Investigation of the effect of different prefabricated intracanal posts on fracture resistance of simulated immature teeth.

AIM: The aim of this study was to assess fracture resistances of simulated immature single-rooted teeth whose roots have been backfilled using 3 different post systems after a 4 mm apical mineral trioxide aggregate (MTA) placement. MATERIALS AND METHODS: Forty-eight maxillary anterior teeth were assigned into four groups. The lengths of each root were standardized by cutting off the coronal and apical portions to obtain 13 ± 1 mm samples and root canals were enlarged. The #6 Peeso reamers were allowed to protrude 1 mm beyond apex to simulate immature teeth. Apical 4 mm of each tooth was filled using MTA. The remaining portions were treated as follows: Group 1 (Control): AH Plus + Gutta-percha cold lateral compaction. Group 2: Glass fiber posts (FRC Postec Plus post) cemented using self-adhesive resin cement. Group 3: Quartz fiber posts (D.T. Light post) cemented using self-adhesive resin cement. Group 4: Zirconia posts (Cosmopost) were placed using self-adhesive resin cement. Specimens were embedded in self-curing acrylic. A compressive load was applied lingually at a crosshead speed of 1 mm/min at an angle of 45º until fracture in a universal testing machine. RESULTS: The mean fracture resistances were 823.17 ± 188.80, 1155.50 ± 190.37, 1208.00 ± 254.32, and 1153.25 ± 195.71 Newtons for Groups 1, 2, 3, and 4, respectively. All experimental groups had significantly higher fracture resistance compared with the control group (P < 0.01). No statistically significant difference was noted between the experimental groups (P > 0.05). CONCLUSIONS: All post systems exerted a similar reinforcing effect to a simulated immature tooth and may be preferred specifically in situations which require additional reinforcement.

An overview of clinical studies on fiber post systems.

Intraradicular posts are useful adjuncts in the restoration of endodontically treated teeth. These systems have undergone a significant evolution in recent years, and fiber-reinforced systems have started to be incorporated into routine clinical care more frequently. Despite the high number of laboratory studies pertaining to the characteristics of fiber posts, clinical studies evaluating their general success rates are rather limited. Since clinical investigations are reliable means to achieve information about the general behavior pattern of materials or techniques, assessment of this data will be beneficial to have a better understanding of fiber-reinforced intraradicular post systems. The purpose of this paper was to make a summary of clinical studies regarding various fiber posts. A PubMed search was conducted and articles dating back to 1990 were retrieved. The paper provides an overview of clinical studies on fiber posts specifically in the last decade as well as commentary analysis.

Predoctoral prosthodontic curricula on removable partial dentures: survey of Turkish dental schools.

This study was conducted to evaluate the predoctoral removable partial denture (RPD) curricula in Turkish dental schools in regards to materials, techniques, and approaches. A questionnaire consisting of eighteen multiple-choice questions was sent by e-mail to the senior members of the prosthodontic departments of seventeen long-established dental schools in Turkey. The response rate was 100 percent. All schools (100 percent) used custom trays for making final impressions of partially dentate arches, taught border molding of the custom tray for the edentulous areas, used modeling plastic impression compound in border molding the final impression trays, and used base metal alloys for RPD frameworks. None of the schools had an in-house laboratory that fabricates RPD frameworks, and none of the students cast the frameworks of their own RPDs. The majority of schools used irreversible hydrocolloid as a final impression (70.6 percent) and dental surveyor (76.5 percent) in the designing of RPDs. The majority of schools did not flask their own RPDs (64.7 percent), did not treat patients using RPDs with attachments (76.5 percent), and did not perform the altered cast technique in bilateral and unilateral distal extension RPD cases (76.5 percent). Six teen schools (94.1 percent) had a minimum number of RPD arches that a student must complete in order to graduate. It was found that predoctoral RPD curricula in Turkish dental schools were both variable and similar.

Predoctoral prosthodontic clinical curriculum for complete dentures: survey in Turkish dental schools.

The aim of this study was to evaluate predoctoral complete denture curricula in the dental schools of Turkey in terms of materials, techniques, and approaches. A questionnaire with twenty-two multiple-choice questions was prepared and sent by e-mail to the directors of the prosthodontic departments of the seventeen long-established dental schools in Turkey. All schools responded for a response rate of 100 percent. All schools (100 percent) reported using irreversible hydrocolloid impression material for preliminary impression, impression compound for border molding, zinc oxide eugenol for a final impression, and heat curing technique for complete denture processing. A majority of schools said they used similar materials in complete dentures: cold cured acrylic resin in fabrication of record bases (70.5 percent) and anatomic teeth for posterior region (70.5 percent). The majority of schools did not use eccentric interocclusal records (76 percent) or occlusal equilibration and face-bow preservation (94 percent) and did not treat patients who require tooth-supported overdentures (70.5 percent). None of the schools taught treatment of implant-retained overdentures in their curriculum. Eleven schools (65 percent) used positioning mandible in centric relation techniques performed by both the clinician and the patient. It can be concluded that dental schools in Turkey have different prosthodontic curricula regarding complete dentures, although some topics are the same.

Evaluation of reasons for extraction of crowned teeth: a prospective study at a university clinic.

OBJECTIVE: The aim of this study was to determine and classify the major reasons for extraction of teeth with full crowns belonging to patients admitted to a university clinic within a specific time frame. METHODS: Two hundred and eight extracted teeth with full crown belonging to 75 patients were included. Apart from demographic information, reasons for presenting to the hospital, the major reason for extraction, the type of the crown (single crown, bridge abutment, abutment for removable prosthesis), presence of posts, age of restorations, presence of an endodontic treatment and quality were recorded. Comparable data were statistically analyzed using the chi-square test. RESULTS: Forty-three (57.3%) of the patients were females, whereas 32 (42.7%) were males with an average age of 63.21 ± 13.56. A statistically significant relationship was determined between age groups and rate of extractions, with the lowest extractions detected in the 35-44 years age group and the highest in the 55-64 years age group (p = 0.001). Tooth mobility was the predominant reason for patients' initial presentation (52.9%). The most encountered reason for extraction was periodontal reasons with a prevalence of 59.1%, followed by caries (26.9%) and periapical lesions (12%); 35.6% of extracted teeth had endodontic treatment. Sixty teeth (81.1%) had incomplete root fillings. There was a significant relationship between extractions and incomplete root fillings (p = 0.001). CONCLUSION: Studies comprising other faculty clinics as well as general practices will be complementary in making more generalized statements regarding the etiology of extractions of crowned teeth.

Impact strength of denture polymethyl methacrylate reinforced with different forms of E-glass fibers.

OBJECTIVE: The purpose of this in vitro study was to determine the reinforcing effect of different forms and concentrations of E-glass fibers on impact strength of denture polymethyl methacrylate. MATERIALS AND METHOD: A total of 91 rectangular specimens (84 specimens for test groups and seven for control group) of a heat-cured acrylic resin were fabricated. The test specimens were prepared by modifying the polymethyl methacrylate with the addition of different concentrations (2.5%, 3%, 4%, 5% by volume) of three types (chopped strand mat, woven and continuous unidirectional fibers) of E-glass fibers. The impact strength was evaluated using the Charpy method. RESULTS: While the 5% continuous glass fiber added test group showed the highest mean impact strength, the lowest value belonged to the 2.5% woven glass fiber containing group. When the impact strength values of chopped strand mat and continuous unidirectional glass fiber added groups at all concentrations were compared with the control group, the differences were statistically significant. The impact strength values of the woven glass fiber added groups at all concentrations were higher than that of the control group. However, the difference was non-significant. CONCLUSION: The impact strength of PMMA was enhanced by including E-glass fibers, increasing parallel with the fiber concentration.

Demographic profile and future expectations of students enrolled in a Turkish private dental school.

The purposes of this study were to obtain information about the social and demographic profile of students enrolled in the first private Turkish dental school, to gather information regarding the reasons for their preferences, and to obtain data about their career expectations. Questionnaires were distributed to 278 students; 229 returned the survey for an overall response rate of 82 percent. Of the respondents, 145 (65.5 percent) were females and seventy-five (34.5 percent) were males; they had an average age of 21.62±1.58. First degree relative (mother, father, sibling) had the greatest influence on the students in choosing dentistry as a career. Fathers and mothers had similar impact on the students' choice of dental profession (45.9 percent and 46.6 percent, respectively). Humanistic feelings, desire to serve others, and reasonable working hours were the predominant reasons that motivated females to become a dentist (p<0.05). Also, academic interest and interest in a medical field were significantly influencing factors for female students (p<0.05 and p=0.001, respectively). One-hundred and ninety-seven students (86 percent) expressed a goal of specializing in a specific branch of dentistry; orthodontics and oral and maxillofacial surgery were the top-ranked specialties. Although only 41 percent of the students were of Istanbul origin, 82.5 percent reported that they wish to practice in Istanbul.

Fatigue resistance of acrylic resin denture base material reinforced with E-glass fibres.

OBJECTIVE: The purpose of the study was to determine the effect of different forms and concentrations (2.5, 3, 4, 5% by volume) of glass fibres (chopped strand mat, continuous and woven) on fatigue resistance of acrylic denture base resin. MATERIAL AND METHODS: The fatigue resistance was measured by applying repeated three-point bending deflection to the specimens, the cycle frequency of 1.05 g and magnitude of deflection of 2.0 mm. The number of loading cycles needed to cause a fracture in the test specimen was considered the fatigue resistance of the specimen. RESULTS: The results of this study revealed that the addition of three different glass fibre forms at all concentrations to acrylic resin did not produce a statistically significant increase in the fatigue resistance (p ≥ 0.05). This study also revealed that there were significant differences (p < 0.05) between glass fibres forms used concerning the effects on the fatigue resistance. CONCLUSION: This study showed that the woven glass fibres had a definite superiority over the chopped fibres and the continuous fibres in regard to the fatigue resistance of the acrylic denture base resin.

Comparison of the fracture resistance of simulated immature permanent teeth using various canal filling materials and fiber posts.

BACKGROUND: The purpose of this study was to compare the fracture resistances of immature teeth treated with MTA along with root canal obturation methods using AH Plus, MetaSEAL, MTA Fillapex sealers + lateral compaction technique, and Unicore quartz fiber posts. MATERIALS AND METHODS: Fifty single-rooted maxillary anterior teeth were divided into five groups. The crowns were dissected and root canals were enlarged. #6 Peeso reamers were allowed to protrude 1 mm. beyond the apex to simulate immature teeth. The apical 4-5 mm of each tooth was filled using Angelus white MTA. The remaining portions of canals were obturated as follows: Group 1: No backfilling (control), Group 2: AH Plus + gutta-percha, lateral compaction, Group 3: MetaSEAL + gutta-percha, lateral compaction, Group 4: MTA Fillapex + gutta-percha, lateral compaction, Group 5: UniCore Fiber posts luted using PermaFlo DC. The specimens were embedded into self-curing acrylic poured into identical cylinders which were mounted on a jig providing a 45° angle. A compressive load increasing at 1 mm min(-1) was applied and the maximum load at which fracture occurred was recorded. Statistical analysis was performed using Kruskal-Wallis and Dunn's multiple tests. RESULTS: The highest fracture resistance was obtained with Group 5 (Fiber posts) whereas Group 4 (MTA Fillapex) yielded the lowest values. The mean fracture resistance value of Group 2 (AH Plus) was significantly higher than Group 4 (MTA Fillapex) (P = 0.001). The mean fracture value of Group 5 (Fiber posts) was significantly higher than Group 2 (AH Plus), Group 3 (MetaSEAL), and Group 4 (MTA Fillapex) (P = 0.02, 0.004, and 0.0001, respectively). CONCLUSION: Within the limitations of this study, UniCore quartz fiber posts provided the highest resistance. This methodology may specifically be advantageous for teeth with arrest of development at early stages, as these teeth are more susceptible to fracture owing to their excessively weak dentinal walls.

Comparative study of the fatigue strength of five acrylic denture resins.

The aim of this in vitro study was to compare the fatigue resistance of three kinds of heat-polymerized acrylic resins (conventional heat-polymerized, rapid heat-polymerized, high impact acrylic resin), a kind of visible light-cured resin and a kind of self-cured acrylic resin. A total of 60 notched and un-notched specimens (65 mm x 10 mm x 3 mm) were fabricated, 12 from each material. The fatigue resistance was measured by applying repeated three-point bending deflection to the specimens. For statistical analysis, Kruskal-Wallis test followed by Dunn's multiple comparison tests were used. The Kruskal-Wallis test revealed significant differences in the fatigue resistance among some groups (p<0.05). Conventional- and rapid-heat polymerized resins had lower fatigue resistance values than heat-polymerized high impact acrylic resin, but the differences were statistically non-significant according to Dunn's test (p>0.05). High impact acrylic resin was also found to have significantly higher fatigue resistance value than that of self-cured resin and light-cured resin (p<0.05). Further, there was no statistically significant difference between the mean fatigue resistance value of visible light-cured resin and self-cured resin (p>0.05).

Alternative restorative approach for treatment of patient with extremely worn dentition.

Changes in tooth structure, missing teeth and decreased vertical dimension of occlusion severely deteriorate the stomatognathic system. This case report describes the treatment of a patient with loss of vertical dimension due to severe wear of maxillary and mandibular teeth. An occlusal splint was used to create an optimum maxillomandibular relationship and to provide restorative space prior to restoration of the remaining teeth. The restoration was accomplished with a hybrid composite material. This treatment has been a less-expensive alternative to full-mouth, fixed porcelain/metal-porcelain restoration while conserving the remaining tooth tissue.

Color stability of different denture teeth materials against various staining agents.

The purpose of this in vitro study was to evaluate the color stability of two brands of porcelain teeth and three brands of acrylic denture teeth. Samples were immersed into three staining drinks as test groups and distilled water as a control. Color measurements of teeth were performed by using a spectrophotometer. Before immersion, the initial color value of each tooth was recorded. Color change values were determined after 1 day, 1 week, 2 weeks, and 4 weeks of immersion. Color differences were characterized using the CIE L*a*b* color space. The color stability of all teeth was significantly affected by the immersion period (p<0.0001). Instant coffee was found to be the most chromogenic agent among the solutions tested (p<0.0001). Among the materials tested, porcelain was found to be more resistant to discoloration. It was concluded that acrylic teeth showed a higher degree of color change and that the amount of color change for each group increased proportionally with time.

Evaluation of the effect of different ferrule designs on the fracture resistance of endodontically treated maxillary central incisors incorporating fiber posts, composite cores and crown restorations.

AIM: The purpose of this study was to evaluate the fracture resistance of endodontically treated maxillary central incisors restored with quartz fiber posts, composite cores, and crowns when different types of ferrule designs were incorporated. METHODS AND MATERIALS: Sixty maxillary incisors were divided into six groups: Group 1 (control): teeth with root canal treatments having a full crown prosthesis; Group 2: teeth with a 2 mm circumferential ferrule; Group 3: teeth with a 2 mm ferrule only in the vestibular region; Group 4: teeth with a 2 mm ferrule only in the palatal region; Group 5: teeth with a 2 mm ferrule in the vestibular and palatal region, having cavities in both proximal areas; and Group 6: teeth with no ferrule. The teeth in the experimental groups were restored with quartz fiber posts-composite cores and full metallic crowns. All experimental teeth were subjected to an increasing compressive force with a crosshead speed of 1 mm/min, until fracture occurred. RESULTS: The median fracture values of groups were as follows: Group 1: 574.4 N, Group 2: 472.4 N, Group 3: 474.3 N, Group 4: 480.7 N, Group 5: 463.1 N, and Group 6: 297.9 N. A statistically significant difference was found between Group 1 and Group 6 (p< 0.01). CONCLUSION: It was concluded different ferrule designs did not have any influence on the fracture resistance of teeth with fiber posts. The results of this study indicate fiber posts can safely be used for their reinforcing properties. Furthermore, there is no significant change in the resistance of teeth with fiber posts regardless of which ferrule design is incorporated. The property of these types of posts is an additional advantage in clinical practice.

Effects of mica and glass on surface hardness of acrylic tooth material.

The purpose of this study was to evaluate the effects of four different ratios of silanized mica filler and milled glass fiber on the surface hardness of an acrylic denture tooth material. Acrylic resin disks made of polymethyl methacrylate (PMMA) used in fabrication of denture teeth were used as the control group. Eight test groups were prepared by adding a ratio of 5%, 10%, 15%, or 20% by weight of silane-treated mica filler or milled glass fibers to the PMMA resin of denture teeth. Surface hardness test was performed for each group. There were statistically significant differences in surface hardness between the control group and 5%, 10%, and 15% mica- and glass-containing test groups (p<0.05). It was determined that addition of 5%, 10%, and 15% of silane-treated mica filler or silane-treated milled glass fiber to the PMMA resin of denture teeth resulted in significantly improved surface hardness.

Fabricating sectional-collapsible complete dentures for an edentulous patient with microstomia induced by scleroderma.

Patients with microstomia who have to wear removable dental prostheses often face the difficulty of being unable to insert or remove the prosthesis because of the constricted opening of the oral cavity. This clinical report describes in detail the prosthodontic management of an edentulous patient with microstomia induced by scleroderma. Sectional-collapsible maxillary and sectional mandibular complete dentures were fabricated by means of sectional trays. With the use of palatal midline hinge and stud attachments, the sectional dentures were successfully and easily inserted and removed.

Effect of mica and glass on acrylic teeth material's color.

The purpose of this study was to evaluate the effect of two different ratios of silanized mica filler and milled glass fiber reinforcement on the color of acrylic denture teeth materials. Ten acrylic resin discs made of acrylic denture teeth material (PMMA) obtained from the manufacturer were used as the control group. Four experimental groups were modified from the control group's PMMA material by adding a ratio of 5% or 10% by weight of silane-treated mica filler or milled glass fibers. Each group consisted of 10 specimens. Measurements were performed using a spectrophotometer CM-2600d, and the color changes were characterized in the Commission Internationale d'Eclairage L*a*b* color space. deltaE* values of 5% mica-, 10% mica-, 5% glass-, and 10% glass-containing sample groups were 2.46, 3.03, 2.16, and 2.59 respectively. There were statistically significant differences in L*, a*, and b* values between the control group and each test group. It was shown that when PMMA denture teeth material was modified with silane-treated mica filler or silane-treated milled glass fibers for the purpose of reinforcement, it would also cause significant changes to the original color of the material.

Persistent sinus tract formation 1 year following cast post-and-core replacements: a case report.

Sinus tracts are paths of drainage for abscesses and can occur both intraorally and extraorally. It is a fact that sinus tracts can heal with proper endodontic therapy. However, there are those types that are persistent and will not respond to any treatment. In these perplexing cases, it may be necessary to elevate a surgical flap to unveil the real etiologic factor. In this article, a case is presented in which 2 persistent and nonhealing sinus tracts were observed around the maxillary left incisor area of a 53-year-old female patient. A difficult cast post-and-core removal had been accomplished to the compromised tooth 1 year previously. A surgical flap had to be reflected, and the cause of the persistent inflammation was determined to be 2 separate root perforations. The granulation tissue was removed, the perforations were sealed with mineral trioxide aggregate, and bone graft was packed in the resorptive bone areas. The symptoms subsided by the time of the 2-week recall. No complaints were noted from the patient during the 4-month follow-up period. This case is a good example that demonstrates the possible complications of post preparation and the necessity of explorative surgery for unveiling the etiologic factor of persistent sinus tract formation.

Investigation of the cleanliness of dentures in a university hospital.

PURPOSE: The purpose of this study was to determine denture cleanliness of a population sample, as well as to investigate denture cleaning habits and attitudes. MATERIALS AND METHODS: Two hundred thirty-four denture-wearing patients were surveyed via a questionnaire to identify types and frequency of use of denture cleaning methods. Patients were also clinically examined to determine denture cleanliness. Dentures were classified as clean, dirty, or extremely dirty based on the level of debris and stain present. The oral mucosa was also examined and rated. RESULTS: The most common regimen employed was brushing with toothpaste (40.59% of patients), while only 1 patient reported soaking the denture in mouthwash. Results showed that 38.9% of patients were not satisfied with their cleansing methods, and 82.9% of patients claimed their dentists did not inform them how to clean their dentures. Only 11.9% of patients had clean dentures. Older dentures tended to be dirtier than newer ones (P = .0001) and had a higher incidence rate of accompanying denture stomatitis (P= .0001). CONCLUSION: In this population sample, most denture wearers did not clean their dentures satisfactorily.