CDE0111

22 I I special _ implants Mini-diameter implants (MDI) are not synony- mous with narrow-diameter implants. MDIs are smaller in diameter than narrow implants and haveadiameterof2.7mmorless.Becauseoftheir smaller diameters, MDIs require minimal inter- dental space while preserving more of the alveo- lar bone following the osteotomies for implant placement. MDIs were initially developed to sup- port transitional prostheses and were ultimately intended to be removed. However, these implants exhibited a bone-to-implant contact similar to that of implants with conventional diameters. Numerous studies have indicated that MDIs appear to be an effective treatment option for missingmandibularincisors.Nevertheless,oneof the primary disadvantages of MDIs is the reduced resistance to occlusal loading. The retention of animplant,however,iscorrelatedtothelengthof the implant and not the diameter. This implies that MDIs may be used in situations where ex- cessive occlusal loading is not present. MDIs of less than 3 mm in diameter are fun- damentally challenged as two-piece designs due to the insufficient strength of their component parts. When the diameter of an implant ap- proaches 3 mm or less, either the abutment screw becomes too small or the internal axial walls of the implant become too thin to with- stand the functioning load. These concerns can be overcome with a one-piece design. One- piece implants have recently received substantial attention in implant dentistry; yet, one-piece im- plants are not new to implant dentistry. While the useofone-pieceimplantshasbeencontroversial, they have been used for decades with reasonable clinical success. Recent variations from early designs have created a renewed interest in this old, but not obsolete concept. Most one-piece implants are composed of three portions—the bone-anchor- ing (fixation thread) portion, transmucosal por- tion and prosthetic abutment portion. The primary disadvantage of one-piece im- plants is related to the fact that these implants must be placed with a one-stage protocol. Therefore, the angulation of the abutment cannot be altered and only minimal modifica- tion of the abutment is possible. Without the prosthetic freedom of the abutment choices, the initial surgical positioning of one-piece im- plants becomes critical in obtaining an optimal result. cosmeticdentistry 1_2011 Fig. 10_Eight weeks post-implant placement. Fig. 11_Friction-fit impression caps. Fig. 12_Working cast. Fig. 13_Top view. Fig. 14_Final prosthesis. Fig. 15_Thirteen-month follow-up. Fig. 16_Peri-apical X-ray. Fig. 10 Fig. 11 Fig. 13 Fig. 14Fig. 12 Fig. 15 Fig. 16