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The Triangle of Bone - |
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By Scott D. Ganz, D.M.D. |
Call (201) 592 - 8888 |
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| Fig. 11 (above) The corrected version of an immediate implant placement. Note the fragile buccal plate of bone. Fig. 12 (below) The osteotomy bisects the triangle of bone, allowing for a longer implant. The completed crown supported by a well-fixated implant. Fig. 13 (above) The periapical radiograph reveals another "triangle of bone" revealing a two-dimensional view of the volume of bone necessary to support the implant and the final restoration. Fig. 14 (below) Following the triangle of bone, the implant will emerge at the level of the adjacent CEJ's. Fig. 15 (above) An angulated transmucosal abutment will serve to secure the final restoration. Fig. 16 (below) The final implant supported porcelain crown replaces the natural tooth without detection. |
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Various techniques have been
described to close this gap, with "guided
tissue regeneration," bone grafts, or
other similar concepts19,20. The apparent "gap" between the buccal plate and
the position of the fixture placed according to the "triangle of bone" concept is important to note. If proper
surgical procedures are utilized, this
"gap" will fill with new bone creating a
wider thickness of bone on the buccal
aspect of the implant than was present
with the natural tooth.
Additionally, in order to achieve
proper emergence profile, and to maximize esthetics, the fixture should be
placed approximately 4mm apical to
the CEJ's of the adjacent teeth. This
will leave enough room for the transmucosal abutments, prosthetic crowns
and enable an esthetic result to be
achieved. Prior to treatment, and then
as a verification of fixture placement,
the periapical radiograph should
reveal a two-dimensional "triangle
of bone" which should be visualized as a diagnostic tool to gain proper
volumetric bone support, and accom
push successful implant reconstruction
[FIG. 13]. Following these guidelines
the angled post, and completed implant supported prosthesis should be
indistinguishable from adjacent teeth
[FIG.14,15,16]. ADVANTAGES The triangle of bone concept as described in this paper offers several advantages to both the implant surgeon and the restorative dentist. [1] Ensure placement of the implant within the greatest volume of alveolar bone. [2] Enable placement of longer fixtures due to increased available bone following the inherent trajectory of the alveolus. Crown-to-root ratios can be improved. [3] May create additional stabilization by engaging better quality cortical bone in the apical area of the implant (bicortical stabilization) [4] If proper surgical techniques are employed, the bone on the buccal aspect of the implant may increase in width, which can help support the implant against lateral forces of occlusion. This extra support can be valuable for the esthetic design of the final prosthesis. [5] Proper emergence profile will result as the implant should emerge at the level of the CEJ of the adjacent teeth. Compromised ridge-lap prosthetic designs can be avoided. [6] The implant is placed parallel to the natural trajectory of the bone. [7] It is postulated that implants placed bisecting the "triangle of bone" will have a better long-term prognosis underfunction. DISADVANTAGES [1] Need for complete understanding of bone topography which may require additional diagnostic aids and surgical templates. This adds time, and additional cost to the procedure in some cases. [2] Correct angulation of the drill during the osteotomy preparation is essential to "bisect" the triangle of bone correctly and prevent perforation of the buccal or lingual cortical plate. [3] In order to achieve the proper emergence profile, an angulated transmucosal abutment is necessary. This is only a disadvantage for those clinicians who do not believe in angulated abutments, or who utilize an implant system that does not offer acceptable prosthetic componentry. If this aspect is not planned prior to the surgical procedure, it can also add an unexpected restorative-laboratory cost. N E X T+ P A G E | The Triangle of Bone |
