4.0 × 12 mm Considerations: A large nasopalatine foramen (incisive canal) may interfere with implant placement. Loss of the facial bone plate may necessitate bone grafting. Restoration: MCR over a custom abutment (UCLA, Atlantis [Astra Tech], or preparable abutment)
Missing: Mandibular central incisor Abutments: Central incisor and lateral incisor Considerations: If at all possible, an implant should be used to support this restoration if there is 7.3 mm between the prospective abutments. If there is not, a fixed partial denture will be required. Severely rotated, malposed, or mobile abutments will contraindicate the use of resin-bonded retainers and might dictate the removal of all of the mandibular incisors. In that instance, implants would be placed in the positions of the lateral incisors. If MCR retainers are required for a tooth-borne fixed partial denture, the preparations very easily could encroach on the pulp, and the patient should be so advised. Endodontic treatment and a dowel core would then be necessary. Retainers: Resin-bonded retainers Pontic: Ovate or modified ridge lap MCR (depending on ridge configuration) Abutment-pontic root ratio: 2.1
Missing: Mandibular central incisor Implant: 3.3 × 12 mm Considerations: A dental implant is the restoration of choice. The factor limiting replacement of a mandibular central incisor with a dental implant is the mesiodistal space available. Ideally there should be 7.3 mm of interproximal space. If inadequate space is available, consider extraction of all mandibular incisors. Place two 4.0 × 12–mm dental implants in the lateral incisor positions and fabricate a four-unit restoration. Restoration: MCR crown over a one-piece implant
Missing: Maxillary lateral incisor Abutments: Central incisor and canine Considerations: Caries and/or restorations on the abutments would require MCR retainers. If the canine is long, well-supported periodontally, and in need of restoration, and if the pontic will not contact in centric relation or excursions, a single-abutment cantilever fixed partial denture could be used. An untouched central incisor and a first premolar in need of restoration would allow a pontic cantilevered from MCRs on the canine and first premolar. Retainers: Resin-bonded retainers Pontic: Modified ridge lap MCR Abutment-pontic root ratio: 2.6
Missing: Maxillary lateral incisor Implant: 3.5 × 12 mm Considerations: The loss of a maxillary lateral incisor frequently results in the collapse of the facial plate of bone. The loss of the facial plate of bone often leads to a facial concavity requiring implant placement too far to the lingual. This will result in an unnatural lingual contour of the crown and a poor implant emergence profile. To correct this problem, bone grafting is required to eliminate the facial concavity. Restoration: MCR over a custom abutment (UCLA, Atlantis, or preparable abutment)
Missing: Mandibular lateral incisor Abutments: Central incisor and canine Considerations: An implant-supported MCR is the overriding choice for restoring this space. Caries and/or restorations on the abutments would require MCR crowns and a fixed partial denture. The patient should be warned of the potential for pulpal involvement with resultant endodontic treatment and a dowel core. Double abutting the central incisors for a fixed partial denture would complicate this case immensely. Cantilever fixed partial dentures are not an option for the replacement of mandibular lateral incisors. Severely rotated, malposed, or mobile abutments may contraindicate the use of a fixed partial denture using adjacent teeth as abutments. In such cases, the removal of all of the mandibular incisors would be necessary. The treatment then would be a canine-to-canine fixed partial denture. Retainers: Resin-bonded retainers Pontic: Modified ridge lap MCR Abutment-pontic root ratio: 2.5
Missing: Mandibular lateral incisor Implant: 3.3 × 12 mm Considerations: A dental implant is the restoration of choice. The factor limiting replacement of a mandibular lateral incisor with a dental implant is the mesiodistal space available. Ideally there should be 7.3 mm of interproximal space. If inadequate space is available, consider extraction of all mandibular incisors. Place two 4.0 × 12–mm dental implants in the lateral incisor positions and fabricate a four-unit restoration. Restoration: MCR over a one-piece implant
Missing: Maxillary first premolar Abutments: Canine and second premolar Considerations: An implant-supported MCR crown would be the restoration of choice. If the canine is unblemished and the second premolar and first molar are restored or will need restoration, a cantilever prosthesis using MCR retainers on the second premolar and first molar is worthy of consideration. A canine-guided occlusal scheme would be necessary to prevent excessive forces on the cantilever pontic. Retainers: MCRs Pontic: Modified ridge lap MCR Abutment-pontic root ratio: 2.1
Missing: Maxillary first premolar Implant: 4.0 × 13 mm Considerations: Inadequate facial bone will require bone grafting for dental implant placement. Implant placement may impinge upon the anterior wall of the maxillary sinus. In this event, sinus modification surgery such as sinus grafting or vertical upfracture may be indicated. Restoration: MCR over a custom abutment (UCLA, Atlantis, or preparable abutment)
Missing: Mandibular first premolar Abutments: Canine and second premolar Considerations: Facial caries or any proximal caries other than incipient will necessitate MCR retainers. If the canine is intact and the second premolar and first molar are restored or will need restoration, a cantilever fixed partial denture can be used, with MCR retainers on the second premolar and first molar abutments. If the patient does not object, an all-metal crown can be substituted on the molar. Retainers: MCRs Pontic: Modified ridge lap or ovate MCR Abutment-pontic root ratio: 2.5
Missing: Mandibular first premolar Implant: 4.3 × 11.5 mm Considerations: The position of the anterior loop of the mandibular canal may interfere with implant placement. Restoration: MCR over a custom abutment (UCLA, Atlantis, or preparable abutment)
Missing: Maxillary second premolar Abutments: First premolar and first molar Considerations: MCR retainers will be required in cases with facial defects such as abfraction or decalcification or when they are requested by the patient. Retainers: MCR on the first premolar and MCR or full coverage gold crown (FGC) on the first molar Pontic: Modified ridge lap MCR Abutment-pontic root ratio: 3.1
Missing: Maxillary second premolar Implant: 4.3 × 11.5 mm Considerations:
