04 Apr Case Report 3
This case series will consist of 3 instances of mechanical failure of restorative parts with a brief description of how these cases were handled. When there is a mechanical failure of parts, creative solutions that work chair side are usually required. The cases will be denoted as A, B and C.
A 65-year-old patient was referred to the surgical practice by the restorative dentist. Following implant placement in the #4 region (maxillary left first premolar) (Figures 15, 16). The restorative treatment was completed uneventfully. However, the patient had reported back to the restorative dentist as the abutment screw had fractured within the implant housing (Figure 17). The restorative dentist was unable to remove the screw and the patient was then sent back to the surgical office for an evaluation. Upon clinical examination it was noted that soft tissue had grown over the implant. The first step was to expose the head of the implant. Following the administration of local anesthetic a 15C blade was used and the soft tissue was excised. After obtaining hemostasis an ‘explorer’ was used to start the process of counter clockwise unscrewing to help loosen the screw. This was a painstakingly slow process. However, once the initial screw loosening was accomplished, the rest of the process was straightforward (Figure 18). Following the removal of the screw, a healing abutment was placed and the patient was then referred back to restorative dentist to complete the restoration for a second time. The restoration was completed uneventfully and the patient has been followed for over a year now.
A 58-year-old patient was referred to the surgical practice for implant placement in the #11 (maxillary left canine) area. Following ridge augmentation and a period of 4 months of healing, an implant was placed in the site (Figure 19). Following a second healing period, the patient was referred to the restoring dentist to have the implant restored (Figure 20) as the implant supported crown had come off following the restoration and a portion of the prosthetic abutment had fractured within the implant (Figures 21, 22). This happened within a week following the restoration of the implant. Since a portion of the abutment had fractured, removal of the piece required force to get it out of the implant housing. Follow consultation with the technical support of the implant manufacturer, it was recommended that a root elevator be used to help remove the piece. Accordingly, a sharp pointed root tip elevator was used and the prosthetic abutment that was within the implant was carefully removed (Figure 23). It is important that this is done very carefully to avoid scratching or gouging the inside of the implant, hence affecting the fit of the replacement prosthetic abutment. Patient had the implant restored for a second time and has been restored for over one year now (Figure 24).
A 55-year old patient was referred to the surgical practice to help remove the healing abutment that had become ‘cold welded’ to the implant. Cold or contact welding is a solid state welding process in which joining takes place without fusion/heating at the interface of the two parts to be welded. Following the placement of the implant and adequate healing period, the patient was referred to the restorative dentist to begin the restorative phase of treatment (Figure 25). The restorative dentist had removed the healing abutments, placed the impression copings and taken fixture level impressions. Following this the healing abutments were placed back on the implant and tightened. When the patient reported for delivery of the implant crowns, the healing abutment on the implant in the #19 (lower left first molar) region could not be removed. The restorative dentist was unable to remove the healing abutment in spite of several attempts to do so. It appeared that the healing abutment had been so tightly torqued in place that it was not possible to remove it. The patient was sent to the surgical office to evaluate the situation. In the surgical office, it was decided to cut a deep slot into the healing abutment that extends across the occlusal surface and into the buccal and the lingual aspects. A surgical elevator was then placed into the slot and pressure was exerted to help loosen the healing abutment. The healing abutment was then removed and replaced with a replacement. The patient was then referred back to the restorative office and proceeded to have the implant restoration completed.
The above examples of mechanical complications are those that can happen in everyday practice. It must be pointed out that mechanical complications like the ones reported in this case series are not very common. Naert et al  reported that after a period of approximately 8 years, the incidence of fixture fracture was about 0.5%, the incidence of abutment screw fracture was about 0.89%, the incidence of gold screw fracture was about 1.24% and the incidence of gold screw loosening was about 5%. Goodacre et al  in reviewing the literature reported that the incidence of prosthesis screw loosening was 7%, the incidence of abutment screw loosening was 6%, prosthesis screw fracture was 4%, abutment screw fracture was 2% and implant facture was 1%. However, knowing what to do when these mechanical problems arise is as important as knowing about handling surgical complications.