CLINICAL GUIDELINE FOR THE VERTICAL POSITIONAL RELATIONSHIP OF MAXILLARY CENTRAL INCISOR EDGES TO UPPER LIP IN REPOSE

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1 CLINICAL GUIDELINE FOR THE VERTICAL POSITIONAL RELATIONSHIP OF MAXILLARY CENTRAL INCISOR EDGES TO UPPER LIP IN REPOSE 1 Abhishek Gaur, Senior Lecturer Department of Prosthodontics Saraswati Dental College 2 & Hospital Lucknow, Arvind Tripathi,Professor & Head Department of Prosthodontics Saraswati 3 Dental College & Hospital Lucknow, Neerja Raj, Reader Department of Prosthodontics Saraswati 4 Dental College & Hospital Lucknow, Atul Bhatnagar, Associate Professor Unit of Prosthodontics and Implantology, Faculty of Dental Sciences Institute of Medical Sciences B.H.U. Varanasi Abstract Aims : To measure the amount of visibility of maxillary central incisors in frontal plane with lips in repose and to evaluate the relationship of upper lip length vertically from the base of the columella to the tip of the philtrum in repose, to the visibility of maxillary central incisors in different age groups and in two genders. Materials And Methods : A total of 150 volunteers in three age groups Group I (20-29 years), Group II (30-39 years) and Group III (>40 years) of 50 subjects each were enrolled in the study. Each group had an equal number of males and females (n=25 each). Measurements were made by manual and digital methods. Results : With increasing age an increase in upper lip length (ULL) was observed both for overall as well as for both the genders. Mean incisal edge exposure (IEE) was found to be decreased in >40 years age group. ULL/IEE ratio was also found to be increasing with increasing age. Males had significantly higher mean values as compared to females for ULL and significantly lower mean values as compared to females for IEE. Digital method showed significantly higher mean values as compared to manual method for both the parameters, however, a strong correlation was observed between digital and manual methods. Conclusion: Parameters affecting vertical position at rest were found to be affected by individual's age and gender, with increasing age a change in interrelationship of ULL and IEE was observed. University Journal of Dental Sciences Original Research Paper Key words : upper lip length, incisor edge exposure, lip repose Source of support : Nil Conflict of interest : None INTRODUCTION : The ultimate aim of oral rehabilitation is to restore the normal contour, comfort, function, esthetics, speech, and health of the stomato-gnathic system. The anterior teeth play an important role in esthetics, phonetics, and incision of food[1]. Simulation of natural arrangement of anterior teeth allows preservation of patient's facial aesthetics and identity[2,3]. Factors governing harmonious arrangement of anterior dentition are the size, form and colour. Several guidelines were suggested to establish the lip lengthincisal edge relationship and, accordingly, the visible amount of anterior teeth. One of the accepted guidelines was the vertical length of the maxillary central incisors extending approximately 2 mm below the relaxed lip8. It also serves to be a helpful guidelines for determining the appropriate vertical dimension of occlusion[9,10]. The visibility of anterior teeth edges with lips at rest or during function is an important factor in attaining a pleasant prosthodontic outcome. However there is lack of sufficient data related to this issue. The purpose of this study was to determine in dentate individuals the vertical positional relationship of maxillary central incisors to upper lip in repose. MATERIALS AND METHODS : The study was conducted at the Saraswati Dental College and Hospital, Lucknow (U.P.). Ethical clearance was obtained from the institutional ethical committee and the consent was taken from the subjects who volunteered to participate in the study. The participants were selected from amongst dental students, employees and patients reporting to the OPD of our college. The study sample comprised of 150 individuals. A total of fifty (50) individuals each from age groups years, years and >40 years respectively comprising the Group I, Group II, Group III of the study respectively. Each group had an equal number of males (n=25) and females (n=25) and thus comprised Subgroup A and Subgroup B of the present study. All the subjects included in the study did not have any missing maxillary or mandibular anterior teeth, anterior spacing or severe attrition. It was ascertained that incisal edge surfaces of both the central incisors was at same level, patients had good gingival and periodontal health and had a skeletal class-i jaw

2 relationship. Individuals having a history of orthodontic treatment, history of dental trauma, having anterior restorations, diastema, crowding, cross bite (unilateral and bilateral), open bite, V- shaped arch and having congenital or acquired defects in head and neck region were excluded from the study. The study was conducted in two parts, viz., Part I - Measurement of the Amount of Visibility of Maxillary Central Incisors in Frontal Plane with Lips in Repose and Part II Evaluation of the Relationship of Upper Lip Length Vertically from the base of the Columella to the tip of the Philtrum in Repose, to the Visibility of Maxillary Central Incisors. For each part of study, measurements were made using direct manual method as well as digital photographic method. Direct manual measurements were made using Electronic Digimatic Vernier Caliper (Mitutoyo, Japan; S.No Calibration Certificate No /310) while digital photographic measurements were made using Sony cybershot DSC - HX1 (10.1 megapixel with 20x optical zoom). PROCEDURE : Part I: In this part of study we measured the amount of visibility of maxillary central incisor tooth surfaces vertically in frontal plane. This study was again sub-divided into two parts regarding linear measurements: In part A the measurements were done by manual method with the help of a digimatic Vernier calipers and in part B the measurements were done on the digital photographs with the help of Corel Draw-14 software. Part A: Manual Method: Volunteers were asked to stand upright with the subject's head and back supported against the wall. One of the tips of the digimatic Vernier calipers was placed at the incisal edge of maxillary central incisor and another tip to the lower border of the upper lip in repose. The measurements were obtained when the subject was asked to determine the self balanced position11,12,13,14 by tilting the subject's head backward and forward with decreasing amplitude to find the most neutral position in between. To prevent the subjects from swaying, the feet were positioned at a comfortable distance apart and slightly diverging. Each subject was asked to say emma with one's face and lower jaw relaxed. As soon as the subject was asked to pronounce emma the amount of visibility of anterior teeth surface vertically in frontal plane in mm was measured by placing the digimatic vernier caliper at the incisal edge of maxillary central incisor to the lower border of the upper lip in repose. Part B: Digital Photographic Method: The position of the subject was standardized with the help of a cephalostat machine. Subject's head positioned for facial photograph through Ear-posts, Nasion supporter and Orbitale pointer of the cephalostat machine. The digital camera was installed on a tripod and its position was adjusted so that the center of the lens of the camera coincided with the tip of the subject's nose (figure 1). Three sequential photographs were obtained in this position with the help of the digital camera (DSC - HX1 Sony cyber shot 10.1 megapixel with 20x optical zoom) mounted on a tripod stand at 60 cm (2 ft) away from the subject. The digital photographs were transferred subsequently to the computer and subjected to Corel Draw-14 software application to measure the visible portion of the maxillary central incisors vertically, from the incisal edge to the lower border of the upper lip in repose. Part II: In this part of study we measured and metrically corelated the relationship of upper lip length from the base of the columella to the tip of the philtrum vertically in repose, to the visibility of maxillary central incisors. This study was again sub-divided into two parts regarding linear measurements. Part A: Subjects were asked to stand upright with one's head and back supported against the wall. One of the tips of the digimatic vernier caliper was placed at the base of the columella and the other tip of the caliper was placed on the tip of the philtrum at the facial midline. The measurements were made when the subject was asked to determine the self balanced position by tilting the subject's head backward and forward with decreasing amplitude to find the most neutral position in between. To prevent the subjects from swaying, the feet were positioned at a comfortable distance apart and slightly diverging. Each subject was asked to say emma with one's face and lower jaw relaxed. As soon as the subject was asked to pronounce emma the upper lip length was measured vertically by placing the digimatic vernier caliper at the base of the columella to the tip of the philtrum15-21 in millimeters, at the facial midline with the lips in repose. Part B: The position of the subject was standardized with the help of a cephalostat machine. Subject's head positioned for facial photograph through Ear-posts, Nasion supporter and Orbitale pointer of the cephalostat machine. Digital camera was installed on the tripod stand and adjusted so that the

3 center of the lens of the camera should coincide with the tip of the subject's nose. Cephalostat machine was used to standardize the position of the subject's head to obtain the facial photograph. The vertical height of the tripod is adjusted so that the lens of the camera coincided with the tip of subject's nose. Three sequential photographs were obtained in this position with the help of the digital camera mounted on a tripod stand at 60 cm (2ft) away from the subject. The digital photographs were transferred subsequently to the computer and subjected to Corel Draw-14 software application to measure the upper lip length vertically from the base of the columella to the tip of the philtrum (in millimeters) at the facial midline with the lips in repose. The data thus obtained by manual and digital photographic methods regarding the measurement of the upper lip length vertically, with lips in repose were duly tabulated and subjected to statistical analysis. RESULTS : For both manual as well as digital measurements, with increasing age an increase in ULL was observed which was significant statistically too for overall assessment and males. Though similar trend was observed among females too yet it was not significant statistically. As compared to males, females had significantly lower man values in all the groups for both manual as well as digital measurements. As compared to manual measurements, digital measurement values were significantly higher but the two values were strongly correlated (Table 1). Table 1: Comparison between Manual and Digital Photographic Technique for Upper Lip Length lower as compared to Groups I and II for overall and males (p<0.05), although Group III females too had lower mean value as compared to Groups I and II but the difference was not significant statistically (p<0.001) (Table 2). Females had higher mean value as compared to males for all the three groups, however, the difference was significant statistically (p<0.05) only for Groups I and II, for both the methods. Comparison of two values showed mean values for digital method being significantly higher as compared to manual method in all the three groups (p<0.001), but the correlation between two methods was strong (r>0.9) (Table 2). Table 2: Comparison between Manual and Digital Photographic Technique for Incisal Edge Exposure Comparison of ULL/IEE ratio showed an steady increase with increasing age which was significant statistically too (p<0.01) irrespective of the method of measurement. For both the methods, males had higher mean value as compared to females for both the methods (Table 3). Comparison of intermethod difference showed no statistically significant difference between two methods for overall assessment (p=0.621), however, the difference was significant statistically for age groups and years (p<0.01) but not for age group >40 years (p=0.650) (Table 3). Table 3: Comparison of ULL / IEE Ratio between Manual and digital methods For IEE, no significant difference among different age groups was observed either for overall as well as either of two genders independently for manual method, however, digital method showed mean value of Group III to be significantly

4 DISCUSSION : The determination of the vertical position of the maxillary anterior teeth is an important criterion in replacement of these teeth. One of the goals in prosthetic replacement is to replace these teeth in positions similar to dentate patients of the same gender, age, race and facial structures. Hence, a clinical study of the averages and ranges of these elements in dentate patients was needed to record1. Anterior tooth selection and arrangement for removable dentures usually depends on standard parameters. The arrangement of the anterior teeth should be individualized to fulfill the esthetic needs while considering the age and sex of the patient. Complete dentures offer the clinician the ultimate freedom in providing patient-accepted esthetics. Given almost infinite variety of tooth molds, sizes, shades, and arrangements available today, the clinician is limited only by his or her imagination and artistic talent22. The amount of maxillary central teeth exposure with the lip in repose is a highly variable position and is dependent on many factors. Considering one central incisor to lip in repose average position is not specific enough to use in edentulous patients of various ages1. The findings of present study also suggest that with age there is variation in vertical relationship parameters (ULL and IEE) and they are gender specific too. The interrelationship between upper lip length (ULL) and incisal edge (IEE) exposure was also seen to be affected by both age as well as gender, thus specifically clearing that the treatment objectives of prosthetic rehabilitation must be dependent on the profile of patients, specifically, his/her age and gender. Thus the findings of present study endorse the dentogenic concept described by Frush and Fisher23 who proposed to use the patient's gender, personality, and age in selecting and arranging anterior teeth. In present study, with increasing age, amount of maxillary central incisor exposed when the lips were at rest decreased from 3.13 mm at age 20 to 0.93 mm at age 60. The opposite occurs for the mandibular incisors, with approximately 0.75 mm showing at age 20 and 1.34 mm at age 60. It is clear from this study that as time and gravity wins out, the tissues surrounding the mouth sag. The visible length of maxillary anterior teeth diminishes and the amount of mandibular anterior teeth visiblity increases. A similar finding was reported by Vig and Brundo24. People with short upper lips display the maximum maxillary anterior teeth surface, while people with long upper lips display more mandibular anterior teeth, which is in agreement with Vig and Brundo24. In complete dentures, the incisal edges of mandibular incisors are established by positioning the central incisor 0.5 mm vertical overlap with the maxillary central and a 1 to 2 mm horizontal overlap25. This indicates that the maxillary central incisor is superior reference than the rest of the anterior teeth in regards to the amount of visible tooth surface. The rest of the anterior teeth showed more variation than the maxillary central incisor. The results of this study showed that maxillary central incisor is the most prominent tooth in the mouth; accordingly, extra care should be taken when selecting its size, form, and positioning. The vertical positioning of the maxillary anterior teeth cannot be established by the visible amount of tooth alone, because they also play an important role in both anterior guidance and phonetics. With respect to use of different methods, we found that digital measurements, despite providing significantly higher mean values as compared to manual measurements provided values which strongly correlated with manual measurements. The significantly higher mean values in digital measurements could be owing to ability of digital photographs to be enlarged upto 5000 times for making measurements. As the objective was to take the vertical rest measurements, during manual measurements owing to extra effort taken not to disturb the vertical rest position might have resulted in some measuremental errors. From the point of view of maintenance of vertical rest position, digital measurement method seems to be a better choice, however, as far as accuracy is concerned, further validation is recommended. Regardless of judgement and technical ability dentist can place artificial teeth more correctly if clues are available as to former natural tooth positions. This study provides baseline information about the vertical positional relationship of maxillary anterior teeth visibility to upper lip in repose. Similar studies on different samples are needed to confirm the results. CONCLUSION : The findings of present study suggested that age and gender have a significant role in determining the parameters affecting vertical rest. Hence, the prosthodontic rehabilitation programmes are recommended to take into account the individual's profile in consideration. Based on the limitations of this study, the following conclusions were drawn:

5 1. Digital Photographic method is a better method for facial measurements in normal repose as it does not affect the normal repose. 2. The treatment planning to provide a normal repose must be made for variability in age and gender. 3. The relationship between Lip length and Incisal edge exposure is not a product of just two variables, i.e. age and gender; rather it is affected by other factors too. An esthetic approach is recommended to find out an ideal relationship. 4. The study tries to explore a normative data, however, the objective of prosthodontic treatment planning is towards providing an esthetic profile, and thus a relationship should be explored in the esthetic profile faces. Figure 1: schematic illustration showing methodology of obtaining standard digital images of the subject for percentile measurement. REFERENCES : 1. Misch CE: Guidelines for maxillary incisal edge position a pilot study: The key is the canine. J Prosthodont. 2008; 17: La Vere AM, Marcroft KR, Smith RC and Sarka RJ: Denture tooth selection: An analysis of natural maxillary central incisor compared to the length and width of the face. PART-I. J Prosthet Dent. 1992; 67: Lau GC, Clark RF: The relationship of the incisive papilla to the maxillary central incisor and canine teeth in southern Chinese. J Prosthet Dent 1993; 70: Silvernabb SI: Physiologic factor in complete denture esthetic. Dent Clin North Am 1967; 52: La Vere AM, Marcroft KR, Smith RC and Sarka RJ: Denture tooth selection: An analysis of natural maxillary central incisor compared to the length and width of the face. PART-II. J Prosthet Dent. 1992; 67: Smith BJ: The value of the nose width as an aesthetic guide in prosthodontic. J Prothet Dent 1975;34: Cessario VA, Latte GH. Relationship between the mesiodistal width of the maxillary central incisor on the pupillary distance. J Prosthet Dent 1984;52: Heartwell CM Jr, Rahn AO. Syllabus of complete denture. 4thed.Philadelphia, Pennsylvania: lea and Febinger 1986.p Mack MR: Vertical dimension: A dynamic concept based on facial form and orophareyngeal function. J. Prosth. Dent. 1991; 66; Mack, MR: Perspective of facial esthetics in dental treatment planning. J. Prosthet Dent. 1996; 75: Cooke MS, Wei SH. The reproducibility of natural head posture: a methodological study. Am J Orthod Dentofacial Orthop 1988; 93: Cooke MS, Five-year reproducibility of natural head posture; a longitudinal study. Am J Orthod Dentofacial Orthop 1990;97: Lundstrom F, Lundstrom A. Natural head position as a basis for cephalometric analysis. Am J Orthod Dentofacial Orthop 1992;101: Peng L, Cooke MS: Fifteen-year reproducibility of natural head posture: A longitudinal study. Am J Orthod Dentofacial Orthop 1999; 116: Miller EL, Bodden R and Jamison HC: A study of the relationship of the dental midline to the facial median line. J Prosthet Dent. 1979; 41: Latta GH: The midline and its relation to anatomic landmarks in the edentulous patient. J Prosthet Dent. 1988; 59: Cardash HS, Ormanier Z and Laufer BZ: Observable deviation of the facial and anterior tooth midlines. J Prosthet Dent. 2003; 89: Johnston CD, Bunder DJ, Stevenson MR: The influence of dental to facial midline discrepancies on dental attractiveness ratings. Eur J. Orthod 1992; 21: Beyer JW, Lindaver SJ. Evaluation of dental midline position, Semin Orthod 1998; 4: Kokich VO Jr, Kiyak HA, Shapiro PA. Comparing the perception of dentists and lay people to altered dental esthetics. J Esthet Dent 1999; 11: Arnett GW, Mc Laughten RP. Facail and dental planning for orthodontists and oral surgeons. St. Louis: Elsevier;

6 2004, p Donovan TE, Derbabian K, Kaneko L, et al.: Esthetic considerations in removable prosthodontics. J Esthet Resto Dent. 2001; 13: Frush JP and Fisher RD: How dentogenic restorations interpret the sex factor. J Pros Dent. 1956; 6: Vig RG and Brundo GC: The kinetics of anterior tooth display. J Prosthet Dent. 1978; 39: Zarb GA, Bolender CL, Hickey JC et al: Creating facial and functional harmony with anterior teeth in Zarb GA (Ed): Boucher's Prosthodontic Treatment for Edentulous patients, (Ed 10). St. Louis, MO, Mosby, 1990, pp CORRESPONDING AUTHOR Dr. Abhishek Gaur Saraswati Dental College & Hospital Lucknow (U.P.) 4/373, Vijayant Khand, Gomti Nagar, Lucknow drabhishekgaur@aol.in, dr.abhishekgaur@ymail.com

Evaluation of dental to facial midline discrepancies and its influence on dental attractiveness ratings in Gujarati (Indian) Population

Original article: Evaluation of dental to facial midline discrepancies and its influence on dental attractiveness ratings in Gujarati (Indian) Population 1Dr. SandhyaShroff, 2 Dr. Kavita Gupta, 3 Dr. Shivali