CAD/CAM technology had evolved extensively from the time when it was first used clinically in the 1980s. Today, CAD/CAM technology can be used to fabricate crowns, design and mill fixed partial denture frameworks, set teeth and fabricate complete dentures as well as to mill interim restorations. An extensive literature review found many research studies on the evaluation of the accuracy of the CAD/CAM ceramic crowns as compared to other ceramic crowns but little research had been done to evaluate the accuracy of interim restorations. This article describes the method in which CAD/CAM as well as conventional interim crowns were fabricated, cemented onto their dies, dye stained, thermocycled as well as sectioned with their marginal discrepancies investigated.

Objectives: Three-dimensional (3D) bioprinting is a manufacturing process that incorporates viable cells into a 3D matrix by adding layer upon layer of material. The objectives of this study are to characterize a novel matrix of collagen and hydroxyapatite and to assess the effects of the 3D bioprinting process on cytotoxicity, proliferation rate, and cytokine expression of Homo sapiens palatal mesenchyme (HEPM) cells. Methods: For this, we prepared a 3D matrix of collagen and hydroxyapatite without and with cells. We used light microscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) to characterize the structure and arrangement of the collagen fibers. We then incubated the matrix with known standards of cytokines to measure adsorption. We assessed the proliferation and viability of HEPM cells in the presence of the 3D construct and after 3D bioprinting. Finally, we assessed the cytotoxicity of this matrix for HEPM cells and assessed its effect on the production of chemokines and cytokines. A one-way fixed effect ANOVA was fit to concentrations of cytokines and pairwise group comparisons were conducted using Tukey’s Honest Significant Differences test (p< 0.05). Results: The matrix was found to contain interwoven strands of collagen and some hydroxyapatite crystals that did not absorb cytokines except for MIP-1a (p< 0.05). The matrix was found to be non-cytotoxic using an AlamarBlue® assay. We found that the cell proliferation rate was lower when seeded on the 3D construct than in 2D culture. We also found that the proliferation rate was very low for the HEPM cells in the 3D bioprinted constructs. In the presence of the 3D construct, the HEPM cells had similar expression profiles of the cytokines measured (P > 0.05 for GM-CSF, IL-6, IL-8, and RANTES). Conclusion: 3D-bioprinting has the potential to be used in dentistry as a novel osteogenic bone grafting material. Here we show that a novel matrix of collagen and hydroxyapatite is non-cytotoxic to HEPM cells and does not induce a proinflammatory response.

These PhD projects represent secondary analyses of data from the ongoing Iowa Fluoride Study (IFS)/Iowa Bone Development Study (IBDS). The aim of this dissertation was to explore the associations between period-specific and cumulative fluoride intakes from birth to age 17, and from birth to age 19 years and bone measures of participants. Also, this dissertation looked into the associations between the clinical presence of dental fluorosis and bone outcomes. Participants have been participating in the IBDS that grew out of the IFS, which is a longitudinal investigation of dietary and non-dietary fluoride exposures, dental fluorosis and dental caries. IFS participants were recruited during 1992-95 from 8 hospital postpartum wards in Iowa, and detailed questionnaires were sent every 1.5-6 months. Data on intakes from water, other beverages, selected foods, dietary fluoride supplements and dentifrice were collected from the questionnaires, and, in combination with water and beverage fluoride levels, combined fluoride was estimated. For the first dissertation project, the association between fluoride intake and peripheral quantitative computed tomography (pQCT)-derived bone outcomes at age 17 were assessed. Participants underwent pQCT of the radius and tibia (XCT-2000) at age 17 years. pQCT results of trabecular bone mineral density (BMD) and bone mineral content (BMC), cortical BMD and BMC, and compression and torsion strength were related to fluoride intake through bivariate and multivariable analyses, adjusting for height, weight, years since peak height velocity, average daily time spent in moderate-to-vigorous intensity physical activity, daily calcium intake, and daily protein intake. P-values < 0.01 were considered statistically significant rather than p< 0.05 due to multiple hypothesis tests. The mean daily fluoride intake estimated by area-under-the-curve (AUC) from birth to 17 years was 0.79 mg (SD = 0.32) for males and 0.70 mg (SD = 0.25) for females. Spearman correlation coefficients between daily fluoride intake and pQCT bone measures were weak (for females r= -0.01 to 0.15 for radius bone outcomes and -0.001 to 0.23 for tibia bone outcomes; for males r= 0.03 to 0.24 for radius bone outcomes and -0.008 to 0.27 for tibia bone outcomes). In sex-specific linear regression analyses for females, partially-adjusted for height, weight, and years since peak height velocity, statistically significant negative associations were detected between all radial bone outcomes and period-specific fluoride intake from 0-8.5 years. Significant positive associations were detected for females between period-specific fluoride intakes from 14-17 years and all tibia bone outcomes, and between period-specific fluoride intakes from 14-17 years and all radius and tibia bone outcomes for males. In the fully-adjusted models, which also included physical activity, protein intake and calcium intake, statistically suggestive negative associations were detected for females during the early fluoride intake period from 0 to 8.5 years and radial cortical bone content and torsion bone strength. A statistically suggestive positive association was found between period-specific fluoride intake from 8.5 to 14 years and torsion bone strength (pSSI) (p< 0.05) for females. For males, statistically significant positive associations were detected between fluoride intake for the period from 14 to 17 years and cortical content and torsion strength (pSSI) at the 0.01 level. The second project examined the associations between period-specific and cumulative fluoride intakes from birth to age 19 years and MDCT-derived bone outcomes at age 19. Age 19 MDCT-derived trabecular and cortical bone micro-architecture scans were acquired at the University of Iowa Comprehensive Lung Imaging Center. MDCT results of the trabecular (volumetric bone mineral density (vBMD), transpose bone mineral density (tBMD), plate trabecula bone mineral density (pBMD), plate width (TS-PW), trabecular thickness (Tb.Th), trabecular spacing (Tb.Sp), trabecular network area (Tb.NA)) and cortical (cortical bone porosity (Cb.Poro), cortical thickness (Cb.Th)) bone were related to fluoride intake through bivariate and multivariable analyses, adjusting for height, weight, years since peak height velocity, average daily time spent in moderate-to-vigorous intensity physical activity, Healthy Eating Index (HEI) score, calcium intake and protein intake. P-values < 0.01 were considered statistically significant rather than p< 0.05 due to multiple hypothesis tests. The mean daily fluoride intake estimated by area-under-the-curve (AUC) from birth to 19 years was 0.81 mg (SD = 0.33) for males and 0.69 mg (SD = 0.27) for females. Spearman correlation coefficients between daily fluoride intake and MDCT bone measures were weak (for females r= -0.001 to 0.20 for trabecular bone outcomes and -0.01 to 0.02 for cortical bone outcomes; for males r= -0.003 to 0.16 for trabecular bone outcomes and -0.09 to -0.02 for cortical bone outcomes). In sex-specific partially-adjusted regression analysis adjusted for height, weight, and years since peak height velocity, no statistically significant associations were found for females or males. In the fully-adjusted models, which also included physical activity, HEI score, and protein and calcium intakes, no statistically significant associations were found for either females or males. The third project explored the associations between dental fluorosis score at age 8 and DXA-derived bone outcomes at age 5. DXA bone assessments of the whole body, proximal femur (hip), and lumbar spine were performed at The University of Iowa in the Clinical Research Center (Hologic QDR-2000 DXA unit). The dental fluorosis score was defined as the proportion of zones with definitive or severe fluorosis per person. In the unadjusted associations between bone outcomes and dental fluorosis score, no statistically significant associations were detected for females at the 0.05 level. For males, a statistically significant negative association was found between hip BMD and dental fluorosis score. Sex-specific partial correlation coefficients were estimated between DXA-derived bone outcomes and dental fluorosis score adjusted for height, weight, physical activity, calcium intake and fluoride intake. No statistically significant associations were found for females. For males, a statistically significant negative association was detected between dental fluorosis score and hip BMD. The findings of this dissertation show that life-long intakes from combined sources for adolescents and young adults living in fluoridated areas in the United States were weakly associated with bone measures at age 17 and 19. Furthermore, it was shown that bone outcomes can’t be predicted by the score of dental fluorosis. Fluoride is a mineral that plays an important role in the mineralization of bone and teeth, as well as in dental caries prevention. Numerous professional health organizations endorse the adjusted fluoridation of public water supplies for caries prevention. Results from this dissertation will also help in supporting additional efforts to promote water fluoridation and expand its use, as this dissertation’s outcomes did not demonstrate adverse outcomes related to bone.

Background Anxiety experienced by individuals visiting the dental office to receive treatment is prevalent in the population. The clinical manifestation of these anxieties is considerable; it is estimated that approximately between 14 and 30 million people in the United States do not seek routine dental care due to dental anxiety. Dentists and other scientists have explored many techniques and procedures in attempts to ameliorate these anxieties and improve patient care. Biofeedback is a process that involves measuring a person's specific bodily functions such as blood pressure, heart rate, skin temperature, muscle tension, or breathing rate, and conveying the information to the patient in real-time. This raises the patient's awareness and therefore the possibility of conscious control of those functions. Evidence has shown biofeedback to be a useful modality of treatment for numerous conditions associated with anxiety. Anxiety has been shown to up-regulate the sympathetic nervous system. When the sympathetic nervous system is up-regulated, the pain threshold is decreased, and physiologic parameters of anxiety are manifested in the patient. This physiological phenomenon is well understood and demonstrates that, with anxiety, the individual will have a decreased pain threshold (i.e., greater response to noxious or painful stimuli). The purpose of the current pilot study is to investigate the use of a novel biofeedback system (RESPeRATE™) to reduce patients' pre-operative general anxiety levels and subsequently the pain associated with dental injections. Methods Eighty-one subjects participated in this randomized controlled study. Forty subjects were in the experimental group and forty-one subjects were in the control group. All subjects were asked to fill out a pre-injection survey (Dental Injection Sensitivity Survey - DISS), measuring baseline anxiety levels. Subjects in the experimental group used a biofeedback technique, while subjects in the control group were not exposed to any biofeedback. All participants then received an inferior alveolar local anesthetic injection. Subjects in both groups were then given a post-injection survey (measuring anxiety levels), and filled out a Visual Analog Scale (VAS). The VAS was designed to measure the subjects' perception of pain of the injection, the overall injection experience, and anticipatory anxiety for future injections. Results The results of the study demonstrated that there was no significant difference between the treatment group and the control group with respect to any of the pre/post-operative anxiety measures as recorded by the DISS. This study did demonstrate that with the use of the RESPeRATE™ device there was a significant difference in the overall injection experience between the experimental group and the control group (p=0.013), as measured by the VAS. A trend towards improved responses for the experimental group was noted with respect to both level of discomfort and ratings of future nervousness; these results did not reach a statically significance of p<.05. Conclusions Future studies and power calculation will be more specific towards the RESPeRATE™ in a dental setting, and lead to more accurate approximations on the number of subjects needed to determine whether the difference was due to chance or due to the treatment modality. It appears that this novel pilot study was underpowered. It would also be feasible to apply the technology to other areas in dentistry where anxiety and sympathetic up-regulation are etiologic components. Areas of future studies may include temporomandibular joint dysfunction, orofacial pain, periodontal disease, and wound healing.

Approximately 26% of the U.S. population between the ages of 65 and 74 years are completely edentulous. Of the different proposed predictors and risk factors, low income and education levels have the highest correlation with tooth loss. While the incidence of complete edentulism in the United States has progressively declined over the past decade, the continued growth of the population strongly suggests that edentulism prevalence will likely remain constant or increase over the next few decades. In patients wearing complete prosthetic appliances, several post-treatment complications may arise, including denture associated Candida species infections and mucosal stomatitis. These type of fungal infections are associated with patient-reported symptoms (e.g. pain or discomfort) and may impede normal oral function. In this study the activity of 11 (antimicrobial and/or antifungal) agents in a dental adhesive carrier against two strains of C. albicans was assessed. In conventional minimal inhibitory concentration (MIC) assays, C. albicans were resistant to histatin 5 and lactoferricin B, yet very susceptible to SMAP28; susceptible to long chain bases sphingosine, dihydrosphingosine, and phytosphingosine; and susceptible to anti-fungal agents amphotericin B, chlorhexidine dihydrochloride, chlorhexidine gluconate, fluconazole, and nystatin. However, in 1% dental adhesive (final concentration) C. albicans were resistant to histatin 5, lactoferricin B, SMAP28, sphingosine, dihydrosphingosine, and phytosphingosine suggesting that the components in denture adhesive may inactivate local innate immune factors in the oral cavity possibly predisposing users to fungal infections in relation to their dental prostheses. In MIC assays in 1% dental adhesive (final concentration) C. albicans were susceptible (p value < 0.05) to amphotericin B, chlorhexidine, dihydrochloride, chlorhexidine gluconate, fluconazole, and nystatin strongly suggesting that these anti-fungal agents could be candidates for inclusion in denture adhesive formulations, and also be used as a prescribed topical treatment in individuals with fungal infections of the oral mucosa.

Dental Caries is still considered one of the most prevalent chronic diseases that affect children in the US. Access to oral care problems could be due to the limited availability of services or unwillingness of people to seek services. As a proposed solution to those challenges, Atraumatic Restorative Technique (ART) was developed in the 1980s as an affordable, patient friendly caries management procedure that does not need extensive operator training or special skills. ART was originally developed to be conducted in field settings; however, after initial evidence of effectiveness, the World Health Organization (WHO) and the International Dental Federation (FDI) promoted the use of ART in modern clinical settings worldwide. In the US, the practice of ART is not believed to be widely used. This may be a result of little attention given to (ART) in dental education and advanced training. This dissertation is comprised of three separate studies that investigated the extent and the factors related to the didactic and clinical instruction on ART in US pre- and post-doctoral pediatric dentistry programs and the factors related to the willingness of pediatric dentists to use ART with their child patients. survey post-doctoral pediatric dentistry program directors and pre-doctoral pediatric dentistry program directors. In study III a different instrument was used to survey pediatric dentists in the US. The survey instruments were tested for content and face validity by cognitive analysis interviews and pilot testing. Using web-based survey methodology, two questionnaires were sent out in May 2010 to investigate self-reported use of ART in educational training institutes (study I and II) and in April 2011, a third questionnaire was sent to a random national sample of pediatric dentists (study III). Using a conjoint design, the third questionnaire asked pediatric dentists to rate their willingness to use ART for 9 patients' scenarios. Eighty eight percent of Pediatric Dentistry Residency programs and 66 % of pre-doctoral pediatric dentistry programs in the US provided clinical training on ART; however only 30% of post-doctoral programs and 14 % of pre-doctoral programs used ART "Very Often/ Often" as a caries management technique for their pediatric patients. Pediatric Dentistry residency programs and pre-doctoral pediatric dentistry programs used ART mainly in primary, anterior, single surface cavities and as an interim treatment. Attitudes toward ART alone and after controlling for other variables explained 35% of the level of training on ART in post- doctoral program and 23% in pre-doctoral pediatric dentistry programs. For study III, conjoint analysis showed that being very young and/or uncooperative were the most important reasons practitioners reported a higher likelihood of using ART. Although insurance coverage was the least important factor overall, not having any insurance was identified as an additional important factor in decisions to use ART. Collectively, our results suggest that that the use of ART is not widespread in the US. In addition, ART is viewed by some as a sub optimum treatment and needs to be modified to conform to the US standards of care. On the other hand, educators and pediatric dentists who had positive views of ART thought it could be a valuable treatment for very young, uncooperative children and children with no insurance.

There are no previous studies validating the accuracy and repeatability of ClearMatch photographic shade analysis system. The purpose of this study was to compare the shade matches performed by a photographic shade analysis system (ClearMatch) with conventional visual shade matching method under simulated clinical conditions. Three shade matching methods were used to match twelve shade tabs under simulated clinical conditions using a Vita Classical shade guide: conventional visual shade matching using 3 human raters (VM – Visual method), photographic shade analysis system (CM - ClearMatch) using two different ways of normalizing the image (CM-A2 and CM-ref respectively). Shade matching for all methods was completed at two separate sessions. The Kappa statistic was used to determine the intra-rater and inter-rater agreement. CIELAB values of the shade results were used to produce scatter plots as well as to calculate the color difference (delta E) between VM and CM groups. There was no inter-rater agreement between VM and CM-A2 (k=0.000 and k=0.015 for the first and second sessions respectively) while VM and CM-ref showed weak agreement (k=0.244 and k=0.091 respectively). Intra-rater agreement was strong in all groups VM, CM-A2 and CM-ref (0.705, 0.803 and 0.681 respectively). CM-A2 had 2 (8.3%) shade matches with a delta E of less than 2.6 (clinically imperceptible), while CM-ref had 12 (50.0%) imperceptible matches. CM-A2 had an additional 16 (66.6%) shade matches with delta E of less than 5.5 (clinically acceptable), while CM-ref had 23 (95.8%) additional acceptable matches. There was poor agreement in exact shade matches between conventional visual shade matching method and the photographic shade analysis system. The repeatability of the photographic shade analysis system was shown to be comparable to conventional visual shade matching. Using conventional shade matching as the gold standard, the capability of this photographic shade analysis system to accurately shade match has not been achieved.

Statement of Problem There are limited studies evaluating the effect of a cyclic load on interim fixed prosthetic materials and its effect on flexural strength. Purpose of Study 1) To verify the flexural strength of previously studied interim fixed prosthetic materials. 2) To establish the flexural strength of new, advanced generation and untested interim fixed prosthetic materials. 3) To determine the effect of cyclic load on the flexural strength of interim fixed prosthetic materials. Materials and Methods Bar-type specimens of Caulk Temporary Bridge Resin, VitaVM CC, Protemp 3 Garant and Radica were fabricated according to International Standards Organization 4049 and American National Standards Institute/American Dental Association specification 27. After being stored in distilled water for 10 days, specimens were divided into Noncycled and Cycled Groups. The Noncycled Group specimens were fractured under a 3-point loading in a Bose Electroforce 3300 testing instrument at a crosshead speed of 0.75 mm/min. Cycled Groups specimens underwent a 6-12 Newton 3 Hertz cyclic load for 20,000 cycles in a Bose Electroforce 3300 testing instrument. Immediately following completion of the cycles, the specimens were fractured under a 3-point loading. Maximal loads to fracture in Newtons were recorded and mean flexural strengths were calculated (n = 20 per group). Comparisons were made with analysis of variance and Tukey's Multiple Comparison Test. Results Noncycled (NC) and Cycled (C) groups order of mean flexural strengths (MPa) from lowest to highest mean were as follows: Caulk (Noncycled - 53.83; C - 60.02), Vita VM CC (NC - 65.96; C - 66.83), Protemp 3 Garant (NC - 75.85; C - 77.18), and Radica (NC - 106.1; C - 115.96). In the Noncycled and Cycled groups, Radica was statistically superior when compared to all materials and Protemp 3 Garant was statistically superior to Caulk Temporary Bridge Resin. There was no statistically significant difference between the material's flexural strengths before and after cycles. Conclusion Within the limitations of this study, 20,000 cyclic loads of 6-12 Newtons at 3 Hertz did not have a significant effect on the flexural strength of interim fixed prosthetic materials. Radica demonstrated significantly superior flexural strength over other materials tested.

The objective of this study was to retrospectively evaluate the prevalence of perineural invasion in cases of mucoepidermoid carcinoma (MEC). The study will determine if previously assessed perineural invasion by original pathology reports would be increased by re-review of the originally hematoxylin-eosin-(H &E) stained slides as well as review of slides reacted immunohistochemically with S100 to enhance visualization of nerves. The study will also assess whether perineural invasion or its absence in MEC is associated with clinical outcome. Thirty-one cases of major and minor salivary gland MEC were reviewed for perineural invasion and compared to the perineural invasion status stated on the original pathology report when available (13/31). All H & E-stained slides were reviewed as well as S100-reacted sections of each case’s tissue blocks that contained tumor. Patient demographics and clinical outcome were collected from electronic medical records. Perineural invasion was identified in 23% (3/13) of tumors in the original reports, 13% (4/31) of the authors' re-review of the same slides, and 29% (9/31) when cases were reacted with S100. A positive relationship was seen between the discovery of perineural invasion on H & E-stained slides and a greater number of foci of perineural invasion. Perineural invasion and larger-diameter nerve involvement was significantly associated with death at 5-year follow-up. In conclusion, immunohistochemical enhancement improves the accuracy, ease and speed of perineural invasion determination. Perineural invasion is a significant factor in the decreased survival outcome of cases of MEC. These findings support continued inclusion of the presence or absence of perineural invasion as a grading parameter in MEC.

No description available.