J Korean Acad Prosthodont.  2019 Apr;57(2):160-170. 10.4047/jkap.2019.57.2.160.

Functional and esthetic improvement through reconstruction of anterior guidance using the modified Dahl principle and copy-milled technique of CAD/CAM system: A case report

• Kim SH
• Choi YS

• KMID: 2444185
• DOI: http://doi.org/10.4047/jkap.2019.57.2.160

Abstract

The anterior guidance is one of the important factors in prosthodontic treatment of anterior teeth. The lingual surface shape of anterior restorations is so critical that small errors of treatment procedure can cause discomfort of the patient and disharmony of the dentition. If the anterior restorations are achieved harmonious anterior guidance through the fabrication and adjustment of provisional restorations, it is important to accurately reproduce the lingual surface shape of provisional restorations as the final prosthesis. In this case report, it was used the modified Dahl principle and copy-milled technique of computer-aided design/computer-aided manufacturing (CAD/CAM) system for systematic diagnosis and treatment. Therefore, we tried to reconstruct the restoration shape more precisely by setting the appropriate anterior guidance and superimposing the digital image of the abutment teeth and the provisional restorations. Thus, by promoting functional and esthetic recovery, this case report demonstrates satisfying results to both the patients and dentist.

Keyword

Dahl principle; Computer-aided design/computer-aided manufacturing; Anterior guidance; Anterior teeth restorations; Occlusion

MeSH Terms

Dentists
Dentition
Diagnosis
Humans
Prostheses and Implants
Tooth

Figure

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  Fig. 1 Modified Dahl principle. (A) Normal anterior relationships, (B) An anterior-superior slide of the mandible in a deeper bite by anterior tooth erosion, (C) Anterior tooth contour repositioned by diagnostic wax-up according to modified Dahl principle.

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  Fig. 2 Initial intraoral examination. (A) Maxillary occlusal view, (B) Mandibulary occlusal view, (C) Maxillary frontal view, (D) Mandibulary frontal view.

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  Fig. 3 Panoramic view at first visit.

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  Fig. 4 Analysis of cephalometric projection. (A) Lateral cephalometric radiograph, (B) Tracing of lateral cephalometric radiograph.

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  Fig. 5 Fabrication of the custom anterior guide table. (A) Right excursion in frontal view, (B) Left excursion in frontal view, (C) Protrusive excursion in lateral view.

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  Fig. 6 Diagnostic wax-up in diagnostic model using the modified Dahl principle. (A) Wax-up on the mandibular anterior teeth, (B) Wax-up on the palatal surface of the maxillary anterior teeth, (C) Facial bite recording and Re-mounting according to facial bite, (D) Wax-up on the labial surface of the maxillary anterior teeth.

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  Fig. 7 Fabrication of the provisional restoration. (A) Full contour wax-up, (B) Provisional restoration.

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  Fig. 8 Duplicated final temporary bridge fabrication by copy-milled technique of CAD/CAM system. (A) Frontal view of maxillary temporary bridge image, (B) Frontal view of maxillary prosthesis, (C) Occlusal view of maxillary temporary bridge image, (D) Occlusal view of maxillary prosthesis.

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  Fig. 9 Final prosthesis setting of mandibular anterior teeth in frontal view.

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  Fig. 10 Semi-articulator mounting procedures. (A) Mounting the diagnostic model to an articulator in frontal view, (B) Mounting the diagnostic model to an articulator in lateral view.

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  Fig. 11 Fabrication of the custom anterior guide table. (A) Left excursion in frontal view, (B) Protrusive excursion in lateral view.

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  Fig. 12 Diagnostic wax-up in diagnostic model using the modified Dahl principle. (A) Wax-up on the mandibular anterior teeth, (B) Wax-up on the palatal surface of the maxillary anterior teeth, (C) Wax-up on the labial surface of the maxillary anterior teeth.

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  Fig. 13 The abutments and duplicated final bridge coping fabrication by copy-milled technique of CAD/CAM system. (A) Frontal view of the abutment, (B) Frontal view of maxillary and mandibulary prosthesis.

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