Extraction Of Maxillary Premolars Research Articles

Effect of fluoride on root resorption following heavy and light orthodontic force application for 4 weeks and 12 weeks of retention

To evaluate the null hypothesis that fluoride intake via drinking water has no effect on orthodontic root resorption in humans after orthodontic force application for 4 weeks and 12 weeks of retention. Forty-eight patients who required maxillary premolar extractions as part of their orthodontic treatment were selected from two cities in Turkey. These cities had a high and low fluoride concentration in public water of ≥2 pm and ≤0.05 pm, respectively. The patients were randomly separated into four groups of 12 each: group 1HH, high fluoride (≥2 ppm) and heavy force (225 g); group 2LH, low fluoride (≤0.05 ppm) and heavy force; group 3HL, high fluoride and light force (25 g); and group 4LL, low fluoride and light force. Light or heavy buccal tipping force was applied on the upper first premolars for 28 days. At day 28, the left premolars were extracted (positive control side); the right premolars (experimental side) were extracted after 12 weeks of retention. The samples were analyzed with microcomputed tomography. On the positive control side, under heavy force application, the high fluoride groups exhibited less root resorption (P = .015). On the experimental side, it was found that fluoride reduced the total volume of root resorption craters; however, this effect was not statistically significant (P = .237). Moreover, the results revealed that under heavy force application experimental teeth exhibited more root resorption than positive control groups. The null hypothesis could not be rejected. High fluoride intake from public water did not have a beneficial effect on the severity of root resorption after a 4-week orthodontic force application and 12 weeks of passive retention.

Assessment of facial profile changes in patients treated with maxillary premolar extractions

OBJECTIVE: Evaluate the facial profile changes of orthodontic treatment with extraction of two upper first premolars, from the perspective of orthodontists, dentists and lay people. METHODS: Facial profiles of radiographs taken before and after treatment of 70 patients with Class II, division 1 malocclusion were traced. The silhouettes of the 70 patients were randomly assembled in an album with, being two profiles on each sheet of the same patient. Then, 30 orthodontists, 30 dentists and 30 lay people chose the more esthetic facial profile (A or B), and the amount of change they perceived between the two profiles before and after treatment, according to a visual analog scale (VAS). RESULTS: The results revealed that 83 examiners preferred the post-treatment profiles, and only three dentists and four lay people chose the profiles pre-treatment more frequently. Thus, the orthodontists often chose the profiles after treatment, followed by dentists, with no statistically significant differences found between dentists and lay people. There were significant differences within groups in the preference of pre- and post-treatment profile. Furthermore, the three groups of evaluators indicated that pre and post-treatment profiles did not differ substantially. CONCLUSIONS: The treatment of Class II, division 1 malocclusion with extraction of two first premolars has a positive effect on facial profile esthetics.

Residents' journal review

Residents' journal review

Extraction of Permanent Maxillary Teeth by Only Buccal Infiltration of Articaine

The aim of this study is to demonstrate whether articaine hydrochloride administered alone as a single buccal infiltration in maxillary tooth removal, can provide favourable palatal anesthesia as compared to buccal and palatal injection of lidocaine. The study population consisted of 30 patients who were undergoing orthodontic treatment, and who required bilateral extraction of maxillary permanent premolars as per their orthodontic treatment plan. On the experimental side, 4% articaine/HCl was injected into the buccal vestibule of the tooth to be extracted. On the control side, 2% lignocaine HCl was injected both into the buccal and the palatal side of the tooth to be extracted. Following tooth extraction all patients completed a 100-mm visual analogue scale (VAS) and faces pain scale (FPS) to rate the pain on extraction. According to the VAS and FPS scores, the pain on extraction between buccal infiltration of articaine and the routine buccal and palatal infiltration of lignocaine was statistically insignificant. The routine use of a palatal injection for the removal of permanent maxillary premolar teeth may not be required when articaine/HCl is used as the local anesthetic.

Orthodontic treatment combined with temporary anchorage device for a case of Class II with osteoarthrosis of the temporomandibular joint

An adult female patient presented with open bite at Orthodontic Clinic, Niigata University Medical and Dental Hospital. The patient was diagnosed as skeletal Class II open bite with Class III molar relationship, because of temporomandibular joint-osteoarthrosis (TMJ-OA) and the congenital absence of the mandibular lateral incisors. To correct anterior open bite, surgical orthodontic treatment was considered, but post treatment stability was unpredictable and doubtful due to condylar erosion on the CT. We therefore determined that nonsurgical treatment with maxillary first premolars extraction and plate type temporary anchorage device (TAD) placement bilaterally for intruding the maxillary molars would be indicated. At the completion of the active treatment, ideal occlusion was achieved without further resorption of the condyles. Even two years after the treatment, the stable occlusion has been maintained. In conclusion, the orthodontic treatment with TAD is one of the potent devices to provide the ideal occlusion for the patient with TMJ-OA.

External apical root resorption in maxillary incisors in orthodontic patients: associated factors and radiographic evaluation

PurposeThis study was performed to evaluate the incidence and degree of external apical root resorption of maxillary incisors after orthodontic treatment and to evaluate particular associated factors related to external apical root resorption.Materials and MethodsThe records and maxillary incisor periapical radiographs of 181 patients were investigated. Crown and root lengths were measured and compared on the pre- and post-treatment periapical radiographs. Crown length was measured from the center of the incisal edge to the midpoint of the cemento-enamel junction (CEJ). Root length was measured from the CEJ midpoint to the root apex. A correction factor for the enlargement difference was used to calculate root resorption.ResultsThe periapical radiographs of 564 teeth showed that the average root resorption was 1.39±1.27 (8.24±7.22%) and 1.69±1.14 mm (10.16±6.78%) for the maxillary central and lateral incisors, respectively. The results showed that the dilacerated or pointed roots, maxillary premolar extraction cases, and treatment duration were highly significant factors for root resorption (p<0.001). Allergic condition was a significant factor at p<0.01. Age at the start of treatment, large overjet, and history of facial trauma were also factors significantly associated with root resorption (p<0.05). There was no statistically significant difference in root resorption among the factors of gender, overbite, tongue-thrusting habit, types of malocclusion, and types of bracket.ConclusionThese results suggested that orthodontic treatment should be carefully performed in pre-treatment extraction patients who have pointed or dilacerated roots and need long treatment duration.

Physical properties of root cementum: Part 20. Effect of fluoride on orthodontically induced root resorption with light and heavy orthodontic forces for 4 weeks: A microcomputed tomography study

The major side effect of orthodontic treatment is orthodontically induced inflammatory root resorption. Fluoride was previously shown to reduce the volume of the root resorption craters in rats. However, the effect of fluoride on orthodontically induced inflammatory root resorption in humans has not yet been investigated. The aim of this study was to investigate the effect of high and low amounts of fluoride intake from birth on orthodontically induced inflammatory root resorption under light (25 g) and heavy (225 g) force applications. Forty-eight patients who required maxillary premolar extractions as part of their orthodontic treatment were selected from 2 cities in Turkey with high and low fluoride concentrations in the public water of ≥ 2 and ≤ 0.05 ppm, respectively. The patients were randomly separated into 4 groups of 12 each: group 1, high fluoride intake and heavy force; group 2, low fluoride intake and heavy force; group 3, high fluoride intake and light force; and group 4, low fluoride intake and light force. Light or heavy buccal tipping orthodontic forces were applied on the maxillary first premolars for 28 days. At day 28, the teeth were extracted, and the samples were analyzed with microcomputed tomography. Fluoride reduced the volume of root resorption craters in all groups; however, this effect was significantly different with high force application (P = 0.015). It was also found that light forces caused less root resorption than heavy forces. There was no statistical difference in the amount of root resorption observed on root surfaces (buccal, lingual, mesial, and distal) in all groups. However, the middle third of the roots showed the least root resorption. With high fluoride intake and heavy force application, less root resorption was found in all root surfaces and root thirds. Fluoride may reduce the volume of root resorption craters. This effect is significant with heavy force applications (P <0.05). The cervical and apical thirds of the root showed significantly greater root resorption after the application of buccal tipping force for 4 weeks.

Relationship between magnitude of immediate loading and peri‐implant osteogenesis in dogs

The purpose of this study was to investigate the influence of the magnitude of immediate loading on peri-implant bone in an animal model of dental implantation. Eight weeks after the extraction of maxillary and mandibular premolars, three implants were inserted bilaterally in the mandibles of six Beagle dogs. One implant was unloaded (UL) as a control, and two implants were loaded immediately with 10 N (mild loading: ML) or 50 N (excessive loading: EL) laterally using a cyclic loading device twice a week for 3 weeks. Fluorescent bone markers were injected to examine bone formation around the implants. The animals were sacrificed 3 weeks after implantation. Peri-implant osteogenesis was assessed by histomorphometric procedures, i.e., measuring bone-implant contact (BIC) and bone density (BD). The UL and ML groups had no peri-implant infection, and newly formed bone was observed over a wide area from the implant neck toward the tip, and in direct contact with the implant surface. In contrast, in the EL group, newly formed bone was rarely observed around the implant neck and there were signs of infection. Both BIC and BD in the ML group were significantly greater than those in the other groups. BIC and BD in the EL group were significantly lower than those in the other groups. A suitable magnitude of load applied immediately after dental implantation promotes peri-implant osteogenesis.

Smile attractiveness in patients with Class II division 1 subdivision malocclusions treated with different tooth extraction protocols

The aim of this study was to compare smile attractiveness between one, three, and four premolar extraction protocols in patients with Class II division 1 subdivision malocclusions and to analyse the aesthetic influence of buccal and posterior corridor widths on smile attractiveness. The sample consisted of posed smile photographs obtained from 66 subjects, divided into three groups according to the treatment-extraction protocol. Group 1 was treated with one maxillary premolar extraction included 23 subjects, group 2 was treated with four premolar extractions included 23 subjects, and 20 patients in group 3 were treated with three premolar extractions. Buccal and posterior corridor widths of each photograph were measured in proportion to the smile width. To rate the posed smile photographs, panels of 70 orthodontists and 46 laypeople used a 10-point scale. There were no significant differences in smile attractiveness scores between the three groups and between orthodontists and laypeople. Also buccal and posterior corridor widths did not differ between the groups and they did not influence the aesthetic scores. It was concluded that smile attractiveness is similar in treatment protocols of one, three, and four premolar extractions and that widths of buccal and posterior corridors do not influence smile attractiveness in these groups.

Sinus Floor Elevation Via the Maxillary Premolar Extraction Socket With Immediate Implant Placement: A Case Series

When immediate implant placement is considered for teeth with close proximity to the sinus floor, apical extension of the osteotomy is significantly limited, and often a staged approach is used. Implant placement into fresh extraction sockets and sinus floor manipulation using bone-added osteotome sinus floor elevation with implant placement are techniques most often used independently or sequentially. Very few reports have described the combined use of immediate implant placement in fresh sockets and the bone-added osteotome sinus floor elevation technique. We present five cases in which a maxillary premolar was extracted and an implant placed into the extraction site with simultaneous abfracture of the sinus floor using osteotomes. All teeth were extracted atraumatically, and sockets carefully debrided and checked for integrity of the walls. After ideal osteotomy preparation, particulate bone graft was placed in the osteotomy and appropriately sized osteotomes were used for sinus floor elevation. After sufficient elevation, implant placement was completed and particulate bone was packed in the bone-implant gap when indicated. All implants were restored after a minimum healing period of 6 months. At the time of final restoration, bone was seen surrounding the implants from the apical portion to the most coronal thread. All five implants healed without complications and were in function for periods ranging from 6 to 12 months. Immediate implant placement with simultaneous osteotome sinus floor elevation is an advantageous combination of two successfully used techniques. This combined approach can significantly reduce the treatment time for implant therapy in teeth with close sinus proximity and provide the operator with the ability to place implants of desired length.

Stability and relapse of maxillary anterior crowding treatment in Class I and Class II Division 1 malocclusions

The maxillary anterior teeth are the most important to facial esthetics because they are the first to show on a smile. Therefore, stability of the maxillary anterior teeth alignment is an important issue. The objective of this study was to compare the stability of maxillary anterior tooth alignment in Class I and Class II Division 1 malocclusions. The sample comprised dental casts of 70 patients with Class I and Class II Division 1 malocclusions and a minimum of 3 mm of maxillary anterior crowding measured by an irregularity index. The patients were treated with extractions and evaluated at pretreatment and posttreatment and at least 5 years after treatment. The sample was divided into 3 groups: group 1, Class I malocclusion treated with 4 first premolar extractions comprising 30 subjects, with an initial age of 13.16 years and 8.59 mm of initial maxillary irregularity; group 2, Class II malocclusion treated with 4 first premolar extractions comprising 20 subjects, with an initial age of 12.95 years and 11.10 mm of maxillary irregularity; and group 3, Class II malocclusion treated with 2 first maxillary premolar extractions comprising 20 subjects, with an initial age of 13.09 years and 9.68 mm of maxillary irregularity. The decrease in the maxillary irregularity index was significantly greater in group 2 than in group 1 during treatment. The stability of maxillary anterior alignment was 88.12% over the long term; 77% of the linear displacement of the anatomic contact points tended to return to their original positions. Stability of maxillary anterior alignment between the 3 groups was similar. The stability of maxillary anterior alignment was high over the long term, but a high percentage of teeth tended to return to their original positions.

Efficacy of 4% articaine hydrochloride and 2% lignocaine hydrochloride in the extraction of maxillary premolars for orthodontic reasons

Background:Articaine is an amide local anesthetic that differs from other agents of its group due to the presence of a thiophene ring instead of a benzene ring, and it is one of the commonly used local anesthetic agents for day care surgeries. Some researches claim that articaine is superior to lidocaine in its biologic profile.Purpose:To evaluate the efficacy, time of onset of anesthesia, duration of action and intra- or post-administration complications of articaine in comparison with lignocaine for bilateral extraction of maxillary premolars for orthodontic reasons.Materials and Methods:The study was carried out in 20 patients visiting the Department of Oral and Maxillofacial Surgery, Yenepoya Dental College and Hospital, Mangalore, needing bilateral extraction of maxillary premolars for orthodontic purposes. A volume of 0.6–1 ml of 4% articaine hydrochloride (HCl) was injected in the buccal vestibule on one side and 1–2 ml of 2% lignocaine HCl was injected on the other side. After attaining adequate anesthesia, the extraction procedure was carried out under aseptic conditions.Results:An onset period 0.975 ± 0.1118 and 2.950 ± 0.5104 min and duration of anesthesia of 72 ± 17.275 and 49 ± 5.026 min was found for articaine and lignocaine, respectively. Statistically significant differences were noted in the perception of pain using the visual analogue scale.Conclusion:Articaine can be used as an alternative to lignocaine, especially in the extraction of maxillary premolars for orthodontic reasons. The clinical advantages including rapid onset, longer duration of action and greater diffusing property over lignocaine and the elimination of the need for a painful palatal injection were demonstrated.

Editor's Comment and Q&A: Crowding and spacing in the dental arches: Long-term development in treated and untreated subjects

<h3>Introduction</h3> The purposes of this study were to analyze long-term changes in anterior spacing and crowding and to compare the development in orthodontically treated and untreated subjects. <h3>Methods</h3> The sample comprised 308 adolescents in the late mixed or early permanent dentition who were examined clinically at the ages of 7 to 17 years and again 25 years later. The treated subgroup of 58 subjects had received orthodontic treatment with fixed or removable appliances or both. All subjects had a full complement of teeth, except for 19 who had premolar extractions as part of their orthodontic treatment plan. <h3>Results</h3> The prevalence of maxillary anterior spacing was substantially and significantly reduced in both the untreated and treated groups from the first examination to the second. The prevalence of mandibular crowding increased significantly in the untreated and the nonextraction treated groups. The prevalence of mandibular crowding in patients treated without extractions increased by 25.6%, significantly more than in the untreated controls. The prevalence of maxillary crowding decreased by 15.8% in patients treated with maxillary premolar extractions, significantly more than in the untreated controls. <h3>Conclusions</h3> Long-lasting developmental factors seem to result in universally reduced maxillary anterior spacing, orthodontic treatment notwithstanding. Compared with untreated subjects, the long-term development of mandibular anterior crowding was unfavorable in subjects treated without extractions. Compared with untreated subjects, the long-term development of maxillary anterior crowding was favorable when treatment included extraction of the maxillary premolars.

Crowding and spacing in the dental arches: Long-term development in treated and untreated subjects

The purposes of this study were to analyze long-term changes in anterior spacing and crowding and to compare the development in orthodontically treated and untreated subjects. The sample comprised 308 adolescents in the late mixed or early permanent dentition who were examined clinically at the ages of 7 to 17 years and again 25 years later. The treated subgroup of 58 subjects had received orthodontic treatment with fixed or removable appliances or both. All subjects had a full complement of teeth, except for 19 who had premolar extractions as part of their orthodontic treatment plan. The prevalence of maxillary anterior spacing was substantially and significantly reduced in both the untreated and treated groups from the first examination to the second. The prevalence of mandibular crowding increased significantly in the untreated and the nonextraction treated groups. The prevalence of mandibular crowding in patients treated without extractions increased by 25.6%, significantly more than in the untreated controls. The prevalence of maxillary crowding decreased by 15.8% in patients treated with maxillary premolar extractions, significantly more than in the untreated controls. Long-lasting developmental factors seem to result in universally reduced maxillary anterior spacing, orthodontic treatment notwithstanding. Compared with untreated subjects, the long-term development of mandibular anterior crowding was unfavorable in subjects treated without extractions. Compared with untreated subjects, the long-term development of maxillary anterior crowding was favorable when treatment included extraction of the maxillary premolars.

Treatment stability in patients with Class II malocclusion treated with 2 maxillary premolar extractions or without extractions

The purpose of this study was to compare the occlusal stability of Class II malocclusion treatment with and without extraction of 2 maxillary premolars. A sample of 59 records from patients with complete Class II malocclusion was used. This sample was divided into 2 groups with the following characteristics: group 1, comprising 29 patients treated without extractions, and group 2, comprising 30 patients treated with extraction of 2 maxillary premolars. Dental cast measurements were obtained before and after treatment and at a minimum of 2.4 years after treatment. The pretreatment, posttreatment, and postretention occlusal statuses were evaluated with the peer assesment rating index. The occlusal indexes at the postretention stage and the posttreatment changes and percentages of posttreatment changes were compared with t tests. The nonextraction and the 2 maxillary premolar extraction treatment protocols of complete Class II malocclusions had no statistically significant differences in occlusal stability. Finishing Class II malocclusion treatment with the molars in a Class II relationship has similar occlusal stability as finishing with the molars in a Class I relationship.

Canine retraction rate with self-ligating brackets vs conventional edgewise brackets

To compare the rates of retraction down an archwire of maxillary canine teeth when bracketed with a self-ligating bracket was used on one side and a conventional bracket on the other. In 43 patients requiring maxillary premolar extraction, a self-ligating bracket (Damon3, SmartClip) was used on the maxillary canine on one side and a conventional bracket (Victory Series) on the other. The teeth were retracted down a 0.018-inch stainless steel archwire, using a medium Sentalloy retraction spring (150 g). The rates of retraction were analyzed using a paired t-test. The mean movement per 28 days for the conventional bracket was 1.17 mm. For the Damon bracket it was 0.9 mm and for the SmartClip bracket it was 1.10 mm. The differences between the conventional and self-ligating brackets were statistically significant: paired t-test, SmartClip, P < .0043; Damon3, P < .0001). The retraction rate is faster with the conventional bracket, probably because of the narrower bracket width of the self-ligating brackets.

Comparação entre os resultados oclusais e os tempos de tratamento da má oclusão de Classe II por meio da utilização do aparelho Pendulum e das extrações de dois pré-molares superiores

OBJETIVO: comparar os resultados oclusais e os tempos de tratamento da má oclusão de Classe II realizado com o aparelho Pendulum e com extrações de dois pré-molares superiores. MÉTODOS: a amostra constituiu-se dos modelos de gesso e das telerradiografias de 48 pacientes com má oclusão de Classe II, divididos em dois grupos de acordo com o protocolo de tratamento. O grupo 1 foi composto por 22 pacientes tratados com o aparelho Pendulum, com idade inicial média de 14,44 anos. O grupo 2 constituiu-se por 26 pacientes tratados com extrações de dois pré-molares superiores, com idade inicial média de 13,66 anos. Os resultados oclusais obtidos pelos dois protocolos de tratamento utilizados foram avaliados em modelos de gesso por meio do índice oclusal PAR, enquanto o tempo de tratamento foi calculado a partir das anotações clínicas presentes nos prontuários. As avaliações foram realizadas por meio do teste t independente. RESULTADOS E CONCLUSÕES: os resultados oclusais obtidos não demonstraram diferenças entre os grupos, porém o grupo 2 apresentou um tempo de tratamento significativamente menor.

Effects of the pendulum appliance, cervical headgear, and 2 premolar extractions followed by fixed appliances in patients with Class II malocclusion

In this retrospective study, we compared the cephalometric effects, the dental-arch changes, and the efficiency of Class II treatment with the pendulum appliance, cervical headgear, or extraction of 2 maxillary premolars, all associated with fixed appliance therapy. The sample of 82 patients with Class II malocclusion was divided into 3 groups: group 1 patients (n = 22; treatment time, 3.8 years) were treated with the pendulum appliance and fixed orthodontic appliances. Group 2 patients (n = 30; treatment time, 3.2 years) were treated with cervical headgear followed by fixed appliances; group 3 patients (n = 30; treatment time, 2.1 years) were treated with 2 maxillary premolar extractions and fixed appliances. The average starting ages of the groups ranged from 13.2 to 13.8 years. Data were obtained from serial cephalometric measurements and dental casts. The dental casts were analyzed with the treatment priority index. The treatment efficiency index was also used. The 3 treatment protocols produced similar cephalometric effects, especially skeletally. Comparisons among the 2 distalizing appliances (pendulum and cervical headgear) and extraction of 2 maxillary premolars for Class II treatment showed changes primarily in the maxillary dentoalveolar component and dental relationships. The facial profile was similar after treatment, except for slightly more retrusion of the upper lip in the extraction patients. The treatment priority index demonstrated that occlusal outcomes also were similar among the groups. The treatment efficiency index had higher values for the extraction group. The effects of treatment with the pendulum appliance or cervical headgear and extraction of 2 maxillary premolars associated with fixed appliances were similar from both occlusal and cephalometric standpoints. Class II treatment with extraction of maxillary teeth was more efficient because of the shorter treatment time. Differences in maxillary incisor retraction should be noted, but these differences might have been due to greater maxillary dentoalveolar protrusion in the extraction group before treatment.

Long-term stability of Class II malocclusion treated with 2- and 4-premolar extraction protocols

The objective of this study was to cephalometrically compare the stability of complete Class II malocclusion treatment with 2 or 4 premolar extractions after a mean period of 9.35 years. A sample of 57 records from patients with complete Class II malocclusion was selected and divided into 2 groups. Group 1 consisted of 30 patients with an initial mean age of 12.87 years treated with extraction of 2 maxillary premolars. Group 2 consisted of 27 patients with an initial mean age of 13.72 years treated with extraction of 4 premolars. T tests were used to compare the groups' initial cephalometric characteristics and posttreatment changes. Pearson correlation coefficients were calculated to determine the correlation between treatment and posttreatment dental-relationship changes. During the posttreatment period, both groups had similar behavior, except that group 1 had a statistically greater maxillary forward displacement and a greater increase in the apical-base relationship than group 2. On the other hand, group 2 had a statistically greater molar-relationship relapse toward Class II. There were significant positive correlations between the amounts of treatment and posttreatment dentoalveolar-relationship changes. Treatment of complete Class II malocclusions with 2 maxillary premolar extractions or 4 premolar extractions had similar long-term posttreatment stability.

Editor's Summary and Q&A: Long-term stability of Class II malocclusion treated with 2- and 4-premolar extraction protocols

Introduction The objective of this study was to cephalometrically compare the stability of complete Class II malocclusion treatment with 2 or 4 premolar extractions after a mean period of 9.35 years. Methods A sample of 57 records from patients with complete Class II malocclusion was selected and divided into 2 groups. Group 1 consisted of 30 patients with an initial mean age of 12.87 years treated with extraction of 2 maxillary premolars. Group 2 consisted of 27 patients with an initial mean age of 13.72 years treated with extraction of 4 premolars. T tests were used to compare the groups' initial cephalometric characteristics and posttreatment changes. Pearson correlation coefficients were calculated to determine the correlation between treatment and posttreatment dental-relationship changes. Results During the posttreatment period, both groups had similar behavior, except that group 1 had a statistically greater maxillary forward displacement and a greater increase in the apical-base relationship than group 2. On the other hand, group 2 had a statistically greater molar-relationship relapse toward Class II. There were significant positive correlations between the amounts of treatment and posttreatment dentoalveolar-relationship changes. Conclusions Treatment of complete Class II malocclusions with 2 maxillary premolar extractions or 4 premolar extractions had similar long-term posttreatment stability.