Abstract
The advancements in computer-aided design and computer-aided manufacturing (CAD-CAM) serve to facilitate the management of clinical challenges in restorative dentistry. This technique article describes the fabrication of implant-supported restorations by using a completely digital workflow to manage a patient with severely tilted implants.
An important factor in successful implant-supported restorations is the appropriate location and angulation of the implant in relation to the planned prostheses. Situations where implant angulation is compromised are often due to inadequate treatment planning and surgical execution and can lead to restorative challenges including difficulty in making definitive implant impressions. While surgical removal of the tilted or misaligned implants is an option, different restorative techniques have been described to overcome this complication.
The use of computer-aided design and computer-aided manufacturing (CAD-CAM) in dentistry has influenced the evolution of implant-supported prosthesis design and fabrication. Intraoral scanning technology has further enhanced the treatment process by improving diagnosis and treatment procedures without compromising either efficiency or accuracy. The combination of intraoral scanning, digital prosthetic design, and fabrication has been used to solve different complex clinical problems. This technique article describes the successful use of intraoral scanning and CAD-CAM technology to fabricate an implant-supported restoration with 2 severely mesiodistally tilted adjacent implants by using selectively modified implant scan bodies.
A healthy 67-year-old man was referred to the department of prosthodontics in Loma Linda University School of Dentistry. His chief complaint was “implants were placed 2 years ago for my missing teeth by an outside dentist, and I am ready for my crowns.” An examination revealed missing mandibular right first and second premolars and 2 severely tilted implants ( Fig. 1 ). Despite the uneven occlusal plane, mounted diagnostic casts in centric relation and clinical examination did not reveal occlusal deflective contacts.
Treatment options for the definitive restorations which included a comprehensive approach to correct the occlusal plane and a conservative option were presented to the patient. The patient was primarily interested in having the dental implants restored and chose the more conservative option. Because of the severe implant tilting, the patient was cautioned that making an impression to fabricate the definitive crowns could be challenging and that removing one or both implants might be necessary if they were deemed unrestorable or could not be restored in a hygienic manner.
Initially, a conventional implant impression was planned for the patient. However, the impression copings had to be significantly modified, which resulted in severe damage and made an accurate impression impossible ( Fig. 2 ). Although modified approaches to recording severely misaligned implants have been published, a digital scanning technique was chosen with a digital workflow.
Technique
- 1.
Select the appropriate scan body (Nobel RP Scanbody; Nobel Biocare) and attach it to the corresponding implant.
- 2.
If severe implant angulation prevents the scan bodies from being seated passively, modify the scan body by using a fine-grit diamond rotary instrument (Brasseler) ( Fig. 3 ). Ensure that the facets on the scan body ( Fig. 4 ) are not damaged during the adjustment. Other systems might use different morphology or even ID codes, and it is imperative for those systems that these markers are not compromised as this could affect scanning accuracy. The facets on individual scan bodies are linked to their specific implant system and connection, so when scanned, the software automatically transfers the data to the laboratory order form. The ID number on the scan body is an additional feature that assists in determining the product and implant for some implant systems.
