survival rates. Intentional replantation remains a viable alternative to extraction. Autotransplantation has a place, particularly in growing patients with an appropriate donor tooth. Single-tooth implants have higher survival rates, but the natural state has intrinsic value. CONCLUSIONS: The first-line treatment option after failure of initial root canal treatment is nonsurgical retreatment. Endodontic surgery, intentional replantation, and autotransplantation should be considered before extraction and replacement by a single-tooth implant. PRACTICAL IMPLICATIONS: Comprehensive case assessment, evaluation of all endodontic options, and risk assessment for caries and periodontal disease are always necessary when choosing the optimal treatment for a patient when initial root canal treatment has failed to heal.

Prevalence of root canal treatment and periapical radiolucency in elders: a systematic review.

INTRODUCTION: Neither the prevalence of periapical radiolucency (PARL), a surrogate for disease, nor the prevalence of non-surgical root canal treatment (NSRCT) in elders have been subjected to systematic review. The purpose of this study was to conduct systematic review and meta-analysis of the prevalence of PARL and NSRCT in elders. METHODS: Inclusion/exclusion criteria were used for defined searches in MEDLINE and Cochrane CENTRAL. Title lists were scanned and abstracts read to determine utility; articles meeting the criteria were analyzed. Weighted mean percentages were calculated for prevalence of PARL, NSRCT, and PARL in both teeth with and without NSRCT. RESULTS: Defined searching produced 3576 titles; 29 prevalence articles were included. Patient samples mostly represented modern populations from countries with very high human development indices. Meta-analyses were performed on up to 74 000 elders' teeth. For those aged 65+, the prevalence of all teeth with NSRCT was extremely high, 21%; the prevalence of all teeth with PARL was quite high, 7%; the prevalence of PARL in NSRCT teeth was high, 25%; and the prevalence of PARL in untreated teeth was surprisingly high, 4%. In elders, the prevalence of NSRCT and PARL separately increased with age; whereas, PARL in NSRCT teeth decreased with age. CONCLUSIONS: In comparison to general adult populations, elders had: a much higher prevalence of NSRCT, a higher prevalence of PARL, a lower prevalence of PARL in NSRCT teeth, and a higher prevalence of PARL in untreated teeth. Teeth saved through NSRCT were preferentially retained by elders.

Prevalence of Enamel Markings on Third Molars.

The purpose of this study was to measure the prevalence of enamel markings in routinely extracted third molars. One hundred donated third molars were examined. All had some marking(s). Caries was almost universal; white snowcapping of cusps and ridges was extremely common; pit and valley defects were very common; spots and bands were very common, most were white; horizontal grooves were common; linear enamel hypoplasia, considered to be a true developmental defect, was rare.

SLC26A Gene Family Participate in pH Regulation during Enamel Maturation.

The bicarbonate transport activities of Slc26a1, Slc26a6 and Slc26a7 are essential to physiological processes in multiple organs. Although mutations of Slc26a1, Slc26a6 and Slc26a7 have not been linked to any human diseases, disruption of Slc26a1, Slc26a6 or Slc26a7 expression in animals causes severe dysregulation of acid-base balance and disorder of anion homeostasis. Amelogenesis, especially the enamel formation during maturation stage, requires complex pH regulation mechanisms based on ion transport. The disruption of stage-specific ion transporters frequently results in enamel pathosis in animals. Here we present evidence that Slc26a1, Slc26a6 and Slc26a7 are highly expressed in rodent incisor ameloblasts during maturation-stage tooth development. In maturation-stage ameloblasts, Slc26a1, Slc26a6 and Slc26a7 show a similar cellular distribution as the cystic fibrosis transmembrane conductance regulator (Cftr) to the apical region of cytoplasmic membrane, and the distribution of Slc26a7 is also seen in the cytoplasmic/subapical region, presumably on the lysosomal membrane. We have also examined Slc26a1 and Slc26a7 null mice, and although no overt abnormal enamel phenotypes were observed in Slc26a1-/- or Slc26a7-/- animals, absence of Slc26a1 or Slc26a7 results in up-regulation of Cftr, Ca2, Slc4a4, Slc4a9 and Slc26a9, all of which are involved in pH homeostasis, indicating that this might be a compensatory mechanism used by ameloblasts cells in the absence of Slc26 genes. Together, our data show that Slc26a1, Slc26a6 and Slc26a7 are novel participants in the extracellular transport of bicarbonate during enamel maturation, and that their functional roles may be achieved by forming interaction units with Cftr.

Protein Interaction between Ameloblastin and Proteasome Subunit α Type 3 Can Facilitate Redistribution of Ameloblastin Domains within Forming Enamel.

Enamel is a bioceramic tissue composed of thousands of hydroxyapatite crystallites aligned in parallel within boundaries fabricated by a single ameloblast cell. Enamel is the hardest tissue in the vertebrate body; however, it starts development as a self-organizing assembly of matrix proteins that control crystallite habit. Here, we examine ameloblastin, a protein that is initially distributed uniformly across the cell boundary but redistributes to the lateral margins of the extracellular matrix following secretion thus producing cell-defined boundaries within the matrix and the mineral phase. The yeast two-hybrid assay identified that proteasome subunit α type 3 (Psma3) interacts with ameloblastin. Confocal microscopy confirmed Psma3 co-distribution with ameloblastin at the ameloblast secretory end piece. Co-immunoprecipitation assay of mouse ameloblast cell lysates with either ameloblastin or Psma3 antibody identified each reciprocal protein partner. Protein engineering demonstrated that only the ameloblastin C terminus interacts with Psma3. We show that 20S proteasome digestion of ameloblastin in vitro generates an N-terminal cleavage fragment consistent with the in vivo pattern of ameloblastin distribution. These findings suggest a novel pathway participating in control of protein distribution within the extracellular space that serves to regulate the protein-mineral interactions essential to biomineralization.

Survival of Intentionally Replanted Teeth and Implant-supported Single Crowns: A Systematic Review.

INTRODUCTION: Although nonsurgical initial root canal treatment and retreatment have high success rates, periapical disease can remain. The survival rates of 2 surgical procedures, intentionally replanted (IR) teeth and implant-supported single crowns (ISCs), have yet to be compared. The purpose of this systematic review and meta-analysis was to examine the literature and quantify the survival of IR teeth and compare it with that of ISCs. METHODS: Systematic searches were enriched by citation mining. Weighted survival means and 95% confidence intervals (CI) were estimated using a random-effects model and compared. RESULTS: The quality of the IR and ISC articles was only moderate. Data for ISCs were much more plentiful than for IR teeth. Meta-analysis revealed a weighted mean survival of 88% (95% CI, 81%-94%) for IR teeth. Root resorption was reported with a mean prevalence of 11%. The weighted mean survival of ISCs was 97% (95% CI, 96%-98%). The mean survival of ISCs was significantly higher than that of IR teeth (P < .001). A recent study on IR teeth indicated that orthodontic extrusion before intentional replantation improved survival rates. CONCLUSIONS: A systematic review and meta-analysis found that the mean survival of ISCs was significantly higher than IR teeth. However, treatment decisions must be based on a wide variety of treatment and patient-specific parameters. Intentional replantation may have a role when ISC is not practicable. Studies using contemporary treatment and analytic methods should be used to identify and measure intentional replant prognostic and treatment variables.

Tooth retention through endodontic microsurgery or tooth replacement using single implants: a systematic review of treatment outcomes.

INTRODUCTION: Clinicians are regularly confronted with difficult choices. Should a tooth that has not healed through nonsurgical root canal treatment be treated through endodontic microsurgery or be replaced using a single implant? Acquiring complete, unbiased information to help clinicians and their patients make these choices requires a systematic review of the literature on treatment outcomes. The purpose of this systematic review was to compare the outcomes of tooth retention through endodontic microsurgery to tooth replacement using an implant supported single crown. METHODS: Searches performed in PubMed, Cochrane Library, Web of Science, and EMBASE databases were enriched by citation mining. Inclusion criteria were defined. Sentinel articles were identified and included in the final selection of studies. Weighted survival and success rates for single implants and endodontic microsurgery were calculated. RESULTS: The quality of the articles reporting on single implants and endodontic microsurgery was moderate. Data for single implants were much more plentiful than for endodontic microsurgery, but the endodontic microsurgery studies had a slightly higher quality rating. Single implants and endodontic microsurgery were not directly compared in the literature. Outcomes criteria were often unclear. At 4-6 years, single implants had higher survival rates than teeth treated with endodontic microsurgery. Qualitatively different success criteria precluded valid comparison of success rates. CONCLUSIONS: Survival rates for single implants and endodontic microsurgery were both high (higher for single implants). Appraisal was limited by a lack of direct treatment comparisons. Long-term studies with a broad range of carefully defined outcomes criteria are needed.

Compound complex curves: the authentic geometry of esthetic dentistry.

Observers are drawn to the intricate and unpredictable way light reflects off the compound complex curved surfaces seen in nature, art, and industry. Teeth are no exception, containing as they do such detail in their gross anatomy, fine anatomic detail, and surface texture. Compound complex curves are particularly important when engineered materials are used to mimic naturally occurring objects, including prosthetic teeth, and they can provide both authenticity and beauty. The purpose of this article was to describe the nature of compound complex curves, their historical context, and their importance in creating natural-looking prostheses. Classically, such curves have been described by using descriptive qualitative methods or quantitative mathematical methods; now these approaches merge. Natural tooth anatomy contains interlinked features at different levels of scale from gross to fine surface texture detail. These curves should be created appropriately for individual restorative treatments.

Effect of porcelain and enamel thickness on porcelain veneer failure loads in vitro.

STATEMENT OF PROBLEM: Bonded porcelain veneers are widely used esthetic restorations. Although high success and survival rates have been reported, failures occur. Fracture is the most common failure mode. Fractures range from incomplete cracks to the catastrophic. Minimally invasive or thin partial veneers have gained popularity. PURPOSE: The aim of this study was to measure the influences of porcelain veneer thickness and enamel substrate thickness on the loads needed to cause the initial fracture and catastrophic failure of porcelain veneers. MATERIAL AND METHODS: Model discoid porcelain veneer specimens of varying thickness were bonded to the flattened facial surfaces of incisors, artificially aged, and loaded to failure with a small sphere. Individual fracture events were identified and analyzed statistically and fractographically. RESULTS: Fracture events included initial Hertzian cracks, intermediate radial cracks, and catastrophic gross failure. Increased porcelain, enamel, and their combined thickness had like effects in substantially raising resistance to catastrophic failure but also slightly decreased resistance to initial Hertzian cracking. Fractographic and numerical data demonstrated that porcelain and tooth enamel behaved in a remarkably similar manner. As porcelain thickness, enamel thickness, and their combined thickness increased, the loads needed to produce initial fracture and catastrophic failure rose substantially. Porcelain veneers withstood considerable damage before catastrophic failure. CONCLUSIONS: Increased enamel thickness, increased porcelain thickness, and increased combined enamel and porcelain thickness all profoundly raised the failure loads necessary to cause catastrophic failure. Enamel and feldspathic porcelain behaved in a like manner. Surface contact damage occurred initially. Final catastrophic failure followed flexural radial cracking. Bonded porcelain veneers were highly damage tolerant.

Nanostructure of carious tooth enamel lesion.

Carious lesions exhibit a complex structural organization composed of zones of higher and lower mineralization, formed by successive periods of cyclic de- and re-mineralization. A thorough understanding of the lesion morphology is necessary for the development of suitable treatments aiming to repair rather than replace the damaged tissue. This detailed understanding includes the entire lesion down to individual crystallites and nanopores within the natural organization of the crown. A moderate lesion, with surface loss and reaching dentin, and a very early lesion were studied. Scanning small-angle X-ray scattering (SAXS) with a pixel size of 20 × 20 µm(2) was used to characterize these lesions, allowing for the identification of distinct zones with varied absorption and scattering behavior, indicative of varied porosity and pore morphology. Despite these differences, the overall orientation and anisotropy of the SAXS signal was unaltered throughout both lesions, indicating that an anisotropic scaffold is still present in the lesion. The finding that crystallite orientation is preserved throughout the lesions facilitates the identification of preventive re-mineralizing strategies with the potential to recreate the original nanostructure.

Patient-centered endodontic outcomes: a narrative review.

INTRODUCTION: Root canal treatment (RCT) success criteria inform us of the path to bony healing and of prognostic factors, but tell little about how the patient perceives, feels, or values RCT. Patients choose, undergo, and pay for RCT, they live with the result, and inform their community. The purpose of this narrative review was to appraise patient-centered outcomes of initial non-surgical RCT and nonsurgical retreatment, in adults. MATERIALS AND METHODS: Patient-centered RCT outcome themes were identified in the extant literature: quality of life, satisfaction, anxiety, fear, pain, tooth survival and cost. Narrative review was applied because the disparate themes and data were unsuited to systematic review or meta-analysis. RESULTS: Application of the Oral Health Impact Profile (OHIP) demonstrated that disease of pulpal origin affects quality of life with moderate severity, primarily through physical pain and psychological discomfort, and that RCT results in broad improvement of quality of life. Satisfaction with RCT is extremely high, but cost is the primary reason for dissatisfaction. Anxiety and fear affect RCT patients, profoundly influencing their behaviors, including treatment avoidance, and their pain experience. Fear of pain is "fair" to "very much" prior to RCT. Pain is widely feared, disliked, and remembered; however, disease of pulpal origin generally produces moderate, but not severe pain. RCT causes a dramatic decrease in pain prevalence and severity over the week following treatment. Survival rates of teeth after RCT are very high; complication rates are low. Cost is a barrier to RCT, but initial costs, lifetime costs, cost effectiveness, cost utility, and cost benefit all compare extremely well to the alternatives involving replacement using implants or fixed prostheses. CONCLUSION: Dentists must strive to reduce anxiety, fear, experienced and remembered pain, and to accurately inform and educate their patients with respect to technical, practical and psychosocial aspects of RCT.