Maxillary incisors initial position and soft-tissue changes in Class II malocclusion extraction protocols / Posição inicial dos incisivos superiores e alterações no perfil facial nos protocolos de extração da má oclusão de Classe II

Introdução: Diferenças da atratividade encontradas entre os protocolos de tratamento Classe II em longo prazo e no pós-tratamento incitou estes estudos. O Elemento II demonstrou que os rostos bem equilibrados tem incisivos superiores posicionados em um relacionamento anteroposterior individualmente calculado com a testa. Deste modo, o Elemento II foi utilizado para investigar as características iniciais dos pacientes. Além disso, para avaliar as mudanças que os protocolos de extrações resultam nos tecidos moles, uma revisão sistemática foi realizada com busca nas bases de dados PubMed, Web of Science, Embase, Scopus e Cochrane. Resultados: O grupo CII teve posição AP dos incisivos superiores mais anteriores quando comparado ao grupo NO. Além disso, as posições AP dos incisivos nos subgrupos de extração foram à frente, quando comparado com o subgrupo NE. Alterações dos tecidos moles estatisticamente significantes foram ângulo nasolabial (NLA) que aumentou de 2,4º a 5,40º no protocolo de extração de 2 pré-molares e de 1º a 6,84º no protocolo de extração de 4 pré-molares. Retrusão dos lábios superior e inferior também foram verificadas, com menor retração do lábio inferior nos grupos de extração de dois pré-molares. Conclusões: Indivíduos com Classe II apresentaram os incisivos superiores significativamente mais protruídos que os indivíduos com oclusão normal. Na Classe II divisão 1, o subgrupo tratado com extrações apresentaram os incisivos significativamente mais protruídos em comparação com o subgrupo sem extrações. Quando Classe II divisão 1 é tratada com extrações de pré-molares, há aumento do NLA e os lábios são retraídos. No entanto, há menor retração do lábio inferior no protocolo de extração de 2 prémolares superiores.(AU)

Introduction: Differences in long-term and posttreatment attractiveness between Class II treatment protocols motivated these studies. Element II demonstrated that well-balanced faces have maxillary incisors positioned in an individually calculated anteroposterior relationship with the forehead. Thus, it was used to investigate the initial characteristics of the patients. Moreover, to evaluate the soft-tissue changes with extraction protocols, a systematic review was performed searching PubMed, Web of Science, Embase, Scopus and Cochrane electronic databases. Results: The CII group had forward incisors AP position when compared to the NO group. Also, the incisors AP positions in the extraction subgroups were forward when compared to the NE subgroup. Statistically significant soft-tissue changes reported included nasolabial angle (NLA) increasing from 2.4 to 5.40 degrees in the 2-premolar extraction protocol and from 1 to 6.84 degrees in the 4-premolar extraction protocol. Retrusion of the upper and lower lips were also verified, with less retraction of the lower lip in the 2-premolar extraction group. Conclusions: Class II subjects presented the maxillary incisors significantly more protruded than normal occlusion subjects. Class II division 1 extraction subgroups demonstrated significantly more protruded incisors as compared to the non-extraction subgroup. When Class II division 1 malocclusion is treated with premolar extractions, the NLA increases and the lips are retracted. However, there is less retraction of the lower lip in the 2- maxillary premolar extraction protocol.(AU)

Avaliação do ângulo nasolabial após o tratamento ortodôntico com e sem extração dos primeiros pré-molares / Assessment of the nasolabial angle after orthodontic treatment with and without extraction of the first premolars

OBJETIVOS: avaliar cefalometricamente as mudanças do ângulo nasolabial em pacientes submetidos ao tratamento ortodôntico com e sem exodontias dos primeiros pré-molares, e correlacionar este ângulo com as alterações na inclinação do incisivo superior, do lábio superior e da base do nariz. METODOLOGIA: a amostra consistiu de telerradiografias iniciais e finais de 30 jovens do gênero feminino, com má oclusão de Classe II, 1º divisão. Quinze foram tratadas com extração dos primeiros pré-molares e quinze sem extrações. Além do ângulo nasolabial, foram avaliadas as inclinações do lábio superior (Ls.PCm.SN7º), do incisivo superior (Is.SN7º) e da base do nariz (PCm.SN7º). RESULTADOS: a posição do lábio superior e a inclinação do incisivo superior foram as únicas medidas que apresentaram um aumento estatisticamente significante, entre os tempos inicial e final, no grupo com extrações. Todas as outras medidas avaliadas, em ambos os grupos, não apresentaram significância estatística. Observou-se uma correlação positiva entre a posição do lábio superior, a base do nariz e o ângulo nasolabial. CONCLUSÕES: 1) ocorreu um aumento significativo no ângulo nasolabial no grupo com exodontia dos primeiros pré-molares, devido, principalmente, às mudanças do lábio superior; 2) o crescimento nasal durante o período do estudo não influenciou nas alterações do ângulo nasolabial; 3) todas as outras medidas analisadas não apresentaram diferenças estatísticas entre os dois grupos, entre os tempos inicial e final; 4) observou-se uma correlação positiva entre o ângulo nasolabial, a inclinação do lábio superior e a base do nariz, em ambos os grupos.

AIM: To cephalometrically evaluate the changes in the nasolabial angle of the patients submitted to orthodontic treatment with and without extractions and correlate them with upper incisor inclination, upper lip position and the base of the nose. METHODS: The sample was composed of pre and posttreatment lateral cephalometric records of 30 female patients with Class II division 1 malocclusion. Fifteen were treated with first premolars extractions and the other fifteen without extractions. The following parameters were measured: nasolabial angle; upper incisor inclination (Is.SN7º angle), upper lip position (Ls-PCm.SN7º angle) and base of the nose (PCm.SN7º angle). RESULTS: The upper incisor inclination and the upper lip position showed a statistically significant increase from T0 to T1 in the extraction group. No statistically significant differences were found for the other parameters in both groups. The correlations between upper lip position, base of the nose and the nasolabial angle were positive. CONCLUSION: 1) There was a significant increase in the nasolabial angle in the extraction group and it was mainly due to changes in the upper lip position; 2) nasal growth during the study period did not contributed to the nasolabial angle increase; 3) all measurements were not statistically different between the 2 groups at T0 and T1, and 4) a positive correlation was found between the nasolabial angle, lip position and base of the nose in both groups.

Comparison of finite element analysis of the closing patterns between first and second premolar extraction spaces / 대한치과교정학회지

OBJECTIVE: The aim of this study was to compare the differences in closing extraction spaces between maxillary first premolar and second premolar extractions using 3-dimensional finite element analysis (FEA). METHODS: Maxillary artificial teeth were selected according to Wheeler's dental anatomy. The size and shape of each tooth, bracket and archwire were made from captured real images by a 3D laser scanner and FEA was performed with a 10-noded tetrahedron. A 10 degrees gable bend was placed behind the bull loop on a 0.017" x 0.025" archwire. The extraction space was then closed through 12 repeated activating processes for each 2 mm of space. RESULTS AND CONCLUSIONS: The study demonstrated that the retraction of anterior teeth was less for the second premolar extraction than for the first premolar extraction. The anterior teeth showed a controlled tipping movement with slight extrusion, and the posterior teeth showed a mesial-in rotational movement. For the second premolar extraction, buccal movement of posterior teeth was highly increased.

A comparative study of pre- and post-treatment cephalometric measurements: Upper premolar extraction only vs. upper/lower premolar extraction groups / 대한치과교정학회지

OBJECTIVE: The objective of this study was to provide guidelines for the diagnosis and successful treatment of orthodontic treatment with upper premolar extraction only. METHODS: The sample group consisted of 40 patients (20 with upper premolar extraction only, 20 with both upper and lower premolar extractions) who showed an overjet of more than 7 mm and were finished successfully. Lateral cephalographs were taken before and after orthodontic treatment. Landmarks showing the position of the upper and lower incisors and the position of the upper and lower lip were determined and angular measurement of these values were obtained for statistical analysis (Mann-Whitney test). RESULTS: At pre-treatment, the position of the lower incisor was less labially inclined and the convexity of the lower lip was smaller in the upper premolar extraction only group than in the upper/lower premolar extraction group. At post-treatment, there was no difference in all measurements except for the position of the lower incisor. A comparison of changes between pre- and post-treatment showed that the retraction of upper & lower incisors and the decrease in convexity of the lower lip were greater in the upper/lower premolar extraction group. CONCLUSIONS: Treatment by upper premolar extraction can be of benefit for patients whose lower incisor proclination and lower lip protrusion are not excessive.

Effect of maxillary premolar extraction on transverse arch dimension in Class III surgical-orthodontic treatment / 대한치과교정학회지

Collective changes caused by orthodontic tooth movement evaluated in a specific treatment modality could give suggestive information on the specific treatment strategy. The aim of this study was to investigate retrospectively the characteristics of the orthodontic tooth movement during surgical-orthodontic treatment in order to provide an effective presurgical orthodontic treatment planning for the maxillary premolar extraction modality in the skeletal Class III malocclusion patient. Pre- and posttreatment dental casts of skeletal Class III malocclusion patients with nonextraction (N=24) and the maxillary premolar extraction (N=31) were collected. The angulation and inclination measuring gauge (Invisitech Co. Seoul, Korea) was used to evaluate the orthodontic tooth movement. The changes in the maxillary and mandibular dental arch widths were also measured from the canines to the second molars. As a result, more palatal inclination change in the maxillary dentition was found with the premolar extraction modality than with the nonextraction modality. Linear regression analysis showed that the inter-arch width coordination was mainly due to the inclination changes of maxillary posterior teeth. We conclude that the indications and proper treatment planning for surgical-orthodontic treatment in skeletal Class III malocclusion with maxillary premolar extraction could depend partly on the magnitude of the transverse inter-arch coordination especially in the maxillary dentition.

Spatial changes of the upper dentition following en-masse space closure: A comparison between first and second premolar extraction / 대한치과교정학회지

The purpose of this experimental study was to evaluate and compare maxillary arch dimensional and positional changes between first and second premolar extraction groups. The Calorific Machine was used to illustrate tooth movement in three dimensions. The experimental teeth except the first or second premolars were embedded in artificial alveolar bone. The extraction space was closed using arch wires with bull loops into which 15 degree gable bends were placed. Before and after space closure, radiographs were taken in the sagittal and occlusal directions using occlusal films. The results showed greater mean maxillary incisor retraction and less anchorage loss in the maxillary first premolar extraction group than in the maxillary second premolar extraction group. Mesiopalatal rotation of anchor teeth was greater after extraction of a maxillary second premolar than a maxillary first premolar (p<.001).

A study of the arch length discrepancy and the diagnostic analysis / 대한치과교정학회지

Predicting the arch length discrepancy by simply comparing the available arch perimeter with tooth materials is merely a 2-dimensional analysis of the teeth movement. However, the real teeth movement takes place 3-dimensionally and is affected by various factors such as, the arch form, the curve of Spee and the axis of the incisors. The purpose of this study is to clarify the relationship between the decrease in the arch perimeter and the horizontal positional change of the incisors after extraction of the 1st bicuspids, for more analytic evaluation of the arch length discrepancy at pre-treatment model analysis stage. In addition to that to evaluate the effect of the curve of Spee, teeth axis to the basal plane, and the incisional crowding to the treatment outcome. All patients were treated at the department of orthodontics, dental hospital, Yonsei university. Inclusion criteria for patients selection were as follows. -Angle classification I malocclusion with bialveolar protrusion -Extraction of 4 1st bicuspids -No tooth anomaly or prosthesis -No abnormal attrition -No ectopically erupted teeth -Angle classification I canine and molar relationship -Less than 3mm of crowding Model analysis of the above patients was performed and the following conclusions were obtained. 1. When the intercanine distance was maintained, the available space for the distal movement of the mandibular incisors after the extraction of the 4 1st bicuspids was larger than the space provided by the extraction of the 4 1st bicuspids. However the difference was less than 1mm. The more tapered the anterior arch form, the larger the difference. 2. Compared to the situation in which the intercanine distance was maintained, when the intercanine distance was expanded to meet the width of the posterior teeth, the incisors could move about 3mm more distally. 3. The positional difference of the incisal tip was insignificant whether the central incisors were moved by tipping or bodily movement. 4. When the anterior crowding was solved without changing the intercanine distance, the larger the anterior arch length was, the more the anterior movement of the incisors. 5. When the curve of Spee was levelled, the increase in the arch perimeter was less than half of the deepest curve of Spee.

Upper and lower second premolar extraction treatment case: Treatment strategy for Class III borderline cases / 대한치과교정학회지

When treating borderline cases which have mild crowding, non-extraction treatment may be considered firstly. But crowding may be reappeared by relapse and it may have problems in esthetics and stability. Secondarily four first premolar extraction treatment may be considered. But this may cause dish-in face by overretracting anterior teeth. In this cases, extraction of four second premolar is preferred because this resolves crowding without aggravating profile and has good stability after treatment. So we review cases treated by four second premolar extraction which show good treatment results and stability. The patients had good profile, Class I molar relationship, mild crowding and skeletal discrepancy and their growth had almost completed.

Comparison of computer-based treatment prediction with true results in bimaxillary protrusion cases / 대한치과교정학회지

This study was performed to assess the accuracy of computer-based treatment prediction for soft tissue profile using Quick Ceph Image Pro(TM) & Quick Ceph 2000(TM) in bimaxillary protrusion cases. The pre- and post-treatment lateral cephalograms of 21 female adults treated by four first premolar extraction were imaged and 9 landmarks and 27 specific soft tissue mesurements were digitized for comparing actual treatment results with computer simulations. The results of this study showed that Quick Ceph Image Pro(TM) & Quick Ceph 2000(TM) tends to overestimate horizontal changes and underestimate vertical changes. In the computer simulation, upper lip showed rolling tendency. The upper lip measurements were disposed to be regular direction but lower lip measurements were varied case by case even if it was statistically insignificant.

Mandibular differential premolar extraction in growing patients / 대한치과교정학회지

The extraction for orthodontic treatment can be adopted for aligning crowded dentition, improving facial esthetics and solving a skeletal discrepancy as alternative for a surgical option. Mandibular second premolar extraction was often selected as treatment plan when there are very little or no space shortage in lower arch or limited retraction of the lower incisors was required. The primary object of this study was evaluate a pretreatment condition and examine the amount of tooth movement for a mandibular second premolar extraction in growing patients. Pretreatment and posttreatment lateral cephalograms of 14 cases that had their four first premolar extracted (4/4 group), 15 cases with upper first and lower second premolar extraction (4/5 group) were selected. Structural method superimposition was conducted to evaluate a difference of dental change between 4/4 and 4/5 group. The results were as follows, 1. Pretreatment factor for 4/4 extraction or 4/5 extraction choice included maxillary incisor axis to occlusal plane, Class II molar relationship, IMPA and interincisal angle. 2. The amount of molar anterior movement in 4/5 group was greater than that of 4/4 group(p<0.05). 3. There was no significant difference between 4/4 group and 4/5 group in aspects of maxillary tooth movement(p<0.05).

Changes in soft tissue chin resulting from premolar extraction and incisor retraction in adult female patients / 대한치과교정학회지

The purpose of this study was to evaluate changes in soft tissue chin thickness and to investigate correlations between hard and soft tissues measurements after orthodontic treatment conducted by premolars extraction and incisor retraction. The sample consisted of 35 female adults with Angle classification class I or class II division 1 malocclusion. Using lateral cephalometric radiographs taken before and after treatment, hard and soft tissue structures were measured and reproducible six landmark on soft chin tissue were used to locate the various points of soft tissue contour of the chin. The results were as follows : 1. There were signigicant correlations between pretreatment B-B', Pm-Pm' and pretreatment vertical skeletal measurements such as angle of MP & HP, angle of MP & PP, ALFH and between a-a', b-b', Me-Me' and measurements of symphyseal morphology such as SL, SW, PL. 2. There were significant decreases at B-B', Pm-Pm' and significant increases at a-a', b-b' between pre-and posttreatment measurements. 3. There were significant correlations among soft tissues changes and hard tissue changes except for changes at B-B' and the range of correlation coefficient was about 0.3-0.4. 4. There were significant differences at deltaUI-VP, angle of LI &

Effects of different orthodontic treatment methods on mandibular third molar eruption / 实用口腔医学杂志

0.05).But there were significant differences in the change in mandibular M3 space among three groups(P

Dentofacial changes in Class I protrusion patients treated with premolar extractions / 대한치과교정학회지

The purpose of this study was to evaluate the dentofacial characteristics and the post-treatment dentofacial changes of those treated by four premolar extractions and to investigate the factors affecting extraction decision. The sample consisted of 35 patients ( 27 females, and 8 males ) with no more than 7.0mm crowding, diagnosed as Class I protrusion. Pre-treatment and post-treatment lateral cephalograms were evaluated. Computerized statistical analysis was carried out using SPSS/PC+ program. The results were as follows. 1. There was no significant change in skeletal pattern after treatment while there was significant change in dentoalveolar and soft tissue pattern. 2. In pre-treatment skeletal pattern, a tendency toward vertical discrepancy was found. 3. In pre-treatment dental pattern, interincisal angle was 113.11degrees, Ul to FH was 117.78degrees and Ll to A-Pog was 7.94mm. Pre-treatment upper and lower lip position was 2.88mm and 5.43mm to E line. 4. After treatment, interincisal angle increased 14.46degrees and upper and lower lip moved back 2.45mm and 12mm to Eline. (p<0.001) 5. The EI was 138.71 before treatment and 148.2 after treatment.

An experimental study of ideal arch form of the Class I malocclusion patients with first premolar extraction / 대한치과교정학회지

This study was designed to get the knowledges of the ideal arch form of the class I malocclusion patients of Koreans with first premolar extraction. The subjects consisted of 98 individuals with class I malocclusion with first premolar extraction. The results were as follows; 1. Author found the ideal arch shape of the class I malocclusion patients with first premolar extraction. 2. Equations of ideal arch form of the class I malocclusion patients with first premolar extraction were obtained from SPSS.

Study on the eruption of the lower third molar in the cases of non-extraction and the extraction of first premolar / 대한치과교정학회지

This study was designed to recognize the factors which can affect the normal eruption of the lower third molar and the eruption rate of the lower third molar in the cases of non-extraction and the extraction of first premolar. The sample consisted of 214 cases of extraction of first premolar and 119 cases of non-extraction, and all of these cases were divided into erupted and impacted lower third molar groups and were analized according to the pantomogram. The results of the study were as follows : 1. The eruption rate of the lower third molar was 54.67 % in the group of extraction of the first premolar and 35.29 % in the non-extraction group. 2. The early inclination of the erupting lower third molar has significant effect in the eruption of it. 3. In the orthodontic treatment, the extraction of first premolar is one of the factors influencing the normal eruption of lower third molar. 4. The available space for the normal enruption of lower third molar was greater in first premolar extraction case than in non-extraction case.