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| ORIGINAL ARTICLE |
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Year : 2012? |? Volume : 1? |? Issue : 2? |? Page : 68-73 |
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A comparative study of vertical lip changes after standard edgewise and preadjusted orthodontic treatments
Morteza Oshagh1, Amir Ali Karamifar2, Parisa Salehi1, Mohammad Mehdi Naseri2
1?Department of Orthodontics, Member of Orthodontic Research Center, Shiraz, Iran
2?Shiraz University of Medical Sciences, Faculty of Dentistry, Shiraz, Iran
| Date of Submission |
05-Jul-2012 |
| Date of Acceptance |
27-Sep-2012 |
| Date of Web Publication |
8-Jan-2013 |
Correspondence Address:
Morteza Oshagh
Department of Orthodontic, Shiraz Dental School, Shiraz
Iran
DOI: 10.4103/2278-9588.105672
Context: Frontal esthetics should equal the profile in importance when planning orthodontic treatment. Soft tissue profile changes associated with orthodontic treatment have been the subject of many studies, but changes in the vertical dimension of the lips after orthodontic treatment by different appliances has received little attention.
Aims: The purpose of this study was to compare the changes of vertical dimension of vermilions after standard and preadjusted orthodontic treatment.
Setting and Design: Retrospective study.
Materials and Methods: In this retrospective study, 60 patients (30 patients treated with standard edgewise appliances and 30 patients treated with preadjusted appliances) were randomly selected from the practice of two experienced orthodontist. Ratios between vermilion height and inter-commisural width were recorded on pre- and posttreatment photographs using Adobe Photoshop software. Data were analyzed with SPSS version 16 software and ANOVA analysis to compare vertical lip changes between two orthodontic systems.
Results: The mean of vermilion height to inter-commisural width ratios after orthodontic treatment in preadjusted group (P = 0.019) and standard group (P ? 0.001) was significantly less than that before treatment. The reduction of this ratio after preadjusted orthodontic treatment was less than that in standard edgewise orthodontic treatment but this difference was not statistically significant (P = 0.127).
Conclusion: In this study, the vertical height of lips decreased significantly after orthodontic treatment in both groups and there was no significant difference in standard and preadjusted appliance. Therefore these changes must be discussed with patients before orthodontic treatments.
Keywords:?Vermilion height, preadjusted appliance, standard edgewise
How to cite this article:
Oshagh M, Karamifar AA, Salehi P, Naseri MM. A comparative study of vertical lip changes after standard edgewise and preadjusted orthodontic treatments. J Cranio Max Dis 2012;1:68-73 |
How to cite this URL:
Oshagh M, Karamifar AA, Salehi P, Naseri MM. A comparative study of vertical lip changes after standard edgewise and preadjusted orthodontic treatments. J Cranio Max Dis [serial online] 2012 [cited?2013 Aug 27];1:68-73. Available from:?https://craniomaxillary.com/text.asp?2012/1/2/68/105672 |
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??Introduction |
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Because treatment mechanics are becoming more effective, there has been an increased emphasis on the soft tissues, both in diagnostic and treatment results. [1] The extraction of teeth as an adjunct to orthodontic treatment is a well-documented procedure, [2] which if based on sound diagnostic criteria, is not detrimental to facial esthetics. [3] Orthodontists have long recognized that the extraction of premolars often is accompanied by changes in the soft-tissue profile. [4] Although these soft tissue changes are usually considered secondary to tooth and skeletal alterations, [5] but the soft tissue does not always respond favorably to hard tissue retraction. [6],[7],[8],[9],[10] Therefore, it is useful for the clinician to know the effects of different treatment options and what they offer the patient. The lip length has a tendency to shorten due to retraction of the maxillary teeth [5] and little vermilion height, is an unesthetic result. [11] Soft tissue profile changes associated with orthodontic treatment have been the subject of many studies, [8],[10],[12],[13],[14],[15],[16],[17] however, changes in the vertical dimension of the lips has received little attention. [18] In addition, the numerous analyses available for evaluating soft-tissue and the lack of standardization in research methods make it difficult to draw conclusions. [19] Jacobs studied vertical lip changes in extraction patients by cephalograms and found that vermilion heights decreased on average 1.6 mm for the upper lip and 1.3 mm for the lower lip during treatment. [15] However, people look beyond traditional cephalometric profile measures when making judgments about facial appearance and also the amounts of change perceived by either orthodontists or laypeople were not related to the amount of change measured cephalometrically. [20] Frontal esthetics should equal the profile in importance when planning treatment and Perkins et al. demonstrated that the effect of changes in vermilion height during treatment on facial esthetics could also be studied with frontal photographs. [18]
Since the facial surface of individual teeth varies markedly in inclination to the true vertical, in the standard edgewise appliance it is necessary to place a varying twist (third-order or torque bends) in segments of each rectangular archwire, in order to make the wire fit passively. However, torque bends are required for every patient in every rectangular archwire, it is doubtful that inclination of incisors after standard edgewise treatment would be ideal or not. Preadjusted appliances use brackets that are custom-made for each tooth, with the goal of minimizing the number of bends in archwires needed to produce an ideal arrangement of the teeth. In theory, inclination of incisors after preadjusted orthodontic treatment would be nearly ideal and it is clear that these inclinations have effects on lips. [21]
Although most previous literature regarding soft tissue behavior during orthodontic treatment has focused on retraction of the vermilion border, there is no information directly concerning the magnitude of changes in the vertical dimension of the vermilion after orthodontic treatment by different appliances. [8],[12],[14],[15],[16],[19],[22],[23],[24],[25] Therefore we wondered how much vermilion height changed during treatment by various orthodontic systems, because we believe these changes can have an important effect on facial esthetics, especially affecting the frontal view of the face. [18] The importance of this investigation to the field of orthodontics is that the findings may aid the clinician in choosing the orthodontic system, which does not have detrimental effects on lip dimension. The purpose of this study was to compare the changes of vertical dimension of vermilions after standard and preadjusted orthodontic treatment.
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??Materials and Methods |
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In this retrospective study a total of 60 patients (34 girls and 26 boys), treated by extraction of first premolar teeth for the relief of crowding or the reduction of incisor protrusion were randomly selected from the practice of two experienced orthodontist. A total of 30 patients (18 girls, 12 boys) had been treated with standard 0.018-inch slot edgewise appliances (Dentaurum, Inspringer, Germany) and 30 patients (16 girls, 14 boys) had been treated with preadjusted 0.022-inch slot edgewise appliances (Dentaurum, Inspringer, Germany) using consistent contemporary biomechanical principles. The sample for the present investigation was drawn from the orthodontic patient records of two of the authors (MO and PS).
High quality pre- and posttreatment photographs, each exhibiting good soft tissue definition in natural head position with lips relaxed, teeth in occlusion, and taken by the same operator, were available for all subjects. The photographs of each subject were taken using a digital camera (Nikon inc. D70, Japan).
Data were obtained from pre- and posttreatment photographs of the patients all of whom met the following additional criteria:
- Age at the beginning of treatment 15 years or above.
- Skeletal class I: A.point- Nasion- B.piont (ANB) = 2-3?, Wits appraisal = 0 to ?1 mm.
- Four first premolars extracted during treatment.
- No congenitally missing teeth (excluding third molars).
- No functional appliance or surgical procedure was used between the two photographs noted above.
To determine if the selected patients had skeletal class I, cephalometric radiographs were traced under standardized conditions in a darkened room, using a viewing light box with opaque sliding screens to reduce peripheral light in the immediate area of interest. Each tracing was completed with the use of acetate sheets (3M TM Unitek, Monrovia, California, USA) and a 0.3 mm mechanical pencil.
None of the patients was treated with expansive devices; however, interarch elastics and headgears were used as required. Class II and III malocclusions were excluded. In addition, every patient who displayed obvious soft tissue tension and strain in his photograph was eliminated from the study.
Vermilion height of lip was measured but because the original photographs were made with slight variations in patient-to-film distances, exact linear measurements of vermilion height was not valuable. Since commissural width assumed to remain constant before and after orthodontic treatment, to control the magnification of photographs, the ratios between vermilion height and inter-commisural width were recorded on photographs. All measurements of photographs were performed using Adobe Photoshop software (version 7.0 Adobe System, San Jose, Calif). To make landmark determination as consistent as possible, the entire series of photographs and lateral cephalometric radiographs were marked by one person.
Data were analyzed with SPSS version 16 software (SPSS, Chicago, IL). We used analysis of variance (ANOVA) analysis to compare vertical lip changes between two orthodontic systems.
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??Results |
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The mean pre- and posttreatment vermilion height to inter-commisural width ratios in the group treated with standard edgewise appliance were 0.383 ? 0.119 and 0.312 ? 0.067, respectively. The mean pre- and posttreatment vermilion height to inter-commisural width ratio in the group treated with preadjusted appliance were 0.331 ? 0.087 and 0.301 ? 0.056, respectively. The mean of vermilion height to inter-commisural width ratios after orthodontic treatment in preadjusted group (P = 0.019) and standard group (P ? 0.001) was significantly less than that before treatment [Table 1].
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Table 1: The mean and standard deviation of vermilion height to inter-commissural width ratios of patients treated by standard edgewise and preadjusted appliance before and after treatment and the difference between after and before treatment
Click here to view
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The reduction of this ratio after preadjusted orthodontic treatment was less than that in standard edgewise orthodontic treatment but this difference was not statistically significant (P = 0.127) [Figure 1].
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Figure 1: The mean vermilion height to inter-commissural width ratios of patients treated by standard edgewise and preadjusted appliance before and after treatment and the difference between after and before treatment
Click here to view
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??Discussion |
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Growth and orthodontic treatment are two major factors to be considered in evaluation of tissue changes. [19],[26] In this study, growth and orthodontic treatment changes of measurements are grouped together. Since the exact age of some patients was not recorded, the measurement of the mean age of the sample was not possible but to limit growth effects on lip dimensions, subjects above the age of 15 years were selected for the present study and were considered to be nongrowing adults. Subtelny showed that the length and thickness of the upper lip stabilized in female subjects after age 15 years. [27] Therefore it is essential that clinicians be aware not only of the likely effects of treatment but also of the general amount and direction of growth expected in facial structures. [28],[29],[30]
The ratio of males to females (1:1.3) in the sample reflected the general attendance patterns of the population presenting for orthodontic treatment (1:1.4). [31]
In this study the vertical height of lips decreased significantly after orthodontic treatment. The fact that significant decrease in the height of the vermilion of the lips occurred should alert clinicians to this possibility in treatment planning. The extent that the height of the vertical aspect of the vermilion of the lips is decreased during orthodontic treatment may determine the ultimate esthetic results for a particular patient. Marked decrease in the height of the vermilion may prove to be esthetically pleasing for the patient with excessive vermilion, but it may be unaesthetic for the patient exhibiting relatively small vermilion heights before treatment. Therefore frontal esthetics should equal the profile in importance when planning treatment. In agreement with our results, Perkins et al. found that during orthodontic treatment, which involved maxillary incisor retraction, statistically significant decreases were seen in the vertical dimension of the vermilion of the lips. [18] Although their subjects were a combination of different extraction and also nonextraction cases and they evaluated cephalometric records of class I and class II, Division I patients. The findings of our study are also in agreement with those of Jacobs. [15]
We used frontal photographs in this study and Stephens et al. also described that what we measure on cephalograms is not what we actually pay attention to when evaluating everyday faces of patients. [20]
Although the earlier studies tried to explain the change of soft tissue profile in response to orthodontic tooth movement by establishing numeric ratios between changes in some soft-tissue measurements, the present study used a different approach because they can explain only profile changes of a greater picture.
The limitation in any soft tissue study involves the influence of voluntary and involuntary muscle activity on soft tissue contours. As noted by Zierhut et al., lip tensions will vary from time to time in one individual. [32] An inability to quantify or control this variable remains a shortcoming of these studies. [33] In response to this concern, every effort was made to eliminate those subjects displaying obvious soft tissue strain. Although in this retrospective study, a relaxed soft tissue posture could not be assured in contrast to a prospective study.
It is particularly important to keep in mind that the soft tissue structures of the face are dynamic and appear dramatically different in animation. [34],[35] For example, when an individual smiles, the commisures of the lips widen and the upper lip height decreases. [11] It might be concluded that decisions about facial esthetics should be made largely from the clinical examination of the patient and also should include the dynamic as well as static aspects of facial form and the smile. [11]
Other variables that may influence vermilion height response to orthodontic treatment include weight gain or loss during treatment, variations in the amount of adipose or muscle tissue present in the lips, area of lip-tooth contact, and lip length. [18],[33] Therefore lip structure seems to have an influence on lip response to orthodontic treatment [1] and patients with thin lips or a high lip strain displayed a significant correlation between incisor movement and lip change, whereas patients with thick lips or low lip strain displayed no such correlation. [19] The soft tissue has been termed "the great compensator for skeletal discrepancies" [36] and the morphology of the soft tissues is a major factor in determining the overall facial esthetics. [26],[27] Moreover, the presence of different internal soft tissue architecture has complicated prediction of the soft tissue responses to treatment. [22] The study of Moseling et al., confirmed the importance of the inherent soft tissue structure in determining both the pretreatment forms and responses to treatment of the upper and lower lips. [26] Consequently, ratios of lip to incisor retraction have gained only limited acceptance because it has been recognized that the interactions that might determine soft tissue changes are complex. [8],[12],[14],[23],[28] Basciftci et al. also found that generalizations concerning the negative effects of extraction of four first premolars on the profile are not true. [1]
In the literature, there are few studies with which the pre- and posttreatment vermilion dimensions can be directly compared. Most studies have been concerned with the profile changes and predictive relationship between incisor retraction and lip position. [8],[15],[16],[19],[24],[25]
Talass et al. found that although the lower lip length increased by orthodontic treatment the variation in soft-tissue response should be discussed with the patient characteristics before the orthodontic procedure. [33] The pretreatment extent of crowding and the method of anchorage preparation and usage should also be considered when trying to anticipate the effects of orthodontic treatment on lip height. [37] Retrospective studies have limitations in interpretation because the reasoning behind the diagnosis and treatment planning for each case can never be fully determined. This particularly applies to samples chosen from a pool treatment by a number of different clinicians. [26] In an effort to overcome such issues, the sample for this study was chosen randomly from the practice of two experienced orthodontist who treat patients according to contemporary biomechanical principles.
The sample bias present because of pretreatment differences between the groups existed, therefore the findings of this study should be interpreted with caution. Moreover, the fact that a two-dimensional assessment was made of three-dimensional structures causes problems of its own. Careful case selection may have influenced the outcome, but the present sample was treated with a single phase of fixed appliance therapy.
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??Conclusion |
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In this study the vertical height of lips decreased significantly after orthodontic treatment in both groups and there was no significant difference in standard and preadjusted appliance. Therefore these changes must be discussed with patients before orthodontic treatments.
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