Archive | 2019
Esthetic rehabilitation of malpositioned implants – A case report
Abstract
The replacement of a missing tooth with an implant prosthesis has revolutionized oral rehabilitation by providing a predictable treatment modality. However, the placement of an incorrectly angulated implant results in several complications posing a demanding clinical scenario for prosthetic rehabilitation. An improperly angulated implant in the anterior esthetic zone can be restored with the help on a 2 unit Paulo Malo prosthesis in order to rectify the angulation, restoring the correct arch form, mask the labial screw holes and is easy to disassemble and repair; providing good retrievability. Keywords: Esthetics, Anterior implant, Malpositioned, Paulo malo prosthesis. Introduction A synergistic pink and white balance in the anterior esthetic zone is the ultimate objective of satisfactory treatment. An amalgamation of exacting patient expectations and compromised pre-existing anatomy manifests as one of the greatest challenges for a restorative prosthodontist. The replacement of a missing tooth with an implant prosthesis has revolutionized oral rehabilitation by providing a predictable treatment modality. The emphasis of treatment has gradually progressed from merely satisfying functional demands to restoring a combination of function and esthetics. The ideal implant placement requires an integration of precise treatment planning, meticulous surgical skills and accurate 3 dimensional implant placement. However, if a clinician falls short in any of the above areas, the prosthetic management of the hard and soft tissues poses a demanding clinical scenario, requiring a well-equipped restorative prosthodontist. Case Report A 20 year old male presented to the Department of Prosthodontics and Implantology, DY Patil University, School of Dentistry, Mumbai with a chief complaint of missing maxillary anterior teeth and requested for the replacement of the same. The patient’s history and clinical examination revealed that the patient had undergone a symphyseal graft followed by immediate end osseous implant placement (Noble Biocare, Replace) with healing abutments for both the maxillary central incisors. Fig. 1a: Intra-oral pre-treatment frontal view Fig. 1b: Intra-oral pre-treatment occlusal view On further examination, the implants were osseo integrated with a severe labio-palatal angulation, increased subcrestal depth (5mm in the 21 region) and compromised position. Hence the patient was given the following treatment options: 1. Surgical removal of the malpositioned implants followed by a second grafting procedure and implant placement in a favorable position. 2. Prosthetic management using a two unit Paulo-malo prosthesis and laminate veneers on the adjacent teeth. The patient was not willing to undergo an additional surgical procedure and opted for the prosthetic management of the existing implants. A closed tray implant level impression was made with addition silicone impression material (Aquasil; Dentsply); the accuracy of which was clarified with the aid of a verification jig. The model was then scanned using an extraoral scanner and a computer aided designing of the prosthetic framework along with the final prosthesis was done on the Exocad software. At this stage it was observed that the adjacent teeth (12, 23) required laminates for establishment of satisfactory proportions and shape correction as the canine had to be converted into a lateral incisor. Aanchal Punjabi Esthetic rehabilitation of malpositioned implants J Dent Specialities. 2019;7(1):49-53 50 Fig. 2: Implant level impression Fig. 3: Trial of verification jig Fig. 4: Buccally tilted implant angulation. Note – correct tooth angulation depicted by the putty index. Fig. 5a, 5b: Computer aided design of prosthetic framework, final crowns and laminates. On approval of the design, a polymethyl methacrylate trial was 3D printed and checked intra-orally for any modifications. Care was taken to ensure a correct angulation of the abutments along the contour of the maxillary arch in addition to a satisfactory level of the gingival zeniths and extra-oral lip support. Fig. 6: Polymethyl methacrylate trial Fig. 7: Intra-oral trial of polymethyl methacrylate crowns Once the alterations were made, the screw-retained, definitive titanium framework was milled using computer aided manufacturing and verified intra-orally. Subsequently, the gingival aspect of the framework was layered with pink ceramic in addition to application of an opaquer over the abutments. Fig. 8: Definitive titanium framework Fig. 9: Ceramic soft tissue moulage on the titanium framework Aanchal Punjabi Esthetic rehabilitation of malpositioned implants J Dent Specialities. 2019;7(1):49-53 51 Fig. 10: Laminate preparation on 12, 23 and trial insertion of screw-retained framework Laminate preparation on 12 and 23 was done using Gurel’s technique to ensure a conservative preparation and a final impression of the prepared teeth along with the titanium framework was made in polyether impression material (Impregum; 3M ESPE). This was followed by a bisque trial of the zirconia with ceramic layering crowns and lithium disilicate laminates. The overjet and overbite was maintained at 1.5mm to ensure a shallow anterior guidance. Thereafter, the ceramic of the various parts of the definitive prosthesis were glazed. The abutment screws were tightened to a torque of 30N, followed by blockage of the screw-access hole with gutta percha and composite resin. Fig. 11: Defintive prosthesis Fig. 12: Intra-oral view of definitive Paulo Malo prosthesis and laminate veneers The zirconia crowns were cemented with a resin reinforced glass ionomer cement (Fuji Cem, GC) and the laminates with a resin cement (Calibra). Fig. 13: Pre-treatment extra-oral view Fig. 14:Post-treatment extra-oral view Fig. 15: Pre-treatment smile Aanchal Punjabi Esthetic rehabilitation of malpositioned implants J Dent Specialities. 2019;7(1):49-53 52 Fig. 16:Post-treatment smile. Discussion Restoration of a malposed implant is one of the most arduous clinical situations encountered by a prosthodontist. The scale of difficulty further escalates when the implant is within the anterior esthetic zone as that requires a tactful balance between the mechanical concepts of prosthetic implantology and satisfactory esthetics. The treatment options available included angulated abutments with single crowns, splinted crowns, hybrid prosthesis or a combination screw-cement retained, Paulomalo prosthesis. 1. Studies by Clelland et al, Pellizzer et al and Bergkvist have suggested that splinted restorations offer load sharing among the components of the rehabilitation and decrease the stress on cortical bone. While the marginal bone loss in both splinted and unsplinted implants was similar, the implant survival rate for splinted implants was statistically higher than the latter in a meta-analysis done by de Souza Batista et al. Therefore, a splinted prosthesis was preferred in order to minimize the risk of micromotion above physiologic limits. 2. Implant supported splinted crowns was the second treatment option, however, due to the unfavorable implant position and angulation, the screw holes would be directed buccally making a screw-retained implant prosthesis an esthetic failure. Additionally, a cementretained prosthesis was deemed unfavorable in this clinical scenario due to the excessive subcrestal depth of the implants, which led to poor accessibility of the implant site for cement removal. This would invariably lead to a downward spread of inflammation, periimplantitis and implant failure in the future. 3. A study conducted by Bozini T et al indicated that the most common prosthesis-related complication were acrylic resin veneer fracture and denture teeth wear. Acrylic resin veneer fracture may be attributed to design issues and/or technical errors, whereas the high frequency of tooth wear was attributed to the inherent limitations of resin denture teeth. Therefore, a hybrid prosthesis was disregarded in this clinical scenario. Keeping the above situation in mind, a screw-cement retained Paulo-Malo prosthesis was the treatment option of choice as this design combined the advantages of both approaches. The screw-retained framework splints the two unfavorably angulated implants together, rectifying the angulation, restoring the correct arch form and is easy to disassemble and repair; providing good retrievability. The titanium framework veneered with gingiva-coloured porcelain conceals the soft and hard tissue defects, particularly in patients with severe alveolar ridge resorption, establishing a good pink and white balance. The crowns were individually cemented to the titanium framework, ensuring that the designed prosthesis could provide optimal esthetics regardless of where the screw access openings were located. This approach is beneficial for prosthesis maintenance and repair and permits the relatively easy cleaning of excess cement. The excessive labial angulation and subcrestal position of the 2 implants documented in the case above, required thorough prosthetic planning with the help of a digital design protocol and polymethyl methacrylate trial, which allowed a 3-dimensional view of the underlying abutment framework and the final crowns at inception. The position of the final prosthetic assembly within the dental arch, shape and contour of the teeth requiring replacement, ratios and proportions of the teeth in the esthetic zone and the pink and white balance were all established with the aid of computer aided design and intra-oral trial. This trial was a scientific approach which gave the patient and clinician a complete picture of the final design, in the process proving to be cost effective and time efficient. Subsequently, the titanium framework was milled using computer aided design and computer aided manufacturing. Conventionally, fabrication of superstructures for implantsupported fixed dental prosthesis was done using the lostwax technique, wh