RESUMEN
A girl with a unilateral cleft lip, alveolus and palate, tooth agenesis, and mild dysmorphic features, without a specific underlying syndrome diagnosis, was genotypically characterized and phenotypically described. Cleft gene panel analysis, single-nucleotide polymorphism (SNP) array, whole genome sequencing (WGS), whole exome sequencing, and quantitative PCR (Q-PCR) analysis were used as diagnostic tests. SNP array revealed a maternal deletion at 16q24.1, encompassing the cleft candidate gene USP10. WES revealed an additional de novo Loss-of-Function variant (p.(Asn838fs)) in the Zinc-Finger-Homeobox-4 (ZFHX4) gene. Q-PCR was performed to explore the effect of the ZFHX4 variant and the deletion in 16q24.1. The mRNA expression of a selection of putative target genes involved in orofacial clefting showed a lowered expression of USP10 (52%), CRISPLD2 (31%), and CRISPLD1 (1%) compared to the control. IRF6 showed no difference in gene expression. This case supports ZFHX4 as a novel cleft gene and suggests USP10 may contribute to the etiology of orofacial clefts in humans.
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Labio Leporino , Fisura del Paladar , Femenino , Humanos , Labio Leporino/genética , Fisura del Paladar/genética , Factores Reguladores del Interferón/genética , Polimorfismo de Nucleótido Simple , Ubiquitina Tiolesterasa/genética , Factores de Transcripción/genética , Proteínas de Homeodominio/genéticaRESUMEN
OBJECTIVES: To prospectively investigate patient-reported outcomes and clinical performance of implant supported overdentures in edentulous Sjögren's disease (SjD) patients compared to subjects without SjD. METHODS: 51 implants were placed in 12 patients with SjD and 50 implants in 12 non-SjD patients to support overdentures. Clinical performance, marginal bone-level changes, patient satisfaction and oral health related quality of life (OHRQoL) were assessed at 1 (T1), 6 (T6), 12 (T12) and 18 (T18) months after placement of the overdenture. Patient satisfaction, ability to chew and OHRQoL were assessed with validated questionnaires. Marginal bone-level changes were measured on standardised dental radiographs. Clinical parameters included implant and overdenture survival, plaque, bleeding and gingival indices, and probing depth. RESULTS: OHRQoL in patients with SjD improved significantly after placement of implant supported overdentures at all measuring moments compared to baseline (p<0.05). Nevertheless, ability to chew tough and hard food was significantly better for non-SjD patients at all timepoints after placement of an implant supported overdenture (p<0.05). Implant survival at T18 was 100% in the patients with SjD and 98% in the non-SS group. Mean marginal bone loss at T18 did not differ between patients with SjD and non-SS patients, 1.12±0.74 mm and 1.43±1.66 mm, respectively (p=0.58). Clinical performance was good with no differences between the groups for all outcome measures (p>0.05). CONCLUSIONS: Implant-supported overdentures have a positive effect on OHRQoL and dental implants can be successfully applied in edentulous patients with SjD with nearly similar outcomes as in non-SjD subjects.
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Prótesis de Recubrimiento , Calidad de Vida , Humanos , Estudios Prospectivos , Satisfacción del Paciente , Prótesis Dental de Soporte ImplantadoRESUMEN
OBJECTIVE: Since Wnt signaling plays an important role in both tooth agenesis and altered intestine homeostasis, the aim was to compare gastrointestinal symptoms in patients with isolated oligodontia caused by a Wnt pathway gene mutation and controls. METHODS: A case-control study was designed to compare self-reported gastrointestinal symptoms among patients with isolated oligodontia, caused by a Wnt signaling gene mutation, and fully dentate controls. The Gastrointestinal Symptom Rating Scale (GSRS) was used to assess gastrointestinal symptoms. Prevalence and severity of gastrointestinal symptoms among patients and age- and gender-matched controls were evaluated. RESULTS: Twenty patients with isolated oligodontia and a pathogenic variant in the wnt pathway genes WNT10A, LRP6, or PAX9 participated. The prevalence of gastrointestinal symptoms was higher in the oligodontia patients compared to their controls (Χ2 (1) = 87.33, p = .008). Mean GSRS total scores (p = .011) and domain scores for "abdominal pain" (p = .022), "reflux" (p = .003) and constipation (p = .030) were higher for these oligodontia patients compared to their controls. CONCLUSION: Gastrointestinal symptoms are more prevalent and more severe in patients with isolated oligodontia and a deficiency in a Wnt pathway-related gene, when compared to controls without tooth agenesis.
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Anodoncia , Humanos , Estudios de Casos y Controles , Anodoncia/genética , Mutación , Vía de Señalización Wnt/genéticaRESUMEN
OBJECTIVES: To prospectively assess the clinical performance and patient-reported outcomes of dental implants in dentate patients with primary and secondary Sjögren's syndrome (pSS and sSS, respectively) compared to patients without SS. MATERIALS AND METHODS: Thirty-seven implants were placed in 17 patients with pSS/sSS and 26 implants in 17 non-SS patients to replace missing (pre)molars. Clinical performance, marginal bone-level changes, patient satisfaction, and oral health-related quality of life (OHRQoL) were assessed at 1 (T1), 6 (T6), 12 (T12), and 18 (T18) months after placement of the superstructure. Marginal bone-level changes were measured on standardized dental radiographs. Clinical parameters included implant and crown survival, plaque, bleeding and gingival indices, and probing depth. Patient satisfaction and OHRQoL were assessed with validated questionnaires. RESULTS: Implant survival at T18 was 100% in the patients with pSS/sSS and 96.2% in the non-SS group. Mean marginal bone loss at T18 did not differ between patients with pSS/sSS and non-SS patients, 1.10 ± 1.04 and 1.04 ± 0.75 mm, respectively (p = .87). Clinical performance was good with no differences between the groups for all outcome measures (p > .05). OHRQoL in patients with pSS/sSS had improved significantly after placement of implant supported crowns at all measuring moments compared to baseline (p < .05). Nevertheless, patient satisfaction and OHRQoL remained significantly higher for patients without SS at all measuring moments (p < .05). CONCLUSION: Dental implants can be successfully applied in dentate patients with pSS/sSS and have a positive effect on OHRQoL.
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Implantes Dentales , Síndrome de Sjögren , Humanos , Síndrome de Sjögren/complicaciones , Estudios Prospectivos , Calidad de Vida , Coronas , Prótesis Dental de Soporte ImplantadoRESUMEN
Tooth agenesis is one of the most common developmental anomalies in man. Oligodontia, a severe form of tooth agenesis, occurs both as an isolated anomaly and as a syndromal feature. We performed exome sequencing on 20 unrelated individuals with apparent non-syndromic oligodontia and failed to detect mutations in genes previously associated with oligodontia. In three of the probands, we detected heterozygous variants in LRP6, and sequencing of additional oligodontia-affected individuals yielded one additional mutation in LRP6. Three mutations (c.1144_1145dupAG [p.Ala383Glyfs(∗)8], c.1779dupT [p.Glu594(∗)], and c.2224_2225dupTT [p.Leu742Phefs(∗)7]) are predicted to truncate the protein, whereas the fourth (c.56C>T [p.Ala19Val]) is a missense variant of a conserved residue located at the cleavage site of the protein's signal peptide. All four affected individuals harboring a LRP6 mutation had a family history of tooth agenesis. LRP6 encodes a transmembrane cell-surface protein that functions as a co-receptor with members from the Frizzled protein family in the canonical Wnt/ß-catenin signaling cascade. In this same pathway, WNT10A was recently identified as a major contributor in the etiology of non-syndromic oligodontia. We show that the LRP6 missense variant (c.56C>T) results in altered glycosylation and improper subcellular localization of the protein, resulting in abrogated activation of the Wnt pathway. Our results identify LRP6 variants as contributing to the etiology of non-syndromic autosomal-dominant oligodontia and suggest that this gene is a candidate for screening in DNA diagnostics.
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Anodoncia/genética , Exoma/genética , Genes Dominantes , Proteína-6 Relacionada a Receptor de Lipoproteína de Baja Densidad/genética , Mutación/genética , Proteínas Wnt/genética , Anodoncia/patología , Estudios de Casos y Controles , Femenino , Células HEK293 , Humanos , Masculino , Linaje , FenotipoRESUMEN
OBJECTIVES: A novel, 3D technique to measure the differences in tooth crown morphology between the MSX1 cases and non-affected controls was designed to get a better understanding of dental phenotype-genotype associations. MATERIALS AND METHODS: Eight Dutch subjects from a single family with tooth agenesis, all with an established nonsense mutation c.332 C > A, p. Ser 111 Stop in exon 1 of MSX1, were compared with unaffected controls regarding several aspects of tooth crown morphology of incisor and molar teeth. A novel method of quantitative three-dimensional analysis was used to detect differences. RESULTS: Statistically significant shape differences were observed for the maxillary incisor in the MSX1 family compared with the controls on the following parameters: surface area, buccolingual dimension, squareness, and crown volume (P ≤ 0.002). Molar crown shape was unaffected. CONCLUSIONS: A better understanding of dental phenotype-genotype associations may contribute to earlier diagnosis of some multiple-anomaly congenital syndromes involving dental anomalies. CLINICAL RELEVANCE: A "shape database" that includes associated gene mutations resulting from developmental syndromes may facilitate the genetic identification of hypodontia cases.
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Anodoncia/genética , Imagenología Tridimensional/métodos , Factor de Transcripción MSX1/genética , Mutación Missense , Corona del Diente/patología , Adolescente , Adulto , Anciano , Análisis de Varianza , Estudios de Casos y Controles , Niño , Femenino , Humanos , Incisivo , Masculino , Modelos Dentales , Diente Molar , Países Bajos , Odontometría/métodos , Estadísticas no Paramétricas , Anomalías Dentarias/genética , Anomalías Dentarias/patología , Adulto JovenRESUMEN
PURPOSE: To assess whether dentin pins increase shear resistance of extensive composite restorations and to compare performance of mini fiber-reinforced composite (FRC) anchors with metal dentin pins in the laboratory. METHODS: 30 extracted sound molars were randomly divided into three groups. Occlusal surfaces were ground flat with a standard surface area and resin composite restorations were made in Group A. In Groups B and C similar restorations were made, with additionally four metal pins placed in Group B and four FRC pins in Group C. Specimens were statically loaded until failure occurred. Failure modes were characterized as intact remaining tooth substrate (adhesive or cohesive failure of restoration) or fractured remaining tooth substrate. RESULTS: Mean failure stresses were 6.5 MPa (SD 3.2 MPa) for Group A, 9.7 MPa (SD 2.6 MPa) for Group B and 9.2 MPa (SD 2.6 MPa) for Group C. Difference in mean failure stresses between Group A and Groups B and C was statistically significant (P = 0.01), while the difference between Groups B and C was not (P = 0.63). Failures of the restoration without fracture of tooth substrate were seen for 80% of specimens in Group A and 20% in Groups B and C (P = 0.04).
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Resinas Compuestas/química , Aleaciones Dentales/química , Materiales Dentales/química , Pins Dentales , Vidrio/química , Grabado Ácido Dental/métodos , Adhesividad , Ácidos Aminosalicílicos/química , Restauración Dental Permanente/instrumentación , Restauración Dental Permanente/métodos , Análisis del Estrés Dental/instrumentación , Dentina/ultraestructura , Recubrimientos Dentinarios/química , Humanos , Ensayo de Materiales , Metacrilatos/química , Ácidos Fosfóricos/química , Cementos de Resina/química , Resistencia al Corte , Estrés Mecánico , Preparación del Diente/métodosRESUMEN
BACKGROUND: Wnt and Wnt-associated pathways play an important role in the genetic etiology of oligodontia, a severe form of tooth agenesis. Loss-of-function mutations in LRP6 , encoding a transmembrane cell-surface protein that functions as a coreceptor in the canonical Wnt/b-catenin signaling cascade, also contribute to genetic oligodontia. METHODS AND RESULTS: We describe a three-generation family with hereditary thrombocytopenia and oligodontia. Genome wide array analysis was performed. The array results from the index patient revealed an interstitial loss of 150 kb in 8p23.1 (chr8:6,270,299-6,422,558; hg19) encompassing MCPH1 and ANGPT2 and an interstitial loss of 290 kb in 12p13.2 (chr12:12,005,720-12,295,290; hg19) encompassing ETV6, BCL2L14 and LRP6. CONCLUSION: This case report shows a three-generation family with hereditary thrombocytopenia and oligodontia with a heterozygous 290 kb novel contiguous gene deletion in band p13.2 of chromosome 12, encompassing LRP6 and ETV6. In this report we discuss the clinical relevance of the deletion of both genes and illustrate the importance of thorough examination of oligodontia patients. Comprising not only the oral status but also the medical history of the patients and their relatives.
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Anodoncia/genética , Cromosomas Humanos Par 12/genética , Eliminación de Gen , Trombocitopenia/genética , Adulto , Angiopoyetina 2/genética , Anodoncia/patología , Proteínas de Ciclo Celular/genética , Niño , Cromosomas Humanos Par 8/genética , Proteínas del Citoesqueleto/genética , Femenino , Humanos , Proteína-6 Relacionada a Receptor de Lipoproteína de Baja Densidad/genética , Masculino , Linaje , Fenotipo , Proteínas Proto-Oncogénicas c-bcl-2/genética , Proteínas Proto-Oncogénicas c-ets/genética , Proteínas Represoras/genética , Síndrome , Trombocitopenia/patología , Proteína ETS de Variante de Translocación 6RESUMEN
In this study we aimed to determine the effect of WNT10A variants on dental development in patients with oligodontia. Forty-three (25 boys and 18 girls) individuals were eligible for this study. Stage of development for each present tooth was assessed using the Demirjian method. In case no corresponding tooth was present, regression equations were applied for dental age to be calculated. The ratio between length of root and length of crown was ascertained for each present tooth in all quadrants. All patients were physically examined by a clinical geneticist and DNA analysis of the WNT10A gene was performed. Linear regression models were applied to analyze the association between WNT10A variants and dental age. The same analysis was applied to study the association between WNT10A variants and root elongation for each present tooth. One ordinal regression model was applied to analyze the association between WNT10A variants and development of present maxillary and mandibular teeth. Thirty-six (84%) patients were detected with WNT10A variants of which six patients displayed evident ectodermal features. Dental age was 1.50 (95% confidence interval (CI): -2.59, -0.42) to 1.96 (95% CI: -3.76, -0.17) years lower in patients with WNT10A variants compared with patients without variants. The development of maxillary canine, maxillary second molar and mandibular second molar was statistically significantly delayed in patients with WNT10A variants compared with patients without variants. The impact of WNT10A variants on dental development increases with presence of the nonsense c.(321C>A p.(C107*)) variant and the number of missing teeth.
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Anodoncia/genética , Diente/fisiopatología , Proteínas Wnt/genética , Adolescente , Anodoncia/diagnóstico por imagen , Anodoncia/patología , Niño , Codón sin Sentido/genética , Femenino , Humanos , Masculino , Mutación , Fenotipo , Diente/diagnóstico por imagen , Diente/microbiologíaRESUMEN
OBJECTIVES: To assess the fracture resistance and failure mode of fiber reinforced composite (FRC) cusp-replacing restorations in premolars. METHODS: Forty-five extracted sound upper premolars were randomly divided into three groups. Identical MOD cavities with simulated buccal cusp fracture and height reduction of the palatal cusp were prepared. In Group A two layers of resin impregnated woven continuous FRC (EverStick Net) were applied. In Group B one layer of unidirectional continuous FRC (EverStick) was used. In Group C no fibers were applied (control). Subsequently, all teeth were restored with resin composite (Clearfil Photo Posterior), subjected to thermocycling (6000 x 5-55 degrees C) and static load tests. Load until fracture was registered for each tooth. Simultaneously, fracture propagation was monitored using acoustic emission analysis (AE). Failure modes were visually assessed. RESULTS: Weibull analysis revealed a characteristic strength and Weibull modulus (m) at 2364.8 N for Group A (m=8.9), 2437.9 N for Group B (m=5.9) and 2160.3N for Group C (m=13.6). Fracture loads were not significantly different (ANOVA, p>0.05). Teeth with FRC showed less fractures below the cemento-enamel junction (CEJ) (38% and 23% for Groups A and B, respectively) than teeth without FRC (93%) (chi-square, p<0.05). The control group showed the least AE energy signals. SIGNIFICANCE: The results suggest that glass FRC does not increase fracture load of premolars with cusp-replacing restorations. However, FRC has a beneficial effect on the failure mode. Woven fibers give more consistent results than unidirectional fibers.
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Resinas Compuestas/química , Restauración Dental Permanente , Corona del Diente , Análisis de Varianza , Diente Premolar , Preparación de la Cavidad Dental , Fracaso de la Restauración Dental , Análisis del Estrés Dental , Vidrio , Humanos , Ensayo de Materiales , Distribución Aleatoria , Espectrografía del Sonido , Análisis de SupervivenciaRESUMEN
PURPOSE: This study aimed to investigate the impact of preradiation tooth loss in patients with head and neck cancer. MATERIALS AND METHODS: Records of 397 (partially) dentate patients who were referred for preradiation oral screening were included. Number and location of teeth lost and occluding pairs lost were determined for different tumor locations. RESULTS: The majority of patients (54%) were affected by tooth loss. Proportion of teeth lost, their location, and proportion of occluding pairs lost were not evenly distributed across tumor locations. The highest proportions of teeth were removed with oral tumors (maxilla: 25%; mandible: 47%). For preradiation preventive extractions only, ie, not taking into account teeth that were lost due to ablative surgery, tooth loss in the mandible was still not evenly distributed across tumor locations, but tooth loss in the maxilla and occluding pairs lost were. CONCLUSIONS: Tumor location affects preradiation tooth loss, though this is primarily a consequence of ablative surgery rather than a consequence of preradiation dental extraction decisions. Since patients with oral cavity tumors are affected most by preradiation tooth loss, treatment planning with regard to functional rehabilitation is desirable for this patient group in particular.
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Neoplasias de Cabeza y Cuello/radioterapia , Extracción Dental/métodos , Pérdida de Diente/etiología , Anciano , Neoplasias de Cabeza y Cuello/cirugía , Humanos , Neoplasias Laríngeas/radioterapia , Neoplasias Laríngeas/cirugía , Neoplasias Mandibulares/radioterapia , Neoplasias Mandibulares/cirugía , Neoplasias Maxilares/radioterapia , Neoplasias Maxilares/cirugía , Persona de Mediana Edad , Neoplasias de la Boca/radioterapia , Neoplasias de la Boca/cirugía , Neoplasias Nasales/radioterapia , Neoplasias Nasales/cirugía , Planificación de Atención al Paciente , Neoplasias Faríngeas/radioterapia , Neoplasias Faríngeas/cirugía , Dosificación Radioterapéutica , Neoplasias de las Glándulas Salivales/radioterapia , Neoplasias de las Glándulas Salivales/cirugíaRESUMEN
PURPOSE: To assess the influence of an additional shoulder preparation on the fracture strength of a cusp-replacing direct resin composite restoration in a premolar that previously had an amalgam MOD restoration followed by fracture of a cusp. MATERIALS AND METHODS: Two preparation designs were tested. In extracted sound premolars an MOD amalgam cavity was simulated followed by fracture of a cusp (Group A). Group B was the same as Group A but a shoulder was added along the cervical outline of the preparation. As a control group, cusp fracture was simulated but no MOD amalgam cavities were prepared. For each group, 14 preparations were made using a copy milling technique. All 42 preparations were restored using a direct resin composite restoration technique. Restorations were loaded until fracture. RESULTS: The fracture strength of the preparation with shoulder was not significantly different from the preparation without the shoulder. The fracture strength of the preparations in the reference group, which had no resistance form, was significantly less than in Groups A and B (ANOVA, P<0.05).
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Preparación de la Cavidad Dental/métodos , Restauración Dental Permanente/métodos , Análisis del Estrés Dental , Corona del Diente/lesiones , Fracturas de los Dientes/prevención & control , Análisis de Varianza , Diente Premolar , Resinas Compuestas , Fuerza Compresiva , Amalgama Dental , Preparación de la Cavidad Dental/efectos adversos , Análisis del Estrés Dental/métodos , Estudios de Evaluación como Asunto , Humanos , Técnicas In Vitro , Mandíbula , Modelos Biológicos , Resistencia a la Tracción , Fracturas de los Dientes/etiologíaRESUMEN
Objective. To assess fracture resistance and failure mode of repaired fiber-reinforced composite (FRC) cusp-replacing restorations. Methods. Sixteen extracted human premolars with fractured cusp-replacing woven (Group (A)) or unidirectional (Group (B)) FRC restorations from a previous loading experiment were repaired with resin composite and loaded to fracture. Results. Differences in fracture loads between groups were not statistically significant (P = 0.34). Fracture loads of repaired specimens were significantly lower than those of original specimens (P = 0.02 for Group (A) and P < 0.001 for Group (B)). Majority of specimens showed failure along the repaired surface. In Group (B) 89% of specimens showed intact tooth substrate after restoration fracture, while this was 28% in Group (A) (P = 0.04). Conclusion. Fractured cusp-replacing FRC restorations that are repaired with resin composite show about half of fracture resistance of original restorations. Mode of failure with a base of unidirectional fibers is predominantly adhesive.
RESUMEN
OBJECTIVES: To compare polymerization efficiency of resin composite basing materials when light-cured through resin composite and fiber reinforced composite (FRC) by testing microhardness. METHODS: Simulated indirect restorations were prepared by application of resin composite (Clearfil AP-X) or FRC (EverStick) to nylon rings with 1.5mm thickness and 8mm diameter, followed by light-curing. Resin composite basing material (Clearfil Majesty Flow or Clearfil AP-X) was applied to identical rings and light-cured through the simulated indirect restorations with exposure times of 20, 40, or 60s. Light-curing though a ring without resin material (=no indirect restoration) served as control. For each combination of basing material and indirect restoration 10 specimens were prepared for each exposure time. Top and bottom surface Vickers microhardness numbers (VHNs) of basing materials were recorded after 24h. RESULTS: After 60s exposure time, VHNs with indirect FRC were not different from control VHNs, while VHNs with indirect resin composite were significantly lower (p<0.001). Linear regression analysis revealed that resin composite basing material used had the greatest effect on top and bottom VHNs (p<0.001). The presence of an indirect restoration resulted in decreased VHNs (p<0.001), with resin composite resulting in lower VHNs when compared to FRC. Moreover, a longer exposure time resulted in increased VHNs (p<0.001). SIGNIFICANCE: Results suggest that polymerization of resin composite basing materials is more effective when light-curing through an FRC than through a resin composite indirect restoration. Prolonging of exposure time, however, is necessary when compared to light-curing without presence of indirect restoration material.
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Resinas Compuestas/efectos de la radiación , Curación por Luz de Adhesivos Dentales , Cementos de Resina/efectos de la radiación , Análisis del Estrés Dental , Dureza , Incrustaciones , Modelos Lineales , Ensayo de Materiales , Metacrilatos/efectos de la radiación , Transición de Fase , Factores de TiempoRESUMEN
PURPOSE: This study aimed to assess the efficacy and short-term effectiveness of the morphology and function of direct and indirect cusp-replacing resin composite restorations. MATERIALS AND METHODS: In 94 patients, 106 cusp-replacing restorations for maxillary premolars were fabricated to restore Class II caries lesions with 1 cusp missing. Fifty-four direct (Clearfil AP-X) and 52 indirect (Estenia) resin composite restorations were placed following a strict protocol. The treatment technique and operator were assigned randomly. Treatment time was recorded for all restorations. One-month postoperative evaluation included assessment of postoperative sensitivity and presence of occlusal and proximal contacts. RESULTS: Treatment time for the indirect technique (68 +/- 17 min) was longer than for the direct technique (45 +/- 13 min). Regression analysis revealed that the restorative method, operator, and location of the preparation outline had a statistically significant effect on the total treatment time. Occlusal contacts were observed in 94% of the direct restorations and in 98% of the indirect restorations (chi-square, P>.05). Mesial proximal contacts were present in 98% of the direct and in 97% of the indirect restorations (chi-square, P > .05). Distal contacts were present in 100% of the restorations for both techniques. Postoperative sensitivity within 1 week posttreatment was reported for 11% of the direct restorations and for 13% of the indirect restorations, but decreased to 4% and 6%, respectively, after 1 month (chi-square, P > .05). CONCLUSION: The results of this study suggest that in the short term, both direct and indirect adhesive techniques are adequate to restore the morphology and function of premolars presenting with Class II caries lesions and a missing cusp.
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Resinas Compuestas , Restauración Dental Permanente/métodos , Adulto , Anciano , Diente Premolar/lesiones , Diente Premolar/patología , Resinas Compuestas/química , Caries Dental/terapia , Preparación de la Cavidad Dental/métodos , Esmalte Dental/lesiones , Restauración Dental Permanente/efectos adversos , Sensibilidad de la Dentina/etiología , Femenino , Estudios de Seguimiento , Humanos , Masculino , Maxilar , Metacrilatos/química , Persona de Mediana Edad , Poliuretanos/química , Cementos de Resina/química , Propiedades de Superficie , Factores de Tiempo , Fracturas de los Dientes/terapia , Resultado del TratamientoRESUMEN
PURPOSE: This study assessed the influence of palatal cuspal coverage on the in vitro fatigue resistance and failure mode of Class II resin composite restorations including replacement of the buccal cusp in premolars. MATERIALS AND METHODS: A master model was made of a maxillary premolar with an MOD amalgam cavity and a simulated fracture of the buccal cusp from the isthmus floor to the CEJ. Using a copy-milling machine, this preparation was copied to 20 extracted human maxillary premolars (group A). Subsequently, the palatal cusp was reduced by 1.5 mm; this modified preparation was copied to 20 additional maxillary premolars (group B). Direct resin composite restorations were made in all teeth. Cyclic load (5 Hz) was applied, starting with a load of 200 N (10,000 cycles), followed by stages of 400, 600, 800, and 1,000 N at a maximum of 50,000 cycles each. Samples were loaded until fracture or to a maximum of 210,000 cycles. RESULTS: Of the restored premolars of group A, 20% withstood all 210,000 loading cycles; in group B, this figure was 55%. In group A, 19% of the fractures ended below the CEJ; in group B, 78% did. CONCLUSION: Palatal cuspal coverage increased the fatigue resistance of Class II resin composite restorations with replacement of the buccal cusp in premolars. However, fractures of restorations with cuspal coverage led to more dramatic failures that made restoration virtually impossible. This suggests caution in lowering remaining cusps for these adhesive restorations in the clinical situation.
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Resinas Compuestas , Fracaso de la Restauración Dental , Incrustaciones , Diente Premolar , Preparación de la Cavidad Dental , Análisis del Estrés Dental , Recubrimientos Dentinarios , Humanos , Incrustaciones/métodos , Cementos de Resina , Fracturas de los Dientes/terapiaRESUMEN
PURPOSE: This study was conducted to expand the knowledge on the incidence of complete cusp fractures of posterior teeth in Dutch general practices. MATERIALS AND METHODS: During a 3-month period, data were obtained from 28 general practitioners, representing 46,394 patients. For each new case of complete cusp fracture, clinicians recorded information using a standard form with questions relating to location of the fracture, cause of fracture, and restorative status of the tooth prior to the cusp fracture. RESULTS: There were 238 cases of complete cusp fracture recorded. The results of this study indicate an incidence rate of cusp fractures of 20.5 per 1,000 person-years at risk. Molars were more frequently registered with cusp fractures than premolars (79% vs 21%). Maxillary molars presented more fractures of buccal cusps (66% vs 34%), while mandibular molars presented more fractures of lingual cusps (75% vs 25%). Almost 77% of the cases had been restored on three or more surfaces. Statistical analysis revealed a positive correlation between history of endodontic treatment and subgingival fracture location. Mastication was most frequently reported as the cause for fracture (54%), although one can argue whether the occlusal force was the cause or the immediate reason. CONCLUSION: This study revealed that complete cusp fracture is a common phenomenon in dental practice and has shown differences in cusp fracture with respect to tooth type and restorative status of the tooth. Teeth with a history of endodontic treatment are susceptible to unfavorable subgingival fracture locations.