Evaluation of marginal and internal fit of lithium disilicate CAD-CAM crowns with different finish lines by using a micro-CT technique.

STATEMENT OF PROBLEM: Whether the precision of fit of computer-aided design and computer-aided manufacturing (CAD-CAM) complete crowns is affected by the finish line configuration is unclear. PURPOSE: The purpose of this in vitro study was to evaluate the marginal and internal fit of CAD-CAM ceramic crowns made from lithium disilicate based on 3 different finish lines (rounded shoulder, chamfer, feather-edge). MATERIALS AND METHODS: Thirty anterior lithium disilicate complete crowns (n=10 per finish line group) were fabricated by following a completely digital workflow based on digital scans made with the TRIOS scanner. The crowns were adhesively cemented on duplicate dies of the respective prepared Typodont teeth, and the marginal gap, absolute marginal discrepancy, and internal gap were evaluated by using microcomputed tomography (µCT). A total of 66 values were obtained for each specimen from sagittal and transaxial sections, and a rendering software program was used to calculate the volume of the cement gap for each specimen by means of 3D region growing. Two-way ANOVA, Tukey post hoc tests with Bonferroni correction, and the Kruskal-Wallis test were used to compare the values between the experimental groups (α=.05). RESULTS: Marginal gap and absolute marginal discrepancy values were statistically significantly different between groups. In ascending order, marginal gap values were 23 ±14 µm for rounded shoulder, 54 ±28 µm for chamfer, and 96 ±36 µm for feather-edge finish lines. Absolute marginal discrepancy values were 96 ±34 µm for rounded shoulder, 124 ±37 µm for chamfer, and 157 ±34 µm for feather-edge finish lines. Internal gap values were 111 ±14 µm for feather-edge, 136 ±22 µm for chamfer, and 168 ±25 µm for rounded shoulder finish lines. The differences in cement volume between groups were not statistically significant (P=.200). CONCLUSIONS: All 3 finish lines produced marginal gaps within the range of clinically accep table values. Lithium disilicate CAD crowns with a rounded shoulder finish line had the best marginal fit but the poorest internal fit, and lithium disilicate CAD crowns with a feather-edge finish line had the best internal fit but the poorest marginal fit.

Oral health in prevalent types of Ehlers-Danlos syndromes.

BACKGROUND: The Ehlers-Danlos syndromes (EDS) comprise a heterogenous group of heritable disorders of connective tissue, characterized by joint hypermobility, skin hyperextensibility and tissue fragility. Most EDS types are caused by mutations in genes encoding different types of collagen or enzymes, essential for normal processing of collagen. METHODS: Oral health was assessed in 31 subjects with EDS (16 with hypermobility EDS, nine with classical EDS and six with vascular EDS), including signs and symptoms of temporomandibular disorders (TMD), alterations of dental hard tissues, oral mucosa and periodontium, and was compared with matched controls. RESULTS: All EDS subjects were symptomatic for TMD and reported recurrent temporomandibular joint (TMJ) dislocations. Abnormal pulp shape (13%) and pulp calcification (78%) were observed in subjects affected with classical EDS. Caries experience was higher in EDS compared with controls and was related to poor oral hygiene, influenced by increased mucosal fragility and restraint of (wrist) joint mobility. The overall periodontal status in EDS was poor, with 62% of EDS subjects presenting high periodontal treatment needs (community periodontal index for treatment need, CPITN = II). CONCLUSION: Oral health may be severely compromised in EDS as a result of specific alterations of collagen in orofacial structures. When considering dental treatment in EDS, a number of tissue responses (mucosa, periodontium, pulp) and precautions (TMJ dislocation) should be anticipated.

Generalized joint hypermobility and temporomandibular disorders: inherited connective tissue disease as a model with maximum expression.

AIMS: To study the relationship between generalized joint hypermobility (GJH) and temporomandibular disorders (TMD) by assessing prevalence and patient characteristics of TMD in a population of patients with maximum expression of GJH as a symptom of inherited connective tissue disease. In addition, diagnostic reliability of a series of clinical signs indicative of temporomandibular joint (TMJ) hypermobility was tested. METHODS: The study sample consisted of 42 subjects with GJH, 24 with Marfan syndrome and 18 with Ehlers-Danlos syndrome. A subgroup of 27 individuals was selected by age (> or = 18 yrs) and was compared to 40 controls with TMD and normal peripheral joint mobility. TMD diagnoses were assigned to each subject according to the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD). RESULTS: In the GJH sample (n = 42), 71.4% of the subjects were symptomatic for TMD. Of those, 13.3% had sought treatment. A myofascial pain diagnosis was made in 69%, disc dislocation with reduction was diagnosed in 85.7%, and TMJ arthralgia in 61.9%. Multiple TMD diagnoses were assigned in 69% of the subjects; of these, 57% had 3 or more subgroup diagnoses. Joint noises (P < .01) and recurrent TMJ dislocations (P < .01) were a frequent finding in adult GJH subjects (n = 27) compared to controls, with symptomatic GJH subjects presenting more and more prolonged dislocation events than asymptomatic subjects (P < .001). TMJ hypermobility signs were expressed significantly more often in GJH compared to controls with TMD and normal joint mobility. CONCLUSION: This study indicates a positive relationship between GJH and TMD.

[Dental symptomatology associated with connective tissue anomalies]. / Symptomatologie dentaire associée aux anomalies du tissu conjonctif.

Subjects affected with inherited disorders, of the connective tissue make up an important population, carrying high risks as to distinct aspects of oral health and dental treatment. These generalized conditions may produce serious clinical symptoms in different orofacial structures, which have to be dealt with, or anticipated, when considering dental treatment. The most prevalent disorders result from deficiency of Type I collagen, an important extracellular matrix protein regulating both the structural and mechanical properties of most of the orofacial tissues. Recurrent jaw fractures, an increased liability for development of temporomandibular disorders, periodontal disease and mucosal fragility, an abnormal tooth color and/or shape, and pulp obliteration may feature as major clinical manifestations of the respective disorders. Deficiency of fibrillin, a protein providing soft tissues with elastic capacities, may produce a long face with a high and narrow palate, an increased liability for the developnet of temporomandibular disorders and periodontal disease, and root dsyplasia. Whenever present, these manifestations/risk factors have to be integrated in dental treatment strategies. In cases with high risk for cardiovascular complications, specific preventive measures, such as cardiac output monitoring and the administration of appropriate local anesthetics, have to be taken before starting any invase dental treatment. The present paper aims to provide the practitioner with an appreciation of the most prevalent inherited disorders of the connective tissue with their respective genetics, molecular aspects of pathology, medical and oral manifestations, and guidelines for dental treatment.

Orofacial manifestations of congenital fibrillin deficiency: pathogenesis and clinical diagnostics.

Mutations in the genes encoding fibrillin, an extracellular matrix protein involved in providing elastic properties to the connective tissues, may result in specific craniofacial and oral anomalies. A number of craniofacial (retrognathia, dolichocephaly, high palate) and dental (root deformity, pulp calcification) manifestations are considered pathognomic for the Marfan syndrome (MFS), a condition caused by congenital fibrillin-1 deficiency. Reports on similar features in congenital contractural arachnodactyly (CCA), caused by fibrillin-2 deficiency, support the hypothesis that fibrillin deficiency might result in a number of morphological anomalies by influencing tissue interaction during growth and development. Hence, clinical manifestations can be related to specific aspects of fibrillin deficiency pathogenesis, and may be adopted as diagnostic tools in the outlook for affected individuals.