Palatal growth studied on human autopsy material. A histologic microradiographic study

Transverse skeletal and dentoalveolar changes during growth

INTRODUCTION

We previously reported that, on average, maxillary molars erupt with buccal crown torque and upright with age, mandibular molars erupt with lingual crown torque and upright with age, and these molar crown torque changes are accompanied by concurrent increases in maxillary and mandibular intermolar widths. Our purpose in this study was to determine the transverse skeletal changes that accompany these molar movements during growth.

METHODS

Thirteen maxillary and mandibular transverse measurements were made by using casts and posteroanterior radiographs from 36 Class I untreated subjects from the Iowa Facial Growth Study at approximately ages 7.6, 10.3, 12.9, 16.5, and 26.4 years. Intermolar arch widths, maxillary basal bone widths (bijugale), and mandibular basal bone widths (bigonion, biantegonion) were recorded for each subject. Also recorded were the maxillary and mandibular cross-arch alveolar process widths measured at the molar gingival crest and the midalveolar level.

RESULTS

The results indicate a pattern of width changes in the maxilla, the maxillary alveolar process, the maxillary first molars, the mandibular first molars, and the mandibular alveolar process that occurs as a gradient in the vertical dimension. The greatest width change occurs superiorly (jugale point). The smallest width change occurs inferiorly (midalveolar point of the mandible). On average, the basal bone of the maxilla increased in width by 5.37 mm; maxillary cross-arch midalveolar process width increased by 3.20 mm (left buccal surface to right buccal surface) and 4.94 mm (left palatal surface to right palatal surface); maxillary intermolar width increased by 3.08 mm; mandibular intermolar width increased by 2.05 mm; and mandibular cross-arch crest level alveolar width increased by 1.60 mm (left buccal surface to right buccal surface) and 1.02 mm (left lingual surface to right lingual surface). The basal bone of the mandible increased in width by 14.54 mm.

CONCLUSIONS

We concluded that transverse molar movements during growth mirror transverse maxillary basal bone width increases, maxillary cross-arch alveolar process width increases, and mandibular cross-arch alveolar process width increases. Furthermore, there is a pattern of width changes in the maxilla, the maxillary alveolar process, the maxillary first molars, the mandibular first molars, and the mandibular alveolar process that occurs as a gradient in the vertical dimension. On the other hand, transverse mandibular basal bone changes, measured as bigonion and biantegonion, do not fit this pattern.

Implant anchorage in orthodontic practice: the Straumann Orthosystem

Dental implants have been used to provide orthodontic anchorage. This article provides an overview of the Straumann Orthosystem implant system (Institut Straumann, Waldenburg, Switzerland) and its application, including the anatomy of the bony palate and contiguous structures. Considerations in placement of the Orthosystem implant include the avoidance of contiguous anatomic structures such as the nasal cavity, the degree of ossification of the palatal suture, and the quality and quantity of bone in the proposed implant site, all of which are discussed in this article.

Correlation between transverse expansion and increase in the upper arch perimeter after rapid maxillary expansion

The purpose of the present study was to assess the correlation between transverse expansion and the increase in upper arch perimeter, after maxillary expansion. Dental casts of eighteen patients were obtained before treatment and again five months after maxillary expansion. Measurements of intermolar width, intercanine width, arch length and arch perimeter were made with a digital caliper on photocopies taken from the dental casts. After assessment of the method error, a multiple regression model was developed following the identification of the best subset of variables. The resulting equation led to the conclusion that the increase in arch perimeter is approximately given by the addition of 0.54 times the intercanine expansion, and 0.87 times the arch length alteration.

A prospective long-term study on the effects of rapid maxillary expansion in the early mixed dentition

INTRODUCTION

The aim of this prospective longitudinal clinical study was to evaluate the short-term and long-term changes in dental-arch dimensions in patients treated with the acrylic splint rapid maxillary expander in the early mixed dentition followed by fixed appliances in the permanent dentition.

METHODS

The dental casts of 51 consecutively treated patients (TG) were compared with those of 26 untreated controls (CG) at 3 different times: pretreatment (T1), after expansion and fixed appliance therapy (T2), and at long-term observation (T3). The mean ages for the TG were 8 years 10 months at T1, 13 years 10 months at T2, and 19 years 9 months at T3. Arch widths, arch depth, arch perimeter, and molar angulation were assessed in all subjects at all observation times. T1-T2, T2-T3, and T1-T3 changes were compared statistically in the TG with respect to the corresponding CG.

RESULTS

Treatment with an acrylic splint RME followed by fixed appliances produced significantly favorable short-term and long-term changes in almost all maxillary and mandibular arch measurements. The amount of change in both maxillary and mandibular intermolar and intercanine widths fully corrected the initial discrepancies. Approximately 4 mm of long-term relative increase in maxillary arch perimeter, and 2.5 mm additional maintenance of mandibular arch perimeter were observed in the TG compared with the CG.

CONCLUSIONS

These results suggest that this protocol is effective and stable for the treatment of constricted maxillary arches, and can relieve modest deficiencies in arch perimeter.

Palatal development of preterm and low birthweight infants compared to term infants - What do we know? Part 1: The palate of the term newborn

Background

The evidence on prematurity as 'a priori' a risk for palatal disturbances that increase the need for orthodontic or orthognathic treatment is still weak. Further well-designed clinical studies are needed. The objective of this review is to provide a fundamental analysis of methodologies, confounding factors, and outcomes of studies on palatal development. One focus of this review is the analysis of studies on the palate of the term newborn, since knowing what is 'normal' is a precondition of being able to assess abnormalities.

Methods

A search profile based on Cochrane search strategies applied to 10 medical databases was used to identify existing studies. Articles, mainly those published before 1960, were identified from hand searches in textbooks, encyclopedias, reference lists and bibliographies. Sources in English, German, and French of more than a century were included. Data for term infants were recalculated if particular information about weight, length, or maturity was given. The extracted values, especially those from non-English paper sources, were provided unfiltered for comparison.

Results

The search strategy yielded 182 articles, of which 155 articles remained for final analysis. Morphology of the term newborn's palate was of great interest in the first half of the last century. Two general methodologies were used to assess palatal morphology: visual and metrical descriptions. Most of the studies on term infants suffer from lack of reliability tests. The groove system was recognized as the distinctive feature of the infant palate. The shape of the palate of the term infant may vary considerably, both visually and metrically. Gender, race, mode of delivery, and nasal deformities were identified as causes contributing to altered palatal morphology. Until today, anatomical features of the newborn's palate are subject to a non-uniform nomenclature.

Conclusion

Today's knowledge of a newborn's 'normal' palatal morphology is based on non-standardized and limited methodologies for measuring a three-dimensional shape. This shortcoming increases bias and is the reason for contradictory research results, especially if pathologic conditions like syndromes or prematurity are involved. Adequate measurement techniques are needed and the 'normal palatal morphology' should be defined prior to new clinical studies on palatal development.

Surgically assisted rapid maxillary expansion (SARME): a review of the literature

Transverse maxillary hypoplasia, in adolescents and adults, is frequently seen in non-syndromal and syndromal patients including cleft patients. In skeletally matured patients, the uni- or bilateral transverse hypoplasia can be corrected by means of a surgically assisted rapid maxillary expansion. The treatment is a combination of orthodontics and surgical procedures and provides dental arch space for alignment of teeth. The procedure also causes a substantial enlargement of the maxillary apical base and of the palatal vault, providing space for the tongue for correct swallowing and thus preventing relapse. In addition, a distinct subjective improvement in nasal breathing associated with enlargement of the nasal valve towards normal values is seen with an increase of nasal volume in all compartments. In this article we give a review on surgically assisted rapid maxillary expansion. We conclude that there is no consensus in the searched literature regarding either the surgical technique, the type of distractor used (tooth-borne or bone-borne), the existence, cause and amount of relapse and whether or not overcorrection is necessary. A proposal for a prospective randomized patient study in order to find answers to the lacunas in knowledge regarding this treatment is done.

Objective growth monitoring of the maxilla in full term infants

OBJECTIVE

To develop a non-invasive method for longitudinal maxillary volume measurements and to provide first normative data.

DESIGN

Thirty-four healthy infants served as a gold standard for a growing population sample. Alginate impressions were taken of the upper jaw within the first week after birth, and consecutively at different stages of development. The plaster casts were digitised by an optical scanner generating a high resolution polygon mesh of each object. The digital models were aligned to a reference coordinate system with an iterative, landmark-independent procedure. Biometric linear and volume measurements were obtained by using feature-dependent calculations independent of landmark placements. Intra-investigator reproducibility was tested by repeated alignments and measurements of 30 randomly selected casts. To assess the effect of mesh resolution, the reproducibility test was repeated with low resolution models. The method was proved to be valid on the defined gold standard consisting of 96 consecutive edentulous casts.

RESULTS

Feature-dependent, linear distances are less error prone (0.56-2.66%) compared to subjectively determined measurements (0.88-3.65%). The same applies to feature-dependent volume calculations (4.34%) compared to subjectively determined volumes (4.95%). Mesh resolution shows an effect (p<or=0.001) only on two linear measurements: palatal depth and palatal length. Growth of the individuals in the population sample was evidently confirmed by the maxillary volume measurements (asymptotic pattern) and by comparisons of head circumference (proportional pattern).

CONCLUSION

The described method is non-invasive, precise and without any risk for the infant. Maxillary volume calculation could serve as an important biometric measurement for bone growth evaluation.

The effects of early headgear treatment on dental arches and craniofacial morphology: an 8 year report of a randomized study

The aim of this study was to determine the long-term effects of early headgear (HG) treatment on craniofacial structures. The total study group comprised 68 children (40 males and 28 females) aged 7.6 years (standard deviation 0.3 years). The children, who had a Class II tendency in occlusion and moderate crowding, were randomly divided into two groups of equal size. In the first group, HG treatment was initiated immediately. In the second group, which served as a control group, only minor interceptive procedures were performed during the first follow-up period of 2 years. During the 8 year follow-up, orthodontic therapy, including fixed appliances and possible extractions, was carried out when necessary. The results showed that the most evident difference between the groups was the wider and longer dental arches in the HG group, which could only partly be explained by the higher rate of extractions in the control group. For the cephalometric measurements, the most significant difference was in the maxillary plane orientation. The peer assessment rating (PAR) score, showing the general outcome of treatment, was at the same level in both groups at follow-up. The deficit of the early HG treatment was the longer mean total treatment time, resulting from the two-phase treatment.

Skeletal and dental response to rapid maxillary expansion with 2- versus 4-band appliances

PURPOSE

Banding a rapid palatal expansion (RPE) appliance to the 2 first molars has been proposed as an equivalent to the conventional 4-band RPE appliance. However, the dentoskeletal response to this treatment has not been evaluated.

MATERIAL

Twenty-eight subjects (aged 8-20 years) who required maxillary expansion were matched by age and randomly assigned to either a 2-band or a 4-band RPE group. Skeletal and dental responses were measured from standardized anteroposterior cephalometric and occlusal radiographs and dental casts before treatment (T1), at the end of expansion (T2), and at 1 year postexpansion (T3).

RESULTS

At T2, suture expansion was 2.5 times greater and arch perimeter was 6-fold larger in the 4-band than in the 2-band group. Both appliances displayed the typical "V" expansion of the suture and "reverse V" expansion of the dental arch. At T3, remineralization reduced the suture opening by 75%, but 95% to 99% of the dental reaction was maintained. The 2-band group demonstrated a significant inverse age-dependent correlation ( r = -0.795), with treatment failure beyond 12 years of age, whereas the 4-band group was age-independent.

CONCLUSIONS

The greater the skeletal resistance, the smaller the sutural response but the greater the dental response to RPE therapy. Four-band RPE is indicated when severe anterior crowding is accompanied by a tapered arch form, and 2-band RPE is recommended in the mixed dentition when mild crowding occurs with posterior constriction.

Deciduous dentition-anchored rapid maxillary expansion in crossbite and non-crossbite mixed dentition patients: reaction of the permanent first molar

This preliminary report describes our evaluation of the behavior of permanent maxillary first molars subsequent to rapid maxillary expansion (RME) in the mixed dentition in crossbite and non-crossbite cases; maxillary deciduous canines and second molars were used as anchorage. The RME appliance was cemented on the maxillary deciduous second molars and canines in 19 (13 females, six males) patients with unilateral or bilateral permanent molar crossbites (Group A) and in 13 (10 females, three males) patients who had no crossbites (Group B). After a mean appliance activation period of 15 days for 4-8 mm expansion, the appliance was stabilized and kept in place as retention for 5-10 months. Neither active nor passive retention was applied on first permanent molars. Impressions of dental arches were made before insertion of the appliance (T1), at stabilization (T2), and at debanding (T3). Dental measurements were registered at T1, T2, and T3. In Group A, the mean maxillary permanent intermolar width was 40.6 mm at T1, 46.0 mm at T2, and 46.3 mm at T3. In Group B, 42.4 mm at T1, 46.3 mm at T2, and 45.4 mm at T3. In all subjects, the intermolar width increased during the active phase, and in Group A the crossbite was corrected and the correction was spontaneously stable. In these patients, deciduous teeth could support the heavy forces produced by the RME appliance. The maxillary intermolar distance was spontaneously increased and then maintained with no retention in Group A. The mean spontaneous expansion of permanent maxillary molars was approximately half of the mean expansion of the screw and the anchor deciduous teeth.

Posteroanterior cephalometric analysis of the parental craniofacial morphology in orofacial clefting

OBJECTIVE

To evaluate the parental craniofacial morphology in orofacial clefting (OFC).

DESIGN

Case-control posteroanterior cephalometric study.

SETTING

The Department of Orthodontics, University of Dundee Dental School, Scotland, United Kingdom.

PARTICIPANTS

Ninety-two parents from a completely ascertained sample of 286 Scottish babies with nonsyndromic OFC and 43 comparison group volunteers from the University of Dundee Dental School.

MAIN OUTCOMES AND MEASURES

A conventional cephalometric analysis was used to measure linear distances and their ratios, angles, and areas. Two-sample Student's t tests and a discriminant analysis were applied to the data, and the clinically important statistically significant variables were identified using an accepted protocol.

RESULTS

Sixty-four linear distances, 10 ratios, 52 angles, and 7 areas statistically significantly differed between the parental and comparison groups (p <.01). Of these, 62 linear distances (22%), 9 ratios (45%), 41 angles (41%), and 6 areas (24%) were clinically important. Asymmetry was a feature of the results. Canonical variates analysis correctly classified 91.3% of the parental group and 90.6% of the comparison group using a series of 36 variables.

CONCLUSIONS

The parental craniofacial morphology in OFC differs significantly from the noncleft population. A larger superolateral face and smaller central midface and, in particular, a clinically significantly smaller maxillary width, in conjunction with skeletal asymmetry, characterize the parents of Scottish children with OFC. These features may be of morphogenetic importance in the etiopathogenesis of OFC in this ethnic group.

The internal structure of bony tissue of a human metopic suture by Soft X-ray

A complete metopic suture was found in the frontal bone of a 79 years old male cadaver. Compact bone matrices were found in the border region of the metopic suture using a Soft X-ray apparatus. The coronal and sagittal sutures were also complete. The appearance of these complete cranial sutures may be due to continuous bone restructuring and resorption in the border region of sutures during brain development of brachy crany.

Surgical and orthodontic rapid palatal expansion in adults using Glassman's technique: retrospective study

In 1984, Glassman et al. described a conservative surgical method of separation of the midpalatal suture in which an osteotomy is done only at the lateral and anterior wall of the maxilla. Between 1991 and 1997, we have operated on 21 patients with maxillary transverse discrepancies using the method that they described. This gave good results in 20 patients. The other, who was operated on at the age of 38 years, developed a fracture of the alveolar process of the maxilla on one side because of ossification of the midpalatal suture. The surgically assisted rapid palatal expansion described by Glassman et al. is suitable for patients up to the age of 30. Older patients require additional surgical separation of the midpalatal suture.

A comparison of different treatment techniques for posterior crossbite in the mixed dentition

In this retrospective investigation, the changes occurring during the treatment of patients with posterior crossbite in the mixed dentition with the use of expansion plate and quad-helix appliances were evaluated and compared with those resulting from growth and development occurring in a control group of patients of similar age and type of malocclusion. The expansion plate group consisted of 13 patients, the quad-helix group of 14 patients, and the control group consisted of 10 children with transverse posterior crossbites in the mixed dentition. The research material was formed from orthodontic models and lateral and frontal cephalometric radiographs from 37 children. It was observed in this investigation that transverse expansion is achieved by both the expansion plate and quad-helix appliances. However, the average period of treatment was 1.2 years for the expansion plate, and 0.6 years for the quad-helix appliance. Although posterior crossbite was corrected in a fairly short period of time, the quad helix appliance caused considerable buccal tipping of the maxillary first permanent molars.

The pathology of the velopharyngeal musculature in cleft palates

AIMS

This article draws attention to a pathological finding in the cleft palate condition that has not been previously described: It is demonstrated that the palatal aponeurosis exists even in cleft palates, but it is disrupted, malpositioned and folded in 2 layers. It is possible to dissect the 2 layers and to unfold the aponeurosis to form a tough tendinous plane. Thus, the retropositioning of the levator veli palatini muscle sling is facilitated.

CONCLUSION

For a normal reconstruction of the cleft palate it is not only necessary to reconstruct the levator veli palatini muscle sling but also to approximate and to suture the fibres of the palatal aponeurosis to the corresponding fibres of the opposite side after unfolding them in a mediodorso-cranial direction. In this manner a continuous palatal aponeurosis can be created and subsequently it can serve as a transmitter of the muscle forces.

Growth sites and growth mechanisms at risk in cleft lip and palate

A newborn with some kind of facial cleft displays certain characteristics of the nose, upper lip, and jaw caused by abnormal influence on specific growth sites and growth mechanisms. Treatment, particularly surgery, attempts to counteract this aberrant development, for both functional and aesthetic reasons. However, not infrequently, therapy impedes future midfacial growth to a greater or lesser degree. To better understand the varying growth influence, this article aims to review certain aspects of growth of the middle third of the face in both normal and cleft subjects. The normal elongation of the maxilla, to give space for the molars, is usually not affected by lip surgery but rather by scar tissue from palatal repair. The displacement of the upper jaw in relation to the vomer is recognized. Early surgery should therefore avoid affecting the growth of the vomero-(pre)maxillary suture if possible. Periosteal growth, necessary for the development of dentoalveolar structures, might be affected by scar tissue from palatal repair. Different ways to reduce the development of palatal scars and their negative effects on growth are discussed.

Stability of orthopedic and surgically assisted rapid palatal expansion over time

At the present time no reports are available on the stability between orthopedic and surgically assisted rapid palatal expansion. This study was designed to examine and compare the dental and skeletal changes over time for both orthopedic maxillary expansion and surgically assisted palatal expansion. The study was divided into two groups. Group one was orthopedically expanded and consisted of 14 males and 10 females. The ages ranged from 6 years to 12 years with a mean of 8.5 years. Group two received surgically assisted rapid palatal expansion and consisted of 12 males and 16 females with ages ranging from 13 years to 35 years and a mean age of 19.25 years. All 52 subjects were white, from the same geographic area, and were treated by the same two operators. Dental models and posterior anterior cephalograms were obtained immediately before and after expansion, at removal of the expansion device, and 1 year after removal of the appliance. A repeated measures analysis of variance test was applied to assess changes over time between groups. The surgical and nonsurgical techniques displayed similar trends over time although the surgical group contained a greater quantity of expansion. Both the orthopedic and the surgical groups showed stable results.

Pathology of the palatal aponeurosis in cleft palate

OBJECTIVE

The palatal aponeurosis is a controversial structure, both in terms of its anatomy and its function. This article points out a pathologic finding in the cleft palate condition that has not been previously described.

DESIGN AND METHOD

By means of surgical dissections, this study demonstrates in detail that the palatal aponeurosis exists even in cleft palates, but it is disrupted, malpositioned, and folded in two layers.

PATIENTS

This dissection method has been performed on more than 150 patients with cleft of the hard and soft palate, with or without cleft of the lip and alveolus. At the time of operation, the children were between 6 and 8 months of age.

RESULTS

It is possible to dissect the two layers of the palatal aponeurosis, to unfold the aponeurosis, and to form a tough tendinous plane.

CONCLUSION

For a functional physiologic reconstruction of the cleft palate, it is necessary not only to reconstruct the levator veli palatini and palatopharyngeus muscle slings, but also to approximate and suture the fibers of the palatal aponeurosis to the corresponding fibers of the opposite side after unfolding them in a medio-dorso-cranial direction. In this manner, a continuous palatal aponeurosis can be created, which subsequently can serve as a transmitter of the muscle forces.

Human palatal growth evaluated on medieval crania using nerve canal openings as references

The purpose of this investigation was to measure postnatal lengthening and widening of the hard palate by use of nerve canal openings as references. The relationship of the dentition to the greater palatine foramina was also investigated. Thirty-nine medieval dry skulls were examined, 22 from children and 17 from adults. All crania were photographed at a 1.1 scale. The dimensions of the maxilla and the location of the dentition were determined from the photographs. The study showed that palatal growth in length in the sagittal plane takes place anterior to the greater palatine foramen. The growth increment in the area between the incisive foramen and the transverse palatine suture is more pronounced than the growth increment in the area between the transverse palatine suture and the greater palatine foramen. The distance from the greater palatine foramina to the posterior margin of the palate did not increase significantly with age. The growth in width seems to continue into adult life. The first permanent molars and the surrounding bone are moved forwards in relation to the greater palatine foramina during growth. The space for the developing maxillary premolars and molars therefore has to be obtained by growth in the transverse palatine suture.

A longitudinal cephalometric study of transverse and vertical craniofacial growth

Longitudinal growth changes were studied from posteroanterior cephalometric radiographs of 25 male subjects from 4 to 25 years of age and 25 female subjects from 4 to 20 years of age who had Class I skeletal and dental patterns. Growth for males continued past age 18 years for all skeletal measurements, except for maxillary width. Growth for females was completed by 17 years for all skeletal measurements. At 6 years of age the transverse measurements had a greater percentage of the adult size completed than vertical measurements for both males and females. Gender differences at age 6 years were in the mean widths for the cranium, face, and maxilla. At age 12 years the differences were in cranial width, maxillary width, and maxillary and mandibular intermolar width (6-6). There were gender differences at age 18 years for all the variables, except for nasal width and mandibular intermolar width (6-6). Regression lines provided strong-to-moderate predictive equations to determine the size of most of the measurements at age 18 years, if the value at age 6 years is known.

Differential growth among components of the palate in rhesus monkeys (Macaca mulatta)

To understand the etiology of maxillary hypoplasia better, which is common in individuals with cleft palate and other craniofacial anomalies, the relative growth and contribution of the maxillary and palatine segments to enlargement of the hard palate was examined in rhesus monkeys. The purpose of the study was to identify and evaluate sites of differential growth of the palatine and maxillary segments as they contribute to the development of the midface and facial prognathism. One hundred and eight male and 107 female skulls ranging from 1.0 to 7.0 years of age were examined. Measurements of the maxillary and palatine lengths, palatal width, midface depth, canine length, and molar surface areas in the ontogenetic sample were collected. Univariate and bivariate statistics were used to describe dimensional changes and evaluate region-specific sex differences. The relative growth of palatal dimensions was evaluated using allometric analysis methods. Significant sex differences were observed (t-test, p < or = .05) for all palatal dimensions by 4 years of age. However, proportions of the maxillary and palatine segments to overall palate length appeared to be similar throughout growth for both sexes. The results suggest that sutures of the midface, in particular the transverse palatine suture, may be important in the bony development of the palate during growth. These sutures may contribute to the overall modulation of palatal development.(ABSTRACT TRUNCATED AT 250 WORDS)

Intercanine widening and sagittal effect of maxillary transverse expansion in patients with cleft lip and palate during the deciduous and mixed dentitions

Since 1977 cleft lip and palate (CLP) patients with maxillary deficiency have received an interceptive orthopedic treatment consisting of (a) transverse expansion, (b) protraction, and (c) fixed retention. Ideally the treatment should be completed early enough to permit spontaneous eruption of the maxillary permanent incisors into normal occlusion without orthodontic intervention. The early transverse expansion considerably increases space so that unerupted malpositioned incisors spread out spontaneously, creating optimal conditions for eruption and root formation. Dental diagnosis in the cleft areas is made easier. Posterior crossbites in 112 CLP patients were expanded with a modified quad-helix appliance cemented with four bands in the deciduous or mixed dentition. Intercanine widening was about 3 mm per month regardless of cleft type. Several authors have claimed that transverse expansion of the upper jaw will increase sagittal overjet. Other authors have not found such an effect. The sagittal effect on the maxilla was studied in 68 CLP patients who had received transverse expansion. Analysis of the lateral cephalograms revealed no significant sagittal dentofacial maxillary treatment effects involving forward movement of maxilla, but a downward clockwise rotation of the mandible was found.

[The causes of and repair procedures in external root resorption following palatal suture expansion with magnetic and conventional dilators. Experimental animal research on Macaca fascicularis monkeys]

Eight Macaca fascicularis monkeys received rapid maxillary expansion with conventional and magnetic appliances. The histomorphometric analysis (SEM) showed increased external root resorption (ERR) in: multirooted teeth, buccal root surfaces, mesiobuccal roots and apical zones. ERR is determined by the impulse, the decrease in the periodontal width and the extent of mineralization of adjacent hard tissues. The microscopic examinations of light, UV and SEM defined two types of cellular cement in ERR areas: a) unfunctional repair cement (slow type), b) functional repair cement (rapid type). The first was characterized by the absence of Sharpey's fibers and by overlapped incremental lines, the second by the formation of new Sharpey's fibers and discriminated incremental lines. These incremental lines indicate five sequential phases with diverse rates of cement apposition, i.e. lag-, incipient-, peak-, steady-, and retreating phase. Therefore, the study recommends the application of a fixed retainer immediately subsequent to rapid maxillary expansion which is followed by an intermittent retention appliance.

[Combined surgical-orthodontic palatine suture expansion in adulthood]

A method of surgical support of a rapid maxillary expansion is described. Specific osteotomies are performed on the attached region of the maxillary zygomatic process and the dorsal and middle part of the hard palate. The results of 14 patients are demonstrated. Almost all patients underwent surgical correction of sagittal and/or vertical jaw relations after a subsequent harmonization. This surgical orthodontic expansion proved to be an efficient and low pain method of preoperative correction of transverse maxillary deficiencies and facilitated the following skeletal surgery.

Growth of the pharynx and its physiologic implications

The bony nasopharynx increases its capacity predominantly by means of vertical development. Analogous to the facial structures is an expression of some somatotopic features that give rise to a higher and more shallow pharyngeal dimension in the dolichocephalic growth pattern. The nasopharynx's ultimate patency, however, depends on the growth and relative size of the soft tissues that line the skeletal boundaries. A decreased patency of the oropharyngeal airway can induce some postural adaptations, which secure a constant sagittal dimension at that level. However, at a certain critical point, purely nasal respiration will be turned into an oronasal breathing pattern, which in turn will elicit more compensatory mechanisms. This muscle recruitment is a possible cause of a deviant vertical craniofacial growth pattern.

Transverse development of the human jaws between the ages of 8.5 and 15.5 years, studied longitudinally with use of implants

We report longitudinal data on the transverse widening of the maxilla and mandible from a sample of normal subjects (11 males and 20 females) with metallic implants of the Bjork type. Data were from measurements on lateral and frontal (posterior-anterior) cephalograms generated at annual intervals between the ages of 8.5 and 15.5 years (although data were not available for all subjects at all time points). The maxillary data were, in general, similar to those reported by Bjork and Skieller (1974, 1977) for a smaller sample of slightly younger boys. During the age interval studied, transverse widening was greater in the more posterior part of the palate. [The mean annual rate of change in the posterior-most (zygomatic) region was 0.43 mm, sd = 0.18 mm; p less than 0.001.] Although the rate of palatal widening was not large in absolute terms, widening appeared to continue throughout the age interval under study, and there was no evidence to support the conventionally accepted idea that palatal growth in the transverse dimension tapers off substantially or even ceases during the age interval under observation. Evidence of statistically significant widening of the mandibular arch by means of transverse rotation of the osseous matrix was noted in nine of the 29 subjects for whom three-dimensional mandibular information was available. For these nine subjects, the estimated annual increase in mandibular arch angle ranged from 0.52 degrees to 1.40 degrees. As far as we are aware, this is the first report of mandibular matrix rotation in the transverse direction from a sample of subjects with metallic implants. The finding that spontaneous changes in this dimension are relatively common raises the possibility that classical attitudes concerning the immutability of osseous relationships in the symphyseal region during growth may be inappropriate.

The effect of rapid maxillary expansion on nasal airway resistance

The purpose of this study was to evaluate changes in nasal resistance to airflow in persons undergoing rapid maxillary expansion and to reevaluate the responses at a 1-year follow-up. Nasal resistance measurements, assessed in four modes (natural state, anterior nares dilation with Tygon tubing, following administration of decongestant, and nares dilation with tubing and decongestant), were taken on a group of 38 patients receiving rapid maxillary expansion and compared with a control group not receiving expansion. Thirty-three of the patients were reevaluated 9 to 12 months after expansion was completed. Eighteen subjects in the control group were also reevaluated. Oral/nasal airflow rates (percent nasality) were recorded for the control group and for some of the expansion patients. Results indicated that some subjects receiving rapid maxillary expansion had a significantly higher nasal resistance than the control group. There was a significant median reduction in nasal resistance following rapid maxillary expansion, measured in the natural state only, and this appeared to be stable up to 1 year after maximum expansion was obtained. Rapid maxillary expansion appeared to effect an expansion at the anterior nares, which contributes to nasal resistance reduction. Individual variation in nasal resistance values was considerable and hence the median response for the group was not a reliable estimate of individual response. Due to the high individual response variability, rapid maxillary expansion is not a predictable means of decreasing nasal resistance.

Quantitation of maxillary remodeling. 1. A description of osseous changes relative to superimposition on metallic implants

Lateral skull radiographs for a set of 31 human subjects were examined using computer-aided methods in an attempt to quantify modal trends of maxillary remodeling during the mixed dentition and adolescent growth periods. Cumulative changes in position of anterior nasal spine (ANS), posterior nasal spine (PNS), and Point A are reported at annual intervals relative to superimposition on previously placed maxillary metallic implants. This in vivo longitudinal study confirms at a high level of confidence earlier findings by Enlow, Björk, Melsen, and others to the effect that the superior surface of the maxilla remodels downward during the period of growth and development being investigated. However, the inter-individual variability is relatively large, the mean magnitudes of change are relatively small, and the rate of change appears to diminish by 13.5 years. For the 19 subjects for whom data were available for the time interval from 8.5 to 15.5 years, mean downward remodeling at PNS was 2.50 mm with a standard deviation of 2.23 mm. At ANS, corresponding mean value was 1.56 mm with a standard deviation of 2.92 mm. Mean rotation of the ANS-PNS line relative to the implant line was 1.1 degree in the "forward" direction. However, this rotational change was particularly variable with a standard deviation of 4.6 degrees and a range of 11.3 degrees "forward" to 6.7 degrees "backward." The study provides strong evidence that the palate elongates anteroposteriorly mainly by the backward remodeling of structures located posterior to the region in which the implants were placed. There is also evidence that supports the idea of modal resorptive remodeling at ANS and PNS, but here the data are somewhat more equivocal. It appears likely, but not certain, that there are real differences in the modal patterns of remodeling between treated and untreated subjects. Because of problems associated with overfragmentation of the sample, sex differences were not investigated.

Maxillary expansion: clinical implications

Clinicians frequently expand the maxilla to correct certain malocclusions. The effects of expansion on facial structures, dentition, and periodontium are reviewed. The implications of these findings for the treatment of patients who need maxillary expansion are discussed.

Longitudinal study of dental arch relationships in Australian aboriginals with reference to alternate intercuspation

The patterns of age change in dental arch breadths and depths were studied longitudinally in Australian Aboriginals, 92 males and 68 females. Three types of change in relative arch dimensions were recognized: a divergent pattern in which the differences between maxillary and mandibular dimensions increased with age, a convergent pattern in which the differences decreased, and a parallel pattern in which the arch differences remained metrically stable. The feature that best distinguished the Aboriginals from Caucasian groups was the high frequency of subjects, 71% of males and 40% of females, who showed a divergent growth pattern. The association between divergent growth in arch breadths and the development of alternate intercuspation, which is characterized by an inability to occlude the teeth on both sides of the arch at the same time, is discussed.

Conservative surgical orthodontic adult rapid palatal expansion: sixteen cases

A conservative surgical orthodontic technique that facilitates the widening of the adult maxilla at the midpalatal suture is presented. This procedure uses only lateral maxillary corticotomies and a maxillary Hyrax split-palate appliance. In all sixteen cases attempted, separation of the midpalatal suture was confirmed by occlusal radiographs and a diastema between the maxillary central incisors.

A radioautographic study of the effect of age on the protein-synthetic and bone-deposition activity in interparietal sutures of male white mice

Groups of male white mice were killed at 4, 5, 6, 7, 8, 9 and 10 weeks of age 2 h after intraperitoneal injection with [3H]-proline. Radioautographic analysis of sections of the interparietal suture demonstrated significantly greater protein-synthetic activity in the para-osseous zones relative to the middle zone (p less than 0.01) and a plateau of lower protein-synthetic activity by 7-8 weeks of age (p less than 0.05). Groups of mice were selected at 4, 6, 8 and 10 weeks of age. Each mouse was injected intraperitoneally with [3H]-proline three times at one-week intervals. Sutural growth rate was determined from incremental lines revealed by radioautographs prepared from serial paraffin sections of the interparietal suture and demonstrated a stabilization of growth by 8 weeks of age. This, together with the grain counting data, suggested that a mouse of 7-8 weeks would provide a suitable model for experimental studies in sutural remodelling response without masking effects by normal growth.

Roentgen stereometry with the aid of metallic implants in hemifacial microsomia

Displacement of the mandible and the maxilla with growth in relationship to the frontal bone was recorded in eleven children with hemifacial microsomia, aged 3 to 14 years at the initial examination. The goals were to assess the efficiency of the method for accurate recording of articular growth and to obtain information on facial development in each of these children. Correction of the skeletal asymmetry was not attempted during observation periods of from 707 to 1,484 days. In continued observations three of the children were treated with functional appliances. Roentgen stereometry with the aid of metallic implants proved to be an efficient method for highly accurate recordings of articular facial growth in relationship to the frontal bone. Displacement of the jaws was asymmetrical in all of the examined children as determined in the frontal and transverse planes of the head. In about 50 percent of the children the degree of asymmetry increased in one plane while it decreased in the other plane. No correlation was found between the extent of the mandibular deformity, as seen on orthopantomograms, and the displacements of the mandible. Generally, the displacement of the maxillary bones corresponded with the displacement of the mandible. Articular growth of the jaws was redirected toward a more favorable pattern in two of the children during the time they used a functional appliance. In the third child the use of a functional appliance had no such effect.

The postnatal development of the palatomaxillary region studied on human autopsy material

Greater understanding of the postnatal region of the maxilla is necessary if the normal growth of the maxillary complex, as well as its reaction to orthopedic forces, is to be comprehended. The area in question was studied at various stages of development, both on dry skulls and on autopsy material. The skull material demonstrated an increasing approximation between the palatal bone and the adjacent bones, the maxilla and pterygoid process. Disarticulation of the bones studied was possible only on skulls representing the infantile and earliest adolescent periods. Attempted disarticulation in the later juvenile and early adolescent periods was always accompanied by fracture of the heavily interdigitated osseous surfaces. The complexity of the articulating surfaces was studied further and, by means of quantitation of the bony surfaces, an "index of complexity" was calculated. The findings of the present study that the palatal bone acts as a "buffer" between two areas of differing intrinsic growth pattern and that the remodeling processes in the area seem to reflect different functional demands to the bony pharynx and the maxillary complex. The rigidity of the area as a result of the observed sutural complexity indicates that the center of rotation for the observed spatial changes in the maxillary complex as a result of orthopedic forces could be localized in the palatomaxillary region.

The relationship of rapid maxillary expansion to surgery with special reference to midpalatal synostosis

This study is a multi-disciplinary approach to the regulation of the maxillary width in adults, based on published histological evidence of midpalatal synostosis and the analysis of nine cases. The treatment involves the maximal use of rapid expansion for movement with the minimal surgical intervention to free maxillae. The results provide a modus operandi for oral surgeon/orthodontist association with a three-stage series of age-related incremental surgical procedures to meet the resistance to maxillary separation and a tie-up with orthognathic surgery. It seems unnecessary to intervene surgically to free the maxillae under 25 years of age. Stage 1 applies between 25 and 30 years, Stage 2 between 30 and 40 years, and Stage 3 between 40 and 50 years. Attention is drawn to the respiratory improvement following these technics.

Frames of reference for the measurement of occlusal change and the integration of data from orthodontic models and cephalometric radiographs

The problems of establishing a suitable basis for the measurement of tooth movements from models is discussed, together with the ways in which such measurements of the occlusion can be related to data from cephalometric radiographs.

Subperiosteal early resection of the mid-palatal suture. A morphological study in twelve patients operated for choanal atresia

Twelve patients with choanal atresia were operated on by a method which involves a subperiosteal resection of the hard palate including the posterior two-thirds of the mid-palatal suture. In 7 patients, admitted for reoperation, peroperative examinations revealed an osseous defect in the posterior part of the hard palate. Biopsies showed that repair in this area was mostly by connective tissue, indicating that formation of new bone, regenerated from periost, is minimal in this part of the palate. Fresh specimens from 5 previously unoperated patients and from the anterior intact part of the palate of the reoperated patients, displayed that the mid-palatal suture was not obliterated even at 26 years of age. Longitudinally orientated intrasutural fibres and signs of active growth were evident up to puberty. The suture seemed to consist of three layers.

Growth of the maxilla in three dimensions as revealed radiographically by the implant method

By use of the implant method the growth of the maxilla was analysed from profile and frontal (postero-anterior) cephalometric radiographs in nine boys with normal primary occlusion who were followed annually up to adult age without receiving any orthodontic treatment.

The proportion of sutural and appositional growth in height was determined from profile radiographs with reference to implants in the infrazygomatic crest. The sutural lowering of the maxillary corpus was, on average, about twice as big as the apposition at the floor of the orbits. The resorptive lowering of the nasal floor amounted to about one-third of the appositional growth in height of the alveolar process.

Our study suggests that the contour of the anterior surface of the zygomatic process could be used as a reference structure in growth analysis as this contour kept a constant relation to implants in the infrazygomatic crest and closely followed the natural growth rotation of the maxilla.

In relation to the implants, the dentition as a whole drifted forward on the maxillary corpus, simultaneously with a smaller decrease in arch length which was partly related to a differentiated development in width of the maxilla.

Measurements between bilateral implants on frontal radiographs proved that the growth in the median suture was greater posteriorly than anteriorly, whereby the two halves of the maxilla rotate in relation to each other in the transverse plane. This was reflected in the development of the dental arch as the increase in the bi-molar width showed a high correlation with the sutural growth posteriorly in the medium suture, while the increase in the bi-canine width was lesser. The forward drift of the dental arch led to a reduction in incisor spacing, which may give rise to an incisal secondary crowding.