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1.
Clin Oral Investig ; 28(4): 220, 2024 Mar 16.
Artículo en Inglés | MEDLINE | ID: mdl-38492074

RESUMEN

OBJECTIVES: This in vitro study aims to compare the fracture resistance of three CAD/CAM materials used in endocrown restoration of interproximal defects in maxillary premolars. MATERIALS AND METHODS: 45 maxillary premolars extracted as part of orthodontic treatment were included. Following standardized root canal treatment, all teeth were prepared into Mesial-Occlusal (MO) cavity types. The samples were then randomly divided into three groups: LD [repaired with lithium disilicate glass ceramics (IPS e.max CAD)], VE [treated with polymer-infiltrated ceramics (Vita Enamic)], and LU [repaired with resin-based nanoceramics (Lava Ultimate)]. Axial static loading was applied using a universal testing machine at 1 mm/min until fracture, and fracture resistance and failure modes were recorded. RESULTS: Regarding Fracture Resistance Values (FRVs), the LD group exhibited significantly higher values than the other two groups, VE (P = 0.028) and LU (P = 0.005), which showed no significant difference (P = 0.778). On the other hand, regarding failure modes, the LD group had a higher prevalence of irreparable fractures compared to the other two groups, VE (P < 0.001) and LU (P < 0.001), which showed no significant difference. CONCLUSIONS: Although lithium disilicate glass ceramics exhibited higher FRVs, they had a lower repair probability. In contrast, polymer-infiltrated ceramics and resin-based nanoceramics contributed to tooth structure preservation. CLINICAL RELEVANCE: For maxillary premolars with interproximal defects following root canal treatment, resin ceramic composites are recommended for restoration to enhance abutment teeth protection.


Asunto(s)
Cerámica , Coronas , Diente Premolar , Ensayo de Materiales , Cerámica/química , Porcelana Dental/química , Resinas Compuestas/química , Polímeros , Diseño Asistido por Computadora , Análisis del Estrés Dental , Fracaso de la Restauración Dental
2.
Odontology ; 112(3): 751-760, 2024 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-38103151

RESUMEN

Despite the success of monolithic zirconia restorations (MZ), metal-ceramic restorations (MC) are still considered the gold standard for fixed prosthetics in the posterior region. This systematic review and meta-analysis aimed to compare the fracture strengths of single-unit MC and MZ in the molar region. This review was based on the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA, 2020) statement. All articles were searched from the PubMed and Web of Science databases until November 18, 2022. All in vitro studies evaluating the fracture strengths of MC and MZ were also included. Statistical analysis was performed with the Comprehensive Meta-Analysis program, with a significance level of 0.05. Out of 753 studies, five were selected. The fracture strengths of MZ and MC did not show any statistically significant difference for both tooth (95% CI - 1.589: 2.118, p = 0.779, z = 0.280) and implant (95% CI - 2.215: 2.191, p = 0.992 z = - 0.010) supported restorations. However, different abutment materials (p < 0.001) and aging treatments (p < 0.001) in tooth-supported restorations displayed a significant statistical difference. Additionally, a significant difference was also observed in subgroup analysis considering different cements (p = 0.001) and load speeds (p = 0.001) in implant-supported restorations. Fracture strengths of MZ and MC did not show a significant statistical difference in implant or tooth-supported single-unit posterior restorations. MZ may be a suitable alternative to MC in single-unit posterior restorations. The results should be interpreted with caution, as the included studies were in vitro.


Asunto(s)
Fracaso de la Restauración Dental , Aleaciones de Cerámica y Metal , Diente Molar , Circonio , Circonio/química , Humanos , Aleaciones de Cerámica y Metal/química , Análisis del Estrés Dental , Materiales Dentales/química , Restauración Dental Permanente/métodos
3.
Odontology ; 112(3): 884-894, 2024 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-38289451

RESUMEN

This in-vitro study aimed to evaluate the fracture strength (FS; N) of composite, feldspathic, and glass-ceramic computer-aided design/computer-aided manufacturing (CAD/CAM) endocrowns after thermomechanical aging. Seventy non-carious human molars were randomly divided into seven groups, according to the CAD/CAM material used for endocrown fabrication. Intact molars without cavity preparations were used as control (n = 10). Following endodontic treatment, standardized endocrown cavities were prepared and endocrowns were fabricated using composite (Cerasmart270, CS and Grandio Blocs, GB), fired and milled zirconia-reinforced lithium silicate (Celtra Duo, CD), leucite-reinforced feldspar ceramic (LRF Initial, LRF), and feldspathic (Cerec Blocks, CE) materials which were luted with universal adhesive (Futurabond U; Voco) and dual-cure resin cement (Bifix QM). Following thermocycling for 20,000 cycles and 480,000 load cycles in a chewing simulator (CS-4.2, SD Mechatronik), FS was evaluated (Instron). Data were analyzed with one-way ANOVA and post hoc Tukey's tests (p < 0.05). FS was significantly influenced by the tested material (p = 0.00). CS had the highest FS, which was not significantly different from intact molars and fired CD (p > 0.05). There were no significant differences in FS between LRF, GB, and CD, which were significantly higher than CE. Most of the failure modes of CS, CD, and GB were repairable, whereas those of CE were irreparable. All the tested materials withstood clinically relevant axial forces. Composite endocrowns exhibited more favorable fracture pattern, whereas feldspathic and leucite-reinforced feldspar ceramic endocrowns exhibited mostly irreparable fractures.


Asunto(s)
Cerámica , Diseño Asistido por Computadora , Porcelana Dental , Análisis del Estrés Dental , Ensayo de Materiales , Diente Molar , Humanos , Técnicas In Vitro , Cerámica/química , Porcelana Dental/química , Resinas Compuestas/química , Circonio/química , Silicatos de Aluminio/química , Materiales Dentales/química , Propiedades de Superficie , Fracaso de la Restauración Dental , Diente no Vital/terapia , Compuestos de Potasio
4.
J Esthet Restor Dent ; 36(2): 295-302, 2024 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-37497796

RESUMEN

OBJECTIVE: Teeth prepared for mesial-occlusal-distal (MOD) restorations have a significant risk of cusp fracture. Crowns and onlays can provide cusp coverage to reinforce posterior teeth at risk. Onlays are often more conservative of tooth structure which may be an advantage for teeth with large MOD preparations. It remains uncertain how onlays and crowns compare for posterior teeth with MOD tooth structure loss. The purpose of this systematic review was to compare the resistance to fracture, success rate, survival rate, and failure rate of teeth with MOD preparations restored with onlays or crowns. MATERIALS AND METHODS: An electronic search queried Medline (PubMed), Embase (Ovid), Scopus, the Cochrane Library, and grey literature (OpenGrey) from database inception through April 29, 2023. RESULTS: After eliminating duplicates and irrelevant records, 32 manuscripts were assessed. Only three publications met the criteria for inclusion. Most exclusions were due to poor reporting of restorative design and the amount of tooth structure remaining, or due to combining various restorative designs. Due to the limited sample size and high heterogeneity, no meta-analysis was conducted. One study observed a better outcome for onlays and two observed no difference. All three studies reported the mode of failure for crowns as more catastrophic whereas teeth with onlays could be salvaged. CONCLUSIONS: Onlays may be an advantageous alternative to crowns for teeth with MOD preparations, but the level of evidence is insufficient to draw meaningful conclusions. CLINICAL SIGNIFICANCE: Current evidence is insufficient to determine whether onlays or crowns are providing a different outcome when used to restore posterior teeth with MOD tooth structure loss. However, the fracture of teeth with MOD tooth structure loss restored with onlays appears to be less catastrophic than when restored with crowns.


Asunto(s)
Coronas , Incrustaciones , Diente , Humanos
5.
Int J Paediatr Dent ; 2024 Feb 25.
Artículo en Inglés | MEDLINE | ID: mdl-38403852

RESUMEN

BACKGROUND: Paediatric-preformed zirconia crowns have been associated with several issues, primarily their inability to be crimped and the need for extensive tooth preparation. Additionally, the capacity to adjust the size, shape, and fit of these crowns is very limited. AIM: To evaluate and compare the fracture strength of four different types of dental crowns intended for paediatric patients. DESIGN: The fracture resistance of four types of paediatric crowns was evaluated using the universal testing machine; freshly extracted primary molars received one of the following: preformed zirconia crowns, custom-made computer-aided design and computer-aided manufacturing (CAD-CAM) zirconia crowns, custom-made CAD-CAM ceramic crowns, and custom-made CAD-CAM hybrid composite crowns. Data were statistically compared using the Kruskal-Wallis test followed by the Bonferroni test, and the level of significance was set at 5%. RESULTS: Results showed that there was a statistically significant difference among the four groups (p < .001). The highest value of fracture force was observed for the milled zirconia crown and the lowest for the prefabricated zirconia. CONCLUSION: The implementation of the CAD-CAM digital crown fabrication technique has the potential to address issues associated with preformed crowns in paediatric patients, particularly in terms of fracture resistance.

6.
BMC Oral Health ; 24(1): 670, 2024 Jun 08.
Artículo en Inglés | MEDLINE | ID: mdl-38851731

RESUMEN

OBJECTIVE: To investigate the fracture resistance and failure modalities of anterior endocrown restorations fabricated employing diverse ceramic materials, and bonded using various cementation methodologies. MATERIALS AND METHODS: Forty maxillary central incisors were divided into two main groups based on the ceramic materials used; GroupI (Zir): zirconia endocrwons (Zolid HT+, Ceramill, Amanngirrbach) and GroupII (E-Max): e-max endocrowns (IPS e.max CAD, Ivoclar Vivadent). Both groups were further split into two subgroups depending on the cementation protocols; subgroup IA "ZirMDP": endocowns cemented with MDP primer + MDP resin cement, subgroup IB (ZirNon-MDP): cemented with MDP primer + non-MDP resin cement, subgroup IIA (E-maxMDP): cemented with MDP primer + MDP resin cement, subgroup IIB (E-maxNon-MDP): cemented with MDP primer + non-MDP resin cement. (n = 10/subgroup). Endocrowns were manufactured using CAD/ CAM. Teeth were subjected to 10,000 thermal cycles. The fracture test was performed at 45o with a palatal force direction until the fracture occurred. Test results were recorded in Newton. The failure mode was examined using a stereomicroscope. A One-way ANOVA test was utilized to compare different groups regarding fracture strength values. Tukey`s Post Hoc was utilized for multiple comparisons. RESULTS: The comparative analysis of fracture strength across the diverse groups yielded non-significant differences, as indicated by a p-value exceeding 0.05. Nonetheless, an observable trend emerged regarding the mode of failure. Specifically, a statistically significant prevalence was noted in fractures localized within the endocrown/tooth complex below the cementoenamel junction (CEJ) across all groups, except for Group IIB, "E-max Non-MDP," where fractures within the endocrown/tooth complex occurred above the CEJ. CONCLUSIONS: Combining an MDP-based primer with an MDP-based resin cement did not result in a significant effect on the anterior endocrown fracture strength. CLINICAL RELEVANCE: Regardless of the presence of the MDP monomer in its composition, adhesive resin cement achieved highly successful fracture strength when used with MDP-based ceramic primers. Additionally, ceramic materials exhibiting elastic moduli surpassing those of dentin are discouraged due to their propensity to induce catastrophic fractures within the tooth structure.


Asunto(s)
Cementación , Análisis del Estrés Dental , Incisivo , Humanos , Cementación/métodos , Técnicas In Vitro , Cementos de Resina/química , Circonio/química , Ensayo de Materiales , Coronas , Fracaso de la Restauración Dental , Cerámica/química , Materiales Dentales/química , Diseño Asistido por Computadora , Porcelana Dental/química
7.
BMC Oral Health ; 24(1): 389, 2024 Mar 26.
Artículo en Inglés | MEDLINE | ID: mdl-38532413

RESUMEN

BACKGROUND: While the concept of angled screw channels has gained popularity, there remains a scarcity of research concerning the torque loss and fracture strength of monolithic zirconia restorations with various screw channel angulations when exposed to thermomechanical cycling. This in-vitro study aimed to evaluate the reverse torque value and fracture resistance of one-piece screw-retained hybrid monolithic zirconia restorations with angulated screw channels after thermomechanical cycling. METHODS: One-piece monolithic zirconia restorations, with angulated screw channels set at 0°, 15°, and 25° (n = 6 per angulation) were fabricated and bonded to titanium inserts using a dual-cure adhesive resin cement. These assemblies were then screwed to implant fixtures embedded in acrylic resin using an omnigrip screwdriver, and reverse torque values were recorded before and after thermomechanical cycles. Additionally, fracture modes were assessed subsequent to the application of compressive load. One-way ANOVA and Bonferroni post hoc test were used to compare the groups (α = 0.05). RESULTS: The study groups were significantly different regarding the fracture resistance (P = 0.0015), but only insignificantly different in the mean percentage torque loss (P = 0.4400). Specifically, the fracture resistance of the 15° group was insignificantly higher compared to the 0° group (P = 0.9037), but significantly higher compared to the 25° group (P = 0.0051). Furthermore, the fracture resistance of the 0° group was significantly higher than that of the 25° group (P = 0.0114). CONCLUSIONS: One-piece hybrid monolithic zirconia restorations with angulated screw channels can be considered an acceptable choice for angulated implants in esthetic areas, providing satisfactory fracture strength and torque loss.


Asunto(s)
Coronas , Cementos Dentales , Circonio , Humanos , Torque , Ensayo de Materiales , Pilares Dentales , Titanio , Tornillos Óseos , Análisis del Estrés Dental , Fracaso de la Restauración Dental
8.
Gen Dent ; 72(2): 23-28, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38411482

RESUMEN

Limited research is available evaluating whether the reported in vitro benefit of immediate dentin sealing (IDS)-namely, increased bond strength to tooth structure-can be acquired in the era of same-day (SD) dentistry. The purpose of this study was to compare the fracture strengths of ceramic overlays fabricated with a delayed dentin sealing (DDS) technique or an IDS technique under 1-hour SD or 2-week multiple-day (MD) delivery conditions. Forty extracted, healthy maxillary third molars were prepared for a lithium disilicate overlay restoration and divided into 4 groups of 10 teeth each. In the SD-DDS group, the teeth were prepared and then stored for 1 hour in artificial saliva, and the adhesion protocol (bonding agent and resin cement) was applied at the time of delivery of the ceramic overlay. In the SD-IDS group, the teeth were prepared, the adhesive protocol was applied immediately, and the teeth were stored for 1 hour before delivery of the overlay. The protocols for the MD-DDS and MD-IDS groups were identical to SD-DDS and SD-IDS, respectively, except that the teeth were provisionalized and stored for 2 weeks prior to delivery of the overlay. Specimens were thermocycled and subjected to cyclic functional loading before they were loaded to failure in a universal testing machine using a rod resting on the buccal incline of the palatal cusp. Two-way analysis of variance tests revealed no statistically significant differences in fracture strength between the groups based on dentin sealing (P = 0.331) or delivery time (P = 0.314). The specimens demonstrated 2 fracture types; either a portion of the ceramic cohesively fractured, leaving the tooth intact, or the ceramic and part of the tooth fractured. There were no instances in which the restoration itself delaminated during fracture testing. A Kruskal-Wallis test indicated there were no statistically significant differences in fracture modes between the groups. In this in vitro study, IDS did not provide a significant increase in the fracture strength of overlay restorations compared with DDS, regardless of whether the restorations were delivered the same day or after 2 weeks of storage.


Asunto(s)
Cerámica , Resistencia Flexional , Humanos , Cerámica/uso terapéutico , Diente Molar , Estado de Salud , Dentina
9.
Clin Oral Investig ; 27(1): 221-233, 2023 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-36161530

RESUMEN

OBJECTIVES: To investigate the fracture strength of angulated hybrid abutments supporting anterior single crowns on narrow-diameter implants (NDIs). MATERIAL AND METHODS: Zirconia abutment with angulations of labial inclination 0° (TZ0Z), 15° (TZ15Z), 30° (TZ30Z) and palatal inclination 15° (TZ - 15Z) was designed on 3.3-mm titanium-zirconium (Ti-Zr) NDIs. Titanium abutment connected with Ti-Zr implant (TZ0T) and 0° zirconia abutment connected with pure titanium (Ti) implant (T0Z) were control groups. Thirty-six un-restored abutments and 36 abutments restored with highly translucent zirconia (HTZ) crowns were tested. Failure loads were compared among 6 groups, and bending moments were calculated for comparison between un-restored and restored abutments. RESULTS: Failure loads of un-restored abutments were affected by the abutment angle. Sixty-seven percent samples in TZ30Z and 83% samples in TZ - 15Z group fractured at the thinnest part of the zirconia abutment and exhibited lower failure load (p < .05). Failure loads of restored abutments were close to or exceeded the maximum bite force of anterior teeth, and no differences were found among six groups (p > .05). Except TZ15Z and TZ0T group, the bending moment increased with the crown construction, especially for TZ30Z and TZ - 15Z groups (p < .001). CONCLUSIONS: The fracture strength of hybrid abutments restored with HTZ crown on Ti-Zr NDIs exceeded the bite forces of anterior teeth for all the groups and were not affected by the abutment angle. CLINICAL RELEVANCE: In terms of fracture strength, Ti-Zr NDIs combined with angulated hybrid abutments and HTZ crowns can be used in the anterior region.


Asunto(s)
Implantes Dentales , Circonio , Titanio , Ensayo de Materiales , Diseño de Implante Dental-Pilar , Pilares Dentales , Fracaso de la Restauración Dental , Análisis del Estrés Dental , Coronas
10.
BMC Oral Health ; 23(1): 537, 2023 08 04.
Artículo en Inglés | MEDLINE | ID: mdl-37542242

RESUMEN

BACKGROUND: Survival of endodontically treated teeth depends on an efficient restoration of the missing tooth structure. OBJECTIVES: This study aimed to investigate the mechanical properties of different endodontic post systems. MATERIALS AND METHODS: Human permanent maxillary central incisors (no.=58) were decoronated and root-filled. The specimens with prepared root canals were randomly divided into Group P: Polyether Ether Ketone (PEEK) post and composite core and Group C: custom-made post-core of PEEK. The cementation of the posts was carried out using self-adhesive resin cement. Nano-hybrid composite resin was used for core fabrication. After cementation, the specimens from each group were randomly divided into two subgroups according to the types of tests utilized: 14 from each group were for the fracture strength test, which was restored with IPS e-max CAD crown, and 15 from each group for the pullout resistance test. A universal testing machine was used for the test performance. RESULTS: The fracture resistance test showed that the values significantly differed among tested posts (P = 0.013). Group P showed the highest fracture resistance. Group C exhibited higher mean pullout resistance values than the other group (P) (P = 0.059). In the two-piece PEEK post and composite core, the predominant type of failure was a core fracture, while in the one-piece PEEK post-core, most types of failures were either in the crown or in the post. CONCLUSIONS: The prefabricated posts are more resistant to fracture than the custom-made posts, with fracture and displacement mainly of the core. In contrast, both showed similar pullout resistance.


Asunto(s)
Técnica de Perno Muñón , Fracturas de los Dientes , Diente no Vital , Humanos , Benzofenonas , Resinas Compuestas/química , Análisis del Estrés Dental , Cetonas , Polietilenglicoles , Polímeros , Incisivo
11.
BMC Oral Health ; 23(1): 566, 2023 08 13.
Artículo en Inglés | MEDLINE | ID: mdl-37574536

RESUMEN

BACKGROUND: Large cavity designs and access cavities impair endodontically treated tooth fracture resistance. As the tooth's strength is known to reduce significantly after the root canal treatment, occlusal loading as a result of functions such as chewing, biting and certain parafunctional tendencies makes the endodontically treated tooth vulnerable to fracture. Hence, after endodontic treatment, it is vital to give adequate and appropriate restorative material to avoid tooth fractures. Accordingly, the choice of such restorative material should be dictated by the property of fracture resistance. OBJECTIVE: The goal of this study was to conduct a systematic review and critical analysis of available data from in vitro studies examining the fracture resistance of endodontically treated posterior teeth restored with fiber-reinforced composites. METHODOLOGY: The Preferred Reporting Items for Systematic Review and Meta-Analysis (PRIS-MA) Statement was used to guide the reporting of this systematic review A comprehensive literature search was performed using MEDLINE (via PubMed), Scopus, ScienceDirect, Google Scholar, and LILACS. A manual search of the reference lists of the articles was also performed. The databases provided a total of 796 studies from the electronic systematic search. The databases provided a total of 796 studies from the electronic systematic search. Two reviewers scrutinized the papers for eligibility based on inclusion/exclusion criteria and extracted data. The studies were assessed for their potential risk of bias. Based on modified JBI & CRIS (checklist for reporting in vitro studies) guidelines, along with the methodology and treatment objective, we have formulated 13 parameters specifically to assess the risk of bias. A total of 18 studies met the inclusion criteria and were included for qualitative analysis. Considering the high heterogeneity of the studies included, a meta-analysis could not be performed. RESULTS: The majority of the included studies had a moderate or high risk of bias. When compared to traditional hybrid composites, fiber-reinforced composites showed increased fracture resistance of endodontically treated teeth in the majority of investigations. On the other hand, limited evidence was found for the bulk fill composites. Moreover, moderate evidence was found for the fracture resistance of inlays and fiber posts with fiber-reinforced composites for core build-up in endodontically treated teeth. No evidence could be found comparing the fracture resistance of endo crowns and fiber-reinforced composites in endodontically treated teeth. CONCLUSION: According to the research, using fiber-reinforced composites instead of conventional hybrid composites improves the fracture resistance of endodontically treated teeth. However, there was a high risk of bias in the research considered. No judgments could be reached about the superiority of one material over another based-on comparisons between other core restorations.


Asunto(s)
Fracturas de los Dientes , Diente no Vital , Humanos , Materiales Dentales , Coronas , Fracturas de los Dientes/etiología , Fracturas de los Dientes/prevención & control , Resinas Compuestas , Análisis del Estrés Dental
12.
Int J Comput Dent ; 0(0): 0, 2023 Mar 16.
Artículo en Inglés | MEDLINE | ID: mdl-36928753

RESUMEN

PURPOSE: Endodontically treated teeth are more susceptible to fractures than vital teeth because of significant coronal and radicular dentin loss during endodontic therapeutic procedures. The objective of this study was to estimate and compare the influence of length and post type on the fracture strength of endodontically treated maxillary central incisors. MATERIAL AND METHODS: In this in vitro study, sixty extracted human maxillary central incisors were decoronated 2 mm above the cemento-enamel junction.They were selected and subjected to standard endodontic treatment ,resulting in preparation with lengths of 5 mm (group 5mm),7,5 mm (group 7,5 mm) and 10 mm (group 10mm). Each group was randomly divided into 2 subgroups according to the post type , zirconia and fiber post. After appropriate surface treatment,they were cementet with resin adhesive cement and restored with zirconia crowns. Thermocycling (5 -55°C, 60 seconds, 1500 cycles) was performed after cementing the zirconia crowns on each tooth. Prepared samples were subjected to compresive static load of 0.5mm / min, at an angle of 130° to the long axis of the roots, using Universal Testing Machine (Matest ) at an cross head speed of 0.5 mm / min, until fracture.The significance of the results was assessed using 2-way ANOVA and the Tukey-Kramer test (α=0.05) Results:The ANOVA analysis indicated significant differences (P<0.05) between the groups. Tukey test revealed no significant difference among the zirconia posts of 5-mm length (26.5 N ±13.4) 7,5-mm length (25.2 N ±13.9), and 10-mm length (17.1 N ±5.2). Also, in the fiber post group, there was no significant difference when posts of 7.5-mm length (13.4 N ±11.0) were compared with the 5-mm (6.9 N ±4.6) and 10-mm (31.7 N ±13.1) groups. The 10-mm long post displayed superior fracture strength, and the 5mm-long post showed significantly lower mean values (P<0.001). CONCLUSION: The fracture strength of zirconia posts (5-mm and 7,5- mm length)was found to be significantly higher than those of fiber posts (5-mm and 7,5- mm length). The 10-mm long fiberpost group demonstrated significantly higher values of fracture strengths and the 5-mm long fiberpost group showed the lowest values for the force resulting in root fracture; these groups were significantly different from each other (P<.001).The fracture strength analysis with Universal Testing Machine is the only method that enables us to estimate the differences between zirconia and fiber posts with different lengths on endodontically treated teeth.

13.
J Prosthodont ; 32(9): 807-814, 2023 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-36482016

RESUMEN

PURPOSE: To evaluate the influence of post type and mechanical aging on compression force resistance, fracture pattern, and stress distribution in weakened roots. MATERIALS AND METHODS: Bovine roots were endodontically treated and widened-and randomly divided into 8 groups (n = 10) according to post type (prefabricated glass fiber post and customized anatomic glass fiber post, milled glass fiber post-and-core, and milled polyetheretherketone post-and-core) and mechanical aging (without and with mechanical aging). Three hundred thousand cycles of mechanical fatigue were performed and compression force resistance (N) was analyzed by two-way ANOVA and Tukey test (α = 0.05). Fracture patterns were reported and stress distribution was analyzed by finite elements analysis. RESULTS: There was a significant effect of post type (p = 0.032) and mechanical aging (p = 0.009), but no double interaction (p = 0.879). Higher values were recorded in the milled glass fiber and polyetheretherketone post-and-core groups compared to the prefabricated glass fiber post groups, and no significant difference was found among anatomic glass fiber post groups and other groups. Reparable fractures were predominant in the milled glass fiber and polyetheretherketone post-and-core groups. Prefabricated glass fiber posts and milled polyetheretherketone post-and-cores showed similar stress distribution. CONCLUSIONS: Post type and mechanical aging influence the compression force resistance and fracture pattern of weakened roots. Milled glass fiber and polyetheretherketone post-and-cores exhibited higher compression force resistance and more reparable fractures compared to prefabricated glass fiber posts. Prefabricated glass fiber posts and milled polyetheretherketone post-and-cores showed similar stress distribution.


Asunto(s)
Técnica de Perno Muñón , Fracturas de los Dientes , Diente no Vital , Animales , Bovinos , Resinas Compuestas , Materiales Dentales , Análisis del Estrés Dental , Vidrio , Ensayo de Materiales , Diente no Vital/terapia
14.
J Prosthodont ; 32(7): 639-645, 2023 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-36270777

RESUMEN

PURPOSE: To examine the fracture strength and fracture mode of flared root canals reinforced with different post and core materials. MATERIALS AND METHODS: Forty endodontically treated bovine teeth structured to mimic human mandibular premolars with flared root canals were reinforced with resin composite and glass fiber post (FRC), composite resin (RC), ceramic core (LD), and ceramic core with resin composite reinforcement (RLD), and restored with single zirconia crowns (n = 10 in each group). The fracture strength and mode of the root canals restored with zirconia crown were assessed. The fracture strength was compared with a one-way analysis of variance (ANOVA) following Tukey HSD tests. A multiple regression analysis was conducted to test the effect of the post/core materials on the fracture loads. Fisher's exact test was used in the failure mode analysis. RESULTS: The mean fracture strength of RLD was significantly higher than RC, FRC, and LD (p < 0.05), while no significant differences were found among RC, FRC, and LD (p < 0.05). The regression analysis found that the fracture strength using the lithium disilicate was significantly lower for the post and higher for the core than that using the resin composite (p < 0.05), and there were no significant difference in the fracture strengths between the resin composite and glass fiber used for the post (p > 0.05). Most of the specimens exhibited root fractures, and no significant differences were observed among the groups (p < 0.05). CONCLUSIONS: The results of this study suggest that reinforcement of flared root canals using a combination of resin composite for the core and lithium disilicate ceramic for the post is superior to resin composite and glass fiber in mechanical properties when restoring a single crown.


Asunto(s)
Técnica de Perno Muñón , Fracturas de los Dientes , Diente no Vital , Animales , Bovinos , Humanos , Resistencia Flexional , Cavidad Pulpar , Fracturas de los Dientes/terapia , Resinas Compuestas , Diente no Vital/terapia , Análisis del Estrés Dental , Vidrio , Ensayo de Materiales , Fracaso de la Restauración Dental
15.
J Prosthodont ; 32(6): 469-481, 2023 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-36705005

RESUMEN

PURPOSE: This systematic review and meta-analysis aimed to summarize available evidence regarding the effect of horizontal glass fiber posts (HGFPs) on fracture strength and fracture pattern of endodontically treated teeth (ETT) compared to controls without HGFP. The review protocol was registered on the OSF registries. METHODS: Literature searches were conducted in MEDLINE/PubMed, Scopus, Web of Science, Embase, Google Scholar, and ProQuest for all relevant studies published up to February 2022. All in vitro studies that assessed the influence of HGFPs on fracture strength and fracture pattern of ETT whether mesio-occluso-distal or mesio-occlusal or DO cavities were considered eligible. Review Manager (RevMan) was used for the meta-analysis. Subgroup and funnel plot analyses were also performed. Quality assessment was conducted by two independent reviewers. RESULTS: A total of 12 articles met the inclusion criteria, and 10 studies underwent quantitative evaluation. The pooled effect showed that fracture resistance of molar teeth restored with HGFP was significantly higher than teeth without HGFP (standardized mean difference [SMD]: 1.61, 95% confidence interval [CI]: 0.14, 3.09, p = 0.03), whereas marginally significant for premolars (SMD: 1.36, 95% CI: -0.00, 2.73, p = 0.05). Regarding fracture patterns, the presence of an HGFP significantly increased the occurrence of restorable fracture patterns for premolars (odds ratios [OR]: 4.15, 95% CI: 1.60, 10.82, p = 0.004) compared to controls, whereas the difference was not significant for molars (OR: 1.09, 95% CI: 0.43, 2.77, p = 0.85). Moderate risk of bias was identified in 9/12 studies; one study showed a high risk of bias and two studies showed a low risk of bias. CONCLUSIONS: Within the limitations of this study, there is evidence from in vitro studies that the use of HGFP increases the fracture resistance of the ETT when compared to teeth without HGFP and also reduces the occurrence of non-restorable fractures for premolars. However, well-conducted in vitro and prospective clinical studies are warranted to validate this finding.


Asunto(s)
Técnica de Perno Muñón , Fracturas de los Dientes , Diente no Vital , Humanos , Resistencia Flexional , Diente no Vital/terapia , Estudios Prospectivos , Vidrio , Análisis del Estrés Dental
16.
Medicina (Kaunas) ; 59(10)2023 Oct 09.
Artículo en Inglés | MEDLINE | ID: mdl-37893515

RESUMEN

Background and Objectives: Although fiber posts are widely used in the restoration of endodontically treated teeth (ETT), their ideal cementation depth into the root canal is still debated in literature. The aim of the present study was to evaluate whether the different intra-radicular insertion lengths of the fiber posts influence the fracture strength of ETT. Materials and Methods: A total of 10 permanent human lower incisors with straight roots of similar length and volume extracted for periodontal reason were sectioned 2 mm above the cement-enamel junction (CEJ) to a total length of 18 mm and endodontically treated in the same manner, then randomly divided into two groups of five each (Groups 1 and 2, n = 5). Two sound incisors, with no endodontic treatment, were used as the control group (Group 3, n = 2). After one week of storage in a humid environment, spaces for fiber post no. 1 (Reforpost, Angelus, Londrina, PR, Brazil) were prepared in the first two groups at a depth of 5 mm (Group 1) and 7 mm (Group 2), and the fiber posts were adhesively cemented using self-adhesive resin cement (Maxcem Elite, Kerr GmbH, Herzogenrath, Germany). After 7 days, the samples were vertically positioned and fixed in a self-curing transparent acrylic resin, up to 2 mm below the CEJ level, and mechanically tested in compression after another week of storage using a displacement-controlled testing machine up to each sample's fracture. The force-displacement curves were recorded for each sample, the means were calculated for each group and a statistical comparative analysis between groups was conducted. Results: Although no statistically significant differences between groups were observed, the highest mean fracture force (N) was recorded in Group 2 (1099.41 ± 481.89) in comparison to Group 1 (985.09 ± 330.28), even when compared to the sound, non-treated teeth (1045.69 ± 146.19). Conclusions: Within the limitations of this in vitro study, teeth where fiber posts were placed deeper into the root canal (7 mm) recorded slightly higher fracture forces in comparison with shorter lengths (5 mm). However, similar biomechanical performances obtained in the mechanical tests showed no statistical differences between the 7 mm and the 5 mm inserted posts.


Asunto(s)
Fracturas de los Dientes , Diente no Vital , Humanos , Resistencia Flexional , Resinas Compuestas , Diente no Vital/terapia , Incisivo
17.
J Clin Pediatr Dent ; 47(6): 171-177, 2023 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-37997249

RESUMEN

The aim of the present study was to evaluate the effect of short fiber reinforced composite on the fracture strength of anterior immature teeth treated with regenerative endodontic procedures. A total of 120 permanent maxillary central incisors were selected, and root lengths were standardized. Except for the positive control group (n = 20), the root canals were instrumented to simulate immature teeth with incomplete root development, and the regenerative endodontic procedure was performed. Twenty instrumented teeth acted as negative controls (n = 20), and the remaining 80 teeth were randomly divided into 4 groups according to the chosen coronal restoration material: bulk fill, short fiber reinforced composite (SFRC), polyethylene fiber (Ribbond Ultra), and flowable composite resin. Each specimen was then subjected to fracture testing using a universal testing machine (AGS-X, Shimadzu, Japan). The load to fracture was recorded. Data were subjected to statistical analysis using analysis of variance and the Tukey Honestly Significant Difference test. A significant difference was detected between the groups (p < 0.05), with the positive control group showing the highest mean fracture strength. The SFRC group had significantly higher values than the bulk fill, polyethylene fiber, flowable composite resin and negative control groups. In conclusion, SFRC has a relatively high fracture strength compared to other materials used in regenerative endodontic procedures. The use of SFRC enhanced the fracture strength of immature permanent teeth.


Asunto(s)
Endodoncia Regenerativa , Fracturas de los Dientes , Diente no Vital , Humanos , Resistencia Flexional , Fracturas de los Dientes/terapia , Resinas Compuestas/química , Dentición Permanente , Polietilenos , Ensayo de Materiales , Análisis del Estrés Dental , Diente no Vital/terapia , Restauración Dental Permanente/métodos
18.
Int Endod J ; 55(10): 1091-1102, 2022 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-35833329

RESUMEN

AIM: The use of high-concentration sodium hypochlorite (NaOCl) as an endodontic irrigant remains controversial because of its potential impact on the fracture strength of endodontically treated teeth. This study evaluated the effects of using different NaOCl concentrations, with 2-min-ethylenediaminetetraacetic acid (EDTA) as the final active irrigant, on the biomechanical and structural properties of root dentine. METHODOLOGY: A new test method, which is more clinically relevant, was utilized to calculate the fracture strength of root dentine. Bovine incisors were used to obtain root dentine discs. The root canals were enlarged to mean diameter of 2.90 mm with a taper of 0.06. The resulting discs were divided into five groups (n = 20) and treated with different concentrations of NaOCl (5.25%, 2.5%, and 1.3%) for 30 min plus 17% EDTA for 2 min. The discs were then loaded to fracture by a steel rod with the same taper through the central hole. The fractured specimens were examined by scanning electron microscopy to evaluate changes in the dimensions of the remaining intertubular dentine and the tubular radius. Micro-hardness was also measured with a Knoop diamond indenter along a radius to determine the depth of dentine eroded by the irrigation. Results were analysed by one-way anova and the Tukey test. The level of significance was set at α = 0.05. RESULTS: The damage by NaOCl increased with its concentration. 5.25% NaOCl greatly reduced the fracture strength of root dentine from 172.10 ± 30.13 MPa to 114.58 ± 26.74 MPa. The corresponding reduction in micro-hardness at the root canal wall was 34.1%. The damages reached a depth of up to 400 µm (p < .05). Structural changes involved the degradation of the intratubular wall leading to enlarged dentinal tubules and the loss of intertubular dentine. Changes in the microstructural parameters showed positive linear relationships with the fracture strength. CONCLUSIONS: With the adjunctive use of EDTA, NaOCl caused destruction to the intratubular surface near the root canal and, consequently, reduced the root dentine's mechanical strength. The higher the concentration of NaOCl, the greater the effect. Therefore, endodontists should avoid using overly high concentration of NaOCl for irrigation to prevent potential root fracture in endodontically treated teeth.


Asunto(s)
Hipoclorito de Sodio , Diente no Vital , Animales , Bovinos , Cavidad Pulpar , Dentina , Ácido Edético/farmacología , Humanos , Irrigantes del Conducto Radicular/farmacología , Preparación del Conducto Radicular , Hipoclorito de Sodio/farmacología
19.
Clin Oral Investig ; 26(9): 5969-5978, 2022 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-35869306

RESUMEN

OBJECTIVES: The aim of this study was to evaluate the mechanical analysis of different three-unit metal-free fixed dental prostheses (FDPs) produced by computer-aided design (CAD)/computer-aided manufacturing (CAM). MATERIALS AND METHODS: A hundred stainless steel die models of a mandibular left first premolar and a mandibular left first molar were prepared. The specimens were divided into five CAD/CAM material groups (n = 20): Group ZIR, a cubic zirconia (DD cube ONE®); Group FRC, FRC resin material (Trinia); Group PEEK, a PEEK material (KERA® starPEEK); Group PEKK, a PEKK material (Pekkton® ivory); and Group COMP, a polymer composite material (BreCAM.HIPC). Compression test was applied to the specimens, and then the results were analyzed statistically using one-way ANOVA and Tukey's tests. In addition, deformation analyses in FDPs were compared with finite element method (FEM). After the compression test, the damage to FDPs was evaluated with a scanning electron microscopy. RESULTS: Although ZIR (2461 ± 93.70 N) showed high fracture load values, FRC (1571 ± 35.96 N) material was found to be advantageous in terms of toughness. These were followed by PEEK (1398 ± 38.26 N), PEKK (1227 ± 44.25 N), and COMP (829 ± 32.33 N), respectively. A ductile fracture was observed in PEEK, PEKK, and FRC due to their elastic structures. The deformation properties examined by the FEM were found to be similar to the compression test. CONCLUSIONS: CAD/CAM high-performance polymers and cubic zirconia material can be used in three-unit FDPs. In three-unit FDPs, the use of FRC material can be advantageous due to both biomechanics and lightness. CLINICAL RELEVANCE: Metal-free CAD/CAM materials may offer new possibilities in three-unit FDPs.


Asunto(s)
Fracaso de la Restauración Dental , Circonio , Benzofenonas , Diseño Asistido por Computadora , Materiales Dentales/química , Porcelana Dental/química , Análisis del Estrés Dental , Ensayo de Materiales , Polímeros , Tecnología , Circonio/química
20.
Odontology ; 110(2): 262-268, 2022 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-34495439

RESUMEN

The aim of this study is to investigate the effect of different restoration methods applied to model teeth with a C-shaped root canal configuration on fracture strength. A total of 76 artificial tooth models were made using images of a molar tooth with a C-shaped root canal anatomy. The teeth were randomly divided into seven groups and different restorations, such as resin composite (2), bundled fiber post and resin composite (3), vertical fiber post and resin composite (4), horizontal fiber post and resin composite (5), woven fiber post and resin composite (6) and composite endocrown (7) were applied to the different groups except control group (1). The artificial teeth were embedded in acrylic blocks and subjected to fracture tests. The data were analyzed using one-way analysis of variance, Monte Carlo Pearson Chi-square, Pearson Chi-square, and Fisher's exact test (P < 0.05). All groups differed in terms of fracture strength (P = 0.001). The highest fracture strength observed in group 6, and there was a significant difference between group 6 and group 4 based on a least significant difference pairwise comparison test. In terms of fracture type, the highest reparability percentage (100%) observed in group 7. The fracture strength values of endocrown restorations and woven fiber-reinforced resin composite restorations were found to be as high as those of the intact models. Considering also fracture restorability, endocrown restorations may be recommended for teeth with C-shaped root canal anatomy. The usage of the 3D tooth models in the studies offer a valuable opportunity in terms of the standardization of the samples, particularly in teeth with anatomical variations. This study shows that using of this technology, homogeneous groups can be created and experimental studies can be improved.


Asunto(s)
Fracturas de los Dientes , Resinas Compuestas , Restauración Dental Permanente/métodos , Análisis del Estrés Dental , Resistencia Flexional , Humanos , Ensayo de Materiales , Diente Molar
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