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PubMed1993

The effects of premolar-extraction: a long-term comparison of outcomes in "clear-cut" extraction and nonextraction Class II patients.

Discriminant analysis was used to assess the anatomical basis of the extraction/nonextraction decision in 238 former Saint Louis University Class II edgewise patients. The resulting discriminant scores (based on six measures of protrusion and crowding) were used to divide this parent sample into three prognostic subgroups: clear-cut extraction, clear-cut nonextraction, and a borderline stratum containing both extraction and nonextraction patients. The "clear-cut" patients--those at the tails of the distribution--were then contacted and asked to return for follow-up records (cephalograms, models, clinical examination); in the end, 62 (33 extraction and 29 nonextraction) were recalled. The average post-treatment interval was about 15 years. Premolar extraction produced a significantly greater reduction in hard- and soft-tissue protrusion. During the post-treatment period, however, both groups underwent essentially the same change: decreased profile convexity and a pattern of dental change/relapse that was correlated with antero-posterior mandibular displacement. Because of their greater initial crowding and protrusion, the various effects summed to make the extraction patients significantly more protrusive at recall. Both treatments produced mesial mandibular displacement, extraction significantly more than nonextraction; however, at recall the two groups did not differ with respect to the signs and symptoms of dysfunction. The present findings, therefore, fail to support the common, influential belief that premolar extraction frequently causes "dished in" profiles, "distalized" mandibles, and, ultimately, craniomandibular dysfunction.

Adolescent↗
PubMed2003

Extraction vs nonextraction: arch widths and smile esthetics.

Dental casts of 30 patients treated with extraction and 30 patients without extraction of four first premolars were randomly selected to determine changes in arch width as a result of treatment. Arch widths were measured from the cusp tips of the canines, premolars, and molars. Posttreatment arch widths were also measured in the midline at a constant arch depth from the most labial surfaces of the incisors. Standardized frontal photographs of the face taken during smiling of 12 extraction- and 12 nonextraction-treated subjects were evaluated. Fifty laypersons judged the esthetics of the smiles. Intercanine width increased less than one mm in both groups, and there was no difference between the two groups. The interpremolar and intermolar distance in both arches decreased significantly from 0.53 to 0.95 mm in the extraction sample, whereas the interpremolar and intermolar widths increased significantly from 0.81 to 2.10 mm in the nonextraction sample. When arch widths of both groups were measured from the most labial surfaces of the teeth at a constant depth, the average arch width of both arches was significantly wider in the extraction sample (1.8 mm wider in the mandible and 1.7 mm wider in the maxilla). The mean esthetic score and the number of teeth displayed during a smile did not differ between the groups. The results indicate that arch width is not decreased at a constant arch depth because of extraction treatment, and smile esthetics are the same in both groups of patients.

Adolescent↗
PubMed1989

Mandibular incisor stability after orthodontic treatment in the upper arch.

The aim of this study was to observe longitudinally the anterior region of the lower jaw when treating only the upper jaw. A comparison was made between a group of 35 children treated with extraction of the maxillary first premolars and a fixed appliance in the upper jaw and a control group of 19 untreated children. The treatment group was studied with plaster models on five occasions: before treatment, at the end of active treatment, at the end of retention, after one year out of retention and at the last registration, in total over about a seven year period. Cephalometric registrations were made before treatment and at the last registration. The control group was studied with plaster models and lateral head films during a period of nine years and their age at the last registration was the same as for the treatment group. The space loss in the anterior region of the lower jaw increased from a mean of 0.4 mm (s.d. 0.82) to 2.5 mm (s.d. 1.52) in the treatment group and from 0.1 mm (s.d. 0.16) to 0.5 mm (s.d. 0.81) in the control group: an extra space loss of 2.0 mm for the treatment group. The main increase was registered during treatment and after retention. Subjective ranking of the plaster models from the final registrations according to the amount of crowding in the lower anterior region also showed a significant difference between the treatment group and the control group, the treatment group showing the largest of crowding. In cases where maxillary protrusion is treated by extraction in the maxilla only, stabilization of the lower arch with fixed orthodontic appliances seems justified.

Adolescent↗
PubMed1985

Long-term periodontal status of teeth moved into extraction sites.

The present study was undertaken to assess the long-term periodontal status adjacent to teeth that had been moved orthodontically into extraction sites. Twelve persons with a mean age of 29.2 +/- 5.7 (SD) years, who had completed orthodontic therapy at least 10 years previously, were examined. The orthodontic treatment had included bilateral premolar extraction in only the maxilla. Interproximal tooth surfaces in the maxilla adjacent to the extraction sites (study group) were compared to corresponding tooth surfaces in the mandible (control group) with respect to plaque, visual inflammation, bleeding after probing, pocket depth, gingival recession, loss of connective tissue attachment, radiographic bone height, and root resorption. Statistical comparisons were made via analyses of variance and t tests. There were no differences between the groups for any clinical parameter except the presence of less visual inflammation in study subjects. Radiographically, there were no differences in crestal alveolar bone levels measured from the cementoenamel junction. Bone height evaluation by the Bjorn method showed less alveolar support in the study group. However, this was due to the influence of root resorption rather than an effect on crestal height. It was concluded that orthodontic movement of teeth into extraction sites had been without detrimental effect upon the adjacent periodontal status.

Adult↗
PubMed1999

Class II, division 1, case with multiple treatment challenges.

This is a case report of a 23-year-old black woman with a skeletal Class II Division 1 malocclusion and an anterior open bite. The maxillary central incisor root was severely dilacerated, a maxillary lateral incisor and canine were transposed, a maxillary canine was impacted near the orbital rim, and a mandibular second premolar was congenitally missing. Selective extractions and attention to detail provided outstanding occlusal function and improved facial esthetics.

Adult↗
PubMed2001

Numerical analysis of a model of organ motion using serial imaging measurements from prostate radiotherapy.

We previously proposed a model for incorporating the effects of organ motion, including the changes in organ shape, into the calculation of dose in a statistical fashion based on serial imaging measurements of organ motion. In the present paper, numerical studies were used to investigate how the accuracy of the statistical calculation of dose depends on the number of organ motion measurements provided as input into the model. The dose calculated statistically with the model was consistently more accurate than the one obtained by directly resampling the serial measurements of organ motion. It was also more robust relative to the random variabilities present in the input organ motion measurements. The results confirm that the model can reproduce the statistical distribution of the organ motions measured in a serial imaging study, including the changes in organ shape, without making any assumptions about the functional form of this distribution. The model allows a more accurate calculation of dose to be performed from a given number of measurements of organ motion than would otherwise be obtained by directly resampling the measured data. It thus maximizes the information that is extracted from serial imaging measurements.

Algorithms↗
PubMed1985

Third molar changes following second molar extractions.

Third molars, both upper and lower, do usually erupt into the place of electively removed second molars. None of the third molars in this study group became impacted during the observation period. Second molars in this study were removed before the roots had formed on the third molars. The bifurcation line appears to be a stable reference on the panoramic radiograph. It is the Author's conclusion that the extraction of permanent second molars is best for many patients, and when judiciously applied it is a reasonably safe and conservative modality in orthodontic care.

Adolescent↗
PubMed1996

Consistency of orthodontic extraction decisions.

Ten orthodontists having completed specialist training, examined on two occasions 1 month apart, the complete pre-treatment records of 60 Class II division 1 patients representing the full range of dental malocclusion severity. At each session the orthodontist recorded whether their proposed treatment involved extractions. The level of agreement both between and within the orthodontists was evaluated with the Kappa statistic. Data analysis revealed that the level of agreement within the examiners was good, however the between examiner agreement was poor. It appeared that the orthodontists were applying different criteria in terms of the extraction decision and this has implications for orthodontic patients.

Adolescent↗
PubMed1977

Occurrence and distribution of interdental gingival clefts following orthodontic movement into bicuspid extraction sites.

Forty patients in active retention following orthodontic tooth movement into premolar extraction sites were examined for the occurrence and distribution of interdental gingival clefts, defined as an invagination of interproximal tissue with definite mesial and distal peaks having a depth of at least 1 mm. Fourteen of the forty orthodontic patients demonstrated clefts in one or more of the premolar extraction sites. No clefts were observed in premolar areas of orthodontic patients who did not require premolar extraction or in patients without previous orthodontic treatment. Interdental clefts occurred most frequently at the buccal aspect of mandibular first premolar extraction sites. The presence of the cleft appears to have clinical implications, both in terms of orthodontic relapse, and maintenance of gingival health.

Adolescent↗
PubMed1994

Determination of tetrahydro-beta-carbolines in urine by high-performance liquid chromatography with suppression of artefact formation.

A high-performance liquid chromatographic method has been developed for the determination of urinary tetrahydro-beta-carbolines. When standing tryptamine with formaldehyde and acetaldehyde under extraction conditions, the significant amounts of artefact 1,2,3,4-tetrahydro-beta-carboline (TBC) and 1-methyl-1,2,3,4-tetrahydro-beta-carboline (MTBC) were formed in a short time. Urine samples added with 2-ethyl-1,2,3,4-tetrahydro-beta-carboline (an internal standard) were treated with fluorescamine, and then with glycine, followed by serial solvent extractions. Such a pretreatment using two-step reactions removed a precursor (trypamine) by extracting its fluorescamine derivative, and enhanced the detection response by consuming excess fluorescamine. It solved the analytical problem that artefact TBC and MTBC are formed during analysis. Reversed-phase ion-pair chromatography using a C8-column and trifluoroacetic acid as a counter ion completed a base-line separation of three analytes within 10 min. The calibration graphs showed a good linearity in the range 0.1-50.0 ng ml-1 of urine samples spiked with standard TBC and MTBC. In the spike experiment, the recovery and relative standard deviation were almost 100% and less than 3.0%, respectively, for both TBC and MTBC. The proposed method enables the determination of the genuine urinary concentrations of TBC and MTBC without involving their artefacts.

Acetaldehyde↗
PubMed2003

Contemporary treatment of a crowded Class II division 1 case.

A 12-year-old Caucasian male presented with a severe Class II division 1 incisor relationship on a mild Skeletal II base with an average maxillary-mandibular planes angle and average lower facial height. Crowding was severe in the upper arch and moderate in the lower arch. Treatment was commenced using Twin Block appliances, and followed by extractions in all four quadrants and fixed appliances. This case illustrates the versatility of the Twin Block appliance in the treatment of those cases exhibiting crowding.

Activator Appliances↗
PubMed1989

Long-term spontaneous changes following removal of all first premolars in Class I cases with crowding.

The purpose of the study was to evaluate the result in adults of Class I malocclusion cases who had all their first premolars extracted as the sole treatment of space deficiency in the mixed or early permanent dentition. The mean age at premolar removal was 10 1/2 years. Forty-two out of 44 cases were re-examined at a mean age of 30 years and 4 months. Observations of dental occlusion and oral health were compared to observations of control samples. The average malocclusion in the adults, as judged by a score method, was similar to that reported for an appliance-treated sample. Marked spontaneous arch alignment and residual space closure with age was seen in most cases. Despite earlier tooth removal, on average crowding developed to about the same degree as that of an non-extraction normal occlusion sample. No detrimental effects were seen with regard to overjet or overbite. Neither did the figures for lower incisor position at the follow-up examination differ from that of the normal occlusion sample. Although tipping of adjacent teeth towards the extraction site was frequent, especially in the mandible, no effect on marginal bone height was evident as judged by comparison with a non-extraction control sample. The results reveal a significant capacity for spontaneous improvements with age in dental arch morphology and relationship in extraction cases, provided that specific features have been looked for in case selection.

Adolescent↗
PubMed1990

Residual lower first premolar extraction space.

Residual lower first premolar extraction space was examined in 43 subjects, 16 male and 27 female, 5 years after extraction; 16 subjects were treated mechanically, 27 had no active treatment. Forty per cent of extraction sites had residual spaces averaging 0.62 mm left and 0.71 mm right. Various parameters were measured to try to establish reasons for non-closure of spaces. These included buccal space condition and incisal space condition measured on the pre-extraction models, and alveolar atrophy assessed on final models. The angulation of second premolars and canine to the maxillary plane and molar space were measured on 60 degrees cephalograms. Changes in these three parameters were measured after superimposing a tracing of the pre-extraction film on the final film. Angulation of lower incisors to the maxillary plane was measured on pre-extraction 90 degrees cephalograms, and change in lower incisor angulation and position measured after superimposing a tracing on the final 90 degrees film.

Alveolar Process↗
PubMed1991

Class III malocclusion: a comparison of extraction and non-extraction techniques.

A retrospective cephalometric study was made of the hard tissue changes in a group of 90 Class III, Skeletal III children, diagnosed as suitable for treatment by orthodontic means alone. Thirty-two were treated by a combination of upper incisor proclination and headgear to an intact mandibular dentition (Group 1), while in 28 the overjet was corrected with mid-arch extractions and Edgewise mechanics (Group 2). The remaining 30 children acted as controls (Group 3). Children were initially examined as male and female subgroups, and where no significant differences were seen data were pooled. In order to standardize the results, treatment/observation effects were presented as average changes per year. The three groups were essentially comparable pretreatment. Following overjet correction, the lower incisors uprighted in both groups, with an improved relationship to the A-Po line: the upper incisors were proclined in Group 1 only. Underlying skeletal changes were restricted to the mandible, which showed a downward and backward hinging, and an increase in lower face height. The improved mandibular position was significantly greater in the non-extraction group and was accompanied by an improvement in facial convexity. In addition, treatment could be started earlier and was completed in a significantly shorter time (Table 1). It would, therefore, appear that, in the short term at least, a non-extraction/headgear approach has advantages over a standard mid-arch extraction/Edgewise technique.

Adolescent↗
PubMed1998

Mandibular changes in persons with untreated and treated Class II division 1 malocclusion.

The growth potential of individuals with Class II malocclusions is of interest to the practicing orthodontist because such malocclusions constitute a significant percentage of cases. The purpose of this study was to evaluate on cross-sectional and longitudinal bases the changes in mandibular length and relationship and maxillary-mandibular relationships in untreated Class II subjects from deciduous to permanent dentition and also to evaluate the effects of orthodontic treatment, with and without the extraction of first premolars, on these relationships. Class II samples were compared with matched normal, untreated individuals. The Class II division 1 (Class II/1) untreated sample comprised 30 subjects, 15 males and 15 females. Each subject had a complete set of data at three stages of dental development-namely, Stage I, after the completion of eruption of the deciduous dentition; Stage II, at the time when the permanent first molars and most of the incisors have erupted (i.e., in mixed dentition); and Stage III, at the completion of eruption of the permanent dentition, excluding third molars. The Class II treated sample comprised 44 subjects (21 males, 23 females) treated with four first-premolar extractions and 47 subjects (20 males, 27 females) treated without extraction. Treatment was accomplished with the use of an edgewise appliance, appropriate extraoral traction, and Class II elastics. The extraction decision was based mainly on the presence of crowding and profile consideration. Records on 35 normal subjects (20 males, 15 females) were available from the Iowa Longitudinal Facial Growth Study. Cephalograms for the normal individuals were matched to the corresponding ages of the Class II cases. With regard to these findings, few consistent differences were noted between the untreated Class II/1 and normal subjects on cross-sectional comparisons. The differences in mandibular length and position were more evident in the early stages of development than at later stages. Longitudinal comparisons of growth profiles indicated that the growth trends were essentially similar between the untreated Class II/1 and normal subjects in the various parameters compared. The comparisons of growth magnitude indicated the presence of greater skeletal facial convexity in the untreated Class II/1 subjects, accompanied by a tendency for a more retruded mandible. Initial comparisons between the Class II/1 treated groups and normal subjects indicated that the Class II/1 malocclusions were associated with a larger overjet, deeper overbite, and greater ANB angle. After a 5-year treatment and observation period, an overall "normalization" in the mandibular and maxillary-mandibular skeletal relationships was noted in the treated Class II/1 subjects in both the extraction and the nonextraction groups compared with normal subjects. The changes were more pronounced in the extraction group.

Adolescent↗
PubMed1997

The effect of premolar extractions on the soft-tissue profile in adult African American females.

The present study was designed to evaluate the effect of four first premolar extractions on the soft tissue profile in African American patients. Pretreatment and posttreatment cephalograms of 28 adult female patients were assessed. The data were subjected to ANOVA, and correlation coefficients were performed between the significantly different dental and soft tissue variables. Variables that showed correlation at r value of greater than 0.6 were subjected to a stepwise multiple regression. The results of the study indicate that retraction of the lower lip correlates with retraction of both maxillary and mandibular anterior teeth. A ratio of 1.2:1 [corrected] was obtained between mandibular incisor retraction and retraction of the lower lip. The relationship between the upper lip and retraction of maxillary incisors was not significant. A ratio of 1.75:1 [corrected] was attained between maxillary incisor retraction and upper lip change. The upper lip correlated most strongly with lower lip retraction. Mandibular incisor angulation was the only hard-tissue variable that could be used as a predictor in a regression model to explain lip response to orthodontic therapy. Changes in the maxillary complex were more difficult to predict because of the complex nature of the soft-tissue integument and the details of muscle tension and soft-tissue tone that were lost by conversion of a three-dimensional structure into a roentgenographic cephalogram. A significant profile change did occur following the extraction of four first premolars and subsequent orthodontic therapy.

Adolescent↗
PubMed2003

Unusual orthodontic retreatment.

This case report describes the retreatment of a patient with a Class II Division 1 malocclusion; she had the same anteroposterior discrepancy after undergoing fixed appliance treatment with extraction of 4 first premolars.

Adult↗
PubMed1977

[Indication and realization of orthodontic extraction therapy].

In establishing the indication for extraction therapy, careful consideration should be given to the unharmonious relationship of the jaw and teeth, the apical bone, the anlage of the wisdom teeth and hypodontia. Beginning with the narrow, contracted dental arch, where extractions are indicated most frequently, the different groups of anomalies are discussed. The most important rules and the optimal time are dealt with at the end of the present review article.

Humans↗