The effect of dental and background facial attractiveness on facial attractiveness and perceived integrity and social and intellectual qualities.

INTRODUCTION: The purposes of this study were to assess the role of dental attractiveness in background facial attractiveness and to evaluate how facial and dental attractiveness influenced raters' opinions of the integrity, social attractiveness, and intellectual attractiveness of the models. METHODS: Photographs of male and female individuals rated by peers as unattractive, average, and attractive were combined with oral images of 4 different levels of dental attractiveness (Index of Orthodontic Treatment Need [IOTN] 1, 5, 7, and 10). Sixty-seven participants meeting the inclusion criteria were recruited as raters. Raters viewed closed-lip smile and open-lip, posed smile of 24 models and rated them for facial attractiveness and integrity and multiple social/intellectual attractiveness dimensions using a Visual Analog Scale. RESULTS: Intrarater reliability was fair to excellent. Analysis of variance showed significant 3-way interactions (P < 0.0001=aim 1; P < 0.005=aim 2) for model sex, facial attractiveness, and dental attractiveness. The contribution of dental attractiveness to facial attractiveness was not fixed or linear, but dependent on dental attractiveness level, background facial attractiveness, and model sex. For both sexes, dental impact on facial attractiveness was neutral or negative when teeth were less than ideal, beginning at IOTN 5 for all background facial attractiveness levels. The impact of dental attractiveness on integrity and social and intellectual attractiveness was also dependent on dental attractiveness level, background facial attractiveness, and model sex. Dental attractiveness can make dramatic differences in Average and Attractive male individuals. CONCLUSIONS: The impact of dental attractiveness on facial attractiveness and integrity and social and intellectual attractiveness was dependent on dental attractiveness level, background facial attractiveness, and model sex. The effect of dental esthetics on facial attractiveness was neutral or negative for both male and female individuals when there was a need for treatment (IOTN 5 or higher) for all levels of facial attractiveness. For both male and female models, lower dental esthetics had a greater effect on more attractive faces. Judgments about integrity and social and intellectual attractiveness were strongly affected by dental esthetics, and these effects were more dramatic and consistent for male faces.

Quantification of facial and smile esthetics.

STATEMENT OF PROBLEM: Whether deviations in alignment discrepancy, width-to-length ratio, application of the golden proportion, or number of teeth revealed in smile affect attractiveness is yet unknown. PURPOSE: The purpose of this analytical study was to quantify dental and facial esthetics to determine whether individuals identified as having superior smiles display differences in alignment discrepancies (angulation between interpupillary and commissure line); width-to-length ratios of maxillary anterior teeth; application of the golden proportion (approximately 1.618:1); and number of teeth revealed in an animated smile when compared with an average population. MATERIAL AND METHODS: An Internet search for "best smile" and "celebrity" identified 108 celebrities. Photographs showing smiles within 10 degrees of a frontal view were collected, while photographs of dental students were used for the control group. Alignment discrepancies, widths and lengths of the anterior teeth, and number of teeth revealed in an animated smile were measured with photo-editing software, and ratios were calculated. The groups were compared with repeated-measures ANOVA, the Mann-Whitney U test, and the Wilcoxon signed-rank test (α=.05). RESULTS: Usable photographs were obtained for 90 celebrities (58 women, 32 men) and compared with photographs of 97 dental students (54 women, 43 men). Statistically significant differences were found for alignment discrepancies (celebrities 0.97, students 1.25, P=.034) and for the number of teeth displayed (P=.049); 22.2% of the celebrities revealed 12 teeth, versus 6.2% of the students. In both groups, significant differences from the golden ratio (1.618:1) for the width of the central incisor/lateral incisor right and left and for the width of the lateral incisor/canine right and left were observed through 95% confidence intervals. Sex and left-right were nonsignificant factors. CONCLUSIONS: Celebrities identified as having a best smile had smaller mean alignment discrepancies and revealed a greater number of teeth in an animated smile than dental students.

Objective assessment of the contribution of dental esthetics and facial attractiveness in men via eye tracking.

INTRODUCTION: Recently, greater emphasis has been placed on smile esthetics in dentistry. Eye tracking has been used to objectively evaluate attention to the dentition (mouth) in female models with different levels of dental esthetics quantified by the aesthetic component of the Index of Orthodontic Treatment Need (IOTN). This has not been accomplished in men. Our objective was to determine the visual attention to the mouth in men with different levels of dental esthetics (IOTN levels) and background facial attractiveness, for both male and female raters, using eye tracking. METHODS: Facial images of men rated as unattractive, average, and attractive were digitally manipulated and paired with validated oral images, IOTN levels 1 (no treatment need), 7 (borderline treatment need), and 10 (definite treatment need). Sixty-four raters meeting the inclusion criteria were included in the data analysis. Each rater was calibrated in the eye tracker and randomly viewed the composite images for 3 seconds, twice for reliability. RESULTS: Reliability was good or excellent (intraclass correlation coefficients, 0.6-0.9). Significant interactions were observed with factorial repeated-measures analysis of variance and the Tukey-Kramer method for density and duration of fixations in the interactions of model facial attractiveness by area of the face (P <0.0001, P <0.0001, respectively), dental esthetics (IOTN) by area of the face (P <0.0001, P <0.0001, respectively), and rater sex by area of the face (P = 0.0166, P = 0.0290, respectively). For area by facial attractiveness, the hierarchy of visual attention in unattractive and attractive models was eye, mouth, and nose, but for men of average attractiveness, it was mouth, eye, and nose. For dental esthetics by area, at IOTN 7, the mouth had significantly more visual attention than it did at IOTN 1 and significantly more than the nose. At IOTN 10, the mouth received significantly more attention than at IOTN 7 and surpassed the nose and eye. These findings were irrespective of facial attractiveness levels. For rater sex by area in visual density, women showed significantly more attention to the eyes than did men, and only men showed significantly more attention to the mouth over the nose. CONCLUSIONS: Visual attention to the mouth was the greatest in men of average facial attractiveness, irrespective of dental esthetics. In borderline dental esthetics (IOTN 7), the eye and mouth were statistically indistinguishable, but in the most unesthetic dental attractiveness level (IOTN 10), the mouth exceeded the eye. The most unesthetic malocclusion significantly attracted visual attention in men. Male and female raters showed differences in their visual attention to male faces. Laypersons gave significant visual attention to poor dental esthetics in men, irrespective of background attractiveness; this was counter to what was seen in women.

Celebrity smile esthetics assessment: Smile angulation.

STATEMENT OF PROBLEM: Whether deviations in the angulation discrepancy between the intercanine and interpupillary line significantly affect attractiveness is unknown. PURPOSE: The purpose of this prospective study was to quantify dental and facial esthetics to determine whether smile angulation discrepancies in individuals identified as having attractive smiles are smaller than those in the average population. MATERIAL AND METHODS: An Internet search for "best smile" and "celebrity" identified 108 celebrities (Test group). Photographs showing smiles within 10 degrees of a frontal view were gathered. In mannequin testing, small head rotation (<10 degrees) was found not to affect the measurements. Photographs of dental students were used for the control group. The angulation discrepancy between the intercanine and interpupillary line was measured using computer software. Groups were compared using the Mann-Whitney U test (α=.05). RESULTS: Usable photographs were obtained for 94 celebrities (62 women, 32 men) and were compared with photographs of 97 dental students (54 women, 43 men). Significant (P<.01) differences in angulation discrepancy were found, with celebrities having smaller mean angulation discrepancies (0.97 degrees) than dental students (1.33 degrees). The differences between men and women were not statistically significant (P>.05). CONCLUSIONS: Celebrities identified as having "best smile" had significantly smaller mean angulation discrepancies than the control group.

Role of facial attractiveness in patients with slight-to-borderline treatment need according to the Aesthetic Component of the Index of Orthodontic Treatment Need as judged by eye tracking.

INTRODUCTION: Previous eye-tracking research has demonstrated that laypersons view the range of dental attractiveness levels differently depending on facial attractiveness levels. How the borderline levels of dental attractiveness are viewed has not been evaluated in the context of facial attractiveness and compared with those with near-ideal esthetics or those in definite need of orthodontic treatment according to the Aesthetic Component of the Index of Orthodontic Treatment Need scale. Our objective was to determine the level of viewers' visual attention in its treatment need categories levels 3 to 7 for persons considered "attractive," "average," or "unattractive." METHODS: Facial images of persons at 3 facial attractiveness levels were combined with 5 levels of dental attractiveness (dentitions representing Aesthetic Component of the Index of Orthodontic Treatment Need levels 3-7) using imaging software to form 15 composite images. Each image was viewed twice by 66 lay participants using eye tracking. Both the fixation density (number of fixations per facial area) and the fixation duration (length of time for each facial area) were quantified for each image viewed. Repeated-measures analysis of variance was used to determine how fixation density and duration varied among the 6 facial interest areas (chin, ear, eye, mouth, nose, and other). RESULTS: Viewers demonstrated excellent to good reliability among the 6 interest areas (intraviewer reliability, 0.70-0.96; interviewer reliability, 0.56-0.93). Between Aesthetic Component of the Index of Orthodontic Treatment Need levels 3 and 7, viewers of all facial attractiveness levels showed an increase in attention to the mouth. However, only with the attractive models were significant differences in fixation density and duration found between borderline levels with female viewers. Female viewers paid attention to different areas of the face than did male viewers. CONCLUSIONS: The importance of dental attractiveness is amplified in facially attractive female models compared with average and unattractive female models between near-ideal and borderline-severe dentally unattractive levels.

Contribution of malocclusion and female facial attractiveness to smile esthetics evaluated by eye tracking.

INTRODUCTION: There is disagreement in the literature concerning the importance of the mouth in overall facial attractiveness. Eye tracking provides an objective method to evaluate what people see. The objective of this study was to determine whether dental and facial attractiveness alters viewers' visual attention in terms of which area of the face (eyes, nose, mouth, chin, ears, or other) is viewed first, viewed the greatest number of times, and viewed for the greatest total time (duration) using eye tracking. METHODS: Seventy-six viewers underwent 1 eye tracking session. Of these, 53 were white (49% female, 51% male). Their ages ranged from 18 to 29 years, with a mean of 19.8 years, and none were dental professionals. After being positioned and calibrated, they were shown 24 unique female composite images, each image shown twice for reliability. These images reflected a repaired unilateral cleft lip or 3 grades of dental attractiveness similar to those of grades 1 (near ideal), 7 (borderline treatment need), and 10 (definite treatment need) as assessed in the aesthetic component of the Index of Orthodontic Treatment Need (AC-IOTN). The images were then embedded in faces of 3 levels of attractiveness: attractive, average, and unattractive. During viewing, data were collected for the first location, frequency, and duration of each viewer's gaze. RESULTS: Observer reliability ranged from 0.58 to 0.92 (intraclass correlation coefficients) but was less than 0.07 (interrater) for the chin, which was eliminated from the study. Likewise, reliability for the area of first fixation was kappa less than 0.10 for both intrarater and interrater reliabilities; the area of first fixation was also removed from the data analysis. Repeated-measures analysis of variance showed a significant effect (P <0.001) for level of attractiveness by malocclusion by area of the face. For both number of fixations and duration of fixations, the eyes overwhelmingly were most salient, with the mouth receiving the second most visual attention. At times, the mouth and the eyes were statistically indistinguishable in viewers' gazes of fixation and duration. As the dental attractiveness decreased, the visual attention increased on the mouth, approaching that of the eyes. AC-IOTN grade 10 gained the most attention, followed by both AC-IOTN grade 7 and the cleft. AC-IOTN grade 1 received the least amount of visual attention. Also, lower dental attractiveness (AC-IOTN 7 and AC-IOTN 10) received more visual attention as facial attractiveness increased. CONCLUSIONS: Eye tracking indicates that dental attractiveness can alter the level of visual attention depending on the female models' facial attractiveness when viewed by laypersons.

Accuracy of ceramic restorations made with two CAD/CAM systems.

STATEMENT OF PROBLEM: Different types of CAD/CAM systems are currently available, but information regarding which system produces the best marginal fit is lacking. PURPOSE: The purpose of this study was to evaluate the effect of 2 different CAD/CAM systems (Cerec inLab, Kavo Everest) on the marginal fit of 2 types of zirconia-based and lithium disilicate crowns. MATERIAL AND METHODS: Forty zirconia-based and lithium disilicate crowns, 20 each, were fabricated with the Cerec inLab and Everest CAD/CAM systems on a specially designed stainless steel die to ensure the standardization of specimen shape and dimensions. The vertical marginal fit for all tested crowns was evaluated by using a digital microscope at ×100 magnification, and the data were tabulated and statistically analyzed with 2-way ANOVA, followed by the Tukey honestly significant difference (HSD) test with a confidence level of .05 to determine the mean differences. RESULTS: The results showed that the CAD/CAM technique, ceramic type, and their interaction had a statistically significant effect on the mean marginal fit of both ceramic types tested. CONCLUSIONS: Better marginal fit values were exhibited by the Everest CAD/CAM technique for both ceramic types tested.

Esthetic considerations related to bone and soft tissue maintenance and development around dental implants: report of the Committee on Research in Fixed Prosthodontics of the American Academy of Fixed Prosthodontics.

In recent years the frequency of and esthetic demand for implant restorations in the esthetic zone has increased. Recent literature has revealed numerous consistent trends which may aid the clinician in achieving predictable esthetics. Maintaining generous facial bone by judicious placement as well as by using implants with diameters of less than 4 mm appears to be beneficial. Avoiding adjacent implants in the esthetic zone while maintaining an implant to tooth distance of between 2 mm and 4 mm seems to aid in bone and soft tissue maintenance. Abutment connections in which the abutment is narrower than the implant offer distinct advantages, most notably increased bone heights. Also, provisional restoration, especially early in treatment provides long-term esthetic benefits.

Smile characterization by U.S. white, U.S. Asian Indian, and Indian populations.

STATEMENT OF PROBLEM: With growing demand for high esthetic standards, dentists must understand patient perception and incorporate their preferences into treatment. However, little is known about how cultural and ethnic differences influence esthetic perception. PURPOSE: The purpose of this study was to determine whether differences in ethnic background, including the possibility of assimilation, affected a layperson's perception of esthetic and smile characteristics. MATERIAL AND METHODS: A survey was developed containing images that were digitally manipulated into a series of barely perceptible steps, changing 1 smile parameter to form a strip of images that displayed that parameter over a wide range. Data were collected with a customized program which randomly displayed a single image and allowed the subject to use the mouse to adjust an on-screen slider according to displayed instructions, that is, "Please move the slider to select the image you find to be most ideal"; or "Please move the slider to select the first image that you find unattractive." A convenience sample (n=288) comprised of U.S. whites, U.S. Asian Indians, and Indians living in India was surveyed. This sample provided a power of .86 to detect a difference of ±1.5 mm. Subjects evaluated images showing the smile arc, buccal corridor, gingival display, vertical overlap, lateral incisal step, maxillary midline to midface, and maxillary to mandibular midline. Rater reliability was assessed with the Fleiss-Cohen weighted Kappa (Kw) statistic and corresponding 95% confidence interval after each question was repeated in a random sequence. Choice differences due to ethnicity were assessed with a multiple randomization test and the adjusted P value with the step-down Bonferrroni method of Holm (α=.05). RESULTS: The Kw for the 17 variables in all 3 groups ranged from 0.11 for ideal vertical overlap to 0.64 for ideal buccal corridor space. Overall reliability was fair to moderate. Differences attributed to ethnicity were demonstrated between the Asian Indians and U.S. whites. Differences attributed to assimilation were demonstrated between U.S. Asian Indians and Asian Indians. Differences between U.S. Asian Indians and U.S. whites can be instructive and demonstrate the relative power of ethnicity and assimilation. A difference between these groups shows the power of ethnicity and no difference between these groups shows the power of assimilation. The ratings of the Asian Indians and the U.S. whites showed a clinically significant difference for Ideal Buccal Corridor and Maximum Smile Arc. There were no significant differences between the U.S. Asian Indians and Asian Indians. There were clinically significant differences between the U.S. Asian Indians and U.S. whites only for Ideal Buccal Corridor. CONCLUSIONS: Ethnicity had a significant effect on the esthetic choices for Buccal Corridor and Smile Arc. There is no conclusive evidence for assimilation.

Influence of recasting different types of dental alloys on gingival fibroblast cytotoxicity.

STATEMENT OF PROBLEM: Surplus alloy from the initial casting is commonly reused with the addition of new alloy. This recasting procedure could affect the cytotoxicity of dental alloys. PURPOSE: The purpose of this in vitro study was to evaluate the effect of repeated casting of high-noble and base metal alloys on gingival fibroblast cytotoxicity. MATERIAL AND METHODS: Disk-shaped specimens (5 × 2 mm, n=60) of a high-noble (Au-Pt) and 2 base metal (Ni-Cr and Cr-Co, n=20) alloys were prepared with 100% new alloy and 50%, 65%, and 100% once recast alloy. The elemental composition of specimens was analyzed with X-ray energy-dispersive spectroscopy. Five specimens from each group were conditioned in saline with 3% fetal bovine serum albumin. The conditioning media were analyzed for elemental release with atomic absorption spectroscopy. Cytotoxic effects were assessed on human gingival fibroblast with a 3-(4.5-dimethylthiazol-2-yl)-2.5-diphenyl tetrazolium bromide (MTT) colorimetric assay. The data were analyzed with 1-way and 2-way ANOVA and Tukey's HSD multiple comparison test (α-=.05). RESULTS: Elemental compositions of Co-Cr and Au-Pt alloys were significantly different among casting protocols. Elemental release of Co-Cr and Ni-Cr alloys was significantly different between new and recast specimens (P<.001). Nickel release increased with recast alloy addition. The 2-way ANOVA showed a significant effect of the casting procedure (P<.001) alloy group (P<.001) and their interaction for cytotoxicity (P<.001). The Ni-Cr alloy groups with 65% and 100% recast alloy had lower cellular activity than all other specimens (P<.001). CONCLUSIONS: The results of this study indicated that alloys containing nickel have increased cytotoxic effects and that composition of the alloys affected the cytotoxicity. Furthermore, recasting nickel-containing alloys with 65% surplus metal addition significantly increased the cytotoxic activity.

Effect of substrate shades on the color of ceramic laminate veneers.

STATEMENT OF PROBLEM: Ceramic laminate veneers are generally fabricated with varying thicknesses ranging from 0.3 to 1 mm, depending on the need to mask discolored teeth or slightly correct the contour of malpositioned teeth. Clinical color reproduction poses a challenge because of color interaction with the underlying substrate, whether tooth structure or esthetic restorative material. PURPOSE: The purpose of this in vitro investigation was to measure the effect of color change resulting from applying 2 shades of ceramic material, translucent (T1) and opaque (O2), to 2 shades of composite resin substrate material, light (A3) and dark (C4), on the overall color of ceramic laminates. MATERIAL AND METHODS: Forty disks were fabricated. Twenty disks (15 × 0.5 mm) were cut from pressed ceramic, 10 disks for each shade (translucent and opaque). Additionally, 20 disks (15 × 4.0 mm) were fabricated from light-polymerized composite resin material, 10 disks for each shade (light and dark). The ceramic disks were bonded to the composite resin disks with clear resin cement. The specimen combinations were divided into 4 groups (n=5). Color measurements were done with a colorimeter (Minolta Chroma Meter CR-200b) configured with diffuse illumination/0-degree viewing geometry. Mean CIE lightness (L*), chroma (C*(ab)), and hue angle (h(ab)) values were obtained. A 2-way analysis of variance (ANOVA) was used to compare the means and standard deviations between the different color combinations (α=.05), followed by Tukey's HSD post hoc test for significant interactions. RESULTS: The 2-way ANOVA showed significant differences (P<.001) in L*, C*(ab), and h(ab) for a change in the composite resin substrate, regardless of the ceramic material shade. There was significant color change from dark to light substrate (P=.044). The mean h(ab) (SD) of dark substrate/opaque veneer was 89.62 (1.5), while the mean h(ab) of light substrate/translucent veneer was 81.23 (1.7). CONCLUSIONS: Within the limitations of this study, the selected color of a 0.5 mm ceramic laminate veneer was significantly affected by the change in color of the supporting substrate.

Smile esthetics from the layperson's perspective.

INTRODUCTION: Computer-based smile esthetic surveys based on slider technology allow more precise control of variables and the possibility of obtaining continuous data. Variations in the perception of smiles from different facial perspectives have not been resolved. The objective of this study was to quantify the ideal and the range of acceptable values for smile variables judged by laypersons from a full-face perspective for comparison with lower-face data. METHODS: Mirrored and symmetric male and female full faces previously determined by peers to be of average attractiveness were used. Ninety-six laypersons judged these smile variables: smile arc, buccal corridor fill, maxillary gingival display, maxillary midline to face, maxillary to mandibular midline discrepancy, overbite, central incisor gingival margin discrepancy, maxillary anterior gingival height discrepancy, incisal edge discrepancy, and cant. The judges manipulated the variables using adjustable image technology that allowed the variable to morph and appear continuous on a computer monitor. Medians for each smile variable were compiled, and the Fleiss-Cohen weighted kappa statistic was calculated to measure reliability. Multiple randomization tests with adjusted P values were used to compare these data with those for lower-face views. RESULTS: Reliability ranged from 0.25 for ideal overbite to 0.60 for upper midline to face, except for upper and lower buccal corridor limits, which each had a kappa value near 0. There were no statistically significant differences between the ratings of male and female raters. The following variables showed statistically and clinically significant differences (>1 mm) when compared with the lower-face view: ideal smile arc, ideal buccal corridor, maximum gingival display, upper to lower midline, and occlusal cant. Although the smile arc values differed because of model lip curvature variations, the principle of tracking the curve of the lower lip was confirmed. For the full-face view, the raters preferred less maximum gingival display, less buccal corridor, more upper to lower midline discrepancy, and less cant of the occlusal plane. CONCLUSIONS: Reliability was fair to moderate with the exception of the buccal corridor limits. Most variables showed no clinically meaningful differences from the lower-face view. The acceptable range was quite large for most variables. Detailed knowledge of the ideal values of the various variables is important and can be incorporated into orthodontic treatment to produce an optimal esthetic smile.

Smile esthetics from patients' perspectives for faces of varying attractiveness.

INTRODUCTION: Delivering an attractive smile is a key element in orthodontic patient satisfaction. Smile characteristics can be affected by the facial context. The purpose of this study was to investigate smile esthetics related to facial attractiveness and sex of the model. METHODS: Attractive, average, and unattractive model faces (2 of each; 3 male, 3 female) determined by peer ratings were combined with 10 smile variables (buccal corridor, smile arc, maxillary gingival discrepancy, gingival display, incisal-edge discrepancy, cant, overbite, central-incisor gingival margin discrepancy, and maxillary midline to face, and maxillary midline to mandibular midline). Each smile characteristic was altered digitally and presented with slider technology to allow a continuous range of choices. Raters chose the ideal and the limits of acceptability. The variables were divided into 6 separate surveys and rated 96 times. Reliability was assessed by answering each question twice. RESULTS: Individual smile variable reliability ranged from fair to excellent, except for the buccal corridor. Clinically significant values were defined as greater than 1.0 mm with statistical significance (P <0.05). Rater sex did not make a difference. Clinical significance was found for smile arc, gingival display, and maxillary midline to face. For females, accentuated smile arcs were preferred for the unattractive and attractive models compared with the average models. The opposite was found for male models. More gingival display was preferred for the attractive and unattractive male and female models compared with the average models. Attractive models were allowed less midline deviation. CONCLUSIONS: Facial attractiveness and model sex impacted smile variables with a facial context, except for occlusal cant. These smile characteristics with a facial context should be considered when diagnosing and planning treatment for an orthodontic patient.

Influence of irrigant, dowel type, and root-reinforcing material on fracture resistance of thin-walled endodontically treated teeth.

PURPOSE: Unresolved controversy exists concerning the optimum restorative material to reinforce the thin-walled roots of endodontically treated teeth to improve their fracture resistance under occlusal load. This study evaluated the effectiveness of irrigant, dowel type, and root-reinforcing material on the fracture resistance of thin-walled endodontically treated teeth. MATERIALS AND METHODS: The root canals of 140 maxillary central incisors were enlarged and equally divided into seven groups according to the canal irrigant: no irrigant (control), 5% hydrogen peroxide, 5% sodium hypochlorite, a combination of 5% hydrogen peroxide and sodium hypochlorite, 15% ethylenediaminotetraacetic acid (EDTA), 10% lactic acid, or 20% lactic acid. Within each group, root canals were lined with composite resin (PermaFlo) or glass ionomer cement (Fuji II LC). A light-transmitting plastic dowel (Luminex) was used to create space for a quartz fiber-reinforced dowel (Aestheti Post) or a titanium alloy dowel (ParaPost XH) and to cure the restorative materials. Following dowel cementation and restoration of the roots with composite core, the teeth were submitted to fracture resistance testing, and data were analyzed with 3-way ANOVA followed by Ryan-Einot-Gabriel-Welsch Multiple Range Test (α= 0.05). RESULTS: Fracture resistance values were significantly different among irrigants, restorative materials, and their interaction (p < 0.001); however, the dowel type was not significantly different (p= 0.51). CONCLUSIONS: Thin-walled roots that had the smear layer removed with lactic acid and that were then lined with composite resin had a higher fracture resistance.

Reinforcement of thin-walled root canal structures for placement of esthetic dowels: a clinical report.

Thin-walled root canals always present a challenge to dentists to select a restorative treatment that does not further weaken the thin tooth structure. The prognosis of dowel and core restorations can be unpredictable. This clinical report describes the treatment of a patient with extensive caries extending into the root canal of an endodontically treated maxillary central incisor. The use of a flowable composite resin in combination with a quartz fiber reinforced post is described, resulting in the rehabilitation of a structurally compromised root canal with satisfactory esthetic and functional outcomes.