Precise jaw relation recorder: An innovative device for prosthodontic rehabilitation.

BACKGROUND: The orchestration of jaw relations in edentulous scenarios poses a significant challenge, demanding acumen, and expertise from the clinician. A myriad of devices, substances, and methodologies are employed to gauge the transverse, vertical, and horizontal spectrums of jaw relations. Traditionally, a synthesis of assorted devices and techniques has been requisitioned to chronicle the spatial dynamics between the maxilla and mandible. Yet, the absence of a solitary apparatus capable of concurrently documenting the triad of jaw relations has been a notable lacuna in prosthodontic rehabilitation. PURPOSE: This discourse expounds on an innovative contrivance, termed the Precise Jaw Relation Recorder. This pioneering instrument is adept at capturing the tripartite jaw relation processes: the occlusal plane's alignment in parallelism to the ala-tragus line, the vertical dimension at repose, and the occlusion as well as the centric relation. The device's strategic utility lies in its ability to facilitate the creation of prostheses that are not only functionally superior but also aesthetically more pleasing. CONCLUSION: Its implementation is a stride toward refining the accuracy of prosthodontic outcomes, thereby elevating the standard of patient care in dental practice.

Biofilm formation on polyetheretherketone and titanium surfaces.

Objective: Polyetheretherketone (PEEK) is a polymer used in devices in orthopedic and dental rehabilitation. The aim of this in vitro study was to compare biofilm formation by a range of important oral bacterial species on PEEK, blasted PEEK, commercially pure titanium (cp-Ti), and titanium-6 aluminium-4 vanadium (Ti6Al4V). Material and methods: Coin-shaped samples were manufactured, and the surfaces were characterized using optical interferometry, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and contact angle measurements. Bacterial species of Streptococcus sanguinis, Streptococcus oralis, Enterococcus faecalis, and Streptococcus gordonii were cultured on the four material surfaces for varying amounts of time. Biofilms were quantified following staining with crystal violet. Results: Roughness and contact angle results showed blasted PEEK > PEEK > cp-Ti = Ti6Al4V. There was increased biofilm formation on blasted PEEK by S. sanguinis, S. oralis, and S. gordonii, whereas the bacterial adhesion was similar on PEEK, cp-Ti, and Ti6Al4V. The bacterial growth of E. faecalis was significantly higher on cp-Ti compared with the other three groups. Conclusion: The results, taking into consideration the biofilm formation, suggest that PEEK should perform as well as cp-Ti or TiAl6V4 when used as a dental restorative material.

Cytotoxicity of titanium carbonitride coatings for prostodontic alloys with different amounts of carbon and nitrogen.

The aim of our work was to examine the cytotoxicity of NiCr alloys coated with Ti(C,N) with different amounts of C and N in the layer on human gingival fibroblasts. Cells were cultured for 24 hours in the alloy extracts or on the surface of tested materials. The viability of the cells exposed to 1-, 3-, 5- and 7-day extracts did not change in comparison to the viability of cells cultured in a control medium assayed by an MTT test. Moreover, the flow cytometry analysis of fibroblasts cultured in direct contact with tested alloys revealed that all coatings except TiC did not induce apoptosis or necrosis. Interestingly, 24 hour fibroblast culture on alloys with Ti(C,N) coatings showed that the number of fibroblasts adhered to these alloys, evaluated by scanning electron microscope, increased with an increase in the content of nitrogen in the layer. The present study demonstrates that Ti(C,N) coatings were not cytotoxic and did not induce apoptosis in Ti(C,N) extracts, nor in direct contact with gingival fibroblasts, and can be considered for biomedical applications in the future.

Clinical factors in prosthodontic treatment of children with genetic defects.

BACKGROUND: Prosthodontic treatment of children with genetic disorders is an area that is rarely examined in the current specialist literature. Few prosthodontists will undertake treatment of such patients, who will more often be referred to an orthodontic specialist. After examining the 4 cases of children with genetic disorders described in this paper, it can be concluded that when a prosthodontist includes a few additional procedures in the treatment process, he or she can successfully help such patients. OBJECTIVES: The aim of this paper is to indicate the clinical difficulties faced by prosthodontists who undertake prosthodontic rehabilitation of children with genetic disorders. MATERIAL AND METHODS: The paper is based on data collected during the prosthodontic treatment of 4 children, aged 5-12 years with genetic defects, and analysis of the body of work concerning these defects and their treatment. RESULTS: Presentation of guidelines for the prosthodontic treatment process and creation of dentures for treated children based on extended procedures. CONCLUSIONS: A prosthodontist is a crucial person in a team of specialists treating disorders within the face among children with a genetic predisposition. A basic knowledge of orthodontics and psychology facilitates the treatment. Prosthetic restoration in the treatment group does not always require complicated operations. Individualization of the tools for downloading orthodontic impressions, designing denture elements and an increased number of checkups are the additional procedures. For the clinician, the emotional aspect of the treatment is the main impediment. Maintaining a good relationship with a patient and his or her caregivers requires interpersonal skills.

Reinforcement in removable prosthodontics: a literature review.

Removable prosthodontics are often associated with mechanical troubles in daily use, such as fracture or deformation. These troubles render prostheses unusable and reduce wearers' QOL. Various reinforcements are used to prevent such problems, but consensus on reinforcement has not been reached. This review aimed to summarise the effects of reinforcement and to propose favourable reinforcement based on material, design and position in the prostheses. Initially, 139 articles were selected by electronic and manual searches. After exclusion of 99 articles based on the exclusion criteria, 40 articles were finally included in the review. Electronic searches were performed for articles published from 2005 to 2015 in PubMed, EMBASE, MEDLINE and Cochrane Library, and manual searches were performed in 10 journals relevant to the topic of removable prosthodontics. For in vitro studies, certain dental alloys and fibres were mainly used. Their forms were different, including complicated forms in dental alloys and various forms in fibres. The materials were examined for mechanical properties like fracture strength, flexural strength and elastic modulus and compared with one another or without reinforcement. There were a few clinical studies and one longitudinal study. Cast metal reinforcement seemed to be most favourable in terms of fracture toughness and stiffness. The most favourable forms differed depending on the prostheses, but placement around thin and deformable areas was effective. However, randomised or longitudinal clinical reports and comparative clinical studies on the use of reinforcement were still lacking and such studies are necessary in the future.

[COMBINED ACRYLIC-POLYPROPYLEN REMOVABLE PROSTHESES FOR PROSTHODONTIC TREATMENT].

The article deals with the development of methods to prevent complications with prosthetic dentures patients with psychiatric status. The authors developed a method of manufacturing the denture using modern thermoplastic materials, the use of which in practice does not cause prosthetic stomatitis in patients with psychiatric status. The proposed methodology has been tested clinically. Based on Schiller- Pisarev and study fixation of prostheses has been shown the advantage of the prosthesis used for prosthetics partial dentition defects that can not be fixed prosthetics in this category of patients.

The Effect of a Combination of Implant Controller and Handpiece from Different Manufacturers on the Torque Value.

PURPOSE: To determine the accuracy of applied torque of different implant controller and handpiece combinations by using an electronic torque gauge. MATERIALS AND METHODS: Four combinations of the following devices were tested: Surgic XT controller (NSK), XIP10 controller (Saeshin), X-SG20L handpiece (NSK), CRB26LX handpiece (Saeshin). For five torque settings, 30 measurements were recorded at 30 revolutions per minute by using an electronic torque gauge fixed to jigs, and means were calculated. RESULTS: Applied torques were generally higher than the set torque of 10 and 20 Ncm and lower than the set values of 40 and 50 Ncm. The average torque deviations differed significantly among the combinations (P < .05). At 10 and 20 Ncm, the Surgic XT/X-SG20L combination yielded the closest value to the intended torque, followed by the XIP10/X-SG20L combination. At 30 Ncm, the XIP10/X-SG20L combination showed the nearest value. At 40 Ncm, the Surgic XT/X-SG20L, XIP10/CRB26LX, and XIP10/X-SG20L combinations showed deviations within 10%. At 50 Ncm, all the combinations showed lower applied torque than the set value. Large standard deviations were observed in the Surgic XT/CRB26LX (13.288) and Surgic XT/X-SG20L (7.858) combinations. CONCLUSION: Different combinations of implant controllers and handpieces do not generate significant variations in applied torque. The actual torque varies according to the torque setting. It is necessary to calibrate devices before use to reduce potentially problematic torque.

Influence of Conventional and Digital Wax-ups on Axial Tooth Contour.

The aim of this study was to evaluate the impact of conventional and digital diagnostic wax-up on the axial tooth contour. Dental models of 15 patients were collected. Each model received conventional wax-up and digital wax-up. The conventional wax-up was based on tooth modification with dental wax on actual models. The digital wax-up involved fitting an average tooth form on virtual pretreatment models. Each wax-up model was digitally superimposed on the corresponding pretreatment model. For each modified tooth, analysis planes were extracted at three locations: mesial line angle, midtooth, and distal line angle. The impact of the following variables was evaluated: interarch location (maxilla vs mandible), intra-arch location (anterior vs posterior), tooth category (incisors, canines, premolars, and molars), and tooth location (midtooth vs line angle). The axial contour of the modified teeth increased after each wax-up, and this increase was directly proportional to the distance from the gingival margin. There is a clear tendency for the digital wax-up to cause a greater contour increase than the conventional wax-up. The anterior teeth were associated with a greater tooth contour increase than posterior teeth and the contour of the molars was the least affected. Although the conventional wax-up contour alteration was significantly less than for the digital wax-up, the actual difference was minimal.

Using double occlusion checking system and Bi-digital O-Ring Test to determine the vertical dimension of occlusion for maxillofacial prosthodontics for patients with long-term pathophysiological condition.

Common practice of establishing occlusal vertical dimension by adopting traditional method for patients with long-term pathological conditions has left the results much less than desired, since the degree of pathological condition for each patient varies from one patient to another, and traditional methods to determine vertical dimension are mostly intended for normal patients. Ideally, the occlusal vertical dimension should be dictated by, and conformed to patient's comfort range for the physiological accommodation to each patient's condition. This article describes a method of a double checking system for occlusion determination by increasing vertical dimension of occlusion (VDO) by 1/2 mm each week to find the most comfort zone and beyond for patient, and then to gradually decrease ½ mm of the VDO each week to the original VDO to double check the comfort zone for the patient. During the process, Bi-Digital O-Ring Test was employed to corroborate, to determine, and to individualize the occlusal vertical dimension for patients with pathological abnormalities. Traditional methods of vertical dimension determination were merely used as a guiding reference in our treatment of those patients. Patient's comfort and discomfort were carefully recorded, compared and studied before the denture prosthesis was fabricated.

The overuse of the implant motor: effect on the output torque in overloading condition.

BACKGROUND: The overloading of the motor affects its performance. The output torque of the implant motor under overloading condition has not been reported. PURPOSE: The purpose of this study was to determine the reliability and the tendency of the output torque when an implant motor is consecutively used. MATERIALS AND METHODS: Three implant motors were evaluated: SurgicXT/X-SG20L (NSK), INTRAsurg300/CL3-09 (KaVo), and XIP10/CRB26LX (Saeshin). The output torque was measured using an electronic torque gauge fixed with jigs. For the 40 and 50 Ncm torque settings, 300 measurements were taken at 30 rpm. Repeated measures of analysis of variance (ANOVA) and one-way ANOVA were used to compare the torque values within each group and between the groups. RESULTS: As repeating measures, the output torque values decreased gradually compared with the baseline. In within-group analysis, the different torque value from the first measurement appeared earliest in NSK motor, followed in order by Saeshin and KaVo motors. NSK motor showed a different torque decrease between 40 and 50 Ncm settings (p < .05). Intergroup analysis revealed Saeshin motor to have the least deviation from the baseline, followed by KaVo motor. NSK motor had the most inconsistent torque at the 6, 8, 9, and 10 repeat counts (p < .05). CONCLUSION: The actual torque decreases when the surgical motor is continuously used. The NSK motor showed more significant decreases in torque than KaVo and Saeshin motors in overloading condition.

Face-bow transfer in prosthodontics: a systematic review of the literature.

An extensive search for randomised controlled clinical trials was accomplished to compare dental prostheses and occlusal splints constructed with or without face-bow transfer, and question whether face-bow transfer may present better clinical results than simpler approaches. Studies were identified by searching electronic databases (PubMed/MEDLINE, Latin American and Caribbean Literature on the Health Science, and Brazilian Bibliography of Dentistry). The keywords 'dental articulator', 'semi-adjustable articulator', 'face-bow', 'jaw relation record' and 'occlusal splint therapy' were used. The minimum inclusion requirements were (i) randomised controlled trials with patients of any age, (ii) comparison between dental prostheses or occlusal splints constructed with or without face-bow transfer and (iii) assessment of clinician's time, number of occlusal contacts, patient satisfaction or masticatory function. The search resulted in the identification of 8779 articles. Subsequently, 8763 articles were excluded on the basis of title and abstract. By the end of the search phase, eight randomised controlled trials were considered eligible. Current scientific evidence suggests that face-bow transfer is not imperative to achieve better clinical results in prosthodontics. Randomised clinical trials suggest that simpler approaches for the construction of complete dentures and occlusal splints may present acceptable results, while no clinical study has investigated its use in fixed and removable partial dentures.

Comparative study of the cutting efficiency and working life of carbide burs.

PURPOSE: The aim of this study was to establish the wear and cutting efficiency of tungsten carbide burs from different manufacturers by performing cutting tests with machinable glass ceramic. MATERIALS AND METHODS: Cutting tests were performed with 70 tungsten carbide burs from seven manufacturers: (A) Coltene/Whaledent, (B) CEI, (C) Meisinger, (D) Axis, (E) Komet, (F) Kerr, (G) Edenta. All groups were examined under scanning electron microscope (SEM) before and after the cutting efficiency test for similarities and differences. A specially designed cutting device was used. An electric handpiece was operated at 200,000 rpm with a 120 ml/min coolant water supply rate. The burs were tested under a 165 g constant load using 3 mm wide Macor ceramic as substrate. For each bur the cutting procedure involved a total of five cuts of 3 minutes on every cut, with a total cutting time for each bur of 15 minutes. Data were analyzed using one-way ANOVA at 95.0% confidence level. RESULTS: Significant differences (p < 0.05) were found in the mean cutting rates of the different groups. Groups A and B showed the highest cutting rates. Higher cutting rates were associated with a longer bur lifespan. SEM photomicrographs of the burs and substrates revealed significant changes on the surfaces after the cutting process. CONCLUSIONS: The morphology characteristics of tungsten carbide burs are related to their effectiveness. The group that presented the worst working life also showed substantial wear on its surface according to the results of SEM.

The effect of ultrasonic instruments on the quality of preparation margins and bonding to dentin.

STATEMENT OF THE PROBLEM: Ultrasonic instruments have recently been developed for finishing crown preparations. They are successful in accessing difficult areas on the preparation margin, but their effects on the dentin surface and on bond strength are contradictory. PURPOSE: The aim was to evaluate the condition of crown preparation margins finished using new ultrasonic instruments and to assess their effects on dentin bond strength. METHODS: Characteristics of tooth surfaces prepared using two different ultrasonic protocols were compared; Perfect Margin Shoulder (PMS) (PMS 3, Satelec, Merignac, France) 1, 2, and 3 (complete finishing) versus PMS 1 and 2 (partial finishing). They were assessed using scanning electron microscopy (SEM) and surface roughness analysis. Bonding of composite resin to dentin surfaces prepared with the complete PMS kit was compared with dentin surfaces prepared with finishing diamond burs, using micro-tensile testing. RESULTS: SEM images revealed a clear difference between the two preparation sequences (PMS 1, 2 versus PMS 1, 2, and 3). Surfaces finished using the PMS tips 1, 2, and 3 appeared continuous, even, and smooth compared with PMS tips 1 and 2 only. The additional use of the PMS 3 uncoated tip enhanced smear layer removal. There was no significant difference when comparing the surface roughness obtained with the PMS 1, 2, and 3 protocol with the PMS 1 and 2 only (p > 0.05). Micro-tensile bond strength was not significantly different between the surfaces prepared with the ultrasonic instruments and the surfaces prepared with the diamond burs (p > 0.05). CONCLUSION: The use of the complete PMS finishing kit (PMS 1, 2, and 3) produced better quality finishing lines than PMS 1 and 2. The use of ultrasonic instruments to prepare dentin resulted in comparable bond strengths to the use of diamond burs. CLINICAL SIGNIFICANCE: The extremely precise preparation margin possible with ultrasonic instruments improves the quality and accuracy of crown preparations, which may lead to better impressions and closer adaptation of restorations. The complete set of three Perfect Margin Shoulder instruments is recommended, which can produce comparable bond strengths to preparations with rotary instruments.

Prosthodontic maintenance requirements of implant-retained overdentures using the locator attachment system.

The aim of this study was to investigate the prosthodontic maintenance requirements of patients rehabilitated with maxillary and mandibular implant-retained overdentures using the Locator Attachment System by retrospectively reviewing case records. Fifty patients made 112 unplanned return visits over a 3-year period. The most common reasons for returning were denture adjustments (n = 45), inadequate retention (n = 39), and loosening of the implant abutments (n = 14). Implant-retained overdentures using the Locator Attachment System have comparable prosthodontic maintenance requirements to other attachment systems. Problems associated with these prostheses are usually simple to resolve chairside.

An audit of dental prescriptions between clinics and dental laboratories.

AIM: To discover the quality of written instructions from dentists to dental technicians and the nature of non-compliant prescriptions. METHOD: An audit of laboratory prescription compliance was conducted within an NHS Trust Dental Teaching Hospital to determine the level of communication between dentists and dental technicians. One hundred and fifty prescriptions were audited from dental undergraduates and qualified dentists throughout the different departments. RESULTS: A total of two-thirds of prescriptions were considered non-compliant and failed to meet relevant ethical and legal guidelines. This problem was seen throughout all departments and at all professional levels. CONCLUSION: A breakdown in communication between dentists and technicians through the use of prescriptions is evident even within a close working environment.

Calibration of T-Scan sensors for recording bite forces in denture patients.

Although measurement of maximum voluntary biting force is an important indicator of health of the masticatory system, few commercially available transducers have been validated for routine clinical use. The T-Scan III system records distribution of relative forces around the tooth row during clenching, but not absolute forces. This study assesses the reliability of T-Scan sensors with and without protection materials and develops calibration curves that allow measurement of absolute forces with the T-Scan III.

In vitro comparison of the cutting efficiency and temperature production of 10 different rotary cutting instruments. Part I: Turbine.

STATEMENT OF PROBLEM: Standards to test the cutting efficiency of dental rotary cutting instruments are either nonexistent or inappropriate, and knowledge of the factors that affect their cutting performance is limited. Therefore, rotary cutting instruments for crown preparation are generally marketed with weak or unsupported claims of superior performance. PURPOSE: The purpose of this study was to examine the cutting behavior of a wide selection of rotary cutting instruments under carefully controlled and reproducible conditions with an air-turbine handpiece. MATERIAL AND METHODS: Ten groups of rotary cutting instruments (n=30) designed for tooth preparation were selected: 9 diamond rotary cutting instruments (7 multi-use, 2 disposable) and 1 carbide bur. One bur per group was imaged with a scanning electron microscope (SEM) at different magnifications. Macor blocks (n=75) were used as a substrate, and 4 cuts were made on each specimen, using a new rotary cutting instrument each time, for a total of 300 cuts. The cuts were performed with an air-turbine handpiece (Midwest Quiet Air). A computer-controlled, custom-made testing apparatus was used to monitor all sensors and control the cutting action. The data were analyzed to compare the correlation of rotary cutting instrument type, grit, amount of pressure, cutting rate, revolutions per minute (rpm), temperature, and type of handpiece, using 1-way ANOVA and Tukey's Studentized Range test (alpha=.05). RESULTS: Compared to the baseline temperature, all rotary cutting instruments showed a reduction of temperature in the simulated pulp chamber. The Great White Ultra (carbide bur) showed a significantly higher rate of advancement (0.15 mm/s) and lower applied load (106.46 g) and rpm (304,375.97). CONCLUSIONS: Tooth preparation with an adequate water flow does not cause harmful temperature changes in the pulp chamber, regardless of rotary cutting instrument type. The tested carbide bur showed greater cutting efficiency than all diamond rotary cutting instruments.

Mandibular single-implant overdentures: a review with surgical and prosthodontic perspectives of a novel approach.

OBJECTIVES: To review the literature on mandibular single-implant overdentures (opposing complete maxillary dentures), and present surgical and prosthodontic perspectives of a novel approach for this treatment option. MATERIAL AND METHODS: An electronic search through the databases of Pubmed, Embase and Medline using the linked key words 'mandibular single implant overdentures' was performed. The search was limited to English language articles published up to August 2008. Hand searches through articles retrieved from the electronic search, peer-reviewed journals and recent conference proceedings were also conducted. RESULTS: A limited number of reports were identified on mandibular single-implant overdentures (opposing maxillary complete dentures). They comprised of case-series reports, short-term prospective trials and current randomized-controlled clinical trials. Different loading protocols with different implant systems have been used, but always with regular diameter implants. Specific anatomical and vascular dangers of the mandibular midline symphysis are identified including a novel surgical approach using a currently available short, wide diameter tapered implant. In addition, the prosthodontic rationale for using a larger attachment system (incorporating a platform switch) for mandibular single-implant overdentures is described. CONCLUSION: The review reveals that there is a lack of published randomized clinical trials using mandibular single-implant overdentures, opposing maxillary complete dentures. Without the evidence from randomized clinical trials, routine use of this novel approach cannot be recommended, compared with using regular diameter implants and matching attachment systems.