Preliminary clinical study of the accuracy of a digital axiographic recording system for the assessment of sagittal condylar inclination.

OBJECTIVES: The aim of this study was to clinically evaluate the accuracy of a digital axiographic recording system in tracing the sagittal condylar inclination. METHODS: An axiographic examination that records the sagittal condylar path during protrusive/retrusive movement was performed on ten patients. Each subject was registered five different times by two different systems: 1) the Cadiax Gamma Diagnostic 4 computerized system as the control; 2) the Zebris Jaw Motion Analyser+  Optic System as the tested digital axiographic recording system. The records obtained allow to calculate the kinematic terminal transverse horizontal axis and the sagittal condylar inclination (SCI) at 3 and 5 mm along the pro-retrusive path. A linear mixed model was used to analyze if there was a statistically significant difference between the two systems. RESULTS: The mean left SCI value recorded by Zebris system were 49.81 ± 10.64° at 3 mm, 48.10 ± 11.04° at 5 mm, while the values recorded by Gamma system were 55.16° at 3 mm, 52.18° at 5 mm. The mean right SCI value recorded by Zebris system were 54.53 ± 10.26° at 3 mm, 51.85 ± 8.55° at 5 mm, while the values recorded by Gamma system were 49.68° at 3 mm, 48.23° at 5 mm. Linear mixed model showed no significant statistical difference between the two systems. CONCLUSIONS: Based on preliminary results, the Zebris Jaw Motion Analyzer+ Optic System demonstrates comparable accuracy to the Cadiax Gamma Diagnostic 4 when measuring sagittal condylar inclination. CLINICAL SIGNIFICANCE: The digital axiographic recording system enables to evaluate sagittal condylar inclination and to adjust virtual articulators in a digital workflow.

Assessment of Sagittal Condylar Guidance with Protrusive Inter-occlusal Method, Panoramic Radiographs, and Lateral Cephalogram: A Comparative Study.

BACKGROUND: Condylar guidance can be determined using the clinical and radiographic methods. The present study was conducted to determine condylar guidance using the protrusive interocclusal wax method, panoramic radiographs, and lateral cephalogram. AIMS: The aim of the study was to compare the correlation between sagittal condylar guidance with protrusive interocclusal method, panoramic radiographs, and lateral cephalogram. MATERIALS AND METHODS: The present study was conducted on 82 dentulous subjects (males 41, females 41). In all subjects, interocclusal registration values and condylar guidance values were measured using panoramic radiographs and lateral cephalograms. RESULTS: The mean ± SD protrusive interocclusal registration value on the left side was 34.01 ± 1.2 mm and 34.08 ± 1.4 mm on the right side. The panoramic radiographs showed 35.12 ± 1.6 mm on the left side and 35.16 ± 1.7 mm on the right side. The mean ± SD protrusive interocclusal registration values on the left side was 34.01 ± 1.2 mm on the left side and 34.08 ± 1.4 mm on the right side. Lateral cephalogram showed 34.35 ± 1.3 mm on the left side and 34.67 ± 1.6 mm on the right side. There was a significant difference between the methods (p < 0.05). CONCLUSION: Sagittal condylar guidance can be evaluated using protrusive interocclusal method. Along with it, other methods such as panoramic radiographs and lateral cephalogram may also be used for recording condylar guidance. CLINICAL SIGNIFICANCE: Lateral cephalogram and panoramic radiographs may be reliable in determining condylar guidance, which can be used in orthodontic treatment planning.

Occlusal Assessment of Zirconia Crowns Designed with the Digital Articulator and Traditional Methods.

PURPOSE: To evaluate and compare the occlusal fit of zirconia crowns designed using a digital articulator method and the traditional method in a self-controlled clinical trial. MATERIALS AND METHODS: Two zirconia crowns each were prepared for 12 patients with a single posterior tooth defect using two different methods: a digital articulator method and the traditional method. In the traditional method, casts were scanned using a model scanner, and the relative positions of the maxillary and mandibular arches were determined by the intercuspal occlusion of the casts. In the digital articulator method, casts were mounted on a mechanical articulator and scanned, and the relative positions were determined by their respective positions in the articulator. Additional dynamic occlusal adjustments of the digital articulator crowns were performed. Both groups of zirconia crowns were milled in a five-axis milling machine. The time required for occlusal adjustments, the occlusal contacts, the occlusal contact distributions, the number of occlusal contacts, the relative occlusal forces, and patient satisfaction (visual analog scale score) were evaluated. Wilcoxon test, McNemar test, and paired t test were used to compare the parameters between the two methods. RESULTS: The occlusal adjustment times for the digital articulator and traditional method crowns were 327 ± 226 seconds and 395 ± 338 seconds, respectively (P > .05). There were no significant differences in occlusal contacts, occlusal contact distributions, number of occlusal contacts, relative occlusal forces, or VAS scores between the two methods (P > .05). CONCLUSION: A digital articulator method for single-crown restoration was applied successfully. Crowns fabricated using a digital articulator or the traditional method can achieve acceptable occlusal fit for single-crown restorations.

Complete assessment of occlusal dynamics and establishment of a digital workflow by using target tracking with a three-dimensional facial scanner.

PURPOSE: To introduce a new and simple digital workflow to record dynamic occlusion, and apply it to occlusal analysis and prosthetic treatment in a virtual environment. METHODS: A table-top scanner (Identica hybrid) was used to transfer fabricated casts into a virtual environment. A facial scanner (Rexcan CS2) was used for facial scanning and target tracking. Four targets were attached to each of the four incisors in the maxilla and mandible to track jaw movement. Target position data were recorded in real time during eccentric movement. The targets were replaced with maxilla and mandible cast scan data, and mandibular movement relative to the maxilla was reconstructed. Four types of antagonist meshes were reconstructed in computer-aided design (CAD) software (EzScan8). The CAD software (Exocad) enabled checking of occlusal contacts in the maximal intercuspation position during eccentric movement. CONCLUSIONS: Target tracking data were transformed into video clips of dental cast scan data, which showed jaw movements in real time. Occlusal contact information was produced by the CAD software. Both dynamic and static occlusion analyses were performed with reconstructed eccentric movement antagonist meshes. Our new method for reconstructing eccentric movements of the mandible can reveal the occlusal dynamics of a patient within a virtual environment.

Digitizing the Facebow: A Clinician/Technician Communication Tool.

Communication between the clinician and the technician has been an ongoing problem in dentistry. To improve the issue, a dental software application has been developed--the Virtual Facebow App. It is an alternative to the traditional analog facebow, used to orient the maxillary cast in mounting. Comparison data of the two methods indicated that the digitized virtual facebow provided increased efficiency in mounting, increased accuracy in occlusion, and lower cost. Occlusal accuracy, lab time, and total time were statistically significant (P<.05). The virtual facebow provides a novel alternative for cast mounting and another tool for clinician-technician communication.

Digital data acquisition for a CAD/CAM-fabricated titanium framework and zirconium oxide restorations for an implant-supported fixed complete dental prosthesis.

This dental technique report describes a digital workflow with digital data acquisition at the implant level, computer-aided design and computer-aided manufacturing fabricated, tissue-colored, anodized titanium framework, individually luted zirconium oxide restorations, and autopolymerizing injection-molded acrylic resin to fabricate an implant-supported, metal-ceramic-resin fixed complete dental prosthesis in an edentulous mandible. The 1-step computer-aided design and computer-aided manufacturing fabrication of titanium framework and zirconium oxide restorations can provide a cost-effective alternative to the conventional metal-resin fixed complete dental prosthesis.

The reliability of computerized condylar path angle assessment.

Recording the track of the mandibular hinge axis and consequently ascertaining the posterior determinants is one of the key requirements for accurately simulating individual oral conditions in the (virtual) articulator. The aim of this study was to determine the reliability of computerized condylar path inclination angle (CPIA) measures and to assess whether the reliability depends on the mandibular dentition. Sagittal and transverse CPIA were measured using computerized axiography (Cadiax Compact 2) at two separate sessions in prosthodontic patients (mean age +/- SD: 64.3 +/- 10.3 years; female: 45%) who were classified into three dentition categories (fully dentate: N = 19, partially dentate: N = 27 and edentulous: N = 19). These measurements were repeated three times at both sessions without removing the computerized axiograph. Reliability was assessed in multilevel analyses using the subject as a grouping variable in linear random-intercept models. Considering all assessment procedures, the patient-specific differences explained 75% of the variance for the sagittal and 38% for the transverse condylar path. This corresponds to the overall reliability of both the sagittal and the transverse CPIA assessment. The dentition had no significant impact on the reliability of the measurements. The sagittal CPIA can be assessed with satisfactory reliability using computerized axiography. It is independent of the status of the dentition, which has no statistically significant impact on the measures. Transverse CPIA measurements have shown poor reliability. Therefore, the electronic determination of the sagittal CPIA is a reliable procedure that can be applied in patients irrespective of the status of the mandibular dentition.

Assessment of speech production with dentures by electromagnetic articulography.

This report investigates the use of electromagnetic articulography (EMA) to compare basic speech patterns between a patient with traditional dentures to those of a normally dentate person. The goal is to assess the efficacy of traditional dentures in order to generate clinical data and works towards the improvement of denture design. Kinematic and acoustic data were acquired for these two subjects using a variety of repetitive vowel-consonant-vowel tasks. Spatiotemporal parameters indicating dynamic properties of the tongue blade and jaw movements, and timing coordination of the movements between them and with the output acoustic signal, were measured and compared within and between the participants. The results show significant differences in both spatial and temporal patterns and variation between individual tasks within each subject's data, as well as a difference in the two subjects' performance of the same task (cross-subject) for select calculated kinematic and latency parameters. It is concluded that there is more variation in spatiotemporal parameters in speech patterns for patients with dentures than without; in particular, latencies of the tongue blade and jaw movements and acoustic landmarks of the consonants, show strategies of movements timing coordination, typical of the speaker with denture.

Complete denture services: clinical technique, lab costs, manpower, and reimbursement. One-year review.

Complete denture services at comprehensive care public health clinics are not common in part because of clinician concerns regarding outcomes. Educational debt forgiveness has attracted recent dental graduates to public health dentistry; however, not all recent graduates receive denture education experiences necessary to attain proficiency. While fundamental patient assessment and denture construction are taught, psychological assessment and communication with denture patients requires experience. A thorough understanding of occlusion, phonetics, esthetics and laboratory steps is also necessary. Expecting recent dental graduates to become proficient providing complete dentures at minimal reimbursement levels, with no mentorship or on-site laboratory support, is unrealistic. Public health dental clinics operate at full capacity performing emergency, preventive and restorative procedures. Complete dentures come with a laboratory fee approximately one-half the total reimbursement, meaning a remake drops clinic revenue to zero while doubling expenses. It is understandable that full schedules, marginal reimbursement, unpredictability and the risk of an occasional failure block clinician interest in providing denture services. This one-year report of services describes a three-appointment complete denture technique offering improved patient and laboratory communication, reduced chair time and controlled cost, resulting in high-quality complete dentures.

Avaliação das dimensões programáveis dos articuladores semi-ajustáveis / Assessment of the programmable dimensions of the semi-adjustable articulador

O articulador semi-ajustável tem o propósito de reproduzir as relações maxilomandibulares estáticas e, parcialmente, as dinâmicas. No entanto, parte destas características depende da qualidade da fabricação dos aparelhos. O objetivo foi aferir os componentes responáveis pela determinação do ângulo de Bennett (AB), da eminência articular (EA) e da distância intercondilar (DI) do articulador semi-ajustável (ASA) Dentflex...

Making occlusion work: I. Terminology, occlusal assessment and recording.

This is the first paper in a two-part series reviewing some of the relevant theoretical aspects of occlusion and describing its application in clinical practice. This article discusses terminology, clinical examination of the occlusion, articulators and interocclusal records.

A clinical and cost-benefit evaluation of five facebows.

OBJECTIVE: Although the use of an arbitrary facebow and a full-sized articulator can reduce laboratory errors, many dentists do not use a facebow routinely because the procedure seems to be both intricate and time consuming. The purpose of the present study was to evaluate four earpiece-type facebows and the Snow facebow and to compare the time required for registration, the ease of manipulation, and cost-benefit considerations. METHOD AND MATERIALS: Twenty-five dentists who routinely used only the Snow facebow were asked, after a brief explanation, to perform registrations with the Snow facebow and four new-generation, earpiece-type facebows. The time required for each facebow registration was recorded. Dentists were also asked to fill out a questionnaire concerning ease of manipulation and cost-benefit factors. RESULTS: The Quick facebow was the facebow of choice of most of the dentists because of its favorable design and usage characteristics and cost-benefit ratio. The Artex 3-D facebow proved to be both the easiest and the fastest to manipulate. The Spring-bow and the Whip-Mix Quickmount were next in rank, and the Snow facebow scored the lowest. CONCLUSION: The use of earpiece-type facebows is both simple and fast, and practitioners judged this type of facebow to be superior to the Snow facebow.

Three-dimensional assessment of the reliability of a postural face-bow transfer.

STATEMENT OF PROBLEM: Incorrect 3-dimensional orientation of a dental cast may compromise the functional and esthetic result of prosthetic restorations. PURPOSE: This study assessed the reliability of a new method to transfer the 3-dimensional orientation of the occlusal plane with a postural face-bow. MATERIAL AND METHODS: The 3-dimensional position of the occlusal plane in 20 subjects (age 20 to 32 years) with a complete dentition in both arches was assessed with a postural face-bow. An irreversible hydrocolloid impression of the maxillary arch was made for each subject and poured in dental stone. The maxillary arch was mounted in an articulator with use of a postural face-bow. The 3-dimensional position of the occlusal plane was then measured and compared to the values obtained with the use of a previously certified, computerized, noninvasive instrument. This instrument digitizes the coordinates of dental and facial landmarks and then calculates the spatial position of the occlusal plane. For each subject, the direct assessment and the face-bow measurement were compared by calculating the absolute difference of the following: the inclination of the occlusal plane relative to the true vertical, frontal plane projection (angle alpha) and sagittal plane projection (angle beta); intercondylar distance; distance of the center of gravity of the anterior part of the maxillary arch to the midpoint of the intercondylar axis; and the maxillary right canine to right condylion distance. Descriptive statistics of the differences were calculated. RESULTS: The postural face-bow appeared reliable and compared well to the computerized assessment, with mean differences ranging from 2.5 degrees to 3 degrees. CONCLUSION: In the population tested, a postural face-bow reliably reproduced the spatial orientation of the occlusal plane relative to the true horizontal plane. This position was transferred to an articulator with limited errors.

Using articulators to enhance clinical practice.

This paper looks at how articulators can be of value in everyday NHS practice. A variation on the conventional classification of articulators is suggested with advice provided for the practitioner who wants to enhance his or her restorative work without immediately investing in high cost equipment. It is argued that rather than prolong chairside time, for specific types of treatment the use of an appropriate articulator and facebow can not only enhance the quality of the completed restoration, but also save on chairside time.

Condylar determinants in a patient population: electronic pantograph assessment.

Posterior condylar determinants play a key role in the establishment of a stable and harmonious occlusal scheme. Various methods exist to record the posterior condylar factors. The Denar electronic pantograph computes these condylar determinants automatically after the execution of a pantographic tracing. Research has validated the accuracy and reliability of this electronic pantograph. Electronic pantographic analysis was carried out on 55 patients referred for various prosthodontic consultations. Values for condylar determinants were recorded and statistically appraised. Values for these condylar determinants were variable with a large range. The variability in condylar values suggests the importance of determining an individual's condylar determinants rather than relying on average values.

Treatment prediction with three-dimensional computer tomographic skull models.

Orthodontic and surgical treatment planning in the conventional articulator is compared with three-dimensional computer tomographic (3D-CT) model surgery in an individually milled skull model. After computer tomography has been completed of the patient's skull that has a bimaxillary asymmetric disharmony, the data set is transferred to generate individually milled polyurethane foam models. The imprecisely delineated dental arches of the skull model are replaced by dental casts that allow the simulation of various orthodontic and surgical treatment procedures. Expected segment displacement, the best osteotomy lines, and the resulting skeletal and dental symmetry in relation to the orthodontic set up can be evaluated. Although the technique is both time-consuming and expensive compared with the traditional treatment planning through the articulator, we have included 3D-CT model surgery in our presurgical work-up of patients with severe dentofacial disharmonies. Especially in asymmetric cases, the individually milled skulls allow a higher precision of orthodontic and surgical treatment planning.

The check record in NHS practice.

Incorrect occlusion is a major cause of complete denture failure. Any technique which has the potential to solve this problem and consequently limit the number of review appointments must be worthy of consideration. The pre-occlusal or precentric check record is an accurate method of verifying the occlusion of complete dentures. Although the check record is taught in many teaching hospitals, it is not widely used in general practice. This is primarily due to the time-consuming nature of the conventional method. A variation on the standard technique is described, which is designed specifically for NHS complete denture practice. The materials used are inexpensive and the procedure takes approximately 10 minutes.