2B-3D Rule for Implant Position Part 1 скачать в хорошем качестве

2B-3D Rule for Implant Position Part 1

Chris Chang, DDS., PhD. 　1. ABO-Certified Orthodontist 　2. Publisher, International Journal of Orthodontics & Implantology 　3. Founder, Newton's A & Beethoven Co., Taiwan 　4. Founder, Podcast Encyclopedia in Orthodontics 　5. Author, iAOI Workbook, 3D iBooks Ortho, Jobsology 1. What is biologic width? Is there a golden rule for implant planning, placement and restoration as the Newton's laws of motion for force prediction? In order to answer this question, one needs to refer back to the biologic system which the implant site attempts to mimic. In the human body, ectodermal tissue serves to protect against invasion from bacteria and other foreign materials. However, both teeth and dental implants must penetrate this defensive barrier. The natural seal that develops around both and protects the alveolar bone from infection and disease, is known as the biologic width. Around natural teeth, the biologic width has been shown to consist of approximately 1mm sulcular depth, 1mm junctional epithelium, and 1mm connective tissue attachment (Fig. 1). To summarize then, the biologic width is equal to 3mm: 1mm sulcular depth, 1mm junctional epithelium and 1mm connective tissue attachment above the crestal bone. This is true on the broad facial surface. In the proximal papillae area, the correct biologic width increases to 4mm. This can be measured on any tooth using the "sounding" technique. This "sounding" technique of the crestal bone is not routinely practiced by most clinicians. However, for anterior esthetic cases where the margin is desired to remain subgingival, this "sounding" procedure will ensure its long term stability and esthetics. The "Sounding" Procedures: First, anesthetize the area to be sounded. Second, use a narrow tipped periodontal probe, place it in the sulcus and lean it away from the tooth while keeping the tip against the enamel. Third, push through the attachment apparatus until the crest of bone is felt. Finally, record three measurements per facial tooth surface. One should be aware that the crest of bone follows the scallop of the cemento-enamal junction (CEJ) but DOES NOT always follow that of the gingival margin. Based on these measurements of the teeth to be restored (proximals and center of facial), one can predict how the tissue will respond post- cementation of the new prostheses. The goal is to keep the prosthesis margin within the sulcular depth without interfering with the junctional epithelium and connective tissue attachment. 2. Does an implant need this defense barrier-biologic width? If a tooth needs a defense barrier to protect its supporting alveolar bone, it is reasonable to assume the same for an implant. Based on the study of Berglundh T, et al., the biologic width that develops around implants at the time of abutment connection has been shown to incorporate tissue zones of similar dimensions which is 1mm sulcular depth, 1mm junctional epithelium, and 1mm connective tissue attachment with insufficient principle fibers. This concept of biologic width around implants has been further investigated by Hermann JS, et al. This group evaluated the impact of the position of the implant-abutment interface relative to the crestal bone and periimplant tissues. The investigation indicated that the biologic width around implants differed according to the depth and position of the interface. When the implant-abutment connection was placed at the gingival level, supracrestal to the alveolar bone (i.e., as in a conventional single- stage implant placement), the biologic width was similar to that of natural dentition. When the interface was placed at a deeper level (i.e., as in a standard submerged implant design), however, the biologic width increased accordingly. The primary difference was found in the depth of the junctional epithelium height, which extended just apical to the interface. The sulcus depth and connective tissue attachment width appeared stable regardless of the level of interface. It was, therefore, determined that implant placement with the implant-abutment interface placed supracrestal to the bone facilitated maintenance of the biologic width with minimal apical bone resorption. In the esthetic area, however, the prosthesis margin should always be placed subgingivally, regardless of whether the implant fixture is a one- or two-stage design. As a general rule, the implant head should be placed 3mm apical to the future labial gingival margin position in order to allow development of the desired emergence profile and esthetics. More importantly, this rule of 3mm depth from the future labial gingival margin is based on the biologic width which develops around the implant. With 3mm in depth from gingival margin, a defense barrier can form and further protect the alveolar bone around the implant which mimics natural dentition.