Summary
Does an advanced or retracted position of the upper and lower incisors lead to modifications in lip position? The aim of our study was to evaluate modifications in lip position following orthodontic treatments.
Material and methods: This study concerned 100 patients who underwent treatment in the dento-facial orthopedic unit in Casablanca. Profile headfilms at the start and at the end of orthodontic treatment were compared using Frapier’s analysis.
The Student test was applied to evaluate the variations in the cephalometric measurements.
Results: We noted a non-significant increase in the nasolabial angle (P = 0.274), a significant decrease in the sagittal posi- tion of the lower vermillion border (PsVei) (P < 0.001) and the sagittal position of the soft-tissue supramentale (PsSmc) (P < 0.001), and a significant increase in the vertical position of the soft-tissue menton (PvMec) (P = 0.035).
Conclusion: The results of this study demonstrate marked improvements in the situation of soft tissues. We suggest further investigation to throw light on the relationship between tooth movement and soft tissue, increasing the size of the sample and taking growth into account.
Ó 2013 CEO. Published by Elsevier Masson SAS. All rights reserved
R esum e
La position des incisives sup erieures et inf erieures lors- qu’elles sont avanc ees ou recul ees va-t-elle conditionner des modifications sur la position des l evres ? L’objectif de notre etude etait d’ evaluer les modifications de la position des l evres secondaires aux traitements orthodontiques.
Mat eriel et m ethodes: Notre etude a port e sur 100 patients qui ont suivi leur traitement au service d’orthop edie dentofaciale de Casablanca. Les t el eradiographies de profil de d ebut et de fin de traitement orthodontique ont et e compar ees en utilisant l’analyse de Frapier. Le test de Student a et e utilis e pour
evaluer les variations des mesures c ephalom etriques.
R esultats: Nous avons not e une ouverture non significative de l’angle nasolabial (p = 0,274), une diminution significative de la position sagittale du vermillon inferius (PsVei) (p < 0,001), et de la position sagittale du supramental cutan e (PsSmc) (p < 0,001) et une augmentation significative de la position verticale du menton cutan e (PvMec) (p = 0,035).
Conclusion: Les r esultats de cette etude ont montr e des am eliorations notables sur les tissus mous. Nous sugg erons de pousser l’investigation pour pouvoir eclaircir la relation entre le mouvement dentaire et les tissus mous en augmentant la taille de l’ echantillon et en consid erant l’effet de la croissance.
Ó 2013 CEO. E´dite´ par Elsevier Masson SAS. Tous droits re´serve´s
Original article
Article original
Ó2013 CEO Published by / E´dite´ par Elsevier Masson SAS All rights reserved / Tous droits re´serve´s
Effect of orthodontic treatment on lip position
Effet du traitement orthodontique sur la position des l evres
Farid BOURZGUI
a,*, Sanaa ALAMI
a, Mourad SEBBAR
a, Taoufik DERKAOUI
a, Mouna HAMZA
a, Zineb SERHIER
b, Mohamed BENNANI OTHMANI
ba
D epartement d’orthop edie dento-faciale, facult e de m edecine dentaire de Casablanca, universit e Hassan II Ain Chok, rue Abou Al Ala^ a zahar (ex V esal), BP 9157, Mers Sultan, Casablanca, Morocco
b
Laboratoire d’informatique m edicale, d epartement sant e communautaire, facult e de m edecine de Casablanca, universit e Hassan II Ain Chok, 19, rue Tarik Ibnou Ziad, BP 9154, Mers Sultan, Casablanca, Morocco
Available online: 13 July 2013 /
Disponible en ligne : 13 juillet 2013*Correspondence and reprints /Correspondance et tires a` part.
e-mail address /Adresse e-mail :faridbourzgui@yahoo.fr (Farid Bourzgui)
International Orthodontics 2013 ; 11 : 303-313 303
http://dx.doi.org/10.1016/j.ortho.2013.05.001
Key-words
· Incisal repositioning.
· Orthodontic treatment.
· Lip position.
· Cephalometrics.
Introduction
The therapeutic demands made on orthodontics are no longer limited to the re-establishment of a stable, functional occlu- sion but extend now to the improvement of facial esthetics [1].
The incisors provide anterior guidance and determine the patient’s esthetic profile by the support they offer to the upper and lower lips; their position is therefore vitally important both for the esthetic and functional results.
The position of the lips is influenced by the position of the incisors, the skeletal type, the size of the nose and chin, and by the thickness and muscle tone of the lips themselves [2]. For many years, it was difficult to predict possible modifications in lip position that might result from advancement or retraction of the incisors [3–7]. Few studies have been made of the associ- ation between incisor repositioning and modifications in lip position [8,9].
So, when upper or lower incisors are advanced or retracted by orthodontic treatment, does this have any effect on lip position?
The aim of our study was therefore to investigate changes in upper and lower lip position in the sagittal and vertical planes with respect to repositioning of the upper and lower incisors.
Material and methods
Our study concerned all patients undergoing treatment in the dento-facial orthopedic unit in Casablanca over a period of 6 months.
Our sample included patients receiving multi-bracket ortho- dontic treatment and for whom a full orthodontic record was available (clinical and radiological examination, diagnosis and treatment plan), whose radiological examinations could be exploited, having been performed in the radiology unit of the Casablanca dental care center (pre-treatment and end- of-treatment panorex and lateral headfilms), and who were at the finishing stage after arch correction or who had termi- nated their orthodontic treatment. Patients having under- gone orthopedic or functional treatment or orthognathic sur- gery were excluded, as were those still in the growth phase.
One hundred patient files were selected on the basis of the above criteria.
Mots-cl es
· Repositionnement incisif.
· Traitement orthodontique.
· Position labiale.
· C ephalom etrie.
Introduction
Les exigences th erapeutiques en orthodontie ne se sont plus limit ees au r etablissement d’une occlusion stable et fonctionnelle, mais aussi a` l’am elioration de l’esth etique faciale [1]. Les incisives forment le guide ant erieur et dessi- nent le profil esth etique du patient gr^ ace au soutien des l evres sup erieure et inf erieure ; leur position rev^ et donc une importance capitale aussi bien sur le plan esth etique que fonctionnel.
La position des l evres est influenc ee par la position des inci- sives, par le sch ema squelettique, par la taille du nez et du menton, et par l’ epaisseur et la tonicit e des l evres [2]. Durant une longue p eriode, il a et e difficile de pr evoir les modifications
eventuelles que peut apporter l’avanc ee ou le recul des inci- sives sur la position des l evres [3–7]. Peu d’ etudes ont etudi e l’association entre le repositionnement des incisives et la modification de la position des l evres [8,9].
Aussi les effets du traitement orthodontique sur la position des incisives sup erieures et inf erieures lorsqu’elles sont avanc ees ou recul ees vont-ils conditionner des modifications sur la posi- tion des l evres ?
Ainsi, l’objectif de notre etude etait d’ etudier les changements de position des l evres sup erieures et inf erieures dans les plans sagittal et vertical en fonction du repositionnement des incisives maxillaires et mandibulaires.
Mat eriel et m ethodes
Notre etude a port e sur tous les patients suivant leur traite- ment au service d’orthop edie dentofaciale de Casablanca pendant une p eriode de six mois.
Ont et e inclus dans notre echantillon les patients ayant
b en efici e d’un traitement orthodontique multi-attaches et
ayant un dossier orthodontique complet (examen clinique et
radiologique, diagnostic et plan de traitement), les patients
dont les examens radiologiques sont exploitables et r ealis es
au sein de l’unit e de radiologie de centre de soins et de
traitement dentaire de Casablanca (radiographies panorami-
ques et t el eradiographies de profil de d ebut et de fin de traite-
ment), ainsi que ceux en etape de finition apr es la phase de
correction des arcades ou ayant termin e leur traitement ortho-
dontique. Ont et e exclus les patients ayant b en efici e d’un
traitement orthop edique ou fonctionnel ou d’une chirurgie
orthognathique et les patients en cours de croissance. Cent
dossiers patients ont et e s electionn es conform ement a` ces
crit eres suscit es.
Tracings of the lateral headfilms at the start and end of treat- ment were made manually by the same operator. Soft tissue profiles were evaluated before and after treatment, using the sagittal and vertical measurements described by Frapier [10].
Frapier analysis
This analysis uses the mandibular implant line described in the superimpositions of Bj€ ork-Nielsen [11]. As this provides a stable reference line, it acts as an orthonormed landmark (X- axis) as does its perpendicular which cuts through its most anterior point (Y-axis).
The orthonormed landmark:
— Ox is thus the implant line in the Bj € ork superimposition;
— Oy is the perpendicular cutting though the most anterior point of the implant line.
The positions of the soft tissue (in mm) are calculated by orthogonally projecting the different points onto the ortho- normed axes (figs. 1 and 2; Table I).
The implant line is a 5 cm imaginary line in the mandibular body generally drawn from the pogonion to the lower section of the last non-emerged germ on the start-of-treatment headfilm.
This line is transferred to the end-of-treatment headfilms by superimposition on the stable structures of the mandible.
The stable structures of the mandible according to Bj€ ork and Skieller [11] and Dibbets [12] are:
— the anterior edge of the symphysis from point B to the pogonion;
— the internal cortical outline of the symphysis;
— the mental foramen and other trabecular structures in the endosteum;
— the cortical outlines of the mandibular canal;
Les trac es des t el eradiographies de profil de d ebut et de fin de traitement ont et e r ealis es manuellement par le m^ eme op erateur. Les tissus mous de profil ont et e evalu es avant et apr es traitement a` partir de mensurations sagittales et verti- cales utilis ees par Frapier [10].
Analyse de Frapier
Cette analyse utilise la ligne implantaire mandibulaire utilis ee dans les superpositions de Bj€ ork-Nielsen [11], qui, en tant que ligne de r ef erence stable, a servi de rep ere orthonorm e (axe des x) avec sa perpendiculaire passant par son point le plus ant erieur (axe des y).
Le rep ere orthonorm e :
— Ox est la ligne implantaire de la superposition de Bj€ ork ;
— Oy est la perpendiculaire passant par le point le plus ant erieur de la ligne implantaire.
Les positions des tissus mous (mm) seront calcul ees par pro- jection orthogonale des diff erents points sur les axes orthonorm es (figs. 1 et 2 ; Tableau I).
La ligne implantaire est une ligne fictive de 5 cm dans le cor- pus, trac ee g en eralement du pogonion a` la partie inf erieure du dernier germe non evolu e sur la t el eradiographie de d ebut de traitement. Cette ligne a et e transf er ee sur la radiographie de fin de traitement en la superposant sur les structures stables de la mandibule.
Les structures stables mandibulaires selon Bj€ ork et Skieller [11] et Dibbets [12] :
— le bord ant erieur de la symphyse du point B au pogonion ;
— la corticale interne de la symphyse ;
— le trou mentonnier et d’autres structures trab eculaires dans l’endoste ;
— les lignes corticales du canal mandibulaire ;
[(Fig._1)TD$FIG]
Fig. 1: Sagittal measurements of soft tissues.
Fig. 1 :Mensurations sagittales des tissus mous.
International Orthodontics 2013 ; 11 : 303-313 305
Effect of orthodontic treatment on lip position
Effet du traitement orthodontique sur la position des levres
[(Fig._2)TD$FIG]
Fig. 2: Vertical measurements of soft tissues.
Fig. 2 :Mensurations verticales des tissus mous.
Table I
Analysis of soft tissues.
Tableau I
Analyse des tissus mous.
Measurement/ Mesure Definition/ Signification
1 PsVei Sagittal position of lower vermillion border/ Position sagittale du vermillon inferius Vei: orthogonal distance from Vei to Y-axis/Distance orthogonale de Vei a` l’axe des Y 2 PsSmc Sagittal position of the soft tissue supramentale/ Position sagittale du supramental cutan e
Smc: orthogonal distance from Smc to Y-axis/Distance orthogonale de Smc a` l’axe des Y 3 PsPogc Sagittal position of the soft tissue pogonion/ Position sagittale pogonion cutan e
Pogc: orthogonal distance from Pogc to Y-axis/Distance orthogonale de Pogc a` l’axe des Y 4 PsMec Sagittal position of the soft tissue menton/ Position sagittale du menton cutan e
Mec: orthogonal distance from Mec to Y-axis/Distance orthogonale de Mec a` l’axe des Y
5 ALM Mentolabial angle/ Angle labiomentonnier
6 ANL Nasolabial angle/ Angle nasolabial
7 Pis Vertical position of the incisal edge of the upper incisors Is relative to the stomion inferius Stoi according to the orthonormed landmark OxOy/ Position verticale du bord libre de l’incisive sup erieure Is par rapport au Stomion inferius Stoi selon le rep ere orthonorm e OxOy 8 Pii Vertical position of the incisal edge of the lower incisors Ii relative to the stomion inferius Stoi
according to the orthonormed landmark OxOy/ Position verticale du bord libre de l’incisive inf erieure Ii par rapport au Stomion inferius Stoi selon le rep ere orthonorm e OxOy
9 PvVei Vertical position of the lower vermillion border relative to the stomion inferius according to the orthonormed landmark OxOy/ Position verticale du vermillon inferius par rapport au Stomion inferius selon le rep ere orthonorm e OxOy
10 PvSmc Vertical position of the soft tissue supramentale relative to the stomion inferius according to the orthonormed landmark OxOy/ Position verticale du supramentale cutan e par rapport au Stomion inferius selon le rep ere orthonorm e OxOy
11 PvPog Vertical position of the soft tissue pogonion relative to the stomion inferius according to the orthonormed landmark OxOy/ Position verticale du pogonion cutan e par rapport au Stomion inferius selon le rep ere orthonorm e OxOy
12 PvMec Vertical position of the soft tissue menton relative to the stomion inferius according to the
orthonormed landmark OxOy/ Position verticale du menton cutan e par rapport au Stomion
— the bony crypt of the last germ not displaying root development.
Data entry and statistical analysis of the results were per- formed using Epi-info 3.5.1.Fr software. The association between incisal repositioning and modifications in lip position was analyzed by means of the Student t-test. The association between two variables was considered statistically significant when P < 0.05.
Results
Our sample was composed of 100 patients, predominantly female (77%), with a mean age of 19.53 years and a standard deviation (SD) = 7.450.
In the vertical dimension, 51% of the patients were hyperdi- vergent, 39% normodivergent and 10% hypodivergent.
Seventeen percent had an anterior deep bite, 6% an open bite and 77% suffered from tooth-size discrepancy.
In the sagittal direction, 47% of the patients were skeletal Class I, 38% Class II and 15% Class III. Fifteen percent of our sample exhibited incisal protrusion, 15% incisal retrusion and 40% bimaxillary protrusion, while 30% had normally-posi- tioned incisors.
In the transverse dimension, 3% exhibited dental arch con- traction and 93% had no abnormalities. Crowding was a prob- lem in 74% of cases.
In 68% of our patients, orthodontic treatment required pre- molar extractions.
Distal movement of the incisors was obtained in 74% of cases, incisal advancement in 13% and a combined movement (advancement in one arch and retraction in the other) in 5%.
Labioversion in the upper arch was produced in 26% of cases, and in the lower arch in 20%. The distal displacement con- cerned the upper arch in 74% of cases and the lower arch in 80%.
Analysis of the results (Tables II and III) shows:
— a significant reduction in the value of the sagittal position of the lower vermillion border (PsVei) from 6.78 mm to 5.59 mm, a reduction of 1.19 mm (P < 0.001);
— a significant reduction in the value of the sagittal position of the soft-tissue supramentale (PsSmc) (P = 0.682), from 3.71 mm to 2.78 mm (P < 0.001);
— a non-significant reduction of 0.08 mm (P = 0.671) in the value of the sagittal position of the soft-tissue pogonion (PsPogc), from 9.60 mm to 9.52 mm;
— a non-significant increase of 0.12 mm (P = 0.603) in the value of the sagittal position of the soft-tissue menton (PsMec), from 6.80 mm to 6.92 mm;
— a non-significant closure of 1.52
(P = 0.393) in the men- tolabial angle (MLA), from 126.79
to 125.27
;
— a non-significant opening of 10.7
(P = 0.274) in the naso- labial angle (NLA), from 101.93
to 112.63
;
— crypte endo-osseuse du dernier germe non evolu e du point de vue radiculaire.
La saisie des donn ees et l’analyse statistique des r esultats ont
et e faites a` l’aide du logiciel Epi-info 3.5.1.Fr. L’ etude de l’asso- ciation entre le repositionnement des incisives et la modifica- tion des positions labiales a et e r ealis ee a` l’aide du test de Student. L’association entre deux variables a et e jug ee statis- tiquement significative quand p < 0,05.
R esultats
Notre echantillon etait constitu e de 100 patients a` pr edomi- nance f eminine (77 %) avec une moyenne d’^ age de 19,53 ans et un ecart-type (SD) = 7,450.
Dans le sens vertical, 51 % des patients etaient hyperdiver- gents, 39 % normodivergents et 10 % hypodivergents. Dix- sept pour cent pr esentaient une supraclusion incisive, 6 % une b eance et 77 % une DDM.
Dans le sens sagittal, 47 % des patients pr esentaient une Classe I squelettique, 38 % une Classe II et 15 % une Classe III. Quinze pour cent de notre echantillon pr esentaient une proalv eolie, 15 % une r etroalv eolie, 40 % une biproalv eolie et 30 % une normoposition incisive.
Dans le sens transversal, 3 % avaient une endoalv eolie et 93 % ne pr esentaient aucune anomalie. Soixante-quatorze pour cent de nos patients pr esentaient un encombrement dentaire.
Chez 68 % des patients, le traitement orthodontique a n ecessit e des extractions de pr emolaires.
Un recul incisif a et e r ealis e chez 74 % des patients, une avanc ee incisive chez 13 % et un mouvement combin e (avanc ee dans une arcade et recul dans l’autre) chez 5 %.
Le mouvement de vestibuloversion a et e r ealis e chez 26 % des patients au maxillaire et chez 20 % a` la mandibule. Le mouvement de recul a et e r ealis e chez 74 % des patients au maxillaire et chez 80 % a` la mandibule.
L’analyse des r esultats a montr e (Tableaux II et III) :
— une diminution significative de la valeur de la position sagit- tale du vermillon inferius (PsVei) de 1,19 mm qui passait de 6,78 mm a` 5,59 mm (p < 0,001) ;
— une diminution significative de la valeur de la position sagit- tale du supramental cutan e (PsSmc) (p = 0,682) qui passait de 3,71 mm a` 2,78 mm (p < 0,001) ;
— une diminution non significative de la valeur de la position sagittale du Pogonion cutan e (PsPogc) de 0,08 mm (p = 0,671) qui passait de 9,60 mm a` 9,52 mm ;
— une augmentation non significative de la valeur de la posi- tion sagittale du menton cutan e (PsMec) de 0,12 mm (p = 0,603) qui passait de 6,80 mm a` 6,92 mm ;
— une fermeture non significative de l’angle labiomentonnier (ALM) de 1,52
(p = 0,393) qui passait de 126,79
a` 125,270
;
— une ouverture non significative de l’angle nasolabial (ANL) de 10,7
(p = 0,274) qui passait de 101,93
a` 112,63
;
International Orthodontics 2013 ; 11 : 303-313 307
Effect of orthodontic treatment on lip position
Effet du traitement orthodontique sur la position des levres
— a non-significant increase of 0.37 mm (P = 0.149) in the value of the position of the upper incisor (Pis), from 4.34 mm to 4.71 mm;
— a non-significant increase of 0.35 mm (P = 0.174) in the value of the position of the lower incisor (Pii), from 3.45 mm to 3.80 mm;
— a non-significant increase of 0.27 mm (P = 0.148) in the value of the vertical position of the lower vermillion border (PvVei), from 7.14 mm to 7.41 mm;
— a non-significant reduction of 0.08 mm (P = 0.826) in the value of the vertical position of the soft-tissue supramentale (PvSmc), from 16.11 mm to 16.03 mm;
— a non-significant increase of 0.23 mm (P = 0.564) in the value of the vertical position of the soft-tissue pogonion (PvPogc), from 27.70 mm to 27.93 mm;
— a significant increase of 0.98 mm (P = 0.035) in the verti- cal position of the soft-tissue menton (PvMec), from 43.44 to 44.42 mm.
Discussion
Several authors believe that orthodontic treatment has an impact on the soft-tissue profile [4] while others note a stable response of these tissues to tooth movements. A positive cor- relation between incisal movement and soft tissue changes
— une augmentation non significative de la valeur de la posi- tion de l’incisive sup erieure (Pis) de 0,37 mm (p = 0,149) qui passait de 4,34 mm a` 4,71 mm ;
— une augmentation non significative de la valeur de la posi- tion de l’incisive inf erieure (Pii) de 0,35 mm (p = 0,174) qui passait de 3,45 mm a` 3,80 mm ;
— une augmentation non significative de la valeur de la posi- tion verticale du vermillon inferius (PvVei) de 0,27 mm (p = 0,148) qui passait de 7,14 mm a` 7,41 mm ;
— une diminution non significative de la valeur de la position verticale du supramental cutan e (PvSmc) de 0,08 mm (p = 0,826) qui passait de 16,11 mm a` 16,03 mm ;
— une augmentation non significative de la valeur de la posi- tion verticale du pogonion cutan e (PvPogc) de 0,23 mm (p = 0,564) qui passait de 27,70 mm a` 27,93 mm ;
— une augmentation significative de la valeur de la position verticale du menton cutan e (PvMec) de 0,98 mm (p = 0,035) qui passait de 43,44 a` 44,42 mm ;
Discussion
Plusieurs praticiens sont convaincus que le traitement ortho- dontique influence les tissus mous de profil [4], alors que d’autres confirment la stabilit e de la r eponse de ces tissus aux d eplacements dentaires. Une corr elation positive entre
Table II
Averages of statistical variables for matched samples.
Tableau II
Moyennes des variables statistiques pour echantillons appari es.
n Before treatment/ Avant traitement After treatment/ Apr es traitement Mean/
Moyenne
Standard deviation/
E cart-type
Mean standard error/
Erreur standard moyenne
Mean/
Moyenne
Standard deviation/
E cart-type
Mean standard error/
Erreur standard moyenne
PSVEI 100 6.78 3.87580 0.38758 5.590 3.80084 0.38008
PSSMC 100 3.71 2.87551 0.28755 2.7800 2.82693 0.28269
PSPOGC 100 9.60 2.44949 0.24495 9.5200 2.40572 0.24057
PSMEC 100 6.80 2.50252 0.25025 6.9200 2.45641 0.24564
ALM 100 126.79 22.0478 2.2048 125.270 15.0761 1.5076
ANL 100 101.93 16.56347 1.65635 112.630 95.3287 9.5329
PIS 100 4.34 2.21665 0.22166 4.7100 2.15226 0.21523
PII 100 3.45 2.5120920 0.2512092 3.8000 2.30502 0.23050
PVVEI 100 7.14 1.96957 0.19696 7.4100 1.99036 19904
PVSMC 100 16.11 3.33302 0.33330 16.0300 3.58294 0.35829
PVPOG 100 27.70 4.67424 46742 27.9300 4.82681 0.48268
PVMEC 100 43.44 6.82438 0.68244 44.4200 6.86990 0.68699
Table III
Student test for matched samples.
Tableau III
Test de Student pour echantillons appari es.
Test of matched samples/ Test echantillons appari es
Matched differences/ Diff erences appari ees t ddl Sig. (bilateral)/
Sig. (bilat erale) Mean/
Moyenne
Standard deviation/
E cart- type
Mean standard error/
Erreur standard moyenne
Confidence interval at 95% of difference/
Intervalle de confiance 95 % de la diff erence Lower/
Inf erieure
Upper/
Sup erieure
Pair 1 PsVei1–PsVei2 1.19 2.84514 0.28451 0.62546 1.75454 4.183 99 < 0.001
Pair 2 PsSmc1–PsSmc2 0.93 2.22136 0.22214 0.48923 1.37077 4.187 99 < 0.001
Pair 3 PsPogc1–PsPogc2 0.08 1.87853 0.18785 0.29274 0.45274 0.426 99 0.671
Pair 4 PsMec1–PsMec2 0.12 2.29747 0.22975 0.57587 0.33587 0.522 99 0.603
Pair 5 ALM1–ALM2 1.52 17.722 1.7722 1.9964 5.0364 0.858 99 0.393
Pair 6 ANL1–ANL2 10.7 97.26424 9.72642 29.99934 8.59934 1.1 99 0.274
Pair 7 Pis1–Pis2 0.37 2.54517 0.25452 0.87502 0.13502 1.454 99 0.149
Pair 8 Pii1–Pii2 0.35 2.5559398 0.255594 0.8571539 0.1571539 1.369 99 0.174
Pair 9 PvVei1–PvVei2 0.27 1.85241 0.18524 0.63756 0.09756 1.458 99 0.148
Pair 10 PvSmc1–PvSmc2 0.08 3.63118 0.36312 0.6405 0.8005 0.22 99 0.826
Pair 11 PvPog1–PvPog2 0.23 3.97684 0.39768 1.01909 0.55909 0.578 99 0.564
Pair 12 PvMec1–PvMec2 0.98 4.58584 0.45858 1.88993 0.07007 2.137 99 0.035
International Orthodontics 2013 ; 1 1 : 303-313 309 Effect of orthodontic treatment on lip position
Effetdutraitementorthodontiquesurlapositiondeslevreswas reported in our study and also by Roos [13] in a sample of 20 patients. On the other hand, the study by Angelle [14]
showed that changes in tooth position are not automatically followed by changes in soft tissue determining the profile.
The 10.7
opening of the nasolabial angle in our sample was not significant. This angle increased from 101.93
to 112.63
. Talass et al. [6] and Ramos et al. [15] found that retraction of the maxillary incisor led to significant upper lip retraction and opening of the nasolabial angle.
Kusnoto [5] found a positive correlation between repositioning of the upper and lower incisors and a change in lip position in a sample of 40 Indonesian adults exhibiting bimaxillary protru- sion. This author noted significant lip retraction and an open- ing of the nasolabial angle after treatment.
In 20 patients who underwent orthodontic treatment with pre- molar extraction, Jamilian et al. [16] reported an opening by 2.6
of the nasolabial angle; however, this result was not significant.
Saelens and De Smith [17], Wholley and Woods [18] and Basciftic and Usmezs [19] noted that extraction of the premo- lars had no influence on the response of the upper lip to incisal repositioning. Bravo [20] recommended that premolar extrac- tion should be avoided when the NLA was greater than 110
. Valentim et al. [21] concluded that modification of lip thick- ness tended to mask any change in lip position following retraction of the upper incisors.
In our study, there was a significant reduction in the values of the sagittal positions of the lower vermillion border (PsVei) and the soft-tissue supramentale (PsSmc) and no significant change in the height of the lower lip [(PvVei) and (PvSmc)]
following repositioning of the lower incisor.
Wilson et al. [22], Young and Smith [23] and also Malki et al.
[10], working with a Moroccan population, noted similar results in their studies, while Bravo [24] found that reposition- ing of the mandibular incisors led to retraction of the lower lip.
Hayashida et al. [8] reported a significant association between modification of the vertical position of the incisal edges of the upper and lower incisors and that of the lower lip.
Rains et al. [25] found no significant correlation between repositioning of the lower incisors and change in lower lip position in a sample of 30 young female adults.
The horizontal position of the lower lip follows the movement of the mandibular incisors. However, the vertical positions of the lips (both upper and lower) depend on the maxillary incisal edge and not on the position of the lower incisors [8].
In our study, there was a non-significant increase in the value of the sagittal position of the menton but a significant increase in the vertical value. Singh [26] and Kasai [27] claimed that
le mouvement incisif et le changement des tissus mous a et e rapport ee par notre etude ainsi que celle de Roos [13] sur un
echantillon de 20 sujets. Par ailleurs, l’ etude de Angelle [14] a montr e que les changements des positions dentaires ne sont pas suivis syst ematiquement des changements des tissus mous profilaires.
L’ouverture de 10,7
de l’angle nasolabial dans notre echantillon n’ etait pas significative. Cet angle passait de 101,93
a` 112,63
. Talass et al. [6], Ramos et al. [15] ont trouv e que le recul de l’incisive maxillaire entraıˆnait le recul de la l evre sup erieure et l’ouverture de l’angle nasolabial de mani ere significative.
Kusnoto [5] a trouv e une corr elation positive significative entre le repositionnement des incisives maxillaires et mandibulaires et le changement de position des l evres dans un echantillon de 40 adultes indon esiens pr esentant une biproalv eolie. L’auteur a enregistr e un recul significatif des l evres et une ouverture de l’angle nasolabial apr es traitement.
Jamilian et al. [16] ont rapport e, chez 20 patients ayant b en efici e d’un traitement orthodontique avec extraction de pr emolaires, une ouverture de 2,6
de l’angle nasolabial ; mais le r esultat n’ etait pas significatif.
Saelens et De Smith [17], Wholley et Woods [18] et Basciftic et Usmezs [19] ont not e que l’extraction des pr emolaires n’influ- en¸ cait pas la r eponse de la l evre sup erieure au repositionne- ment des incisives. Bravo [20] a recommand e d’ eviter les extractions des pr emolaires quand l’ANL est sup erieur a` 110
. Valentim et al. [21] ont conclu que la modification de l’ epaisseur des l evres tend a` masquer le changement de la position de celles-ci suite au recul des incisives maxillaires.
Notre etude a montr e une diminution significative des valeurs des positions sagittales du vermillon inf erieur (PsVei) et du supramental cutan e (PsSmc) et que le repositionnement de l’incisive mandibulaire n’entraıˆnait pas de modifications signif- icatives en hauteur au niveau de la l evre inf erieure [(PvVei) et (PvSmc)].
Wilson et al. [22], Young et Smith [23] ainsi que Malki et al. [10]
qui ont travaill e sur une population marocaine, ont trouv e des r esultats similaires dans leurs etudes, alors que Bravo [24]
trouvait que la l evre inf erieure reculait a` la suite du reposition- nement de l’incisive mandibulaire.
Hayashida et al. [8] ont rapport e qu’il existait une association significative entre la modification de la position verticale des pointes incisives sup erieures et inf erieures et celle de la l evre inf erieure.
Rains et al. [25] n’ont pas trouv e de corr elation significative entre le repositionnement de l’incisive inf erieure et la modifi- cation de la position de la l evre inf erieure chez un echantillon de 30 femmes adultes jeunes.
La position horizontale de la l evre inf erieure suit le mouvement des incisives mandibulaires ; cependant, les positions verti- cales des l evres (sup erieure et inf erieure) d ependent de la pointe incisive maxillaire et non pas des incisives mandibu- laires [8].
Dans notre etude, la position sagittale du menton a subi une
augmentation non significative alors que la position verticale
du menton a subi une augmentation significative. Singh [26] et
incisal repositioning had no direct effect on the soft tissue of the chin but did encourage growth, thereby explaining the observed increase in tissue thickness that improves facial esthetics.
In our study, the mean mentolabial angle was 126.79 W 22.0478
. This angle decreased slightly but not significantly (1.52
) following treatment.
Kusnoto [5] noted a significant opening of the mentolabial angle after incisal retraction in a population exhibiting bimax- illary protrusion. Looi and Mills [28] reported an increase in the mentolabial angle of 5.3
after premolar extraction in 60 Class II division 1 patients.
There was a non-significant lowering of the incisal edges, probably due to the relative rise in the stomion inferius which served as a reference point for the vertical and sagittal mea- surements. This was also reported by Malki et al. [10] in 60 patients who underwent treatment including extraction of the four premolars.
We worked on a sample of 100 patients (with a strong pre- dominance of treatments with extractions) which is still insuf- ficient to allow the changes that occur in lip positioning in response to incisal advancement or retraction to be more precisely compared and described in the form of millimetric ratios, as was the case in most similar studies that take into account the direction of recorded movement [6,8,29].
These studies used superimposition methods that have often given rise to controversy, and paid little or no attention to changes in the vertical dimension [6].
It would seem that lip response is influenced not only by the degree of incisal repositioning but also by the structure of the lips themselves [8]. Lip morphology, type of treatment (with or without extractions, and type of extraction) and patient sex and age can also be responsible for individual differences in soft tissue response [30].
Conclusion
This study has shown that incisal repositioning can be extremely effective for improving lip position, thereby offering a stronger evidential basis for this mode of treatment.
The results of the study show marked improvements in soft tissues even though the differences in mean values were some- times barely or non-significant.
The relationship between tooth movement and soft tissue is too complex to be examined in a relatively simplistic way. We suggest further investigation to shed more light on the precise nature of this relationship by increasing sample size and tak- ing into account the effect of growth.
Kasai [27] ont affirm e que le repositionnement incisif n’a pas un effet direct sur les tissus de recouvrement du menton, mais il agit en favorisant la croissance, ce qui explique l’augmenta- tion de l’ epaisseur enregistr ee am eliorant l’esth etique faciale.
Dans notre etude, la moyenne de l’angle labiomentonnier etait de 126,79 W 22,0478
. Cet angle a l eg erement diminu e a` la suite du traitement (1,52
) sans significativit e.
Kusnoto [5] a trouv e une ouverture significative de l’angle labiomentonnier apr es recul des incisives chez une population pr esentant une biproalv eolie. Looi et Mills [28] ont rapport e une ouverture de l’angle labiomentonnier de 5,3
apr es extrac- tion de pr emolaires chez 60 patients pr esentant une Classe II division 1.
Les pointes incisives ont connu une descente non significative, cette descente serait due a` la remont ee relative du stomion inf erieur a` partir duquel les mesures verticales et sagittales sont r ealis ees. Cela a egalement et e rapport e par Malki et al.
[10], chez 60 patients ayant b en efici e d’un traitement avec extraction des quatre pr emolaires.
Nous avons obtenu un echantillon de 100 patients (avec une forte pr evalence de traitements avec extractions dans notre
echantillon) qui reste encore insuffisant pour pouvoir comparer et exprimer de mani ere plus pr ecise les change- ments op er es au niveau des positions des l evres en r eponse au repositionnement des incisives (avanc ee ou recul) sous forme de rapports millim etriques, comme ce fut le cas pour la plupart des etudes men ees dans ce sens et qui prennent en consid eration la direction du mouvement enregistr e [6,8,29].
Ces etudes utilisaient des m ethodes de superpositions qui ont
et e souvent controvers ees et pr^ etaient peu d’attention ou n egligeaient compl etement les modifications op er ees dans le sens vertical [6].
En outre, il semblerait que la r eponse des l evres est influenc ee non seulement par la quantit e du repositionnement des inci- sives mais aussi par la structure propre des l evres [8]. La morphologie des l evres, le type de traitement (avec ou sans extractions et le type de l’extraction), le sexe et l’^ age du patient peuvent etre responsables des diff ^ erences individuelles dans la r eponse des tissus mous [30].
Conclusion
La pr esente etude a montr e que le repositionnement des inci- sives peut s’av erer extr^ emement efficace dans l’am elioration de la position labiale, offrant ainsi une plus forte justification fond ee sur les preuves pour cette modalit e de traitement.
Les r esultats de cette etude ont montr e des am eliorations notables sur les tissus mous m^ eme si les diff erences de moyennes etaient parfois peu ou non significatives.
La relation entre le mouvement dentaire et les tissus mous est trop complexe pour ^ etre examin ee de mani ere relativement simpliste. Nous sugg erons de pousser l’investigation pour pouvoir eclaircir de mani ere pr ecise la nature de cette relation en augmentant la taille de l’ echantillon et en consid erant l’effet de la croissance.
International Orthodontics 2013 ; 11 : 303-313 311
Effect of orthodontic treatment on lip position
Effet du traitement orthodontique sur la position des levres
Disclosure of interest
The authors declare that they have no conflicts of interest concerning this article.
D eclaration d’int er^ ets
Les auteurs d eclarent ne pas avoir de conflits d’int er^ ets en relation avec cet article.
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Effect of orthodontic treatment on lip position
Effet du traitement orthodontique sur la position des levres
