Use of the universal scan template to achieve a predictable optical impression: Preliminary data of a case series study in complete edentulous patients.

BACKGROUND: Full-arch IOS scan of edentulous areas rehabilitated with dental implants is nowadays still described as an unpredictable procedure. To improve the accuracy, a universal scan template (UST®) is proposed in this article. The clinician can easily assemble the template with a mechanical coupling, by matching the scan bodies with objects of known dimension characterized by specific markers. The UST® facilitates the scanning of an entire arch on scan bodies, reducing the learning curve, simplifying acquisition movements, shortening the scanning time, and drastically reducing the risk of distortions and aberrations of the scans. MATERIALS AND METHODS: In a case series study on 12 patients, the improvement in the accuracy of the scans with UST® was validated by comparing the STL files derived from scans with and without the guide in place. A titanium bar was produced from each optical impression. RESULTS: The bars obtained from the optical impressions taken without UST® were found to be nonpassive in the mouth in the majority of the cases. On the contrary with the use of UST® we obtained 12 passive prosthetic rehabilitations. CONCLUSIONS: The proposed solution may represent a valid method to improve the predictability of full arch optical impressions on implants.

Influence of Implant Scanbody Wear on the Accuracy of Digital Impression for Complete-Arch: A Randomized In Vitro Trial.

The aim of this study was to evaluate the influence of implant scanbody (ISB) wear on the accuracy of digital impression for complete-arch. A polymethylmethacrylate (PMMA) edentulous mandibular model with four internal hexagonal interlocking conical connections was scanned with an extraoral optical scanner to achieve a reference file. Four cylindrical polyetheretherketone (PEEK) ISBs were scanned 30 times with IOS, and the test files were aligned to the reference file with a best-fit algorithm. For each analog linear (ΔX, ΔY and ΔZ-axis) and angular deviations (ΔANGLE) were assessed. Euclidean distance (ΔEUC) was calculated from the linear deviation, reporting a mean of 82 µm (SD 61) ranging from 8 to 347 µm. ΔANGLE error mean was 0.33° (SD 0.20), ranging from 0.02 to 0.92°. From a multivariate analysis, when ΔEUC was considered as a response variable, a significant influence of ISB wear by scan number in interaction to position for implant 3.6 was identified (p < 0.0001); when ΔANGLE was considered as a response variable, a significant effect of position 3.6 was recorded ((p < 0.0001). The obtained results showed that the ISB wear negatively influenced the accuracy of IOS, suggesting that ISB base wear could be detrimental for the seating of ISBs on angulated implants.

Can transfer type and implant angulation affect impression accuracy? A 3D in vitro evaluation.

Impression accuracy is fundamental to achieve a passive fit between implants and the superstructure. Three transfer types were tested to evaluate the differences in impression accuracy and their efficiency in case of different implant angles. A master model with four implant analogues placed at 0°, 15° and 35° was used. 27 impressions were taken with three different types of impression coping: closed tray technique coping (CT), open tray technique coping (COT) and telescopic open tray coping (TOT). The impressions were poured. Analogues were matched with scan bodies to be scanned and exported in STL. An implant bar was designed from each STL and another one from the master model. A comparison between these bars was obtained. Linear and angular measurements for every type of coping were calculated for different angulations. The collected data were analyzed with ANOVA test (95% of confidence). Student's t test showed a significative discrepancy (p ≤ 0.001) on linear and angular measurements on Δx, Δy, Δz with different transfer types as well as diverse implant positioning angles (p ≤ 0.001). Within the limitations of this study, it can be concluded that the coping type and the implants divergence may be significant parameters influencing the impression accuracy.

Cervical necrotizing fasciitis by dental abscess treated with negative pressure wound therapy: Case report.

Necrotizing fasciitis is a severe soft tissue infection very uncommon in head and neck. This infection could be very aggressive involving subcutaneous tissue and fascial planes and can be rapidly fatal. Negative pressure wound therapy (NPWT) has emerge recently and became very popular in treating complicated wounds. A case of necrotizing fasciitis in cervical region from an odontogenic infection is presented. After surgical debridement, a NPWT device was installed. NPWT provides advantages compared to conventional debridement and drainage. This method is recommended as an alternative in treating necrotizing fasciitis in head and neck, because it eradicates infection and provides comfort to the patient.

Psychometric properties and operating characteristics of the Spanish-adapted version of the CRAFFT questionnaire in adolescents from Greater Buenos Aires. / Propiedades psicométricas y características operativas de la versión adaptada al castellano del cuestionario CRAFFT en adolescentes del conurbano bonaerense.

INTRODUCION: The Car, Relax, Alone, Forget, Family and Friends, Trouble (CRAFFT) questionnaire is an instrument used in the screening for problematic alcohol and substance use, abuse or dependence in adolescents. While there is a Spanish-adapted and validated version for Argentine adolescents (CRAFFTa), it cannot be applied indiscriminately because it has not been assessed in different sociocultural settings. OBJECTIVE: To assess the transferability of the CRAFFTa as a screening tool for problematic alcohol and drug use, abuse or dependence in an adolescent population of low socio-economic level. POPULATION AND METHODS: An anonymous survey was administered to low-income adolescents living in Greater Buenos Aires and attending two secondary schools. The Spanish-adapted version of the CRAFFT questionnaire, validated for its use in Argentina, was administered, while the Problem Oriented Screening Instrument for Teenagers, substance use and abuse subscale (POSITuas) questionnaire was used as a reference test. RESULTS: A total of 146 questionnaires were completed (completion rate: 89.6 %). Reliability was 0.681; criterion validity: 0.697; sensitivity: 93.4; specificity: 72.5; precision: 0.886; positive predictive value: 0.898; negative predictive value: 0.966. Compound reliability was 0.872; average variance extracted: 0.718. Convergent validity was acceptable in the confirmatory factor analysis, and a single-factor structure was used. CONCLUSION: The operating characteristics of the CRAFFTa questionnaire are acceptable for its use in the screening for problematic alcohol and substance use, abuse or dependence in a low-income adolescent population.

Introducción. El cuestionario Car, Relax, Alone, Forget, Family and Friends, Trouble (CRAFFT) es un instrumento de tamizaje de riesgo de consumo problemático, abuso o dependencia de alcohol y sustancias en adolescentes. Si bien cuenta con una versión validada y adaptada al castellano para su utilización en adolescentes argentinos (CRAFFTa), su uso no puede generalizarse, ya que no ha sido evaluado en diferentes contextos socioculturales. Objetivo. Evaluar la transferibilidad del CRAFFTa como herramienta de pesquisa de consumo problemático, abuso y dependencia de alcohol y otras sustancias en una población adolescente de bajo nivel socioeconómico. Población y métodos. Se encuestó en forma anónima a una muestra de adolescentes de una localidad de bajos recursos del conurbano bonaerense que concurrían a dos escuelas secundarias. Se aplicó el cuestionario CRAFFT adaptado al español y validado para su uso en Argentina, y se empleó el cuestionario Problem Oriented Screening Instrument for Teenagers substance use and abuse subscale (POSITuas) como prueba de referencia. Resultados. Se obtuvieron 146 cuestionarios completos (tasa de respuesta del 89,6 %). La confiabilidad fue 0,681; validez de criterio: 0,697; sensibilidad: 93,4; especificidad: 72,5; precisión: 0,886. Valor predictivo positivo: 0,898; y negativo: 0,966. La fiabilidad compuesta fue 0,872; varianza media extractada: 0,718. La validez convergente fue aceptable en el análisis factorial confirmatorio, y se empleó una estructura unifactorial. Conclusiones. Las características operativas del CRAFFTa son aceptables para su uso en el rastreo de consumo problemático de alcohol y abuso de sustancias en una población adolescente de bajos recursos.

A Comparative 3D Finite Element Computational Study of Three Connections.

Masticatory overload on dental implants is one of the causes of marginal bone resorption. The implant-abutment connection (IAC) design plays a critical role in the quality of the stress distribution, and, over the years, different designs were proposed. This study aimed to assess the mechanical behavior of three different types of IAC using a finite element model (FEM) analysis. Three types of two-piece implants were designed: two internal conical connection designs (models A and B) and one internal flat-to-flat connection design (model C). This three-dimensional analysis evaluated the response to static forces on the three models. The strain map, stress analysis, and safety factor were assessed by means of the FEM examination. The FEM analysis indicated that forces are transmitted on the abutment and implant's neck in model B. In models A and C, forces were distributed along the internal screw, abutment areas, and implant's neck. The stress distribution in model B showed a more homogeneous pattern, such that the peak forces were reduced. The conical shape of the head of the internal screw in model B seems to have a keystone role in transferring the forces at the surrounding structures. Further experiments should be carried out in order to confirm the present suppositions.