Full mouth rehabilitation with implant fixed prostheses using POP bow system and 3D printing gothic arch tracer in a patient with unilateral facial nerve palsy

Lee S., Jeong C., Yun M., Huh J., Lee S.

Sun M., Tan X., Zhang N., Lou Y., Wu Q., Yu H.

Children with ectodermal dysplasia and complete anodontia experience difficulties in oral rehabilitation because of the small arch size. A case of a 7-year-old boy, whose arch size (length and width) was 30-40% smaller than that of a male adult and who presented with difficulties in jaw relation recording using commercially available devices is described. A digital workflow involving a mini arch tracer was introduced. Primary impressions were made using three-dimensionally (3D) printed mini trays produced based on the patient's computed tomography images, and digital primary casts were obtained based on the scanned and reversed primary impressions. The final custom impression trays with mini tracing plates were designed based on the primary casts. In addition, the hand shank, retention plate, and retainers were placed on the designed custom trays and 3D-printed to produce an individual arch tracer system. In addition, two height-checking buckles were designed to help adjust the height of a tracing screw. Finally, the jaw relation of the patient was recorded and transferred, and a set of complete dentures were delivered, satisfying both the patient and his family.

Qu F., Du X., Liu W.

An appliance was designed and fabricated by using computer-aided design and computer-aided manufacturing (CAD-CAM) and 3-dimensional (3D) printing to combine a custom tray with an intraoral Gothic arch. This helped simplify centric relation recording and combined definitive impression making and centric relation recording into a single step.

Fang Y., Fang J., Jeong S., Choi B.

Few studies have reported the application of digital technology for the process of impression and interocclusal recordings in edentulous patients. This article describes a digitizing system for generating digital edentulous models with a jaw relationship by taking direct digital impressions and a virtual bite registration using intraoral digital scanning. A specialized scan retractor was used to make digital impressions of edentulous jaws in patients' mouths using an intraoral scanner. Virtual bite registration was obtained with optical scanning of the buccal surfaces of both jaws at the occlusal vertical dimension. The registration was then used as a reference for aligning both jaws. Digital edentulous models that include the jaw relationship would be clinically beneficial for the fabrication of complete dentures in edentulous patients.

Viswanath A., Gordon S.M.

Ueno T., Baba K., Fueki K., Ai M., Ohyama T.

Yurkstas A.A., Kapur K.K.

Numerous methods of registering centric relation have been described in the literature.1-9 They can be classified as (1) static, (2) graphic, (3) physiologic or functional, and (4) cephalometric. Two of the most popular methods of registering centric relation are the intra-oral Gothic arch (needle-point) tracing, and the wax recording procedure. Both of these methods have been criticized for their inaccuracies. Hanau10 pointed out the “resilient and like effect,” Realeff, of the supporting tissues as the chief source of error in registering maxillomandibular relationships.

Rahman M.M., Kohno S., Kobayashi H., Sawada K.

The object of this study was to determine the best inclination of the intra-oral tracing device to get optimum condylar position with the registration of tapping movement. Three appliances with different tracing plate inclinations were used in five healthy subjects. The tracing plates were set at 0 degrees to occlusal plane (horizontal); at the angle formed by drawing a line from condylar point to the stylus position at occlusal plane (inclined); then at the angle half to inclined (half-inclined). Subjects made Gothic arch and tapping movements (n = 30) at a 30 mm interincisal distance with the head Camper plane horizontal. The incisal and condylar points were tracked with a 6-degree-of-freedom jaw movement tracking system. The location of gothic arch apex, the distribution and mean position of 30 tapping points from intercuspal position were analyzed in incisal and condylar point between the appliances. Data were analyzed with repeated measures one-way anova. Results showed that mean position of tapping points were significantly different among the appliances. Half-inclined appliance recorded tapping points in a convergent area nearer to intercuspal position (IP) than other appliances. In all appliances, the contact points of the tapping movement were anterior to Gothic arch apex.

MILLSTEIN P.L.

A study was conducted to evaluate the accuracy of casts made in Type IV dental stone. The results indicate that all casts distort, but that significant differences exist between various brands of die stone.

Carroll W.J., Woelfel J.B., Huffman R.W.

Utilization of either of the two described methods by dentists is recommended as a simple means to routinely record or provide centric relation closures. The leaf gauge (1 to 6 mm thick) can be made from plastic or x-ray film or it can be purchased. The anterior acrylic resin jig can be made in a few minutes directly in the mouth by the dentist or an assistant or by a technician using mounted casts. Both methods avoid adaptive mandibular closure patterns and dentist-guided jaw closure as well as other commonly unrecognized errors in assessing occlusal contacts.

Palik J.F., Nelson D.R., White J.T.

Abstract The validity of the Hanau ear-bow to transfer an arbitrary hinge axis to a Hanau articulator was clinically compared with a Hanau kinematic face-bow. The study was conducted with 18 randomly selected patients. This investigation demonstrated a significant statistical difference between the arbitrary axis located with an ear-bow and the terminal hinge axis. This discrepancy was significant in the anteroposterior direction but not in the superior-inferior direction. Only 50% of the arbitrary hinge axes were within a 5 mm radius of the terminal hinge axis, while 89% were within a 6 mm radius. Furthermore, the ear-bow method was not repeatable statistically. Additional study is needed to determine the practical value of the arbitrary face-bow and to pursue modifications to improve its accuracy.

Myers M., Dziejma R., Goldberg J., Ross R., Sharry J.

These data suggest that the widely held belief that thumb pressure can position the mandible consistently more posterior than the position indicated by the Gothic arch apex is unfounded. Furthermore, this study provides no evidence to support the contention that the dentist-assisted jaw relation is more reproducible than the relation indicated by the Gothic arch apex.

Kantor M.E., Silverman S.I., Garfinkel L.

A measuring device was used to determine levels of consistency and relative patterning of centric relation records obtained from 15 dentulous subjects. The subjects tested were between the ages of 21 and 45 years. Clinical methods used for recording centric relation were tested. Six records were made with each technique. The data were then analyzed in relation to consistency and displacement patterns.