Premolar Extraction Patients Research Articles

Treatment outcome comparison of Invisalign vs fixed appliance treatment in first premolar extraction patients

In this study, we compared the dentitional changes after Invisalign and conventional orthodontic treatment with 4 first premolar extractions. This retrospective study included 57 patients whose orthodontic treatment involved the extraction of 4 first premolars because of bialveolar protrusion. A total of 27 patients were treated with Invisalign (mean age, 25.5 ± 5.2 years) and 30 patients with the fixed appliance (mean age, 24.4 ± 5.8 years). The angular and linear changes of the maxillary and mandibular central incisors, second premolars, first molars, and second molars were measured from the recordings on the basis of the lateral cephalograms taken before and after treatment. The angular changes of the canines and second premolars were measured using panoramic radiographs. The overbite and interincisal angle increased significantly in the Invisalign group compared with in the conventional fixed appliance group (P<0.05). The maxillary central incisors showed increased lingual tipping in the Invisalign group (P<0.05), whereas there was no statistically significant difference in the angular change of the mandibular incisors between groups (P>0.05). The maxillary first and second molars showed mesial tipping in the Invisalign group (P<0.05). The maxillary second premolars, first and second molars, and the mandibular second molars showed mesial movement in the Invisalign group (P<0.05). The Invisalign group showed more statistically significant lingual tipping of the maxillary central incisors, distal tipping of the maxillary canines, and mesial tipping of the maxillary first and second molars after maximum retraction of the anterior teeth compared with the fixed appliance group.

The effect of maxillary first and mandibular second premolar extractions on the posterior Bolton ratio

The anterior and overall Bolton ratios and their application in orthodontics are widely known. However, little has been reported about the posterior Bolton ratio, how it is affected by the extraction of posterior teeth, and its application in orthodontic treatment planning. This study aimed to investigate how extracting maxillary first and mandibular second premolars affects the posterior Bolton ratio. The sample included 55 patients with Class I occlusion within 1 standard deviation of ideal anterior and overall Bolton ratios. The digitized models were subjected to virtual extraction of maxillary first premolars and mandibular second premolars and setup of posterior teeth in ideal occlusion. If space closure compromised occlusion, the teeth were moved to achieve ideal cusp-fossa or cusp-marginal ridge occlusion. The ideal setups were measured for residual interproximal spacing. Statistical analysis used R statistical software (version 2018; R Core Team, Vienna, Austria). The ideal nonextraction posterior Bolton ratio was determined from the sample to be 105.77 ± 1.99%. The ideal expected posterior Bolton ratio for maxillary first and mandibular second premolar extraction patients was 106.52 ± 2.52%. This significantly differed from the expected posterior Bolton ratio for the 4 first premolar extractions. Patients finished with an average of 1.28 mm net residual spacing between mandibular first premolars and first molars; 38.2% of patients finished with at least 1.5 mm of residual space, and 9.1% of patients finished with at least 2 mm of residual space. A patient with ideal anterior, posterior, and overall Bolton ratios treated with maxillary first and mandibular second premolar extractions to ideal occlusion will likely finish with some spacing in the mandibular dentition.

The predictability of orthodontic tooth movements through clear aligner among first-premolar extraction patients: a multivariate analysis

BackgroundThe purpose was to determine the predictability of tooth movements through clear aligner among premolar extraction patients and to explore the effects of various factors on tooth movements.MethodsA total of 31 extraction patients (10 males and 20 females; age 14–44) receiving clear aligner treatment (Invisalign) were enrolled in this study. The actual post-treatment models and pre-treatment models were superimposed using the palatal area as a reference and registered with virtual post-treatment models. A paired t test was used to compare the differences between actual and designed tooth movements of maxillary first molars, canines, and central incisors. A multivariate linear mixed model was performed to examine the influence of variables on actual tooth movements.ResultsCompared to the designed tooth movements, the following undesirable tooth movements occurred: mesial movement (2.2 mm), mesial tipping (5.4°), and intrusion (0.45 mm) of first molars; distal tipping (11.0°), lingual tipping (4.4°), and distal rotation of canines (4.9°); lingual tipping (10.6°) and extrusion (1.5 mm) of incisors. Age, crowding, mini-implant, overbite, and attachments have differential effects on actual tooth movements. Moreover, vertical rectangular attachments on canines are beneficial in achieving more predictable canine and incisor tooth movements over optimized attachments. Lingual tipping and extrusion of incisors were significantly influenced by the interaction effects between incisor power ridge and different canine attachments (p < 0.05).ConclusionsIncisors, canines, and first molars are subject to unwanted tooth movements with clear aligners among premolar extraction patients. Age, crowding, mini-implant, overbite, and attachments influence actual tooth movements. Moreover, vertical rectangular attachments on canines are beneficial in achieving more predictable incisor tooth movements over optimized canine attachments.

Mandibular dental changes following serial and late extraction of mandibular second premolars.

To determine changes in occlusal curves and dental tipping occurring from mandibular second premolar serial extraction, early extraction of deciduous mandibular second molars with missing second premolars, and late second premolar extraction compared with untreated controls. Information was collected from 85 subjects at three time points: T0, prior to serial extraction; T1, after serial extraction and drift prior to orthodontic treatment, and pretreatment for the late premolar extraction patients; and T2, posttreatment. Untreated age- and gender-matched controls were used for comparison. Three occlusal curves were measured on digitized mandibular casts, and dental tipping was assessed using lateral cephalograms. At T0, there were no significant differences among groups. At T1, there was significant steepening of Monson's sphere and the curve of Wilson between early and late extraction and control groups. At T2, the differences in Monson's sphere and the curve of Wilson were fully corrected. At T1, there were significant differences in the tipping of mandibular 6's, 4's, and 3's between the early extraction groups compared with the late extraction and control groups. At T2, these differences in tipping were fully corrected. There were no differences in mandibular incisor tipping between groups at T1 or T2. Serial extraction produced steeper occlusal curves and significant tipping of mandibular first molars, first premolars, and canines after extraction and physiologic drift (T1). Accentuated occlusal curves and tooth tipping were fully corrected following orthodontic treatment (T2). Mandibular incisor position was unchanged by serial or late second premolar extraction.

Micro-osteo perforation effects as an intervention on canine retraction

ObjectiveTo evaluate the rate of canine retraction, mesial movement of molar and pain perception in maxillary first premolar extraction patients with or without flapless cortical perforations (FCPs). MethodsThirty adult patients with class II div I malocclusion were randomly allocated with the help of SPSS software to either perforation or conventional group for carrying out this randomized parallel group-controlled trial in 1:1 ratio. Maxillary first premolars were extracted and after canine retraction, distance between the tip of the canine and midpoint of incisal edge and the distance between the cervical midpoints on the height of contour of respective cinguli was measured. Also, mesial movement of molar and pain perception were assessed in both groups. Three bilateral cortical FCP of 1.5 mm diameter were made in the perforation group. Data were analyzed with the help of SPSS software with an intention-to-treat the FCP approach. ResultsSignificant canine retraction in patients with FCP (mean retraction of 6.68 ± 0.60 [measured at crown tip level] and 5.97 ± 0.71 mm [measured at mid cervical level]) was revealed, while patients with conventional mechanics had mean retraction of 2.54 ± 0.49 and 2.33 ± 0.46 mm. Mesial movement of molar also showed significant difference (FCP = 0.48 ± 0.11 mm and Conventional = 0.65 ± 0.19 mm). Pain perception in control group was significantly lower in day 1 and 2. ConclusionFCPs are an effective method of accelerating the rate of canine retractions by 2–3 fold of tooth movement, however, pain perception was high in day 1 and 2.

Dentoskeletal and soft tissue changes associated with miniscrew anchorage in customized lingual orthodontics.

ObjectivesThe goal of this study was to analyze skeletal, dental, and soft tissue changes of patients treated with customized lingual systems and to evaluate the clinical effectiveness of miniscrew anchorage.MethodsNine upper first premolar extraction patients who were treated with customized lingual appliances were included in this study. Miniscrews were used for reinforcement of molar anchorage. Cephalometric films and study models were obtained before treatment (T1), after alignment (T2), and after treatment (T3). Treatment effects were analyzed by cephalometric radiographs and study models.ResultsThe upper anterior teeth were retracted significantly at T2 and T3 (4.41 ± 4.14 mm and 5.51 ± 2.48 mm, respectively). During space closure, the upper first molars showed slight mesial movement (1.50 ± 1.97 mm). The intercanine width of the upper arch increased at T2 (1.59 ± 1.81 mm), but decreased at T3 (0.11 ± 1.00 mm). The sella-nasion-A, A-nasion-B, and mandibular plane angles were not significantly changed at T3. The upper lip showed continuous retraction at both T2 and T3 (1.40 ± 1.46 mm and 2.32 ± 2.48 mm, respectively).ConclusionsBy using miniscrew anchorage for lingual orthodontics, patients’ dental and soft tissue changes considerably improved and molar anchorage was reinforced.

Extraction of maxillary canines: Esthetic perceptions of patient smiles among dental professionals and laypeople.

Maxillary canines are generally considered important both cosmetically and functionally. Most claims on the importance of maxillary canines, however, have been based on expert opinions and clinician-based studies. There are no scientific studies in the literature reporting on their cosmetic importance or how laypeople perceive a smile treated by maxillary canine extractions. Our objective was to investigate whether there is any difference in the perceptions of patients' smiles treated by extracting either maxillary canines or first premolars, as judged by orthodontists, dentists, and laypeople. This retrospective study included 24 participants who had unilateral or bilateral extraction of maxillary permanent canines and fixed appliances in the maxillary and mandibular arches to comprehensively correct the malocclusion, selected from orthodontic patients treated at Chesterfield Royal Hospital NHS trust in the United Kingdom over the last 20years. The control group of patients had extraction of maxillary first premolars followed by fixed appliances and finished to an extremely high standard judged by the requirement that they had been submitted for the Membership in Orthodontics examination. The finished Peer Assessment Rating scores for this group were less than 5. The end-of-treatment frontal extraoral smiling and frontal intraoral views were presented for both groups. The photographs were blinded for extraction choice and standardized for size and brightness using computer software (Adobe Photoshop CC version 14.0; Adobe Systems, San Jose, Calif). The work file was converted to an editable pdf file and e-mailed to the assessors. The assessor panel consisted of 30 members (10 orthodontists, 10 dentists, and 10 laypeople), who were purposely selected. The measures were rated on a 10-point Likert scale. The attractiveness ratings were not statistically significantly different between the canine extraction and premolar extraction groups, with a mean difference of 0.33 (SD, 0.29) points. A 1-way repeated-measures analysis of variance to test the difference in scores among the laypeople, orthodontists, and dentists (n=30) showed no statistically significant difference (Wilks lambda=0.835; P=0.138), and the Bonferroni test indicated that no pair-wise difference was statistically significant. No statistically significant difference was found in the smile attractiveness between canine extraction and premolar extraction patients as assessed by general dentists, laypeople, and orthodontists. Further high-quality studies are required to evaluate the effect of canine extraction and premolar substitution on functional occlusion.

Comparison of orthodontic treatment outcomes in nonextraction, 2 maxillary premolar extraction, and 4 premolar extraction protocols with the American Board of Orthodontics objective grading system

The aim of this study was to compare the orthodontic clinical outcomes of 2 maxillary premolar extraction, 4 premolar extraction, and nonextraction treatment protocols. The sample for this retrospective study was selected randomly from the archives of postgraduate orthodontic clinics in various cities in Turkey. Posttreatment records including dental casts and panoramic radiographs of 1098 patients were divided into 3 groups: group 1 comprised 269 patients treated with 2 maxillary first premolar extraction, group 2 comprised 267 patients treated with 4 premolar extraction, and group 3 comprised 562 patients treated with a nonextraction protocol. Only 1 researcher evaluated all subjects using the American Board of Orthodontics objective grading system. There were no statistically significant differences among the 2 maxillary premolar extraction, 4 premolar extraction, and nonextraction treatment groups for alignment, marginal ridge height, buccolingual inclination, overjet, and interproximal contact measurements. Statistically significant differences were found in occlusal contacts, occlusal relationships, and root angulation measurements between the 4 premolar extraction and the nonextraction groups. The nonextraction patients had more teeth in occlusion than did the 4 premolar extraction patients. The nonextraction patients finished with more satisfactory sagittal dental relationships. The 4 premolar extraction group had the least satisfactory sagittal dental relationships. The nonextraction patients finished with better root angulations.

Effect of retraction materials on gingival health: A histopathological study

Background:Gingival retraction methods are used in dentistry for impressions of subgingival crown margins, such as, mechanical, chemical, chemicomechanical, and surgical. These methods may injure the gingival sulcular epithelium. Hence, the present study is carried out to evaluate the effect of different retraction materials, such as, Expasyl, Magic Foam Cord, and impregnated retraction cord on the gingival sulcular epithelium.Materials and Methods:This study included 30 cases of bilateral premolar extraction patients with Loe and Silness gingival index zero. Retraction materials were kept in the dry, isolated labial gingival sulcus for the required time. The retraction materials were removed by rinsing with water. Retracted gingiva of 2 – 3 mm from the gingival margin along with the tooth was extracted and the decalcified sections were microscopically studied. Data analysis: Data were analyzed by applying the chi-square test.Results:This study showed better results with retraction paste as compared to the retraction cord, and there was a significant association between retraction materials and the relative degree of injury to the sulcular epithelium.Conclusion:There is a significant association between retraction materials and gingival sulcular epithelium. It can be stated that impregnated retraction cord, may be used commonly but it needs proper tissue manipulation and is technique sensitive. Newly advanced material in the form of retraction paste like Expasyl or Magic Foam Cord was found to be better than cord as assessed histologically, it respects periodontium.

The effects of first premolar extractions on third molar angulations.

The purpose of this study was to determine the relationship between the inclinations of second and third molars during a two- to 2.5-year period in patients treated orthodontically both with and without premolar extractions. Records of 37 first premolar extraction patients and 33 nonextraction patients were examined. The pretreatment and posttreatment panoramic radiographs were analyzed. The angles were measured between the long axis of the third molar and the occlusal plane and between the long axis of the third molar and the long axis of the second molar. Changes in third molar angulations from pretreatment to posttreatment for two groups were compared by Mann-Whitney U-test. Statistical analysis revealed that mandibular third molars showed an improvement in angulation relative to the occlusal plane in the first premolar extraction group.

Activation time and material stiffness of sequential removable orthodontic appliances. Part 3: Premolar extraction patients

The purpose of this study was to describe the movement of teeth adjacent to premolar extraction spaces during space closure with aligner appliances and then fixed appliances. The sample included 24 subjects from a larger study investigating an aligner system. All subjects had at least 1 premolar extracted as part of treatment. Dental casts and panoramic radiographs were measured for tooth tipping adjacent to extraction spaces at 3 treatment points: T0, initial; T2, end of aligners; and T3, end of fixed appliances. Chart records were reviewed for information about time in treatment. Treatment with aligners resulted in significant tipping of the teeth adjacent to premolar extraction sites. When followed by fixed appliances, these teeth were significantly uprighted. Aligner treatment followed by treatment with fixed appliances took an average of 40 months. In premolar extraction patients treated with aligners, dental tipping occurs but can be corrected with fixed appliances. This dual modality treatment might require more time than treatment with fixed appliances alone.

An extraction approach to borderline tooth size to arch length problems in patients with satisfactory profiles

Patients with mild to moderate tooth size to arch length discrepancies(TSALD), and profiles on the full side of the satisfactory range (“borderline” patients), can be treated with the extraction of premolars without a detrimental effect on the face. Pre- and posttreatment facial photographs of 51 consecutively treated four second premolar extraction patients were judged by 95 laypersons. Their assessment was that the “mouth area” of these patients was improved or not adversely affected 92% of the time. The stability of borderline patients treated with extractions of premolars was determined to be well within clinically accepted standards (<3.5 mm, Little's irregularity index [II]) 85% of the time. The 23 patients studied were found to have a mean II of 2.83 mm 12-years postretention. Various treatment techniques used in these types of problems are discussed. Examples and the results achieved with various approaches are shown.

Stability and relapse of mandibular anterior alignment: University of Washington Studies

For more than 40 years, research in the Department of Orthodontics, University of Washington (Seattle, WA) has focused on a growing collection of more than 800 sets of patient records to assess stability and relapse of orthodontic treatment. All patients had completed treatment a decade or more before the last set of data. Evaluation of treated premolar extraction patients, treated lower incisor extraction patients, treated nonextraction cases with generalized spacing, patients treated with arch enlargement strategies, and untreated normals showed similar physiologic changes: (1) Arch length decreases after orthodontic treatment. (2) Arch width measured across the mandibular canine teeth typically reduces posttreatment, whether or not the case was expanded during treatment. (3) Mandibular anterior crowding during the posttreatment phase is a continuing phenomenon well into the 20-to-40 years age bracket and likely beyond. (4) Third molar absence or presence, impacted or fully erupted, seems to have little effect on the occurrence or degree of relapse. (5) The degree of postretention anterior crowding is both unpredictable and variable and no pretreatment variables either from clinical findings, casts, or cephalometric radiographs before or after treatment seem to be useful predictors.

Influence of serial extraction on growth and development of the maxilla and mandible

Variations in treatment times for serial extraction and late premolar extraction patients may be due to differences in the time needed to flatten the occlusal curves. In this study, we compared tooth tipping and occlusal curves in patients treated by serial extractions or late premolar extractions with untreated controls.Mandibular dental casts and cephalometric radiographs were collected from 90 subjects (30 Class I control subjects, 30 patients with serial extractions, and 30 with late premolar extractions) at 3 time points: T0, baseline for the controls and serial extraction patients; T1, after natural drift and preorthodontics for the controls and the serial extraction patients, and pretreatment for the late premolar extraction patients; and T2, after comprehensive orthodontic treatment for the serial extraction and the late premolar extraction groups. The long axes of the central incisor, canine, and first molar to the palatal plane were measured on digitized headfilms to determine the direction and the amount of tipping between the time points. Three occlusal curves were measured by sphere fitting cusp-tip landmarks on digitized mandibular casts.From T0 to T1, incisors and canines in the patients with serial extractions tipped distally. Molars at T1 in the patients with serial extractions were tipped forward more than in the late premolar extraction patients and the controls. From T1 to T2, canines and molars in the patients with serial extractions were uprighted.Serial extractions produce steeper occlusal curves and distal tipping of the incisors and canines after drift (T1). Posttreatment (T2) occlusal curves in the patients with serial extractions are steeper than in the late premolar extraction patients and controls (except for the curve of Spee). After the serial extractions, orthodontic treatment included incisor and canine proclination, with molar uprighting and occlusal curve flattening.