Adaptation of Complete Denture Base Fabricated by Conventional, Milling, and 3-D Printing Techniques: An In Vitro Study.

AIM: The aim of this study was to compare the adaptation of complete denture base (CDB) manufactured by three different techniques: conventional, milling, and three-dimensional (3-D) printing. MATERIALS AND METHODS: A master cast was duplicated to create 60 gypsum casts. Twenty casts (n = 20) were attributed to each group. In the computer-aided design and computer-aided manufacturing (CAD/CAM) groups (milling and 3-D printing), the 40 gypsum casts reserved for these two groups were scanned. An STL file was obtained and a master CDB was designed and then fabricated according to each technique. In the conventional group, a polyvinyl siloxane putty mold was obtained from the milled CDB, and this mold was used to fabricate 20 conventional denture bases by compression molding using the silicon-gypsum technique in a bronze flask. The inner surfaces of the obtained 60 CDB were scanned and superimposed over their corresponding master cast. Deviation analyses were calculated using digital subtraction technique. Five functional areas (posterior palatal seal, anterior border seal, crest of the ridge, maxillary tuberosities, and palate) were selected to evaluate the variations in CBD adaptation. RESULTS: Based on the results and color maps of all selected regions, milling technique offers the best adaptation. The crest of ridge in the conventional technique showed the least adaptation and the posterior palatal seal in the 3-D printing technique showed the best adaptation. CONCLUSION: Within the limitations of this study, the CAD/CAM fabrication techniques seem to offer better adaptation of CDB compared to the conventional fabrication technique. Milled CDBs presented the most homogeneous distribution of adaptation, yet the 3-D printing process seems a promising techniques that needs to be addressed and perfected. CLINICAL SIGNIFICANCE: The CAD/CAM technologies can help overcome many limitations related to conventional impressions and therefore should be well investigated to improve the edentulous patient's quality of life.

Evaluation of the Adaptation of Complete Dentures Fabricated Using Intraoral Scanning and Conventional Techniques.

AIM AND OBJECTIVE: This study aimed to digitally analyze the 3-dimensional variations existing between conventional impressions and intraoral scans made in edentulous maxillae. MATERIALS AND METHODS: Ten (n = 10) edentulous maxillae of patients seeking a maxillary complete denture were scanned using an intraoral scanner. The same participants were subject to the conventional impression procedure for the fabrication of maxillary complete dentures. The dentures' intaglio surfaces were scanned and superimposed over their corresponding IOS files with a 2-base best-fit alignment. Deviation analyses were calculated using the digital subtraction technique. Four anatomical regions were preselected to evaluate the deviations at these sites (posterior palatal seal, anterior border seal, the crest of the ridge and palate). RESULTS: Based on the results and color maps of all selected regions, the overall difference between the two scans [IOS and denture intaglio surface scanning (DISS)] was not significant. The IOS technique allowed for predictable outcomes of treatment compared to those observed with conventional impression. The palatal area seems to be the region with the least deviation, while the highest incidence of discrepancy was reported in the anterior border seal. CONCLUSION: Within the limitations of this study, the IOS technique allowed the capturing of intraoral tissues and their immediate interpretation and transfer to a designing software making the impression procedure faster and easier. CLINICAL SIGNIFICANCE: The computer-aided design (CAD)/computer-aided manufacturing (CAM) technologies can help overcome many limitations related to conventional impressions and therefore should be well investigated to improve the edentulous patient's quality of life.

Dental pulp stem cells and the management of neurological diseases: An update.

Medical research in regenerative medicine has brought promising perspectives for the use of stem cells in clinical trials. Stem cells are undifferentiated cells capable of multilineage differentiation and available in numerous sources in the human body. Dental pulp constitutes an attractive source of these cells since collecting mesenchymal stem cells from this site is a noninvasive practice that can be performed after a common surgical extraction of supernumerary or wisdom teeth. Thus, tissue sacrifice is very low and several cytotypes can be obtained owing to these cells' multipotency, in addition to the fact that they can be cryopreserved and stored for long periods. Mesenchymal stem cells have high proliferation rates, making them favorable for clinical application. These multipotent cells, present in biological waste, constitute an appropriate resource in the treatment of many neurological diseases.

Dental Pulp Stem Cells and Neurogenesis.

Recent advances in regenerative medicine and cell-based therapy are bringing promising perspectives for the use of stem cells in clinical trials. Stem cells are undifferentiated cells capable of multilineage differentiation and available in numerous sources in the human body. Dental pulp constitutes an attractive source of these cells since collecting mesenchymal stem cells from this site is a noninvasive procedure which can be done following a common surgical extraction of supernumerary or wisdom teeth. Thus tissue sacrifice is very low and several cytotypes can be obtained owing to these cells' multipotency, in addition to the fact that they can be cryopreserved and stored for long periods. Mesenchymal stem cells have high proliferation rates making them favorable for clinical application. These multipotent cells present in a biological waste constitute an appropriate support in the management of many neurological disorders. After a brief overview on the different types of dental stem cells, this chapter will focus on the characteristics of dental pulp stem cells, their handling and applications in neural tissue engineering, as well as neural induction protocols leading to their potential therapeutic use in the management of neurological diseases.

Fit of pressed crowns fabricated from two CAD-CAM wax pattern process plans: A comparative in vitro study.

STATEMENT OF PROBLEM: Subtractive and additive computer-aided design and computer-aided manufacturing (CAD-CAM) wax pattern processing are 2 methods of fabricating a pressed ceramic crown. Whether a subtractive milled wax pattern or a pattern from the micro-stereolithography additive process produces lithium disilicate crowns with better marginal and internal fit is unclear. MATERIALS AND METHODS: Ten silicone impressions were made for a prepared canine tooth. Each die received 2 lithium disilicate (IPS e.max) copings, 1 from milled wax blocks and 1 from additive wax. The replica technique was used to measure the fit by scanning electron microscopy at ×80 magnification. Collected data were analyzed using the paired Student t test for the marginal and internal fit. For the occlusal fit, the difference in scores did not follow a normal distribution, and the Wilcoxon signed rank test was used (α=.05). RESULTS: The mean marginal, axial, and occlusal fit showed no significant differences when the 2 CAD-CAM manufacturing processes were compared (P>.05). For the marginal fit, the mean (±SD) values were 105.1 µm ±39.6 with the milled process and 126.2 µm ±25.2 for the additive process. The mean values were 98.1 µm ±26.1 for the axial fit in the milled process and 106.8 µm ±21.2 in the additive process. For the occlusal fit, median values (interquartile interval) were 199.0 µm (141.5 to 269.9) for subtractive manufacturing and 257.2 µm (171.6 to 266.0) for micro-SLA manufacturing. CONCLUSIONS: No significant difference was found between the fit of the 2 techniques. The mean values of axial and occlusal median values were 10 and 5 to 6 times greater than machine's nominal values.

Marginal and internal fit of pressed ceramic crowns made from conventional and computer-aided design and computer-aided manufacturing wax patterns: An in vitro comparison.

STATEMENT OF PROBLEM: To our knowledge, no studies have evaluated the influence of the wax fabrication technique on the internal adaptation and marginal accuracy of pressed ceramic single crowns. PURPOSE: The purpose of this in vitro study was to compare the marginal and internal fit of a lithium disilicate crown fabricated either from conventional waxing or from a subtractive milled wax pattern. MATERIAL AND METHODS: Ten silicone impressions were made for a maxillary canine prepared to receive a complete crown. Two pressed lithium disilicate glass ceramic copings were made on the die poured from each impression. The first was from a conventional wax pattern and the second from milled wax blocks. The replica technique was used to measure the fit by scanning electron microscope at ×80 magnification. Collected data were analyzed with the paired Student t test for the marginal and wall fit. For the occlusal fit, the difference in scores did not follow a normal distribution, and the Wilcoxon signed ranks test was used (α=.05). RESULTS: The mean values +SD were 170.3 ±50.7 µm for the marginal fit and 130.3 ±21.6 µm for the internal fit with the conventional technique. For the computer-aided design and computer-aided manufacturing (CAD-CAM) technique, they were 105.1 ±39.6 µm and 98.1 ±26.1 µm. Statistical significance was found for the marginal and internal fit (P<.05). The occlusal fit median and interval interquartile scores were 305.0 µm (269.9 to 334.4) for conventional fabrication and 199.0 µm (141.5 to 269.9) for subtractive manufacturing. The differences were not statistically significant (P>.05). CONCLUSIONS: The subtractive CAD-CAM waxing technique resulted in the improved fit of a pressed lithium disilicate crown by decreasing the marginal discrepancies and internal adaptation.

Epigenetic changes in mesenchymal stem cells differentiation.

Epigenetic factors are known to play a major role in determining stem cell fate and differentiation. Mesenchymal stem cells are the most studied population of stem cells due to their important applications in experimental biology and regenerative medicine. After a brief overview on mesenchymal stem cells, this review aims to highlight the role of epigenetic changes on mesenchymal stem cells biology and differentiation protocols with a focus on osteocytic, chondrocytic and adipocytic differentiation. Chromatin remodeling, DNA methylation, histone modifications and miRNA expression will be investigated. The impact of epigenetics on transdifferentiation of mesenchymal stem cells will also be discussed. Indeed, epigenetic modulation appears to constitute a promising experimental target in stem cell basic and translational research.

Dental pulp stem cells and osteogenesis: an update.

Dental pulp stem cells constitute an attractive source of multipotent mesenchymal stem cells owing to their high proliferation rate and multilineage differentiation potential. Osteogenesis is initiated by osteoblasts, which originate from mesenchymal stem cells. These cells express specific surface antigens that disappear gradually during osteodifferentiation. In parallel, the appearance of characteristic markers, including alkaline phosphatase, collagen type I, osteocalcin and osteopontin characterize the osteoblastic phenotype of dental pulp stem cells. This review will shed the light on the osteogenic differentiation potential of dental pulp stem cells and explore the culture medium components, and markers associated with osteodifferentiation of these cells.

Onychomadesis in a 9-month-old boy with hand-foot-mouth disease.

BACKGROUND: Nail abnormalities in childhood are generally uncommon. Recently, onychomadesis is described as a rare, late complication of hand-foot-mouth disease, which is a viral illness commonly seen in the pediatric age group. It is therefore important to elucidate the presentation of this entity, especially in the context of the hand-foot-mouth disease. CASE PRESENTATION: We report a case of onychomadesis in a 9-month old Lebanese boy who presented to the emergency department with rapidly progressing nail changes involving all four extremities. These changes appeared few days after the healing of cutaneous lesions of hand-foot-mouth disease. CONCLUSIONS: This case highlights the importance of recognizing the association between onychomadesis and hand-foot-mouth disease in order to avoid unnecessary treatment and to reassure the patient's parents.