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ePaper created 2015-03-07, 18:13:20 | version 1.33.01
I technique _ CBCT diagnostic ing a cotton roll under the lip as demonstrated in the cross-sectionalslice,bringsthelip(yellowarrows)far enough away from the tooth, root and alveolus to fully appreciate the region of interest. The vestibule can be defined (red arrow), and the thickness of the soft tissue attached to the alveolus superior to the tooth root. The soft tissue biotype can also be seen as thick or thin (pink arrow), as well as the facial cortical bone. The enhanced diagnostic appreciation of the tooth-root-alveolar complex can help prevent com- plications when implants are placed parallel to the toothsocket(Fig.9a).Iftheimplantweretobeplaced asperthesimulationinFig.9a,withanabutmenttra- jectory projecting through the clinical crown (green), the implant would perforate into the incisal canal. If the desired restoration was to be a screw-retained crown, the screw-access hole would need to project through the lingual/palatal aspect of the crown, dic- tating a different trajectory for the implant (Fig. 9b). At minimum, the resulting implant position would require bone grafting to cover the exposed threads. Therefore, the trajectory of the tooth in relationship to the alveolar housing could not be confirmed without cross-sectional imaging, avoiding potential iatrogenicdamage,orcomplicationsfromamalposi- tioned implant. Another clinical case that utilised the ‘lip-lift’ clearly illustrates the advantages of placing a cotton rollinthelabialvestibule(Fig.10a).Thelipispositioned awayfromanareawhereatoothhadbeenlost(yellow arrows). A simulated implant is placed within the re- maining alveolar bone with an abutment projecting (orange) through a radiopaque marker, which helped to define the desired tooth position (yellow outline). The facial thickness of the soft tissue can be appreci- ated and measured (pink arrow), as the shape of the remaining alveolus curved superiorly to the floor of thenose(redarrow).Theincisalcanalcanalsobeseen (greenarrow).Usingonlytheoutlineofthesimulated implant (green) and virtual tooth (yellow outline), in- spection of the potential implant receptor site, thick- ness of the soft tissue (pink arrow) and adjacent vital structurescanbegreatlyenhanced(Fig.10b).Theapi- calportionoftheimplantcanbeseenincloseproxim- itytotheincisalcanal(greenarrow).Ideally,inorderto supportthesofttissueemergenceprofile,abonegraft shouldbeconsidered.However,itshouldbenotedthat without the actual abutment trajectory, the position of the implant may not provide the best aesthetic or functionaloutcome. Theuseofthe‘lip-lift’technique in coordination with the interactive treatment plan- ning software helps to define the volume of bone required to fill the defect to achieve optimal results (yellow outline) (Fig. 11). Measurements can be deter- mined, and a decision can be made to obtain the pro- jected volume of bone from an autologous source, bonebankallograft,processedxenograft,orsynthetic material.Inaddition,understandingtheshapeandex- tentofthelabialvestibulecanaidinplanningtheflap design, and tissue release to obtain tension-free clo- sure after graft/membrane placement. Fig. 5_Software segmentation simulates a virtual extraction from the alveolus, illustrating the socket anatomy, the thin facial cortical plate (yellow arrows), and the palatal bone thickness (green arrow). Fig. 6_The software allows each image to be enlarged for closer inspection. Fig. 7_A simulated implant of the appropriate diameter and length can be positioned within the virtual socket illustrating: (a) thin facial cortical bone (yellow arrow); (b) thicker palatal bone (green arrow); and the facial ‘gap’ between the implant and the facial cortical plate (red arrows). 08 I cone beam1_2015 Fig. 5 Fig. 6 Fig. 7