Effects of extraction and nonextraction treatment on class I and class II subjects

This study aims to examine the profile as well as the dentoalveolar and skeletal effects of extraction or nonextraction treatment in a wide range of patients including Class I and Class II, division 1 cases. Results achieved with extraction and nonextraction modalities have also been compared. The study was performed on pretreatment and posttreatment lateral cephalograms of 87 orthodontic patients. There were no significant differences between the pretreatment values of extraction and nonextraction Class I groups, whereas SN-GoGn (degrees), maxillary incisor to A-Po (degrees), mandibular incisor to A-Po (mm), Co-Gn (mm), overjet (mm), and overbite (mm) measurements of extraction Class II group were significantly higher before the treatment. After treatment, these differences were eliminated in the Class II group; however, incisors were significantly protruded in both nonextraction groups. No other differences in profile or lip position were found between the extraction and nonextraction groups. The results of this study indicate that in successfully treated cases, whether by extraction or nonextraction, the same soft and hard tissue profile posttreatment end points were reached except for the incisor positioning, which is rather easier to anticipate than profile and soft tissue changes. The simple statement that extraction means a more retrusive or dished-in profile seems to be unacceptable. It seems that a more thorough assessment and investigation including pretreatment extent of crowding and factors related to anchorage, soft tissue thickness, and strain should be carried out.     

Influence of extraction and nonextraction orthodontic treatment in Japanese-Brazilians with class I and class II division 1 malocclusions.

BACKGROUND: The primary objective of this retrospective, longitudinal, cephalometric investigation was to study the influence of extraction and nonextraction orthodontic treatment on the facial height of Japanese-Brazilian children with Class I and Class II Division 1 malocclusions. METHODS: The sample included 59 mesocephalic patients distributed into 4 groups: group 1: Class I patients treated with 4 first premolar extractions; group 2: Class I patients treated nonextraction; group 3: Class II Division 1 patients treated with 4 first premolar extractions; group 4: Class II Division 1 patients treated nonextraction. The overall initial mean age of the groups was 12.14 years, and all groups were treated with standard edgewise appliances for a mean period of 2.49 years. The pretreatment and posttreatment stage comparison and the intergroup comparison of the treatment changes were conducted between extraction and nonextraction groups in the Class I and Class II malocclusion samples with t tests. RESULTS: The amounts of changes in the absolute magnitude of posterior and anterior facial heights and in the ratios of lower posterior facial height/lower anterior facial height and lower anterior facial height/total anterior facial height were similar between extraction and nonextraction treatment in both Class I and Class II malocclusions.     

A long-term comparison of nonextraction and premolar extraction edgewise therapy in "borderline" Class II patients.

The long-term effects of extraction and nonextraction edgewise treatments were compared in 63 patients with Class II, Division 1 malocclusions who were identified by discriminant analysis as being equally susceptible to the two strategies. A lateral cephalogram, study models, and a self-evaluation of the esthetic impact of treatment were obtained from each of the 33 extraction and 30 nonextraction subjects. The average posttreatment interval was 14.5 years. Although the two strategies produced significant, long-lived differences in the convexity of the profile and the protrusion of the dentition (the nonextraction patients were about 2 mm "fuller"), half of the nonextraction patients and three fourths of the extraction patients ultimately presented with less than 3.5 mm of lower incisor irregularity. The two groups showed an essentially identical pattern of posttreatment relapse/settling that was related more to the differential growth of the jaws than to the posttreatment position and orientation of the denture. Because in the end the various tooth movements tended to cancel one another, excess mandibular growth was also the most important net contributor to the molar and overjet corrections. In the process, both groups showed a marked forward displacement of the mandible, both at the chin and at the condyle. Finally, although it is probable that most of the present sample would today be treated by expansion, the 30 patients who actually received this presumably correct treatment rated their appearance no more highly than did the extraction subjects.(ABSTRACT TRUNCATED AT 250 WORDS)     

Prospective study of posttreatment changes in the temporomandibular joint.

The purpose of this follow-up prospective longitudinal study was to determine what changes occurred in the condyle/fossa relationship after treatment. Orthodontic posttreatment records, including corrected tomograms of 106 white patients (58 Class I and 48 Class II Division 1), from a pretreatment sample of 232 patients, were analyzed. The average pretreatment age was 13.6 +/- 3.0 years. The average length of treatment was 2.3 +/- 0.6 years for the Class I group and 2.8 +/- 0.9 years for the Class II Division 1 group. With orthodontic treatment, the condyle became more concentrically positioned, and a significant (P <.05) decrease in left and right anterior, posterior, and superior joint spaces was observed in most subjects. There was no statistically significant correlation between changes in the condyle/fossa relationship based on age, gender, skeletal or dental variables, signs or symptoms of temporomandibular disorder, headgear use, type of elastics, or nonextraction vs extraction treatment.     

Mandibular growth direction with conventional class II nonextraction treatment

The purposes of this study were (1) to compare the direction of mandibular growth (MGD) during treatment and retention for a group of treated Class II patients with untreated controls, and (2) to investigate the relationship between the MGD during treatment and the pretreatment skeletal structure. Pretreatment, posttreatment, and 2 years posttreatment lateral cephalograms of 26 Class II, Division 1 subjects who were treated "nonextraction" with low- or straight-pull headgears were compared with an untreated control group of 15 subjects. Mandibular growth direction was interpreted as the movement of the point gnathion relative to the S-N line when successive tracings were superimposed on the S-N line at S. On average, MGD appeared more vertical during treatment. Posttreatment MGD was generally more horizontal than that during treatment but was also extremely variable. Three of the pretreatment skeletal measures studied, especially the articular angle (SArGo), were significantly related to MGD during treatment. The inclination of the mandibular ramus is apparently an important indicator of how mandibular growth will respond to Class II treatment mechanics.     

The esthetic impact of extraction and nonextraction treatments on Caucasian patients

This investigation was designed to compare the esthetic effects of extraction and nonextraction treatments. Panels of 58 laypersons and 42 dentists evaluated randomly presented pre- and posttreatment profiles of 70 extraction and 50 nonextraction Class I and II Caucasian patients. The samples were similar at the outset; however, at the end of treatment, the extraction patients' faces were, on average, 1.8 mm "flatter" than the faces of nonextraction subjects. The flatter faces were preferred by both panels, dentists more so than laypersons. In general, nonextraction treatment was seen as having little effect on the profile, whereas the perceived effect of extraction treatment was a statistically significant function of initial soft tissue protrusion-the greater the initial protrusion, the greater the benefit. The point at which a reduction in protrusion produces a perceived improvement was explored by way of regression analysis. Both panels saw extraction as being potentially beneficial when the lips were more protrusive than 2 to 3 mm behind Ricketts' E-plane. It is concluded that extraction treatment can produce improved facial esthetics for many patients who present with some combination of crowding and protrusion.     

Treatment outcomes of growing Class II Division 1 patients with varying degrees of anteroposterior and vertical dysplasias, Part 2. Profile silhouette evaluation.

The purpose of this study was to evaluate pretreatment and posttreatment soft tissue profiles of 4 groups of growing Class II Division 1 patients treated with fixed orthodontic appliances and headgear. One hundred patients were grouped according to the severity of their initial retrognathia and vertical skeletal status. Standardized pretreatment and posttreatment profile silhouettes of each patient were randomized and projected for scoring by panels of lay persons and orthodontic residents. Statistical analysis consisting of nonparametric procedures showed that (1) as the initial skeletal discrepancies between the 4 groups worsened, the initial profiles were judged to be more unattractive (P <.001); (2) there was no perceived difference in the final profiles between the 4 groups; and (3) significantly greater improvement was measured for those with greater initial skeletal discrepancies (P <.05). This study demonstrated that, with appropriate and timely treatment with fixed orthodontic appliances and headgear, growing Class II Division 1 patients can undergo significant profile improvement, and, on average, even those more severely affected can achieve profile improvement so that they can be judged as attractive as those initially less severely affected.     

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.(Am J Orthod Dentofacial Orthop 1998;113:661-73)     

Cephalometric markers to consider in the treatment of class II division 1 malocclusion with the bionator

The principal aims of this study were to find the cephalometric predictors for good treatment results of bionator therapy and to justify bionator therapy as an early phase I treatment for patients with Class II Division 1 malocclusion. Forty subjects who had Class II Division 1 malocclusion and who were treated with the bionator were selected for this study. They were classified into a good treatment result group and a poor treatment result group in reference to the posttreatment molar relationship, posttreatment overbite and overjet, posttreatment profile, and existence of relapse. Thirty-one cephalometric variables were analyzed on the pretreatment lateral cephalograms by t-test to evaluate differences between the 2 groups. The variables that differed significantly were analyzed by discriminant analysis to assess their predictability. The study showed that horizontal growth pattern, close to normal anteroposterior relationship between the maxilla and mandible, upright mandibular incisor, and retrusive lower lip were important predictors for good results. In particular, protrusion of the lower lip was the most important factor for the determination of the treatment results. In addition, the treatment times were much shorter for patients with these good predictors. The present study supports the premise that bionator therapy can produce clinically stable and favorable results if the patients are appropriately selected with the use of these diagnostic criteria.     

Predictors for Class II treatment duration.

BACKGROUND: The purpose of this study was to identify clinical factors that predict treatment length for patients with Class II malocclusions. METHODS: A sample of 237 active retention patients representing 3 observational groups (Angle Class I nonextraction, and Class II Division 1 extraction and nonextraction), based on specific selection criteria, was obtained from 3 private offices. From the patient records, data were collected in these categories: (1) patient information, (2) model information, (3) pretreatment cephalogram information, and (4) treatment information. Two regression analyses were completed, with total treatment time as the dependent variable for both models. RESULTS: The first regression analysis (Class I and Class II patients) indicated significant predictors for the patient, model, and cephalometric variables. These predictors included age, pretreatment overjet, and pretreatment ANB angle. The second regression analysis (Class II treatment variables) identified the following factors as significantly associated with treatment length: (1) type of Class II appliance, (2) number of months of Class II appliance wear, (3) number of months of interarch elastic wear, (4) maxillary expansion, (5) number of debonds, and (6) average time (weeks) between appointments. CONCLUSIONS: Six variables explained 56.7% of the variation in Class II treatment length. Further research is required to help explain more of the variance associated with treatment duration.     

The effect of first premolar extraction on vertical dimension.

The purpose of this study was to evaluate the vertical changes occurring in Class I patients treated orthodontically with first premolar extraction and to compare these changes with those occurring in Class I patients treated orthodontically without extractions. Records of 40 Class I nonextraction cases (24 girls, 16 boys) and 40 Class I maxillary and mandibular first premolar extraction cases (23 girls, 17 boys) were obtained. The pretreatment and posttreatment cephalograms were digitized, and 6 linear and 8 angular cephalometric measurements were selected to evaluate vertical changes. Evaluation of the treatment results of the extraction and nonextraction cases showed that the vertical changes occurring after the extraction of maxillary and mandibular first premolars were not different than those occurring in the nonextraction cases.     

Long-term profile changes in extraction and nonextraction patients.

INTRODUCTION: The purpose of this investigation was to determine the long-term differences in soft tissue profile changes between extraction and nonextraction patients who had been treated to the same incisor position and lip line. METHODS: Twenty extraction and 20 matched nonextraction patients, with posttreatment and long-term follow-up (average 15 years) records, were selected from a single private orthodontic practice. Posttreatment and long-term follow-up profile photos of the patients' nose, lip, and chin areas were evaluated by 105 orthodontists and 225 laypeople, who indicated their preferences and the amount of change they perceived among the 40 profiles. The patients had similar dental protrusion, soft tissue profile measurements, and ages at the posttreatment observation. RESULTS: No significant cephalometric differences between the extraction and nonextraction groups were found at long-term follow-up; both groups showed similar long-term changes. Significant (P < .05) differences were found between males and females at long-term follow-up; male lips became relatively more retrusive, and their profiles became flatter. Significant (P < .05) changes in the profiles were also perceived over time, but there was no relationship between the amount of change perceived and profile changes measured cephalometrically. There were also no significant (P < .05) differences in preferences between orthodontists and laypeople, between extraction and nonextraction patients, or between males and females. CONCLUSIONS: If extraction and nonextraction patients are treated to the same incisor position and lip line, the treatment modality does not affect long-term soft tissue profile changes. Furthermore, the amounts of change perceived by either orthodontists or laypeople were not related to the amount of change measured cephalometrically.     

Cephalometric comparison of maxillary second molar extraction and nonextraction treatments in patients with Class II malocclusions

This retrospective cephalometric study compared the nature of the skeletodental correction of maxillary second-molar extraction and nonextraction treatments in correcting Class II malocclusions. The sample comprised 50 Class II, deep-bite, low-angle adolescents; half were treated with maxillary second-molar extraction and half were treated without extraction. Pretreatment and posttreatment lateral cephalograms were analyzed. Analysis relied primarily on the method of Lysle Johnston that evaluates sagittal changes in the teeth and supporting bones relative to the functional occlusal plane. All 18 cephalometric variables examined were statistically equivalent between the 2 groups at the start of treatment. In contrast, several skeletodental treatment changes differed significantly. The maxillary second-molar extraction group exhibited distal movement of the maxillary first molar (1.2 mm vs 0.0 mm), and there was greater flaring of the mandibular incisors in the nonextraction group (9.1 degrees vs 3.5 degrees ). The upper incisor root was torqued lingually in both groups, but there was more anterior crown movement in the nonextraction group (2.0 mm vs 0.0 mm). Also, the extraction group finished active treatment 7 months sooner on average. Sagittal molar correction in the maxillary second-molar group was a result of distalizing in the maxillary arch, whereas anchorage was expended in the mandibular arch to correct the malocclusion in the nonextraction group. In properly selected Class II malocclusions, maxillary second-molar extraction is a viable alternative treatment choice.     

Cephalometric changes associated with treatment using the activator, the Fr?nkel appliance, and the fixed appliance

Treatment with the activator, the Fr?nkel appliance, and the edgewise appliance was compared in three separate groups; each group consisted of twenty-five nonextraction cases of Class II, Division 1 malocclusion. Hard- and soft-tissue profile changes caused by growth and treatment were assessed by means of pretreatment and posttreatment lateral cephalograms. Anterior movement of A point was 1.6 mm more in the activator group than in the fixed-appliance group. The most anterior point on the maxillary incisor moved 1.5 mm more distally in the fixed-appliance sample than in the functional groups. Among the three groups, the activator sample showed the most anterior movement of the mandible (2.3 mm); the fixed group showed the least (0.6 mm). The fixed-appliance group showed more posterior rotation of the mandible than the activator group. However, relative to cranial base, the movement of the mandibular symphysis was not statistically different in the three groups. There were little differences among the treatment groups with regard to changes in the soft-tissue profile. In clinical terms, there was a remarkable similarity in the changes that occurred in the three treatment groups.     

A comparative cephalometric study of Class II, Division 1 nonextraction and extraction cases.

1. Cephalometric tracings of thirty Class II, Division 1 cases without extraction and twenty-five Class II, Division 1 cases with extraction were evaluated and statistically compared by means of the overbite depth indicator (ODI) and the anteroposterior dysplasia indicator (APDI). 2. The mean ODI in the nonextraction group, in particular, was significantly higher than that of the extraction group. 3. Three clinical examples were presented to demonstrate the values of ODI and APDI as adjuncts to cephalometric differential diagnosis. 4. With respect to the vertical component it may be concluded that the lower the ODI value from the normal mean a case presents, the greater the incidence of an extraction procedure as a compromise for the poor skeletal pattern. 5.With respect to the horizontal component the initial APDI reading indicates the severity of skeletal discrepancy. When the posttreatment APDI reading falls below the normal mean, a relapse is probable: the lower the figure a case possesses, the greater the chance of relapse. In such incidences an extraction procedure must be provided to ensure the stability of occlusion.     

The relationship between the curve of spee,relapse, and the Alexander discipline

Exaggerated curves of Spee are frequently observed in dental malocclusionsthat present with deep vertical overbites. During orthodontic treatment such excessive curves of Spee are usually leveled and, in most instances, this leveling will result in a reduction of the anterior overbite. The Alexander Discipline provides a good example of modern straight-wire orthodontic techniques that purport an ability to treat abnormal variations in the depth of the occlusal plane. The records of 31 randomly selected patients treated by nonextraction with the Alexander Discipline were studied. The results show that the Alexander Discipline levels the curve of Spee in Class II, Division I deep-bite cases and that when relapse occurs, the curve of Spee returns to a lesser extent than was present before orthodontic treatment. With the Alexander Discipline, a pretreatment curve of Spee that is not completely level posttreatment has a slightly higher incidence and magnitude of relapse than a pretreatment curve of Spee that is completely level posttreatment. This study indicated that, based on the pretreatment curve of Spee, there is no ability to predict relapse in mandibular intercanine width, overbite, overjet, mandibular incisor irregularity, and arch length in Class II, Division I deep-bite cases treated with the Alexander Discipline.     

Maxillary anterior alignment stability in Class I and Class II malocclusions treated with or without extraction

Objective:To compare the postretention stability of maxillary incisors alignment in subjects with Class I and II malocclusion treated with or without extractions.Materials and Methods:The sample comprised 103 subjects with initial maxillary anterior irregularity greater than 3 mm and was divided into four groups: group 1 comprised 19 patients with Class I malocclusion treated with nonextraction (mean initial age = 13.06 years); group 2 comprised 19 patients with Class II malocclusion treated with nonextraction (mean initial age = 12.54 years); group 3 comprised 30 patients with Class I malocclusion treated with extractions (mean initial age = 13.16 years); group 4 comprised 35 patients with Class II malocclusion treated with extractions (mean initial age = 12.99 years). Dental casts were obtained at three different stages: pretreatment (T1), posttreatment (T2), and long-term posttreatment (T3). Maxillary incisor irregularity and arch dimensions were evaluated. Intergroup comparisons were performed by one-way analysis of variance followed by Tukey tests.Results:In the long-term posttreatment period, relapse of maxillary crowding and arch dimensions was similar in all groups.Conclusion:Changes in maxillary anterior alignment in Class I and Class II malocclusions treated with nonextractions and with extractions were similar in the long-term posttreatment period.     

Unbiased quantitative testingof conventional orthodontic beliefs

This study used a preexisting database to test in hypothesis form the appropriateness of some common orthodontic beliefs concerning upper first molar displacement and changes in facial morphology associated with conventional full bonded/banded treatment in growing subjects. In an initial pass, the author used data from a stratified random sample of 48 subjects drawn retrospectively from the practice of a single, experienced orthodontist. This sample consisted of 4 subgroups of 12 subjects each: Class I nonextraction, Class I extraction, Class II nonextraction, and Class II extraction. The findings indicate that, relative to the facial profile, chin point did not, on average, displace anteriorly during treatment, either overall or in any subgroup. Relative to the facial profile, Point A became significantly less prominent during treatment, both overall and in each subgroup. The best estimate of the mean displacement of the upper molar cusp relative to superimposition on Anterior Cranial Base was in the mesial direction in each of the four subgroups. In only one extraction subject out of 24 did the cusp appear to be displaced distally. Mesial molar cusp displacement was significantly greater in the Class II extraction subgroup than in the Class 11 nonextraction subgroup. Relative to superimposition on anatomical “best fit” of maxillary structures, the findings for molar cusp displacement were similar, but even more dramatic. Mean mesial migration was highly significant in both the Class II nonextraction and Class II extraction subgroups. In no subject in the entire sample was distal displacement noted relative to this superimposition. Mean increase in anterior Total Face Height was significantly greater in the Class II extraction subgroup than in the Class II nonextraction subgroup. (This finding was contrary to the author's original expectation.) The genera lizability of the findings from the initial pass to other treated growing subjects was then assessed by retesting modified hypotheses against a second database stored sample that earlier had been drawn randomly from two other orthodontic practices. The implications of the author's study strategy to the design of future shared digital databases is discussed briefly.     

Arch width changes in extraction and nonextraction treatment in class I patients

The aim of this retrospective study was to examine the dental arch width changes of extraction and nonextraction treatment in Class I patients. The study was performed on pretreatment and posttreatment dental casts of 60 patients (30 extraction and 30 nonextraction). The mean ages were 14.3 +/- 2.02 years for the extraction group and 14.1 +/- 2.9 years for the nonextraction group. The maxillary and mandibular crowding was -6.7 +/- 3.1 and -6.3 +/- 2.8 mm for the extraction group and -4.5 +/- 3.6 and -2.1 +/- 3.5 mm for the nonextraction group, respectively. The intercanine and intermolar arch width measurements were measured using a digital caliper. Paired samples t-test was used to evaluate the treatment changes within each group. To compare the changes between groups, independent samples t-test was performed. At the start of treatment, the maxillary and the mandibular intercanine and intermolar widths of both groups did not differ statistically. At the end of treatment, maxillary and mandibular intercanine widths of both groups increased significantly. The mandibular intermolar width decreased significantly for the extraction group and the maxillary intermolar width increased significantly for the nonextraction group. The decrease in maxillary intermolar width for the extraction group and the increase in mandibular intermolar width for the nonextraction group were not significantly different. No differences were observed between the groups in maxillary and mandibular intercanine widths. Maxillary and mandibular intermolar width indicated a significantly larger value in the nonextraction group than that in the extraction group.     

Class II non-extraction patients treated with the Forsus Fatigue Resistant Device versus intermaxillary elastics

OBJECTIVE: To evaluate the Forsus Fatigue Resistant Device (FRD) as a compliance-free alternative to Class II elastics. MATERIALS AND METHODS: A sample of 34 (14 female, 20 male) consecutively treated nonextraction FRD patients (12.6 years of age) were matched with a sample of 34 (14 female, 20 male) consecutively treated nonextraction Class II elastics patients (12.2 years of age) based on four pretreatment variables (ANB, L1-GoMe, SN-GoMe, and treatment duration). Pretreatment and posttreatment cephalometric radiographs were traced and analyzed using the pitchfork analysis and a vertical cephalometric analysis. t-Tests were used to evaluate group differences. Group differences were evaluated using t-tests. RESULTS: No statistically significant differences were found in the treatment changes between the groups. There was a general trend for mesial movement of the maxilla, mandible, and dentition during treatment for both groups. The mandibular skeletal advancement and dental movements were greater than those in the maxilla, which accounted for the Class II correction. Lower incisor proclination was evident in both groups. Vertically, the maxillary and mandibular molars erupted during treatment in both groups, while lower incisors proclined. With the exception of lower molar mesial movements and total molar correction, which were significantly (P < .05) greater in the Forsus group, there were no statistically significant group differences in the treatment changes. CONCLUSIONS: The Forsus FRD is an acceptable substitute for Class II elastics for noncompliant patients.