Evaluation of intensity standards of tungsten-halogen and led curing units / Evaluación de estándares de intensidad de unidades de curado tugsteno-halógenas y leds

Current evidence indicates that the minimum light intensity of photo curing units required to polymerize in a reliable way a composite resin, in increments of 2mm, is 300mW/cm2. The recent introduction of new generations of composite resin materials for large volume increments, partially contrasts with ISO 4049 (2009), calling for the use of light intensity of 1,000mW/cm2. Therefore, it is considered relevant to carry out periodic measurements of the emission intensity of light-curing units of clinical use. The aim of this study was to test the intensity [mW/cm2] of a representative sample of tungsten-halogen and LED photopolymerization units used in private and public health service in different areas of the Valparaíso Region in Chile. This was achieved through the use of dental radiometers, without considering the variables of intensity modification over time (either spontaneously, by undesirable inherent characteristics of the device, or by programs of intensity modification in time), or the density of accumulated power needed. This in vitro diagnostic test, evaluated a sample of 507 units, 107 halogen and 400 LED, for a period of around one month, using two radiometers as measuring instruments. For LED units the Bluephase Meter® radiometer, from Ivoclar-VivadentTM was used, and for halogen units we used the Coltolux® from ColténeTM. As a result, 85% of the LED and halogen units achieved the minimum requirements of intensity needed for the polymerization of conventional dental biomaterials. However, only 25% from the tested units achieved a power density of 1,000mW/cm2.

3D Volume Rendering and 3D Printing (Additive Manufacturing).

Three-dimensional (3D) volume-rendered images allow 3D insight into the anatomy, facilitating surgical treatment planning and teaching. 3D printing, additive manufacturing, and rapid prototyping techniques are being used with satisfactory accuracy, mostly for diagnosis and surgical planning, followed by direct manufacture of implantable devices. The major limitation is the time and money spent generating 3D objects. Printer type, material, and build thickness are known to influence the accuracy of printed models. In implant dentistry, the use of 3D-printed surgical guides is strongly recommended to facilitate planning and reduce risk of operative complications.

PECULIARITIES OF THE OCCLUSION FORMATION IN DENTAL IMPLANT SUPPORTED ARTIFICIAL TEETH.

The aim of this study was to assess and develop an effective computer technology assisted method for improved treatment of dental implant patients. Both an experimental and clinical assessments were conducted. The experimental part was performed to develop the mathematical models for calculating and analyzing the tensely deformed condition (TDC) in the system "non-removable prosthesis - dental implant - lower jaw " (PIJ). Clinical study was conducted on 76 patients with previously placed dental implant supported prostheses in the posterior parts of the lower jaw (with and without signs of bone receding around the implants) allocated into three groups. Results of the study allowed the authors to suggest an effective computer technology supported method for assessing the required angles of dental implants, which provides an opportunity for individual calculation of the dental implant in the bone of the mandible depending on the direction of functional load.

NON-REMOVABLE DENTURE PROTOTYPES, EFFECTIVE IN DENTAL IMPLANTATION.

Temporary prosthesis transformed into a prosthetic prototypes and manufactured by CAD/CAM technologies (computer copy milling) are used to specify the final form of future permanent restoration and to correct occlusal relationships, vertical size of non-removable dentures, and their occlusal surfaces. A progressive loading on bone tissue in the implantation area and soft tissues formation, have been assessed. In this regard, the choice and placement of temporary mini-implants, as the supports for non-removable denture prototypes for the period of osseointegration of two-stage intraosseous dental implants, are the issues of great importance. Temporary dental implants are the object of complex loads of different magnitude, duration and direction. The action of the prosthesis is closely related to load delivery to the surface of dental implant between the components of the system - "implant-temporary prosthesis". According to the study results, minimization of the momentum acting on temporary implants in the mesiodistal direction allows reducing stress level in the areas of permanent implant placement.

[Diagnossis and treatment of complicated anterior teeth esthetic defects by combination of whole-process digital esthetic rehabilitation with periodontic surgery].

OBJECTIVE: To explore a new method of whole-process digital esthetic prosthodontic rehabilitation combined with periodontic surgery for complicated anterior teeth esthetic defects accompanied by soft tissue morphology, to provide an alternative choice for solving this problem under the guidance of three-dimensional (3D) printing digital dental model and surgical guide, thus completing periodontic surgery and digital esthetic rehabilitation of anterior teeth. METHODS: In this study, 12 patients with complicated esthetic problems accompanied by soft tissue morphology in their anterior teeth were included. The dentition and facial images were obtained by intra-oral scanning and three-dimensional (3D) facial scanning and then calibrated. Two esthetic designs and prosthodontic outcome predictions were created by computer aided design /computer aided manufacturing (CAD/CAM) software combined with digital photography, including consideration of white esthetics and comprehensive consideration of pink-white esthetics. The predictive design of prostheses and the facial appearances of the two designs were evaluated by the patients. If the patients chose the design of comprehensive consideration of pink-white esthetics, they would choose whether they would receive periodontic surgery before esthetic rehabilitation. The dentition design cast of those who chose periodontic surgery would be 3D printed for the guide of periodontic surgery accordingly. RESULTS: In light of the two digital designs based on intra-oral scanning, facing scanning and digital photography, the satisfaction rate of the patients was significantly higher for the comprehensive consideration of pink-white esthetic design (P<0.05) and more patients tended to choose priodontic surgery before esthetic rehabilitation. The 3D printed digital dental model and surgical guide provided significant instructions for periodontic surgery, and achieved success transfer from digital design to clinical application. The prostheses were fabricated by CAD/CAM, thus realizing the whole-process digital esthetic rehabilitation. CONCLUSION: The new method for esthetic rehabilitation of complicated anterior teeth esthetic defects accompanied by soft tissue morphology, including patient-involved digital esthetic analysis, design, esthetic outcome prediction, 3D printing surgical guide for periodontic surgery and digital fabrication is a practical technology. This method is useful for improvement of clinical communication efficiency between doctor-patient, doctor-technician and doctors from different departments, and is conducive to multidisciplinary treatment of this complicated anterior teeth esthetic problem.

Intended and Achieved Torque of Implant Abutment's Screw using Manual Wrenches in Simulated Clinical Setting.

OBJECTIVE: To measure the difference between the intended torque and the achieved torque by the operator using the spring-style mechanical torque-limiting device (MTLD). MATERIALS AND METHODS: Inexperienced and experienced clinicians used one spring-type MTLD to torque two abutment screws of each anterior and posterior implants, which were attached to two digital torque meters through a jaw model. The jaw model was part of a preclinical bench manikin attached to a dental chair. The intended torque value was 35 N cm (recommended by manufacturer) and the technique of torquing was observed for all the participants (instantaneous and repeated). The mean torque value was calculated for each subject for the anterior and posterior implants independently; t-test was used to compare between the intended and achieved torque values and to compare between the experienced and inexperienced clinicians (p ≤ 0.05). RESULTS: Thirty-seven clinicians participated, with an overall mean torque value of 34.30 N cm. The mean torque value of the achieved torque (34.30 ± 4.13 N cm) was statistically significantly less than the intended torque (p = 0.041). The male clinicians produced more statistically significantly accurate torque value (34.54 ± 3.78 N cm) than the female clinicians (p = 0.034), and the experienced clinicians produced more accurate torque values (34.9 ± 5.13 N cm) than the inexperienced clinicians (p = 0.048). CONCLUSION: Within the limitation of this study, the use of MTLDs did not always produce consistent torque values and the technique by which the operators use the MTLD might affect the torque value.

High-Tech Hygiene: Technologies Making a Difference in Oral Care.

Technology has greatly influenced all phases of the dental hygiene process of care. Chairside diagnostic tools and self-monitoring devices improve early detection of lesions and previously undetected oral/systemic diseases, facilitate assessment of systemic health status, and support patient engagement in self-care. Collectively, improved patient assessment reduces risks for medical emergencies and promotes patient safety. Technological advances enable better visualization of hard and soft tissues during the assessment phase, aid decision-making with planning and delivery of appropriate oral care interventions, and facilitate evaluation of patient outcomes related to dental hygiene treatment. Additional research is needed to support the benefits of patient-centered technologies designed to affect behavioral change.

Understanding dental CAD/CAM for restorations--dental milling machines from a mechanical engineering viewpoint. Part B: labside milling machines.

Nowadays, dental numerical controlled (NC) milling machines are available for dental laboratories (labside solution) and dental production centers. This article provides a mechanical engineering approach to NC milling machines to help dental technicians understand the involvement of technology in digital dentistry practice. The technical and economic criteria are described for four labside and two production center dental NC milling machines available on the market. The technical criteria are focused on the capacities of the embedded technologies of milling machines to mill prosthetic materials and various restoration shapes. The economic criteria are focused on investment cost and interoperability with third-party software. The clinical relevance of the technology is discussed through the accuracy and integrity of the restoration. It can be asserted that dental production center milling machines offer a wider range of materials and types of restoration shapes than labside solutions, while labside solutions offer a wider range than chairside solutions. The accuracy and integrity of restorations may be improved as a function of the embedded technologies provided. However, the more complex the technical solutions available, the more skilled the user must be. Investment cost and interoperability with third-party software increase according to the quality of the embedded technologies implemented. Each private dental practice may decide which fabrication option to use depending on the scope of the practice.

Understanding dental CAD/CAM for restorations - dental milling machines from a mechanical engineering viewpoint. Part A: chairside milling machines.

The dental milling machine is an important device in the dental CAD/CAM chain. Nowadays, dental numerical controlled (NC) milling machines are available for dental surgeries (chairside solution). This article provides a mechanical engineering approach to NC milling machines to help dentists understand the involvement of technology in digital dentistry practice. First, some technical concepts and definitions associated with NC milling machines are described from a mechanical engineering viewpoint. The technical and economic criteria of four chairside dental NC milling machines that are available on the market are then described. The technical criteria are focused on the capacities of the embedded technologies of these milling machines to mill both prosthetic materials and types of shape restorations. The economic criteria are focused on investment costs and interoperability with third-party software. The clinical relevance of the technology is assessed in terms of the accuracy and integrity of the restoration.

Characterizing the output settings of dental curing lights.

OBJECTIVES: For improved inter-study reproducibility and ultimately improved patient care, researchers and dentists need to know what electromagnetic radiation (light) is emitted from the light-curing unit (LCU) they are using and what is received by the resin. This information cannot be obtained from a dental radiometer, even though many studies have used a dental radiometer. METHODS: The light outputs from six LCUs (two QTH and four broad-spectrum LED units) were collected in real-time using an integrating sphere connected to a fiberoptic spectrometer during different light exposures. RESULTS: It was found that the spectral emissions were unique to each LCU, and there was no standardization in what was emitted on the various ramp (soft-start) settings. Relative to the normal use setting, using the ramp setting reduced the radiant energy (J) delivered from each LCU. For one of the four broad-spectrum LED LCUs, the spectral emissions in the violet range did not increase when the overall radiant power output was increased. In addition, this broad-spectrum LED LCU emitted no light from the violet LED chip for the first 5s and only emitted violet light when the ramp phase finished. CONCLUSIONS: A single irradiance value derived from a dental radiometer or from a laboratory grade power meter cannot adequately describe the output from the LCU. Manufacturers should provide more information about the light output from their LCUs. Ideally, future assessments and research publications that include resin photopolymerization should report the spectral radiant power delivered from the LCU throughout the entire exposure cycle.

Understanding the Potential of Digital Intraoral and Benchtop Scanning Workflows.

Although the overwhelming majority of dental offices now use digital radiography and patient records, relatively few yet use either stand-alone intraoral scanning systems (6%) or complete systems that combine intraoral scanning with computer-aided design and computer-aided manufacturing (12%). This should change as dentists become more aware of the numerous advantages scanning systems offer in terms of patient care and communication of patient information, particularly with the dental laboratory. This article reviews the various types of scanner architecture as well as potential workflow models.

Intraoral scanning systems - a current overview.

There is no doubt today about the possibilities and potential of digital impression-taking with the aid of intraoral optical impression systems, and the past few years have seen a considerable increase in the range of optical intraoral scanners available on the market. On the strength of numerous innovations and a wider range of indications in orthodontics and implantology, intraoral scanning systems appear to be a highly promising development for the future. Digital impression-taking with intraoral scanners has already shown itself in some respects to be clearly superior to conventional impression- taking. Particularly worthy of mention is the versatile integration of digital impressions into diagnostic and treatment concepts to provide a customizable healthcare solution for the patient. It remains exciting to look forward to future developments that will allow us to observe digital impression-taking--as with other digital applications already established in everyday life--becoming firmly established in the routine of dentistry and dental technology. This article presents an overview of the benefits and limitations of digital impression-taking using intraoral scanning systems, and includes a summary of all the relevant intraoral scanners available on the market at present.

Orthodontic scanners: what's available?

The popularity and availability of virtual technology in orthodontics for the replacement of hard-copy records with electronic records is growing rapidly, with a move towards a 'digital' patient for diagnosis, treatment planning, monitoring of treatment progress and outcome. As part of this ongoing development, three-dimensional digital models of the dental arches have the potential to replace traditional plaster models and their associated limitations for treatment planning, appliance construction and simulated treatment outcomes. This article provides the reader with a summary of the currently available benchtop model scanners and intraoral scanners. It is likely that this technology will become increasingly common-place within the orthodontic profession over the next decade.

Clinicians reaping benefits of new concepts in impressioning.

While conventional elastomeric impression materials are still being used to generate excellent impressions, the future of impression-taking is undoubtedly with digital intraoral scanners. Advances in scanning systems are making this technology easier to use and more practical for dentists.

Influence of occlusal loading force on occlusal contacts in natural dentition.

PURPOSE: Proper occlusal contact is important for the long-term success of prosthodontic therapy. We clarified the effects of occlusal loading force on occlusal contact in natural dentition by comparing measured values for occlusal loading and occlusal contact area. METHODS: Masseter muscle activity was measured in 10 subjects (2 male, 8 female; mean age, 27 years) with natural dentition using electromyography, with clenching at full strength with nothing interposed between the upper and lower teeth defined as 100% maximum voluntary contraction (MVC). Pressure-sensitive film (Occluzer) was used to examine occlusal contact points at 20, 40, 60, 80, 100 and 120% MVC. A material for checking accuracy of fit (BiteEye) was used to examine occlusal contact points at 20, 40, 60 and 80% MVC. ANOVA and the Bonferroni method were used to assess the results, with the level of significance set at 5%. Coefficients of variation (CV) were also calculated by dividing the standard deviation by the mean. RESULTS: Occlusal loading and occlusal contact area increased with clenching strength; however, CV showed differences between the methods at low and high MVC. CONCLUSIONS: With Occluzer, testing should be carried out at clenching strength ≥ 60% MVC. With BiteEye, testing should be carried out from light clenching strength at 20% MVC to moderate clenching strengths at 40-60% MVC. Occluzer and BiteEye (10 µm) gave similar occlusal contact areas at 60-80% MVC. These results suggest that combined use of Occluzer and BiteEye gives an accurate picture of occlusion from weak to strong clenching strength.

Usefulness of a rotation-revolution mixer for mixing powder-liquid reline material.

PURPOSE: The purpose of this study was to evaluate the distribution of bubbles, degree of mixing, flowability and mechanical strength of powder-liquid reline material by manually and with a rotation-revolution (planetary) mixer, and to determine the usefulness of a rotation-revolution mixer for this application. METHODS: Powder-liquid reline material (Mild Rebaron, GC, Tokyo, Japan) was mixed with a powder to liquid ratio of 1:0.62 according to the manufacturer's instruction. Two methods were used to mix it: mixed by manually ("manual-mixing") and automatically with a rotation-revolution mixer (Super Rakuneru Fine, GC, Tokyo, Japan; "automatic-mixing"). Disc-shaped specimens, 30 mm in diameter and 1.0mm in thickness, were used to observe the distribution of bubbles in at 10× magnifications. Flowability tests were carried out according to the JIS T6521 for denture base hard reline materials. A three point bending test was carried out by a universal testing machine. Elastic modulus and flexural stress at the proportional limit were calculated. RESULTS: A median of 4 bubbles and inhomogeneous were observed in manual-mixed specimens. However, no bubbles and homogeneous were observed in automatic-mixed specimens. Flowability was within the JIS range in all mixing conditions and did not differ significantly across conditions. The elastic modulus was the same for manual-mixed and automatic-mixed specimens. On the other hand, the flexural stress at the proportional limit differed significantly between manual-mixed and automatic-mixed specimens. CONCLUSION: The results confirm that rotation-revolution mixer is useful for mixing powder-liquid reline material. Automatic-mixing may be recommended for clinical practice.