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At least 253 records · Page 14Linked to original sources

PubMedDate not supplied

Two-year clinical performance of a polyacid-modified resin composite and a resin-modified glass-ionomer restorative material.

This study compared the clinical performance of a polyacid-modified resin composite and a resin-modified glass-ionomer restorative material over two years. Thirty-four pairs of restorations of Compoglass and Fuji II LC were placed in caries-free cervical erosion/abfraction lesions without tooth preparation. Restorations were clinically evaluated at baseline, 6, 12, 18 and 24 months using modified Ryge/USPHS criteria. A significantly higher incidence of failed restorations was found with the polyacid-modified resin composite (p < 0.05).

Adult↗

PubMedDate not supplied

Clinical evaluation of a resin-modified glass ionomer adhesive system--results at three years.

One hundred non-carious cervical lesions were restored with either Silux Plus or Estio LC resin composite using Fuji Bond LC as the bonding agent. Thirteen patients of mean age 60.5 years participated in the study. The retention rate at three years was: Silux Plus, 94%; Estio LC, 100%; total, 97%. Marginal discoloration of aesthetic significance was present around three restorations, two of which were in one patient.

Chi-Square Distribution↗

PubMedDate not supplied

Microhardness of carious deciduous dentin.

The purpose of this study was to measure the microhardness values of deciduous dentin and to compare the values as a function of position in the caries-affected layers of dentin including transparent, adjacent sound dentin, and dentin regions far from and not related to caries. Seven extracted or exfoliated deciduous anterior teeth that had dentin caries on a proximal surface were sectioned parallel to the long axis of the tooth. Ten sectioned and polished specimens were dehydrated and dried. Microhardness was measured with a Knoop indenter and correlated with wet-SEM micrographs. All data were statistically analyzed using a two-way ANOVA with subsequent Tukey-Kramer multiple comparison tests at p < 0.05. The hardness decreased from the dentinoenamel junction to the pulp chamber wall, except for the region under the caries. The hardness values of the region under the caries were significantly lower than those of other regions except for the inner region. For both the carious and sound sides, the hardness values of the inner region were significantly lower than those of the outer and middle regions. In comparing the hardness among regions in the carious and sound sides, the hardness of the outer, middle, and inner regions on the carious side was significantly lower than those in the sound side.

Analysis of Variance↗

PubMedDate not supplied

Three-year clinical evaluation of a polyacid-modified resin composite (Dyract).

The aim of this study was to clinically evaluate a polyacid-modified resin composite (Dyract; Dentsply deTrey). Forty-one Dyract restorations were placed (36 in noncarious cervical cavities and five in anterior approximal cavities), and assessed after three years. The retention rate was 97% for the cervical restorations; however, 16 restorations showed some degree of marginal discoloration, sometimes severe. Color match and surface integrity were highly satisfactory throughout the trial. Dyract has now been superseded by Dyract AP, and the manufacturers should consider recommending mandatory enamel etching.

Acid Etching, Dental↗

PubMedDate not supplied

Tooth-colored filling materials for the restoration of cervical lesions: a 24-month follow-up study.

The recently developed resin-modified glass ionomer cements and the polyacid-modified composites are promising alternatives to conventional materials for restoring cervical defects. This clinical study evaluated the clinical condition of cervical fillings 24 months following placement. The study subjects were 197 cervical restorations placed on incisors, canines and premolars in 37 patients for restoration of erosion/non-carious lesions (69 cases), primary carious lesions (57 cases) and the replacement of deficient restorations (71 cases). The teeth were randomly divided into four groups for restoration with either Tetric (composite, Group A: n = 36), Dyract (compomer, Group B: n = 79), Fuji II LC (resin-modified glass ionomer cement, Group C: n = 51) or Photac-Fil (resin-modified glass ionomer cement, Group D: n = 31). The evaluation was done single-blind at baseline, 8 and 24 months after the placement of the fillings, according to a modified USPHS rating scale. The assessment criteria were color stability, anatomical form, surface texture, marginal integrity, marginal discoloration and loss of filling. Statistical analysis was completed using Pearson chi-square and Fisher's exact test at a significance level of 5% (p < 0.05). After the 24-month period, the composite restorations showed superior results. The compomer fillings demonstrated conditions that were only slightly worse. A substantial number of the resin-modified glass-ionomer fillings were evaluated with bravo or even charlie scores in respect to at least one of the criteria assessed.

Adult↗

PubMedDate not supplied

Post retention and post/core shear bond strength of four post systems.

As clinicians we continue to search for a post system which will give us maximum retention while maximizing resistance to root fracture. The introduction of several new post systems, with claims of high retentive and resistance to root fracture values, require that independent studies be performed to evaluate these claims. This study tested the tensile and shear dislodgment forces of four post designs that were luted into roots 10 mm apical of the CEJ. The Para Post Plus (P1) is a parallel-sided, passive design; the Para Post XT (P2) is a combination active/passive design; the Flexi-Post (F1) and the Flexi-Flange (F2) are active post designs. All systems tested were stainless steel. This study compared the test results of the four post designs for tensile and shear dislodgment. All mounted samples were loaded in tension until failure occurred. The tensile load was applied parallel to the long axis of the root, while the shear load was applied at 450 to the long axis of the root. The Flexi-Post (F1) was significantly different from the other three in the tensile test, however, the Para Post XT (P2) was significantly different to the other three in the shear test and had a better probability for survival in the Kaplan-Meier survival function test. Based on the results of this study, our recommendation is for the Para Post XT (P2).

Acid Etching, Dental↗

PubMed2000

Biomechanics of cervical tooth structure lesions and their restoration.

OBJECTIVE: The purpose of this study was to evaluate photoelastically the effects of a cervical tooth structure lesion and its restoration on stress distribution within a tooth. METHOD AND MATERIALS: Three-dimensional composite models of a maxillary first premolar with a buccal cervical lesion were fabricated. Two types of cervical lesion were tested: one was wedge shaped and had a sharp line angle at the apex of the lesion, and the other was more rounded and saucer shaped. Vertical loads of 10 lb were applied to the unrestored and restored models at the tip of the buccal cusp, the tip of the lingual cusp, and the center of the occlusal surface. The resulting stresses within the tooth model were monitored and recorded photographically in the field of a circular polariscope arrangement. RESULTS: In the unrestored situation, stress concentrated at the apex of the lesion, regardless of the lesion configuration. However, the sharper, wedge-shaped lesion demonstrated a more severe stress concentration. In the restored situation, stress around the lesion apex and the lingual cervical lesion decreased, while stresses at the gingival and occlusal margins of the lesion increased, compared with the unrestored situation. These tendencies were most obvious when the buccal cusp was loaded. CONCLUSION: The presence of a cervical lesion changed occlusal load-induced stress distribution and concentrated stress at the apex of the lesion. The shape and dimension of the lesion governed the severity of stress concentration. Restoration of the cervical lesion relieved concentrated stress at the apex of the lesion.

Bicuspid↗

PubMedDate not supplied

An alternative hypothesis from veterinary science for the pathogenesis of noncarious cervical lesions.

An alternative hypothesis to abrasion and erosion for the pathogenesis of noncarious cervical lesions was put forward in 1984; the so-called occlusal theory suggested that tensile stresses from occlusal overload could be involved in the pathogenesis of noncarious cervical lesions and that bending stresses applied to teeth could cause disruption of the surface enamel, resulting in increased susceptibility to dissolution and abrasion at the affected sites and in the development of wedge-shaped lesions. This theory has gained increased acceptance in recent years, although absolute scientific evidence has been scant. These lesions also occur in animals, in particular, the domestic cat, in which they are called feline odontoclastic resorptive lesions. A variety of theories about pathogenesis of these lesions have been put forward, but there is some evidence that occlusal overload may be a contributory factor in the development of an inflammatory response in the periodontal membrane and the presence of enzymes associated with resorption in the gingival crevice. Further investigation may help define a common etiology between the pathogenesis of feline odontoclastic resorptive lesions and noncarious cervical lesions.

Acid Phosphatase↗

PubMedDate not supplied

Histomorphologic changes in the gingiva and pulp of overretained primary teeth.

This study examined the influence of overretention on the tissues of human primary teeth. The range of overretention was two to thirty-two years. Light microscopy and computerized morphometry were utilized for histologic assessment of twenty-five sites of twenty-one teeth. Dentinoclasts were found on the resorbing root surface of nine teeth; polymorphonuclear leucocytes were found in the pulp of fourteen teeth; and monocytes were present in all pulps. The apical and coronal ends of the junctional epithelium were apical to the cemento-enamel junction in eighteen and fourteen teeth, respectively. Significant correlations were found between the extent of overretention and gingival height, the length of the junctional epithelium and the extent of apical migration of the junctional epithelium. Present and previous findings indicate that odontoclastic activity in the pulp is reduced with overretention; and while at the beginning of overretention there is a lower percentage of pulps with polymorphonuclear leucocytes in the pulp, with an extended period of overretention an increase in this percentage takes place.

Adolescent↗

PubMed2001

Shades of a color. Illusion or reality?

Attaining the highest clinical level in esthetic and cosmetic dentistry necessitates the development of artistic skills; of balancing illusion with reality. The shade of a tooth is a combination of color and light and varies in different light conditions. Understanding the differences in color shades is the basis to creating illusions. Understanding light and color, and the reality of illusions, allows the clinician to design and sculpt a smile, to modify a flawed display artistically so that patients may perceive it as natural and more attractive, and to design laminates and veneers, class III, class IV, and cervical cavities.

Color↗

PubMedDate not supplied

Radiographic assessment of the alveolar bone height in children and adolescents with familial dysautonomia.

PURPOSE: Familial dysautonomia (FD) is a progressive neuropathy, characterized by somatic and skeletal abnormalities, and by a variety of oral and diet disturbances. The purpose of the study was to assess the alveolar bone height at the molar areas of children and adolescents with FD. METHODS: The distance from the cemento-enamel junction (CEJ) to the alveolar bone crest (ABC) was measured on routine diagnostic bitewing radiographs of nine males and seven females with FD (mean age = 122 months) and in those of two matching groups (C1 = 119 months; C2 = 122 months). RESULTS: The mean values for the maxilla were significantly larger than those in the mandible. A positive significant correlation was found between the CEJ-ABC measurements of the primary and the permanent teeth, and between the CEJ-ABC measurements and age. The mean values per patient for the CEJ-ABC distances of the FD group were smaller than the control groups, but the difference was not statistically significant. The CEJ-ABC measurements in the primary and the permanent molars were smaller in the FD group, and in the premolars and permanent cuspids they were larger than those in the two control groups. These differences were not statistically significant. No differences were found between the FD and the control groups in the primary cuspids. CONCLUSIONS: The alveolar bone height of children and adolescent with familial dysautonomia does not differ from that of healthy controls.

Adolescent↗

PubMed2000

Micromorphological investigation of noncarious cervical lesions treated with demineralizing agents.

PURPOSE: The purpose of this study was to examine the micromorphology of noncarious cervical lesions (NCCL) and the change occurring after acid conditioning. MATERIALS AND METHODS: Nine wedge-shaped lesions, 9 saucer-shaped lesions, and 5 third molars with prepared cervical cavities were used. All NCCLs exhibited a hard, smooth surface with no discoloration. The teeth were sectioned and divided into three groups, each containing the three lesion types. Teeth in Group I were not etched, and teeth in Groups II and III were etched with 35% phosphoric acid and 20% polyacrylic acid/3% aluminum chloride, respectively. Field emission SEM and atomic force microscopy were used to examine the lesion surfaces. RESULTS: The surfaces of the prepared cervical (control) lesions were covered with a smear layer. Treatment with phosphoric acid and polyacrylic acid resulted in removal of the smear layer, although some residual smear layer was found on the surface treated with polyacrylic acid. The images of the untreated surfaces of NCCL showed highly mineralized dentin with complete obliteration of the dentinal tubules. After treatment with phosphoric and polyacrylic acids, the images revealed demineralization of the surface, which was more pronounced on those treated with phosphoric acid. CONCLUSION: The mineral deposits on the surface of NCCL decreased the effect of acid conditioning. Although there was no apparent difference between the two forms of NCCL used in this study, further work is needed to better understand these lesions.

Acid Etching, Dental↗

PubMed2001

Improving cervical restorations: a review of materials and techniques.

INTRODUCTION: There is a great variety of cervical lesions and an increased need for treatment because patients complain either about esthetics, hypersensitivity, or even food impaction. The cumulative effects of noncarious dental tissue loss are increasingly evident within any population. The prevalence of these noncarious lesions has been estimated at between 31% and 56%, with 85% of the population showing some loss of tooth structure in the cervical area. Since more elderly patients will keep their teeth for a longer time, the problems regarding the cervical areas of the teeth will increase. Therefore, the challenge for the dentist is rather substantial, since it has been shown that the longevity of these cervical restorations is not as great as that of other restorations. The purpose of this review is to summarize some facts about cervical lesions, the different tooth-colored restorative materials and their application, and the assessment of the clinical performance of these materials.

Age Factors↗

PubMed1999

Full-ceramic CAD/CIM anterior crowns and copings.

The purpose of the investigation was to examine the marginal and internal fit of Cerec anterior crowns and crown copings. The marginal and internal fit of Cerec anterior crowns (n = 18) and copings was examined on each of six anterior model tooth preparations, with different types of butt-margin crown preparation design on different teeth: 1.) straight flat (tooth 22), 2.) following the CEJ with mid-approximally steep curvature angles of 90 degrees mesial and 40 degrees distal (tooth 21) and 3.) same as 2, but with obtuse angles of 130 degrees and 150 degrees (tooth 41). The anterior crowns were machined on Cerec 2 units using Mark II ceramic (Vita), and the Cerec copings using In-Ceram Spinell (Vita). Laboratory slip-cast In-Ceram spinell anterior crown copings served as controls (n = 18). All reconstructions were seated (with adhesive) on the preparations, and the width of the marginal interface was measured circumferentially using SEM at 150x magnification. After cross-sectioning all samples in the bucco-oral direction, the internal fit was measured using this same technique. The marginal width of computer machined Cerec CAD/CIM anterior crowns (59.9 +/- 5.6 microns) was significantly (p < 0.01) lower than that of machined (73.4 +/- 12 microns) and slip-cast In-Ceram spinell copings (75.5 +/- 17 microns). The internal fit values of the slip-cast copings (94.1 +/- 20 microns) were significantly (p < 0.001) lower than those of the Cerec Mark II anterior crowns (141.3 +/- 21 microns) and copings (146.8 +/- 17 microns). Cerec CAD/CIM machined anterior full-ceramic crowns and copings showed excellent fit in comparison with slip-cast In-Ceram spinell copings. In terms of the marginal and internal fit, there were no significant differences (p > 0.05) between the different butt-margin preparation designs. Selected clinical cases demonstrate the high esthetics of anterior Cerec crowns.

Acrylates↗

PubMed2000

[Prevalence of taurodontism at the level of the molar in the black Senegalese population 15 to 19 years of age].

This study was done to establish the prevalence of taurodontism using the criteria of SCHIFMAN and CHANANNEL, the first and second molars on the panoramic radiograph of 150 consecutive 15-19 year-old Senegalese people were assessed. Results have shown that taurodontism was present in 48% of patients (18.8% of teeth). Taurodontism was greater in females (% compared % in male) but the difference was not significantly, it was found that was significantly greater in the maxillary and in the second molar.

Adolescent↗

PubMed2000

Altered passive eruption.

Biologic contributions to the smile play an important role in esthetics. The impact of the gingival complex on the esthetic qualities of a smile are significant, and both patients and dentists are developing a greater appreciation for the impact of gingiva on the beauty of a smile. Historically, the focus of periodontal therapy has been on managing patients with longer-appearing teeth secondary to attachment loss through pathology or as a result of periodontal surgery. Nevertheless, early diagnosis and treatment, as well as modern techniques and materials, have helped periodontology evolve to a point where such problems occur less frequently.

Epithelial Attachment↗

PubMedDate not supplied

Vertical shoulder preparation design for porcelain laminate veneer restorations.

The clinical success of porcelain laminate veneers depends on numerous factors that include the framework of the dental and gingival structures and their ability to withstand masticatory forces. In order to ensure aesthetic harmony, the clinician must reproduce numerous anatomical components (e.g., cementoenamel junction, points of concavity, developmental lobes, line angles, incisal edge survey form) in restorations while simultaneously providing sufficient functional integrity. This article demonstrates the vertical shoulder preparation design, which enhances the aesthetics and stabilization factors of porcelain laminate veneer restorations.

Adult↗

PubMedDate not supplied

Fracture behavior of human mandibular incisors following endodontic treatment and porcelain veneer restoration.

PURPOSE: Because of existing controversy, the present study investigated the individual and combined effects of endodontic treatment and porcelain veneer restoration on the fracture behavior of human mandibular incisors. MATERIALS AND METHODS: Forty extracted intact human mandibular incisors were assigned to four groups of ten with a similar range of labiolingual widths at the cementoenamel junctions. Group A consisted of intact teeth; group B consisted of endodontically treated teeth; group C teeth were restored with labial porcelain veneers; and those of group D were endodontically treated and had labial porcelain veneers. All teeth were subjected to a slow continuous loading test at 30 degrees to the long axis of the teeth and 1 mm below the incisal edge on the labial side. RESULTS: Fracture forces were 415 +/- 220 N, 370 +/- 89 N, 420 +/- 128 N, and 448 +/- 156 N for groups A, B, C, and D, respectively. Root fracture was the most common mode of failure. There were no statistically significant differences between the groups in terms of fracture forces and modes of failure. CONCLUSION: Human mandibular incisors with endodontic treatment and/or porcelain veneer restorations were able to withstand the same magnitude of oblique loading as intact teeth. Endodontic treatment and/or porcelain veneer restoration did not affect the mode of failure of mandibular incisors.

Acid Etching, Dental↗