smile analysis in Orthodontics

Smile analysis from the orthodontic perspective.
Major determinants of smile esthetics are discussed based on the discussions of the Proffit and Graber

1. Orthodontic Diagnosis and Smile Analysis

2. Smile – The Orthodontic Perspective

3. Attributes of Smile Extraoral Features Incisal Display Smile Arc Buccal Corridors Lip Esthetics Smile Symmetry Occlusal Cant

4. Attributes of Smile Intraoral Features Tooth Size and Shape Tooth Proportions Gingival Margins Black Triangles Tooth Shade

5. Smile Esthetics and Maxillary Incisal Display

6. Incisal Display Incisal display at rest (incisor stomion ) Minimal Incisal Display Normal Incisal Display Excessive Ginigival Display

7. Gummy Smile Greater than 2mm of gingival display at smile Prevalence in General Population 1 7% of young adult males 17% of young adult females Prevalence in Orthodontic Patients 2 26% of all o rthodontic patients Gummy Smile as Chief Complaint 2 10% of orthodontic patients Diamond O. Facial esthetics and orthodontics. J Esth Dent. 1996;8:136-43. Peck S, Peck L, Kataja M. The gingival smile line. Angle Orthod 1992;62:91-100 .

8. Reduced Incisal Display More common in men than women 1 Sign of aging 1 1mm reduction in every decade of after age 30 years Can be iatrogenic 40% of orthodontically treated subjects have significant smile arc flattening 2 da Motta AF, de Souza MM, Bolognese AM, Guerra CJ, Mucha JN. Display of the incisors as functions of age and gender. Aust Orthod J. 2010 May;26(1):27-32. Ackerman JL, Ackerman MB, Brensinger CM, Landis JR. A morphometric analysis of the posed smile . Clin Orthod Res. 1998 Aug;1(1):2-11 .

9. The most important esthetic goal in orthodontics is to achieve a balanced smile, which can be best described as an appropriate positioning of teeth and gingival scaffold within the dynamic display zone* * Ackerman MB, Ackerman JL. Smile analysis and design in the digital era. J Clin Orthod 2002;36:221-36.

10. Smile analysis should involve evaluation of certain elements in specific sequence * :- Dento-facial analysis Dento-labial analysis Dento-gingival analysis Dental analysis. * Mc Laren EA, Cao PT. Smile analysis and esthetic design: “In the zone”. Esthet Dent 2009;5:44-8 .

11. DENTO FACIAL Midline B . DENTO LABIAL Incisor display Smile arc Smile symmetry Buccal corridor C . DENTO GINGIVAL Gingival health Height and contour of gingiva D. DENTAL Contacts and connectors Embrasures Crown height and width Mesiodistal width

12. A.DENTO-FACIAL ANALYSIS MIDLINE The starting point of the esthetic treatment plan is the facial midline. One of the goals of the orthodontic treatment is to achieve maxillary and mandibular midlines that are coincident-both with each other and with the facial midline.

13. The most practical guide to locate the facial midline is to use two anatomical landmarks as references* :- Nasion the base of the philtrum, also referred to as the cupid’s bow in the center of the upper lip. A line drawn between these landmarks not only locates the position of the facial midline but also determines the direction of the midline. * Morley J, Eubank J. Macroesthetic elements of smile design. J Am Dent Assoc 2001;132:39-45.

14. Ideally the maxillary central incisor midline should coincide with the facial midline. However if it is not possible, then the midline between maxillary central incisors should be strictly vertical and parallel to the facial midline.

15. B. DENTO-LABIAL ANALYSIS MAXILLARY INCISOR DISPLAY AT REST The average maxillary incisor display at rest is 1.91 mm in men and 3.40 mm in women. The amount of incisor show at rest is the most important esthetic parameter because decreased incisor display is characteristic of ageing. This steady decline in maxillary tooth exposure at rest with aging, is accompanied by an increase in mandibular incisor display

16. Maxillary incisor display on smile / Lip line The lip line is the amount of vertical tooth exposure on smiling i.e the height of the upper lip relative to the maxillary central incisors.

17. The lip line is optimal when the upper lip reaches the gingival margin, displaying the total cervico-incisal length of the maxillary central incisors, along with the interproximal gingivae while smiling

18. Reverse or non-consonant smile arc is the one in which the incisal edges of the maxillary anterior teeth are curved in reverse to the upper border of the lower lip.

19. Reverse smile arc occurs when the centrals are shorter than the canines along the incisal plane which can be due to occlusal malfunction or loss of vertical dimension. Parallel and straight smiles provide better esthetic than reverse smile.

20. iii. SMILE SYMMETRY An asymmetry in the smile can be due to:- Asymmetric smile curtain Transverse cant of the maxillary occlusal plane.

21. iv. BUCCAL CORRIDOR Buccal corridor refers to dark space (negative space) visible during smile formation between the corners of the mouth and the buccal surfaces of the maxillary teeth. It is measured from the mesial line angle of the maxillary first premolar to the interior portion of the commissure of lips.

22. It is represented by a ratio of th intercommissure width divided by the distance from the first premolar to first premolar

23. Buccal corridor is directly influenced by arch form. The ideal arch is broad and conforms to a U shape and is more likely to fill the buccal corridors than narrow and constricted arch.

24. Buccal corridor should be kept to a minimum as it is unattractive, but at the same the buccal corridor should not be completely eliminated.

25. C. DENTO-GINGIVAL ANALYSIS GINGIVAL HEALTH It is of utmost importance that the gingival tissues are in a complete state of health prior to the initiation of any treatment

26. ii. HEIGHT, SHAPE AND CONTOUR OF THE GINGIVA Establishing the correct gingival levels for each individual tooth is the key in the creation of pleasing and harmonious smile. The gingival margins of the central incisors should be at the same level or slightly incisal to that of the canines the gingival margins of the lateral incisors should be towards incisal when compared to central incisors and canines.

27. The discrepancies in the levels of gingival margin may be caused by attrition of the incisal edges ankylosis due to trauma in a growing patient severe crowding The gingival margins can be leveled by orthodontic intrusion or extrusion or by periodontal surgery, depending on the lip line, the crown heights, and the gingival levels of the adjacent teeth.

28. Gingival shape implies the curvature of the gingiva at the margin of the tooth . In an esthetic smile, the volume of the gingiva from the apical aspect of the free gingival margin to the tip of the papilla is about 40-50% of the length of the maxillary anterior tooth and fully fills the gingival embrasure.

29. D. DENTAL ANALYSIS CONTACTS AND CONNECTORS There is distinction between a connector space and a contact point. The contact points between the anterior teeth are generally smaller areas that can be marked by passing articulating ribbon between the teeth. The connector is a large, broad area that can be defined as the zone in which two adjacent teeth appear to touch.

30. The contact points of maxillary teeth move progressively gingivally from the central incisors to the premolars, so that there is a progressively larger incisal embrasure, whereas connectors decreases in size from the centrals posteriorly.

31. An esthetic relationship exists between the interproximal connectors of anterior teeth that is referred to as the 50-40-30 rule

32. ii. EMBRASURES The incisal embrasures are the triangular spaces incisal to the contact point. Ideally these should display a natural, progressive increase in size or depth from the central to the canine.

33. Ideally the embrasures show progressive increase in size or depth from the central to the canine. The contact point moves apically as we proceed from central to canine

34. The individuality of the incisors will be los t if their incisal embrasures are not properly developed. Also, if the incisal embrasures are too deep, it will tend to make the teeth look unnaturally pointed. As a rule, a tooth distal to incisal corner is more rounded than its mesio incisal corner.

35. iii. CROWN HEIGHT AND WIDTH Crown height combined with percentage of incisor display is the deciding factor in the amount of tooth movement required to improve the smile index. The vertical height of the maxillary central incisors in the adult is normally between 9 and 12 mm.

36. Most references specify the central incisors to have about an 8:10 width/height ratio. In one of a recent study the optimal width-to-length ratio for the maxillary central zone was found to be between 75% and 85% of the length. Smiles with these values were most often considered “esthetic to highly esthetic.”

37. iv. MESIO-DISTAL WIDTH The centrals must be the dominant teeth in the smile and they must display pleasing proportions. They are the key to the smile. The shape and location of the centrals influences or determines the appearance and placement of the laterals and canine

38. The apparent width of the lateral incisor should be 62% of the width of the central incisor. The apparent width of the canine should be 62% of that of the lateral incisor.

39. The apparent width of the first premolar should be 62% of that of canine. This ratio of recurring 62% proportions appears in a number of other relationships in human anatomy is referred to as the “Golden proportion.”