Serial Cephalometric Radiographs Research Articles

Cephalometric superimposition in orthodontics-A review

Superimposition is a method where serial cephalometric radiographs or tracings are taken for the same patient at different time intervals that is before, during and after treatment and superimposed on the biologically defined plane or surface to study changes in jaw and tooth positions respectively as a result from growth, treatment or a combination of two. With the progress of the orthodontic treatment as well as growth, detailed follow-up is important to monitor the changes from the treatment mechanics applied in order to enhance the dental and jaw function and dentofacial esthetics of an individual. The article aims at presenting a comprehensive review on the various methods of superimposition for proper evaluation of changes occurring in an individual following growth and treatment.

Reliability of cephalometric superimposition for the assessment of craniofacial changes: a systematic review.

Superimposition of serial cephalometric radiographs enables the assessment of craniofacial changes over time, and therefore, several methods have been suggested in the literature. The aim of the present study is to summarize and critically evaluate the available evidence on the reliability of methods used to superimpose serial cephalometric radiographs. Electronic searches were performed in MEDLINE, EMBASE, Google Scholar, and Cochrane Databases, without time limit (last update: 1 November 2020). Unpublished literature was searched on the Open Grey and Grey Literature Report databases. Studies that tested the accuracy, precision, or agreement between different cephalometric superimposition techniques, used to evaluate the craniofacial changes due treatment or growth. Reference lists of relevant articles were screened and authors were contacted, if needed. All study selection steps, data extraction, and risk of bias (QUADAS-2 tool) assessments were performed independently by two authors on predefined forms. There were 27 eligible studies. From these, 17 tested superimpositions methods on the anterior cranial base, 10 on the maxilla and 12 on the mandible. There were three studies that compared superimpositions on the cranial base with those on the maxilla and one that compared the cranial base with the mandibular superimposition. There was high heterogeneity among studies in terms of sample size, growth, radiographic machines, selection criteria, superimposition methods, references, and outcomes measured. Furthermore, almost all studies presented important methodological limitations, with only two studies having unclear risk of bias and the rest 25 presenting high risk. Currently, there is no cephalometric superimposition method that has been proved to deliver accurate results. There is an urgent need for further research in this topic, since this is a primary assessment method to assess craniofacial changes over time for several relevant disciplines. PROSPERO (CRD42020200349).

Skeletal stability of surgery-first bimaxillary orthognathic surgery for skeletal class III malocclusion, using standardized criteria

The purpose of this study was to compare the postoperative stability following bimaxillary surgery performed either with or without preoperative orthodontic treatment, in class III malocclusion patients. These patients were enrolled using standardized inclusion criteria. Forty patients with a class III malocclusion were included in this retrospective study. Inclusion criteria were class III malocclusion with and without premolar extraction, <3mm midline deviation, and <5mm arch width discordance. Patients were assigned to the conventional bimaxillary surgery group (n=20) or the surgery-first bimaxillary surgery group (n=20). Serial cephalometric radiographs obtained before surgery (T0), at 2 months after surgery (T1), and at 6 months after surgery (T2) were used to assess the variation in surgical change (T0 to T1) and postsurgical change (T1 to T2). Eight linear and three angular parameters were used to evaluate postoperative stability. With respect to postsurgical changes, significant differences were observed in the changes for the vertical reference plane to the posterior nasal spine, horizontal reference plane to B-point, and occlusal plane angle in both groups. No statistically significant differences in the relapse rates were observed between the two groups. No significant differences were observed between the two groups in terms of the postoperative stability.

Natural reference structures in the human maxilla: a systematic search in children with tantalum implants.

The aim of the study was to locate stable natural reference structures (NRS) in the maxilla as seen on lateral cephalometric radiographs. Retrospective radiographic analysis. Paired serial lateral cephalometric radiographs of 27 children (aged 7·1-13·5 years at the initial radiograph and a mean interval of 3·9 years between radiographs) with a minimum of three Björk-type tantalum implant markers in the left maxilla were examined for the presence of NRS. The pairs of radiographs were converted to digital image format, superimposed and registered using stable implants. Potential NRS were located by visual examination of the superimposed images and tested for morphological and spatial stability using automated computer-based analysis employing cross-correlation. NRS were detected in 24 of the 27 subjects (median: 4; range: 1-9 NRS). The number of NRS was statistically significantly negatively correlated with the interval between the radiographs (rrank = -0·422; P = 0·03), but not significantly correlated with the age at the initial radiograph (rrank = 0·23; P = 0·26). Those NRS found above the nasal floor were both morphologically and spatially stable over periods of several years. The most conspicuous of these were the mid-portion of the anterior contour of the zygomatic process beyond 9 years of age and the junction of the corticated walls of the infra-orbital canal with the internal surface of the maxilla. This study has demonstrated the existence of several NRS visible on the lateral cephalometric image of the maxillae. The most prominent NRS should be sufficient in most cases to permit accurate orientation of serial cephalometric radiographs.

Skeletal and Dental Variables Related to the Stability of Orthognathic Surgery in Skeletal Class III Malocclusion With a Surgery-First Approach

The objectives of the study were to identify the parameters related to skeletal stability after orthognathic surgery in skeletal Class III malocclusion using a surgery-first approach and to analyze the factors correlated with surgical relapse. Forty-five consecutive patients were included. Serial cephalometric radiographs were traced and superimposed to investigate surgical stability at the initial examination, 1 week postoperatively, and after orthodontic debonding (12.22 mo after surgery). Patient grouping was based on the amount of horizontal relapse at the innermost point of the contour of the mandible between the incisor tooth and the bony chin, the B point (less stable group, n = 15; highly stable group, n = 18). Parameters, such as presurgical skeletal and dental variables, the amount of surgical setback, and total treatment duration, were compared between groups and analyzed for correlations with surgical stability. The mean setback at the innermost point of the contour of the mandible between the incisor tooth and the bony chin was 11.19 mm, and the mean relapse rate was 12.46%. The amount of surgical setback, overbite (positive values), overjet, depth of the curve of Spee, and lower anterior facial height showed statistically significant differences between groups. The amount of surgical setback, overbite (positive values), overjet, and depth of the curve of Spee showed statistically significant correlations with the amount of relapse. Skeletal relapse of the mandible increased significantly as the overbite increased. The factors for instability in the surgery-first approach include a larger overbite, a deeper curve of Spee, a greater negative overjet, and a greater mandibular setback. The initial overbite may be an indicator to predict possible skeletal relapse of mandibular setback.

Longitudinal posteroanterior changes in transverse and vertical craniofacial structures between 10 and 14 years of age.

Longitudinal growth changes in the transverse and vertical craniofacial dimensions occurring between 10 and 14 years of age were evaluated in 22 female and 23 male subjects. All subjects were healthy, had a clinically acceptable occlusion, and had not received orthodontic or orthopedic therapy before. Serial cephalometric radiographs were taken at ages 10, 11, 12, and 14 years. In studying the P-A cephalograms, seven transverse and five vertical measurements were used. The effects of age and sex on the transverse and vertical growth of the craniofacial structures were investigated by means of analysis of variance and Bonferroni multiple comparison test. The results of the study revealed that all measurements studied were affected by age, and cranial, facial, nasal, and maxillary widths were affected by sex. The most pronounced age-related increases occurred in the mandibular width for transverse measurements and in the total facial height for vertical measurements in both sexes during this study.

Comparison of hand-traced and computerized cephalograms: Landmark identification, measurement, and superimposition accuracy

The purposes of this study were (1) to investigate the variations of landmark identification between film and digital cephalometric tracings, (2) to compare the ability of Quick Ceph 2000 (Quick Ceph Systems, Inc, San Diego, Calif) to measure the linear and angular measurements with the hand-traced method, and (3) to compare Quick Ceph 2000 superimpositions to the hand-traced method of superimpositions that are currently accepted by the American Board of Orthodontics (ABO). We used 30 sets of serial cephalometric radiographs of growing patients from 1 orthodontic office. Fiduciary x- and y-axes were drawn in pencil on the T1 radiographs in the regions of the cranial base, the maxilla, and the mandible. The fiduciary lines were transferred to the digital and film serial cephalograms by regionally superimposing the tracings as described in the ABO Phase III examination handbook. A Mann-Whitney test was done to compare the median and Delta of the T1 and T2 values for each measurement acquired by hand and by Quick Ceph. There was no difference in the identification of cephalometric landmarks made manually vs digitally with Quick Ceph 2000. There was no difference in acquiring consistent cephalometric values for the measurements required by the ABO for the Phase III clinical examination manually vs digitally by using Quick Ceph 2000. There was no difference in the regional superimpositions of the mandible, the maxilla, and the cranial base, manually vs digitally with Quick Ceph 2000.

Long-term outcome of surgical Class III correction as a function of age at surgery

In this study, we assessed whether the likelihood of a positive overjet 5 to 10 years after Class III surgery was affected by age at the surgery or the type of surgery and evaluated the amount and pattern of postsurgical growth. Cephalometric measurements including overjet were evaluated from immediately postsurgery and long-term recall cephalograms of 104 patients who had had surgical Class III correction and at least 5-year recalls. The patients were classified as younger (<age 18 years for females at the surgery or 20 years for males) or older and by type of surgery (maxilla only vs mandibular only or 2 jaw). For the younger patients, the timing of treatment was based largely on serial cephalometric radiographs that eventually showed minimal or no mandibular growth. Long-term changes in overjet and other cephalometric characteristics in the younger and the older patients were similar. No patients in the sample had negative overjet in the long term, but zero overjet (<1 mm) was observed in some patients in all groups. Patients who had mandibular setback at any age were 2.6 times more likely to have zero overjet in the long term (P = .003) than those with maxillary surgery alone. For the younger patients, the likelihood of zero overjet in the long term was not significantly different from patients who were treated later (P = .87), with or without mandibular surgery. The data support the use of serial cephalometric radiographs, with surgery deferred until little or no mandibular growth is observed, to determine the timing of Class III surgery in younger patients.

Longitudinal Study of Untreated Skeletal Class I Subject's Growth and Development with Mc Namara Cephalometric Analysis

ABSTRACTThis study evaluated longitudinal craniofacial changes in 14 female and 14 male Turkish subjects between 9 and 18 years of age who had not undergone orthodontic or orthopedic treatment. All of the subjects had a skeletal and dental Class I relationship. Serial cephalometric radiographs were taken at ages 9, 14, and 18 years. The effects of age and sex on the sagittal and vertical growth of the craniofacial structures were investigated using analysis of variance (repeated measures ANOVA) and the Tukey HSD test. We observed remarkable mandibular growth augmentation from 9 to 18 years in both sexes, and the effective mandibular length changes were nearly double the maxillary length changes. In both sexes, the mandibular plane angle decreased, while the lower anterior face height increased. Angles SNA and SNB increased remarkably, and angle ANB decreased. Our findings revealed that craniofacial alterations are affected by age, the dimensions Co-A and Co-Gn, angle SNB, and the nasolabial angle, and the differences were statistically significant in both sexes. In conclusion; The growth change between T1 and T2 was greater than that between T2 and T3 and generally, the mean values in males were greater than those in females.

Early Timely Treatment of Class III Malocclusion

The protraction facemask has been widely used in the treatment of Class III malocclusion with maxillary deficiencies. However, the benefit of this early treatment modality is not clear. One of the reasons orthodontists are reluctant to render early orthopedic treatment in Class III patients is the inability to predict mandibular growth. The use of a single cephalometric radiograph to predict excessive mandibular growth has severe limitations. The use of serial cephalometric radiographs taken a few years after facemask treatment, and a Growth Treatment Response Vector (GTRV) analysis to individualize and enhance the accuracy in predicting excessive mandibular growth, is presented and proposed. This article discusses the rationale for early timely treatment of Class III malocclusion, the indications and contraindications for early Class III treatment, and provides a method of predicting excessive mandibular growth using the GTRV analysis.

Professor B. C. Leighton

Professor Barry Leighton, who was born on 29th August 1920, died in Addenbrooke’s Hospital, Cambridge, in the early hours of Sunday, 20th October 2002, after a long period of physical incapacity. He qualified in 1943 at King’s College Hospital, London, where he also met his future wife, Diana, who was nursing. Some of his early work was carried out in Birmingham with Humphries and continued when he returned to King’s—where he undertook his massive research projects in longtitudinal studies. These constitute the only study of the kind in the British Isles including serial cephalometric radiographs, and are probably unlikely to be repeated. He came to be head of Orthodontics at King’s and in 1968 was appointed Professor of Orthodontics in the University of London. Many will have passed through his hands as students and many others will have known him through his works and societies. In 1954 in conjunction with Professor Tom White of Glasgow and Jim Gardiner of Sheffield he produced the first much needed textbook to be published in Britain on orthodontics for dental students. This has maintained its popularity and it is now also used in India. Previously orthodontics had only been included in major texts as just another part of the practice of dentistry. Barry always had an interest in history and published papers on the early history of the British Society for the Study of Orthodontics (BSSO). Since the mid 90s he also produced the original drafts for many chapters in the recently published history of the British orthodontic societies. He was intimately associated with the BSSO and served on the Council, becoming Secretary and President and eventually an Honorary Member and the recipient of the Special Service Award. More recently he was President of the British Orthodontic Society. He was also a long time member of the European Orthodontic Society and maintained close contact with many members, particularly the members of the AngloScandinavian Orthodontic Study Circle. He was awarded an Honorary Doctorate of the Karolinska Institute in Stockholm which he valued greatly. The abiding memory of Barry is of a modest, quiet, gentle man with total integrity who was always ready to help colleagues. However, you would be unwise if you presumed, for there was a steadfast will and constancy below the surface, coupled with a wry sense of humour, a gentle smile and sparkling eyes. We extend our sincere sympathy to his widow Di and to his children and grandchildren. Alan C. Campbell Journal of Orthodontics, Vol. 30, 2003, 97

Dynamic cranioplasty for brachycephaly in apert syndrome: long-term follow-up study.

Brachycephaly is a characteristic feature of Apert syndrome. Traditional techniques of cranioplasty often fail to produce an acceptable morphological outcome in patients with this condition. In 1996 a new surgical procedure called "dynamic cranioplasty for brachycephaly" (DCB) was reported. The purpose of the present study was to analyze perioperative data and morphological long-term results in patients with the cranial vault deformity of Apert syndrome who were treated with DCB. Twelve patients have undergone surgery performed using this technique since its introduction in 1991 (mean duration of follow-up review 60.2 months). Eleven patients had bicoronal synostosis and one had a combined bicoronal-bilambdoid synostosis. Perioperative data and long-term evolution of skull shape visualized on serial cephalometric radiographs were analyzed and compared with normative data. Changes in mean skull proportions were evaluated using a two-tailed paired-samples t-test, with differences being considered significant for probability values less than 0.01. The mean operative blood transfusion was 136% of estimated red cell mass (ERCM) and the mean postoperative transfusion was 48% of ERCM. The mean operative time was 218 minutes. The duration of stay in the intensive care unit averaged 1.7 days and the mean hospital stay was 11.8 days. There were no incidences of mortality and few complications. An improvement in skull shape was achieved in all cases, with a change in the mean cephalic index from a preoperative value of 90 to a postoperative value of 78 (p = 0.000254). Dynamic cranioplasty for brachycephaly is a safe procedure, yielding high-quality morphological results in the treatment of brachycephaly in patients with Apert syndrome.

Facial Growth in Adulthood after Primary Periosteoplasty or Primary Bone Grafting in UCLP

Abstract Objective: The primary research aim of this study was to compare long-term differences in craniofacial morphology at adulthood between two groups of unilateral cleft lip and palate (UCLP) patients: one operated by primary periosteoplasty and the other by primary bone grafting. Design: The two groups were followed longitudinally at 5-year intervals; this study examined the 15- to 20-year age range. Setting: University hospital/center located in Prague, Bohemia, Czech Republic. Patients: 17 men with primary bone grafting, 29 men with primary periosteoplasty. Interventions: Primary bone grafting or periosteoplasty. Methods: Serial cephalometric radiographs. Main outcome measures: Conventional cephalometric and finite element measures. Results: The mandibular symphysis was larger in the bone-grafted group. The periosteoplasty group displayed a more horizontal growth of the mandible with less rotation than the bone-grafted group. There were no other significant differences. Conclusions: We conclude th...

Longitudinal cephalometric changes in the maxilla, mandible and maxillary-mandibular relationship between 10 and 14 years of age

Abstract In the present study, longitudinal growth changes in the maxilla, mandible, and maxillary-mandibular relationship occurring between the ages of 10 and 14 years were evaluated in 19 female and 15 male subjects. All subjects had a clinically- acceptable occlusion, a normal growth pattern, and none had undergone orthodontic treatment. Serial cephalometric radiographs were taken at the ages of 10, 11, 12, and 14 years. The effects of age and sex on the sagittal growth of the jaws were studied by means of variance ana lysis. The results show that A-Ptm, B-Ptm, Pg-Ptm, A'-Ptm, B'-Ptm, and S-N-Pg measurements were affected by age, and the measurements A-Ptm, A'-Ptm, Wits and ANB by sex. Duncan's multiple range test was applied to those measurements where F values were found to be statistically significant. As a result, it was observed that the greatest growth changes occurred between 12 and 14 years old.

The validity of two methods of mandibular superimposition: A comparison with tantalum implants

The aim of this investigation was to examine and compare the validity of Björk's and Ricketts' methods for the superimposition of serial cephalometric radiographs of the mandible for the analysis of changes over the duration of routine orthodontic treatment in growing subjects (approximately 2 years). Pre- and posttreatment lateral cephalometric radiographs of 23 children, with tantalum markers implanted in the mandible, were studied. The differences in position of six dental and skeletal landmarks between superimposition on Björk's structures and on Ricketts' corpus axis were compared with those on the basis of the implants. A rotational effect was found for corpus axis resulting from differential movement of Xi point with growth, whereas Björk's method yielded results essentially similar to those of the implant-based superimposition. This resulted in statistically significant median differences between the two methods for all landmarks except pogonion and menton. The magnitude of the differences increased with distance from the central core of the mandible and were generally greater horizontally than vertically. Although most differences were less than 2 mm, approximately 10% of the subjects showed differences greater than 4 mm for molar and incisor landmarks. These findings suggest that, for growing subjects, Björk's method should be preferred Ricketts', which cannot be relied on to indicate the true (intramandibular) changes during orthodontic treatment in growing subjects. (Am J Orthod Dentofacial Orthop 1998;113:263-70.)

Binder syndrome: staging of reconstruction and skeletal stability and relapse patterns after LeFort I osteotomy using miniplate fixation.

The present study prospectively assesses the skeletal stability in a consecutive series of Binder syndrome patients (n = 7), aged 16 to 20 years, who underwent LeFort I osteotomy fixed with miniplates and the associated morbidity. All patients underwent a one-piece LeFort I osteotomy fixed with four miniplates in conjunction with orthodontic treatment during the period of 1986-1992. Five of seven patients underwent iliac grafting to their deficient premaxilla and interpositionally at their osteotomy sites. Six of seven patients underwent bone graft augmentation of their deficient nose (four costochondral, one cranial, and one iliac). Serial cephalometric radiographs were taken at standard intervals after surgery (1 week, 6-8 weeks, 1 year). Horizontal, anterior vertical, and posterior vertical directional changes were then measured at each interval. With the radiographs superimposed, the amount of change was measured by the method of anatomic best fit. The 1-year postoperative cephalograms also were assessed for overjet and overbite. The medical records were reviewed for morbidity. Each patient had a complete set of longitudinal records. Follow-up ranged from 1.5 to 5.5 years at the close of the study. Perioperative morbidity was unremarkable, other than one patient whose cranial bone graft dehiscence through the nasal skin required regrafting. The mean (effective) maxillary advancement for the group was 6.0 mm, with 5.9 mm maintained 1 year later. The mean anterior vertical change of the maxilla was 4.2 mm, with 3.1 mm maintained; whereas the mean posterior vertical change was 2.8 mm, with 2.2 mm maintained. All patients maintained a positive overjet and overbite at 1 year. In our series, a staged reconstructive approach for Binder syndrome was carried out in the teenage years and included orthodontic treatment, orthognathic surgery, and nasal augmentation. The extent of skeletal relapse of the LeFort I osteotomy fell within a range that could be managed effectively to maintain a long-term positive overjet and overbite.

Some Methods of Assessing Postnatal Craniofaciodental Growth: A Retrospective of Personal Research

The purposes of this review and summary are to evaluate several selected significant clinical and basic science methods utilized to assess growth of bone(s), and in particular craniofaciodental growth: appositional and resorptive (bone), endochondral (bones), and sutural (bones). This personal retrospective report includes in part anthropometry, impressions and casts, vital markers, histology, radiopaque implant markers with and without serial cephalometric radiographs, and autoradiography. Knowledge obtained from the use of these various methods on rats, ground squirrels, rabbits, pigs, dogs, monkeys, and humans has contributed to a deeper and more fundamental understanding of both the processes and roles that craniofaciodental biology plays in the advancement not only of basic biology but also of craniofacial surgery. Growth and development of the skeletal system has an important role in determining body form. The dynamics of growth of bones is a complicated process. A number of different methods have been described by which growth of bones can be evaluated on both a quantitative and qualitative basis. No single method, however, should be relied on, because although it may have certain definite advantages, it also has its limitations. The use of all available methods at both the basic and the clinical science levels will give a more complete and accurate understanding of the problems associated with the growth of bone(s). Many of us are concerned with the correction of malformations and deformations that can be a result of faulty growth of bones. Thus, further knowledge obtained in regard to the sites, direction, and amount of growth as well as pattern, rate, and mechanism will lead not only to a more accurate diagnosis of the bony defect but also to a better understanding of both prevention and treatment.

The stability of segmentalized LE fort I osteotomies with miniplate fixation in patients with maxillary hypoplasia

Purpose: This study evaluates the postsurgical stability of segmentalized Le Fort I osteotomies with miniplate fixation in patients with maxillary hypoplasia. Materials and Methods: Eighteen adult patients who had undergone segmentalized Le Fort I osteotomy for anterior and inferior repositioning of their hypoplastic maxilla were studied radiographically. The positional change of five maxillary landmarks (PNS, ANS, A, U1, and UM) were measured on serial cephalometric radiographs according to a reference frame constructed by using the SN line for superimposition, sella as the origin of the coordinates, and a line parallel to Frankfort horizontal plane as the x-axis. The positional changes of all variables were measured twice, and the means were calculated for analysis. The paired t-test was used for statistical analysis. Results: Statistically significant mean vertical change ( P < .01) was found in the anterior maxilla, with U1 having moved up by 27.8% (1.5 mm) of its initial downward surgical movement by 1 year postoperatively. U1 and UM had moved forward 2.0 mm and 1.5 mm, respectively ( P < .01) by 1 year postoperatively, but the bony landmarks had no statistically significant change in their horizontal positions. Conclusion: Although statistically significant postsurgical changes were found at 1 year postoperatively, overcorrection is not recommended because of the large individual variation observed and the relatively small magnitude of the relapse.

Longitudinal growth changes in the sagittal relationship of maxilla and mandible

This is a longitudinal study of the growth pattern in sagittal linear measurements at points A, B, and pogonion relative to the pterygoid vertical plane in a Class I sample. Serial cephalometric radiographs were traced and digitized at ages 6, 12, 18, and 24 years. The results indicated that between the ages of 6 and 24 years there was a total growth increment of 6.07, 7.53, and 11.17 mm at points A, B, and pogonion, respectively, in the female Class I sample and 9.49, 11.65, and 16.21 mm at points A, B, and pogonion, respectively, in the male sample. Although the actual change in length of these measurements was larger in the male subjects than in the female subjects, in terms of percentage of growth increment in each of these three measurements from age 6 to 24 years, the anterior movement at point B relative to point A, and at pogonion relative to points B and A was approximately the same for both male and female subjects. When each of the subjects in both male and female samples was rank-ordered according to the size at age 6 years, considerable individual variation was noticeable for most persons within the group. The individual variation in growth pattern in each of the different measurements continues to raise questions about growth prediction and its application in visual treatment objectives. (A M J O RTHOD D ENTOFAC O RTHOP 1995;107:79-90.)

A comparison of the Herbst and Fränkel appliances in the treatment of Class II malocclusion

This study investigated the treatment effects produced by two types of functional appliance, one primarily tooth-borne (the Herbst appliance) and one primarily tissue-borne (the FR-2 of Fränkel). Serial cephalometric radiographs from 45 patients who had been treated with the acrylic splint Herbst appliance and from 41 patients who had been treated with the FR-2 appliance were compared with serial radiographs of 21 untreated persons with Class II malocclusions. Treatment effects were identified through the use of a conventional cephalometric analysis. The results of this study indicated that both appliances had influenced the growth of the craniofacial complex in treated persons. Significant skeletal changes were noted in both treatment groups, with both groups showing an increase in mandibular length and in lower facial height, as compared with controls. Greater dentoalveolar treatment effects were noted in the group wearing the tooth-borne functional appliance than in those wearing the tissue-borne appliance.