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ePaper created 2015-09-18, 13:26:18 | version 1.38.0
CLINICAL PRACTICE smile, seeing no more than 2mm of gingiva when the patient is fully smiling is ideal6. Finally, the incisal line should come very close to and almost touch the lower lip, being no more than 2mm away2. These guidelines are somewhat subjective and should be used as a starting point for determining proper incisal edge position. Dentogingival aesthetics Gingival margin placement and the scalloped shape, in particular, are well discussed in the literature. As gingival heights are measured, heights relative to the central incisor, lateral incisor, and canine in an up/down/up relationship are considered aesthetic (Fig. 6). However, this may create a false perception that the lateral gingival line is incisal to the central incisor. Rather, in most aesthetic tooth relationships, the gingival line of the four incisors is approximately the same line (Fig. 6), with the lateral incisor perhaps being slightly incisal.[7] The gingival line should be relatively parallel to the horizon for the central incisors and the lateral incisors and symmetric on each side of the midline2,8. The gingival contours (i.e., gingival scallop) should follow a radiating arch similar to the incisal line. The gingival scallop shapes the teeth and should be between 4mm and 5mm (Fig. 7)9. Related to normal gingival form is midline placement. Although usually the first issue addressed in smile design, it is not as significant as tooth form, gingival form, tooth shape, or smile line. Several rules can be applied when considering modifying the midline to create an aesthetic smile design: . The midline only should be moved to establish an aesthetic intra- and inter-tooth relationship, with the two central incisors being most important. . The midline only should be moved restoratively up to the root of the adjacent tooth. If the midline is within 4mm of the centre of the face, it will be aesthetically pleasing. . The midline should be vertical when the head is in the postural rest position Evaluating dental aesthetics Part of evaluating dental aesthetics for smile design is choosing tooth shapes for patients based on their facial characteristics (e.g., long and dolichocephalic, or squarish and brachycephalic). When patients present with a longer face, a more rectangular tooth within the aesthetic range is appropriate. For someone with a square face, a tooth with an 80% width-to-length ratio would be more appropriate. The width-to-length ratio most often discussed in the literature is between 75% and 80%, but aesthetic smiles could demonstrate ratios between 70% and 75% or between 80% and 85% (Figs. 8–10)1. The length of teeth also affects aesthetics. Maxillary central incisors average between 10mm and 11mm in length. According to Magne, the average length of an unworn maxillary central to the cementoenamel junction is slightly over 11mm10. The aesthetic zone for central incisor length, according to the authors, is between 10.5mm and 12mm, with 11mm being a good starting point. Lateral incisors are between 1mm and a maximum of 2mm shorter than the central incisors, with the canines slightly shorter than the central incisors by between 0.5mm and 1mm (Fig. 11). The inter-tooth relationship, or arch form, involves the golden proportion and position of tooth width. Although it is a good beginning, it does not reflect natural tooth proportions. Natural portions demonstrate a lateral incisor between 60% and 70% of the width of the central incisor, and this is larger than the golden proportion11. However, a rule guiding proportions is that the canine and all teeth distal should be perceived to occupy less visual space (Fig. 12). Another rule to help maintain proportions throughout the arch is 1-2-3- 4-5; the lateral incisor is two-thirds of the central incisor and the canine is four-fifths of the lateral incisor, with some latitude within those paces (Fig. 13). Finally, contact areas can be moved restoratively up to the root of the adjacent tooth. Beyond that, orthodontics is required (Fig. 14). Creating a digital smile designed in Photoshop Although there are digital smile design services available to dentists for a fee, it is possible to use Photoshop CS5 software (Adobe Systems) to create and demonstrate for patients the proposed smile design treatments. It starts by creating tooth grids— predesigned tooth templates in different width-tolength ratios (e.g., 75% central, 80% central) that can be incorporated into a custom smile design based on patient characteristics. You can create as many different tooth grids as you like with different tooth proportions in the aesthetic zone. Once completed, you will not have to do this step again, since you will save the created tooth grids and use them to create a new desired outline form for the desired teeth. Follow these recommended steps: . To begin creating a tooth grid, use a cheek- retracted image of an attractive smile as a basis (e.g., one with a 75% width-to-length ratio). Open the image in Photoshop and create a new clear transparent layer on top of the teeth (Fig. 15). This transparent layer will enable the image to be outlined without the work being embedded into the image. . Name the layer appropriately and, when prompted to identify your choice of fill, choose “no fill,” since the layer will be transparent, except for the tracing of the tooth grid. . To begin tracing the tooth grid, activate a selection tool, move to the tool palette, and select either the polygonal lasso tool or the magnetic lasso tool. In the authors’ opinion, the polygonal works best. Once activated, zoom in (Fig. 16) and trace the teeth with the lasso tool. . To create a pencil outline of the tooth, with the transparent layer active, click on the edit menu in the menu bar; in the edit drop-down menu, select “stroke”; choose black for colour, and select a twopixel stroke pencil line (Fig. 17), which will create a perfect tracing of your selection. Click “OK” to stroke the selection. Select (trace with the lasso selection tool) one tooth at a time and then stroke it (Fig. 18). Select and stroke (trace) the teeth up to the second premolar (the first molar is acceptable; Fig. 19). . The image should be sized now for easy future use in a smile design. In the authors’ experience, it is best to adjust the size of the image to a height of 720 pixels (Fig. 20) by opening up the image size menu and selecting 720 pixels for the height. The width will adjust proportionately. . At this time, the tooth grid tracing can be saved, without the image of the teeth, by double-clicking on the layer of the tooth image. A dialog box reading “new layer” will appear; click “OK.” This process unlocks the layer of the teeth so it can be Continued on page 11 September 2015 Pakistan Edition DENTAL TRIBUNE 7 18 19 20 21 22 2726252423 Fig. 18: Image of the central incisor with a two-pixel black stroke (tracing).—Fig. 19: Image of the teeth traced up to the second premolar to create a tooth grid.—Fig. 20: Size the image in Photoshop.— Fig. 21: Save the grid as a .png or .psd file type and name it appropriately. Create other dimension grids using the same technique.—Fig. 22: To determine the digital tooth size, a conversion factor is created by dividing the proposed length by the existing length of the tooth.—Fig. 23: Select the ruler tool in Photoshop.—Fig. 24: Measure the digital length of the central incisor using the ruler tool.—Fig. 25: Measure the new digital length using the conversion factor created earlier.—Fig. 26: Create a new transparent layer and mark the new proposed length with the pencil tool.—Fig. 27: Open the image of the chosen tooth grid in Photoshop and drag the grid on to the image of teeth to be smile designed. This will create a new layer in the image to be smile designed. 28 29 30 31 32 3736353433 Fig. 28: Adjust the grid as required while maintaining proper proportions by using the free transform tool from the edit menu.—Fig. 29: Modify the grid shape as necessary using the liquify tool.— Fig. 30: Select all of the teeth in the grid by activating the magic wand selection tool and then clicking on each tooth with the grid layer activated (highlighted) in the layers palette.—Fig. 31: Use the selection modify tool to expand the selection to better fit the grid shape.—Fig. 32: Activate the layer of the teeth by clicking on it. Blue-coloured layers are active.—Fig. 33: With the layer of the teeth highlighted, choose“liquify”; a new window will appear with a red background called a “mask”.—Fig. 34: Shape one tooth at a time as needed by selecting “wand”.—Fig. 35: Once all of the teeth have been shaped, use the liquify tool.—Fig. 36: Tooth brightness is adjusted using commands from the dodge tool menu or image adjustments menu.—Fig. 37: Image of all the teeth whitened with the dodge tool. 1819202122 2829303132