Esthetic and Operative Dentistry Course

Asso.Prof.Dr. Ameer Hamdi Al-Ameedee

BDS, HDD, MsC in Operative Dentistry (Bagdad).PhD in Esthetic and Operative Dentistry (Labanon).

Asso.Prof.Dr. Ameer Hamdi Al-AmeedeeBDS, DDS, MsC, Ph.D, in Esthatic and Operative Dentistry.

ESTHETIC CONSIDERATIONS

Does beauty really come from the inside out or does your physical appearance play the greater role?

Do we really think beauty is only skin deep or are our brains hard wired to think otherwise?

What is beauty?

The secret of beauty and attractiveness has been a quest of humans for as long as we have been civilized

Many women – even some men - spend up to one-third of their income on improving their looks

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Is that portion of the discipline that deals with achieving the ultimate in appearance.Escape from artificiality.

EstheticBranch of philosophy dealing with beauty.

Art and science of dentistry applied to create or enhance the beauty of an individual within functional and physiological limits.

Esthetic dentistry

Appearance Zone: This is the anterior oral area where esthetics is of prime concern and which is visible on smiling, from maxillary premolar to premolar (usually 1st molars also).

Depends on the person’s self-image, mouth size, teeth size, smile width, lip size and tightness.

Factors Affecting Esthetics

1- SOFT TISSUE MANAGEMENT A-FINISH LINE FORMATION. B-IMP RESSION PROCEDUR. C - THE TEMPORARY RESTORATION.

2 -TOOTH REDUCTION3 -SHADE SELECTION4 - COLOR VARIATION

5- TRANSLUCENCY

6 -SURFACE CHARACTERIZATION

7 -DEGREE OF GLOSS8-TOOTH FORM,SIZE AND ARCH POSITION

9 -OPTICAL ILLUSON

1 -SOFT TISSUE MANAGEMENT

Optimal soft tissue health should be established before any restorative procedures.

Many aspects of prosthetic treatment may cause esthetically detrimental changes in theform of changes in gingival form ,color or position following cementation.

A- Finish line formationWith subgingival margins ….. every effort must be made to produce minimal soft tissueinjury .

Retraction Cord Technique-The preparation is completely established - with a suprra-gingival finish line.-Then a retraction cord is placed in the sulcus and temporarily displace the gingiva laterally and apically

-Finally, the finish line can be lowered without soft tissue injury.-Too large or too many cords --------- excessive trauma.

-Healthy gingival tissue, one thin cord -------- anterior teeth

-Single medium-sized ------------- posterior teeth.

-Excessive instrument pressure exerted in placing the excessively large cords----gingival damage.

-Blanching (evidence of reduced blood supply) is often observed immediately after placement of cord rapidly disappears.

An impression must provide detailed information about :

The prepared teeth, Surrounding intact teeth, Associated soft tissues

B-IMP RESSION PROCEDUR.

-Remove all cord from the sulcus as the impression material is syringed around the prepared teeth.-Removal of the impression from the mouth, then check the gingival sulcus with an explorer and remove any remnants of retained impression material.

-Severe tissue reactions when the impression material is left in the sulcus.

Inadequate soft-tissue management

Causes of finish line not visible in the impression:

Bleeding from inflamed gingiva displacing the impression material

Tendency of the gingival cuff to recoil and displace partially set impression material

because of inadequate bulk Sulcus impression tearing

Retraction cordTwo-cord techniqueRotary curettage

Electrosurgery Laser troughing

C - THE TEMPORARY RESTORATION

1-Properly contoured2-Well adapted to the preparation margin

3-Should possess a very smooth surface4-Establish cervical embrasures to provide access for oral hygiene aids

5-Left not more than two to three weeks6-Overcontouring leads to food trap and hence complicating the periodontal status.7-Interdental papilla is often neglected due to improper design of interdental space.

8-Crown contours should be such that it should not provide any niche for plaque retention and should promote self-cleaning.

9-Open embrasures to allow easy access to the interproximal area for plaque control.10-An over contoured embrasure will reduce the space intended for the gingival papilla

and causing pressure and irritation on the papilla, also inhibits effective oral hygiene

laceration of the gingiva with rotary instruments + poor temporary restoration.

Final restoration …………… fails to vertically reach the finish line of the prepared tooth

Overextended or under extended restoration

plaque accumulation at the margin of the restoration.

A uniform duplication of the form and contours of the natural dentition.

2 -TOOTH REDUCTION

Insufficient tooth reduction poor esthetics

Development of adequate color requires a certain thickness of porcelain

The facial reduction should be 1 to 1.5 mm.

The areas to be considered during preparation :1 -labioincisal aspects.

2 -Cervical portion of the facial surface.

A) The facial surface should be reduced in two planes; one nearly parallel with the path of insertion, and one parallel with the incisal two-thirds of the facial surface of the tooth

B) One plane reduction parallel with the path of insertion may result in insufficient space for porcelain in the incisal 1/3 of the tooth

C) One plane reduction which creates adequate space for the restoration both in the shoulder and the incisal areas, will endanger the pulp entity and produce overtapered restoration.

inadequate facial reduction, the laboratory fabrication can be handled in one of two ways

1- develop proper contour in the restoration, results in a lack of color vitality due to insufficient porcelain thickness: External and internal color modification to enhance the esthetics of the restoration.

2- over-contoured restoration to develop proper color leading to plaque accumulation which affects the gingival health.

3 -SHADE SELECTION

Shade interpretation

Difficulty in color matching …precise matching of a desired shade can be difficult.

The original color of a tooth is the color one sees as a result of the reflection, refraction, deflection, and absorption of light by the enamel, the dentin, and possibly the pulp. The color seen in a tooth is the result of combined optical effects of the layers of tooth structure, the translucency and thickness of the enamel and color of the underlying dentin.

The esthetic dentistry, using a combination of science and art, involves the use of colors to create a natural tooth like restora tion, color and shade are very important because teeth are multi-chromatic with color variations from cervical to incisal, every tooth in the mouth from the central incisors to molars, both upper and lower, varies in color.

Color that is perceived is the result of a light source, the object that absorbs, transmits, reflects or scatters the light from the source, and the interpretation of the result by the human visual system

Light form of visible energy that is part of the radiant energy spectrum. Radiant energy possesses specific wavelengths, which may be used to identify the type of energy

In 1666 Isaac Newton discovered that white light can be broken down into a rainbow of color

In nineteenth century that German physiologist Ewald Hering first described the now familiar color circle.

In 1905, Albert Henry Munsell, an American artist and art teacher, further modified the color circle, devising a system of color organization that centered around three unique aspects of color: hue, chroma, and value. Using these three aspects, was able to construct a three-dimensional color wheel

Color Mixing

Light mixture- primary colors: red, green, blue.Additive mixture system- mixing of two of the light mixture primary colors red + blue = magenta red + green = yellow green + blue = cyan

Pigment mixture system: yellow, cyan, magenta

Color of the Human Teeth

Clark was the first to accurately describe the color of the human teeth in 1931

Dr. E. B. Clark, a dentist, produced the first data in 1931.He indicated the Hue ranged from 6 YR (yellow-red) to 9.3 Y (yellow).The Value ranged from 4 to 8, and the Chroma ranged from 0 to 7.

Lemire and Burk found:The Hue range from 8.9 Y to 3.3 Y, a Value range of 5.8 to 8, and a Chroma range from 0.8 to 3.4

Goodkind and Schwabacher:Identified the Hue range as 4.5 YR to 2.6 Y, the Value range as 5.7 to 8.5, and the Chroma range from 1.1 to 5.

Guidelines for Clinical Shade Selection

1.light2.amount lighting3.location of lighting 4.restricting light5.surrounding colors 6.tone of selection7.patient position 8.tooth condition9.comparison prcds. 10.selectiodistance11.verification 12.diagram13.photograph

Vita 3D stapes 1 (Value)

1-Determine the lightness level (value)

2-Hold shade guide to patient’s mouth

3-Start with darkest group moving right to left

4-Select Value group 1, 2, 3, 4, or 5

Munsell color system extends from zero to ten, black is zero and white is ten

Vita 3D stapes 2 (Chroma)

Select the chroma1-From your selected Value group, remove the middle tab (M) and spread the samples out like a fan

2-Select one of the three shade samples todetermine chroma

Vita 3D stapes 3 (Hue)

Determine the hue

Check whether the natural tooth is more yellowish or more reddish than the shade ample selected

Shade matching using the VITA Easyshade Compact:1-“Tooth areas” mode selected. Note the active dot appearing in the cervical third of the tooth on the screen.2-Wand tip on the buccal surface at the cervical third of the tooth. 3-“OK” signal in the cervical third and active dot in the middle third on the screen. 4-Wand tip on the buccal surface at the middle third of the tooth.

Color research continued to evolve based on the Munsell color model. In 1976, The Commission Internationale de l’Eclairage (CIE), an international color research group founded in 1931, published the CIELAB color system.

In this 3-dimensional color system, L* refers to brightness (0 to 100), a* represents red (+a*) vs. green (-a*) and b* indicates yellow (+b*) vs. blue (-b*). When a* and b* are zero, the L value represents the continuum of black to white. The CIELAB model offers some advantages over other color models. The L*a*b* color space was designed to correlate with perceptions of color.

CIELAB COLOR SYSTEM

Color Differences CIELAB

Is often used to measure changes in color, including changes in tooth color from use of whitening products. Color difference equations are used to quantify the color change. ΔL*, the change in brightness,

5- OK signal in the cervical and middle thirds and active dot in the incisal third on the screen.6-Wand tip on the buccal surface at the incisal third of the tooth. 7- OK signal in the cervical, middle, and incisal thirds on the screen. 8-VITAPAN Classical and VITAPAN 3D-Master shades that are closest to the natural tooth structure color shown on screen. Note: The nonslip infection-control shield has been omitted from this series of photos for dem onstration clarity.

Factors can be responsible for poor color matching

1-A poor selection may have been made from available shades, or it may not be possible to match the natural teeth with the available porcelain colors.

2. The dental laboratory may have failed to reproduce the selected shade from the available materials or there may have been insufficient information to effect a satisfactory color modification.

3. The tooth reduction is insufficient in certain areas, or the metal framework or opaque porcelain, or both, may be too thick, leaving insufficient space for dentin porcelain.

4. Also, the porcelain may not have been handled in such a manner as to reveal its inherent coloration.

COLOR VARIATIONS AMONG TEETH

1- Maxillary anterior teeth

canines pigments

related to the dentine thickness..lateral incisor slightly less pigmentation than the central incisor,related to the faciolingual dentine thickness, which is often slightly less ona maxillary lateral incisor.

cervically : dentin is more than enamel. Incisally the enamel is thicker than the dentin, which increases the translucency.

The canines exhibit the greatest color intensity, with the incisors usually appearing the same.

If a variation in the incisors exists, it is the opposite of that found in the maxillaryincisors.

The lateral incisor pigmentation owing to the larger crown dimension.

2 -Mandibular anterior teeth :

5- TRANSLUCENCY

Translucency of the tooth helps to give the appearance of vitality. Translucency is most obvious in the incisal portion, in which the ratio of enamel to dentin is high.

Duplication of this feature in ceramic restoration is to seem “alive.”

Translucency is important during conversation or smiling specially forPatients with a low smile line, only the incisal portion of their teeth isvisible, so duplication of this character is essential for these patients.

Degree to which light is transmitted rather than reflected.

Translucency also affects the esthetic quality of the restoration. The degree of translucency is related to how deeply light penetrates into the tooth or restoration before it is reflected outward.

Normally light penetrates through the enamel into dentin before being reflected outward. This affords the lifelike esthetic vitality characteristic of normal, unrestored teeth.

Shallow penetration of light often results in a loss of esthetic vitality Illusions of translucency also can be created to enhance the realism of a restoration.

Color modifiers (also referred to as tints) can be used to achieve apparent translucency and tone down bright stains or characterize a restoration.

Translucency increases from cervical to incisal. Incisal edges, cusp tips and proximal surfaces are areas of high translucency.

An anterior tooth sometimes has an area of slight incisal opacity. This area is frequentlycomposed of enamel, the opacity is due to an optical effect created by refraction of light as it strikes the incisal edge (halo effect).

Reproduction of this effect by shaping the incisal edge of the ceramic restoration so that it possesses the exact lingual slope and thickness of adjacent teeth.little surface stain applied lingually or incorporated internally, can enhance the desired result. Surface stain located lingually may wear off during function.

6 -SURFACE CHARACTERIZATION

Young teeth characteristically exhibit significant surface characterization, whereas teeth in older individuals tend to possess a smoother surface texture caused by a brasional wear. The surfaces of natural teeth typically break up light and reflect it in many directions .The restored areas of teeth should reflect light in a similar manner to un restored adjacent surfaces.

surface texture controls the reflection of light

When light strikes a restoration surface, it should create a reflection pattern similar to that of adjacent teeth, thus enhancing the color match.

Developing the desired light reflection on a restoration’s surface by meticulous duplication of the height of contours and depressions on the facial surface. The number of depressions, their location, form, and depth can be recorded by close-up photographs taken from different angles and by the working cast.

7 -DEGREE OF GLOSS

1 - Surface gloss on ceramic restoration affects the reflection of light, functions in conjunction with surface characterization to enhance theappearance of the restoration.

2 - Excessive gloss lightens the color

3 -Too long heating or heating at elevated temperatures during glaze firingcan exhibit exaggerated gloss, in addition to excessive flowing of the surfaceand loss of surface characterization.

4 -Combining different degrees of gloss at different areas creates the desirable natural play of reflection of light.

5-Introducing highly glazed wear facets in older patients improves esthetics.

8-TOOTH FORM,SIZE AND ARCH POSITION

Restoration of a single maxillary central incisor is one of the most difficult esthetic situations. By contrast, if the restoration is slightly out of alignment with its contralateralcounterpart, , it is usually better for restorations to be shaped like their contralateral counterpart when they are located adjacent to unrestored teeth.

But if all of the readily visible teeth are being restored andthere is no color-matching problem, it may be estheticallyadvantageous to create slight alterations in form and positionto escape from artificiality.

Esthetics depend on proportion. An object is considered beautiful if it is properly proportioned, Concepts of proportion are probably based on what is found in nature. A ratio of approximately 1.619 to 1 between succeeding terms is considered pleasant, and is known as the golden proportion.

Golden proportion of the tooth restoration

When a line is bisected in the golden proportion, the ratio of the smaller section to the longer one is the same as the ratio of the larger section to the whole line.

We dentists find the proportions of the central incisor very beautiful, but we have not been able to find a Golden Proportion relationship between the obvious width and height. The problem was recently solved when Dr Stephen Marquardt, an eminent Oral surgeon in California, discovered that, “The HEIGHT of the central incisor is in the Golden Proportion to the WIDTH of the TWO central incisors.” as below:

Golden proportion of the tooth restoration

The golden proportion is a athematically constant ratio between the larger and smaller length. The ratio is approximately 1.618:1 In terms of proportion, the smaller tooth is about 62% the size of the larger one.

The Golden Proportion results from the division of a straight line in such a way that the shorter part is to the longer part as the longer part is to the whole. Each ratio equals 0.618.

9 -OPTICAL ILLUSONIs the art of changing perception making an object appear different than it actually is.

Illusion is the art of changing the perception to cause an object to appear different than it actually is.This concept is particularly useful in solving problems associated with presence of space limitations (too much or too little space) or other problems that may make it impossible to duplicate the original form.

The principles of illumination and reflection can be manipulated by the dentist and the technician to change the apparent size and shape of a tooth through illusion.The law of the face: The face of the silhouette of the tooth is the area on the facial surface of anterior and posterior teeth that is bounded by the transitional line angles as viewedfrom the facial (buccal) aspect.

The law of the face:

In anterior teeth, the transitional line angles mark the transition from the facial surface to the mesial and distal surfaces, the incisal edge and cervically.

The tooth surface slopes lingually towards the mesial and distal approximating surfaces and towards the incisal edge and the cervical root surface from theseline angles, producing light reflections in different directions corresponding to the sloping direction of each surface, thus creating shadows in these areas.

The face of the tooth andtransitional line angles

Only the face of the tooth or the silhouette will reflect the light forwards and anteriorly.

By reducing or increasing the portion of the tooth reflecting light forwards (the face) we create the illusion of smaller or wider, shorter or longer teeth respectively

Creating equal apparent faces in two dissimilar adjacent teeth, makes dissimilarly sized teeth look similar; as their faces reflect light in the same way .

Disharmony treated by optical illusion

The concept of the law of the face becomes apparent and more important when dealing with canines and posterior teeth.

From the frontal view only a portion from the canine and posterior teeth are visible. In this view, the canine face is bounded by the mesial transitional line angle, the cervical transitional line angle and the midlabial ridge.

The distal half of the tooth is usually not visible from the frontal view. Moving the midlabial ridge and the incisal tip mesially (a, b), will create the illusion of a narrower tooth.

In addition, moving the distal transitional line angle more mesially ( c) will give the illusionof equal mesial and distal faces and the tooth will look smaller both from frontal and side views.

Principle of line

white hypoplastic lines, accentuated developmental grooves, vertical texturing illusion of height

Stain lines, texturing, straight incisal edges illusion of width

These lines create illusions by breaking up the smooth reflecting surface causing ruptures in the continuity of the linear reading of the surface making the tooth appear longer or shorter, wider or narrower.

Characterized or textured surfaces produces shadows and shadow position can determine how the mind will interpret the form.

Arrangement of teeth

The position or arrangement of teeth can create illusion of decrease width.

When teeth are placed in linguo-version, not only its real width is masked by the more prominent approximating teeth, but the effect of increased a hadowing also its size.

Slight lingual rotation of anterior crowns may solve the problem of wide space by narrowing the areas that reflects light forward; thus decreasing the apparent width

Staining

Not only used to duplicate the natural variation of the tooth color, but also to create and enhance illusion through manipulation of shape.

Darker stains optical illusion of smaller size

Increasing the value ( increase whiteness) closer area

Decreasing the value(increase grayness) less prominent area

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