The influence of anterior guidance and condylar guidance on mandibular protrusive movement

THREE-DIMENSIONAL ASSESSMENT OF THE SAGITTAL CONDYLAR INCLINATION IN SKELETAL CLASS II PATIENTS BASED ON COMPUTER AIDED DIAGNOSIS AXIOGRAPH AND CONE-BEAM COMPUTED TOMOGRAPHY

Great variation has been found in sagittal condylar inclination (SCI) values among individuals with different skeletal structures. Therefore, average value articulators cannot fully represent the physiological characteristics of the mandible, or reproduce its sagittal movements. The purpose of this study was to measure the SCI value of skeletal Class II patients by two different three-dimensional assessments, and to evaluate the correlation and consistency between the two methods. A total of 23 patients (aged 15–65 years) diagnosed with skeletal Class II malocclusion were recruited from the Stomatological Center of Shunde Hospital, Southern Medical University. Subjects were divided into three groups based on different A point–nasion–B point angle (ANB), and angle between the upper central incisor and Frankfort horizontal plane (U1-FH). Bilateral SCI values were measured using computer-aided diagnosis axiography (CADIAX) and cone-beam computed tomography (CBCT). Statistical analysis showed that the SCI value measured by CADIAX was significantly higher than that measured by CBCT. Significant differences were found among different ANB and U1-FH groups, and the average value of the [Formula: see text] group was the highest. Our findings indicate that the measurement of SCI by CADIAX cannot be replaced by CBCT, and it is recommended that personalized measurements of SCI values in skeletal class II patients be carried out. Individual SCI measurement can help coordinate the physiological characteristics of patients in dental treatment, benefit the health of temporomandibular joint and improve the long-term outcome. Our results suggest that the SCI values obtained by CBCT is different from the real SCI values of patients, and we will look for a simpler and more accurate clinical method to measure SCI value in future research.

Use of Implant-Supported Custom Milled Impression Copings to Capture Soft-Tissue Contours and Incisal Guidance

A technique is presented where a custom milled impression coping is used to replicate the clinically established anterior incisal guidance to the definitive prosthesis when multiple implants are restored in the esthetic zone. A conventional impression is initially made, then the stone cast is scanned, and a digitally designed custom screw-retained, implant-supported interim prosthesis is milled from a polymethylmethacrylate (PMMA) billet. This is aimed to digitally design the pontic areas, contour the gingival soft tissue, and establish an anterior incisal guidance. A custom milled impression coping (CMIC) is then fabricated. The CMIC has contours similar to the contours of the interim prosthesis and is fabricated from a PMMA billet. Titanium inserts are placed in the interim prosthesis and the CMIC. The CMIC is inserted intraorally and used for the final impression by using a custom tray and by following the open tray impression protocol. With the proposed technique, the exact contours of the digitally designed and clinically verified interim prosthesis are used to fabricate the definitive restoration.