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PubMed1995

Reactions of the mandible to experimentally induced asymmetrical growth of the maxilla in the rat.

The purpose of this investigation was to examine the interrelation in growth and morphogenesis between the maxilla and the mandible. Asymmetrical growth was induced in the maxilla of 10-day-old LE/T rats by means of unilateral artificial synostosis of the frontonasal and frontopremaxillary sutures. Untreated rats were used as controls. Biometric and microscopic observations were made at the ages of 30, 50, and 100 days. The arrest of sutural growth was followed by reduced sagittal growth of the maxilla, significantly more so on the treated side. Its anterior part became bent towards the treated side and rotated around the sagittal axis. In response to the primary alteration in maxillary shape, the mandible adapted by developing a secondary asymmetry in that it was shorter on the treated side than on the contralateral side throughout the experiment and shorter on the untreated side than in the untreated controls at 30 days. When the distances were adjusted for body weight, the mandibular length on the untreated side appeared to be virtually unaffected by the experimental procedure or even exceeded the control value at 50 days. The mandibular ramus was higher on the treated side than on the contralateral side at 30 days, and became bilaterally higher than in the untreated controls with increasing age. The results imply that the growth in length of the mandible follows that of the maxilla to some extent and are indicative of a restraining effect of the shortened maxilla on mandibular growth. The existence of a mechanism responsible for keeping the height of the ramus the same on both sides is suggested.

Aging↗

PubMed1999

Initial orthopaedic displacement compared with longitudinal displacement of the maxilla after a forward force application. An experimental study in dogs.

The aim of this study was to compare the initial orthopaedic displacement of the maxilla in vivo and the longitudinal changes after a forward force application. The sample consisted of five 1-year-old dogs. An anterior force of 5 N on the maxilla was applied by a coil spring system pushing between Brånemark implants and a maxillary splint. The initial displacement of the maxilla after force application was measured by means of speckle interferometry. The longitudinal displacement of the maxilla after a force application during 8 weeks was measured by superimposing standardized lateral cephalograms. The initial, as well as the longitudinal, displacement of the maxilla of the dogs was in a forward direction with some counterclockwise rotation. There was no statistical difference between the initial and longitudinal displacement. The biological response after force application during 8 weeks can be predicted by the initial orthopaedic displacement.

Animals↗

PubMed2000

Biological arches and changes to the curvilinear form of the aging maxilla.

The facial skeleton can be conceptualized as a series of arches aligned along a vertical axis, with regional differences in shape. Previous work suggested that the maxilla undergoes differential growth with time. Because these arch forms resemble geometric forms, it may be possible to measure changes to their shape with the aging process. A contour analysis of the aging maxilla was undertaken. Computed tomographic data were assembled retrospectively. Only men were studied, and they were divided into two groups: young (aged 18 to 24 years; n = 6) and old (aged 40 to 66 years; n = 6). The computed tomography data were reconstructed into three-dimensional images and underwent standardization for comparison purposes. An axial view of the maxilla along the Frankfort horizontal was used for analysis. To quantify changes between curves, measurements were made of the vertical distance from eight equidistant points along each curve perimeter to a standardized baseline. Average arch forms for young and old men were then generated for comparison purposes. Each of the eight points along the older maxillary arch form existed further from the baseline than the younger arch form. This difference reached statistical significance at three of the eight points measured along the two curves. The greatest difference occurred at point 8 (p = .0006), which was at the medial maxilla near the nasomaxillary junction. The results of the study suggest that the actual contour of the maxilla undergoes changes as a result of the aging process. Mathematically defined idealized skeletal contours could help guide reconstructive surgery and aesthetic augmentation of the facial skeleton in the future. In addition, certain soft tissues of the face and torso seem to share a common shape (an alpha contour). This shape may also exhibit idealized forms open to quantitative analysis. The skeletal arch form and alpha contour most likely exhibit sexual dimorphism and will require further investigation. The ubiquity of the arch form in nature and possible implications for growth and development of the human facial skeleton are also discussed.

Adult↗

PubMed1997

Hypothetical mortality risk associated with spiral tomography of the maxilla and mandible prior to endosseous implant treatment.

Radiation dose delivered from the SCANORA radiography unit during the cross-sectional mode for dentotangential projections was determined. With regard to oral implantology, patient situations of an edentulous maxilla and mandible as well as a single tooth gap in regions 16 and 46 were simulated. Radiation doses were measured between 0.2 and 22.5 mGy to organs and tissues in the head and neck region when the complete maxilla or mandible was examined. When examining a single tooth gap, only 8% to 40% of that radiation dose was generally observed. Based on these results, the mortality risk was estimated according to a calculation model recommended by the Committee on the Biological Effects of Ionizing Radiations. The mortality risk ranged from 31.4 x 10(-6) for 20-year-old men to 4.8 x 10(-6) for 65-year-old women when cross-sectional imaging of the complete maxilla was performed. The values decreased by 70% when a single tooth gap in the molar region of the maxilla was radiographed. The figures for the mortality risk for examinations of the complete mandible were similar to those for the complete maxilla, but the mortality risk decreased by 80% if only a single tooth gap in the molar region of the mandible was examined. Calculations according to the International Commission on Radiological Protection carried out for comparison did not reveal the decrease of the mortality risk with age and resulted in a higher risk value in comparison to the group of 35-year old individuals in calculations according to the Committee on the Biological Effects of Ionizing Radiations.

Adult↗

PubMed2002

Reconstruction of the anterior maxilla with platelet gel, autogenous bone, and titanium mesh: a case report.

BACKGROUND: Reconstruction of defects in the anterior part of the maxilla to enable implant placement is a challenging treatment. Recent studies have suggested that the use of autogenous platelet gel may contribute to improved healing of bone grafts. PURPOSE: A case is presented in which particulated autogenous bone, platelet gel, and a titanium mesh were used for alveolar bone reconstruction of the anterior maxilla prior to implant placement. MATERIALS AND METHODS: Corticocancellous bone from the iliac crest was mixed with a preparation of autogenous platelet gel (platelet-rich plasma, thrombin, and calcium chloride) and placed against a titanium mesh fixed to the bone of the palate in a patient with severe resorption of the anterior maxilla. After 4.5 months of healing the mesh was removed and titanium implants were placed. A prolonged healing period of 8 months was allowed before healing abutments were placed and a fixed dental bridge was fabricated. RESULTS: Healing was uneventful, and the anterior maxilla had increased in height and width during the initial healing. All implants became integrated and have been supporting a fixed dental bridge for over 3 years with no dramatic dimensional changes of the graft. CONCLUSIONS: This case demonstrates that particulated autogenous bone and platelet gel may be used for reconstruction of the anterior maxilla. Autogenous growth factors in the gel possibly contributed to the positive outcome. Controlled clinical studies are needed to evaluate the effect of using platelet-rich plasma.

Adult↗

PubMed2002

Three-dimensional analysis of morphological changes in the maxilla of patients with cleft lip and palate.

OBJECTIVE: Three-dimensional (3-D) morphological changes in the maxilla of patients with cleft lip and palate (CLP) have been recorded, mainly using two-dimensional cast analyses. Although these seem to be insufficient, no standardized 3-D method has been developed until now. In this study, accuracy, precision, and validity of a newly developed 3-D digital computer-aided procedure to visualize and metrically analyze the growth of the edentulous maxilla of infants with CLP have been evaluated. PATIENTS: The method was applied to 10 infants with complete unilateral CLP. INTERVENTIONS: Consecutive casts of the maxilla (1 week and 3, 6, and 12 months) of each patient were optically measured with a 3-D laser scanner. Following digitizing, the casts were computer reconstructed, aligned, and superimposed using specialized computer software. The distances between the surfaces were measured. Additionally, the surfaces were segmented perpendicular to the alveolar crest, the reference points being C1, C1', C2, C2', and I. The volumes of the resulting segments were determined and compared with one another. RESULTS: The newly developed analysis enables a visualization of the extent and direction of morphological changes in the maxilla of infants with CLP. With this method it is possible to quantify these changes of the volume of defined alveolar segments. CONCLUSIONS: The 3-D analysis developed is an ideal tool for the examination of 3-D morphological changes in the edentulous maxilla of patients with CLP. The results will serve as the starting point for a longitudinal study on the efficacy of different methods, not only of presurgical infant orthopedics but also of surgical procedures.

Alveolar Process↗

PubMed2002

Comparison of the effect of supraperiosteal versus subperiosteal dissection on the growing rabbit maxilla.

OBJECTIVE: To achieve closure of wide unilateral cleft lip repair without tension of the cleft lip margins, a large undermining, especially of the anterolateral surface of the maxilla, is needed. Two types of dissection are feasible: supraperiosteal or subperiosteal. The aim of this study was to investigate whether there are differences in maxillary growth between healthy rabbits after supraperiosteal or subperiosteal dissection. METHODS: Twenty-four male 7-week-old New Zealand white rabbits were divided randomly into three groups: eight control animals (untreated); eight animals undergoing supraperiosteal dissection of the left surface of the maxilla, and eight animals undergoing subperiosteal dissection of the left surface of the maxilla. All of the treated animals were operated on by the same surgeon at age of 7 weeks and sacrificed at 27 weeks together with control group animals. Seven cephalometric measures (representing aspects of maxillary length, width, and height), on the left side, were taken on the cleaned skull of the rabbits, and the results were analyzed statistically. RESULTS: No significant differences in maxillary growth were noted across the three study groups. CONCLUSIONS: The supraperiosteal or subperiosteal undermining of the anterolateral surface of the maxilla does not seem to interfere with the growth of the normal maxilla in the rabbit.

Alveolar Process↗

PubMed1999

Surgically-assisted orthopedic protraction of the maxilla in cleft lip and palate patients.

Fourteen children, aged 8 to 13 years, with unilateral or bilateral cleft lip and palate, were treated by an incomplete Le Fort I osteotomy without down-fracturing the maxilla, followed by traction of the maxilla by face mask for twelve weeks. Our results revealed a mean maxillary forward movement of 7.2 mm after three weeks of traction, followed by a retention period of nine weeks for callus maturation. There was an associated minor downward movement of the maxilla that caused a slight increase in the lower facial height, which improved the facial esthetics of the patients. The advantages of this method are: i) it allows for early skeletal advancement of the maxilla with new bone formation in the osteotomy line, ii) there is no need for inter-maxillary fixation of young patients and no need for rigid fixation of the maxilla by miniplates that can damage teeth buds and roots at this age, and iii) it can be used in young patients to improve esthetic appearance, an important factor in the psychological development of adolescents.

Adolescent↗

PubMed2001

[The growth of the maxilla in humans. What place for the premaxilla?].

INTRODUCTION: The growth of the maxilla in man is still debated. Many authors described an anterior part of the maxillary bone, called premaxilla distinct from the maxilla proper. This description referred to the existence in animals of an incisive or premaxillary bone which does not exist in man. Is this distinction pertinent in the human facial growth? MATERIAL AND METHODS: To settle this question, we performed a histologic study in eight embryos and fetuses aged from 40 days to 10 weeks post conceptional (PC) and an anatomic dissection of 3 palates of fetuses aged from 22 to 30 weeks PC. RESULTS: We found only one maxillary point of ossification, and the growth of the anterior part of the maxilla cannot be separated from the global growth of the maxilla. DISCUSSION: The independence of the anterior part of the maxilla in man is very limited during the growth and cannot justify the term of premaxilla.

Cranial Sutures↗

PubMed2003

The zygomaticus implant protocol in the treatment of the severely resorbed maxilla.

The zygomaticus dental implant, designed by NobelBiocare, was developed primarily for the treatment of the severely resorbed maxilla. Brånemark has reported an overall success rate of 97.6% with the placement of over 200 zygomatic implants during the period 1989 to 2001. There are well-defined characteristics within the patient's resorbed skeletal frame which guide the surgical placement of the zygomatic implant, thus determining whether the surgeon should use an implant with a 45 degrees or 55 degrees angulated head. This allows implant-supported restoration of the resorbed maxilla with a fixed cross arch prosthesis in the maxilla without a bone graft to the posterior maxilla. The use of a modified head angulation of 55 degrees, with implant placement as close to the crest of the edentulous ridge as possible, allows restorative clinicians to achieve an ideal restorative position in the posterior maxilla. The use of a zygomatic implant with a 55 degrees head reduces the buccal cantilever by 20%.

Bone Resorption↗

PubMedDate not supplied

Survival analysis of endosseous implants in grafted and nongrafted edentulous maxillae.

PURPOSE: The aim of this study was to analyze and compare the survival rates of endosseous implants placed in the edentulous maxillae of patients in whom bone augmentation was undertaken prior to or in conjunction with implant placement with survival rates in patients who did not undergo bone augmentation. MATERIALS AND METHODS: This study included 2 retrospective patient groups: the graft group, which included 64 patients with 437 implants, and the nongraft group, which included 118 patients with 683 implants. The patients were treated consecutively between 1990 and 1996. In addition, the retrospective patient groups were also followed prospectively using a standardized clinical and radiographic study design. RESULTS: The implant survival rate was 75.1% for the graft group and 84.0% for the nongraft group after a mean follow-up of 5 to 6 years, a statistically significant difference. However, there was no difference with regard to the prosthesis survival rate, and after reoperation, more grafted patients had a fixed prosthesis at the end of the study (87.5% versus 85.3%). Implant failure appeared to be related to the original jawbone volume in the anterior regions. In the premolar region, where the inlay graft technique was used, the implant survival rate for the graft group was comparable to that of the nongraft group. The graft group had significantly more failures than the nongraft group in the incisor region, but not in the canine, premolar, or molar regions. DISCUSSION: The majority of implant failures occurred before loading. Occlusal overload during the healing period may have been a causative factor. CONCLUSIONS: The overall implant survival rate was lower in grafted maxillae than in nongrafted maxillae after a mean of 5 to 6 years of follow-up. Analysis revealed that jawbone volume in the anterior regions at the start of treatment was directly related to implant survival rates in both groups: the greater the volume, the higher the survival rate. Moreover, the implant survival rate was similar in grafted posterior edentulous maxillae of classes V and VI and in nongrafted posterior edentulous maxillae of classes III and IV.

Adult↗

PubMed2006

[Three-dimensional changes of maxilla after rapid maxillary expansion].

OBJECTIVE: To investigate three-dimensional changes of maxilla after rapid maxillary expansion (RME). METHODS: Ten patients treated with RME were included in the study. Spiral CT images were used to evaluate three-dimensional changes of the maxilla. A three-dimensional reference frame was set up. RESULTS: (1) ANS, PNS' and PNS displaced downward and forward. ANS-PNS plane rotated clockwise in the mid-sagittal plane. ANS-PNS' plane, which represents the real position of maxilla, was not changed in the mid-sagittal plane. The palatal suture was expanded in taper shape and two halves of the maxilla rotated in the frontal plane. (2) The maxillary suture was opened wider in the middle and narrower at both ends, which was like a spindle. CONCLUSIONS: Three-dimensional changes were found after RME treatment. Spiral CT was useful in the three-dimensional evaluation of maxilla.

Adolescent↗

PubMed1989

[Studies on the development and growth of the human maxilla--special references to the anterolateral, infratemporal and orbital surfaces].

Morphological and macroscopical studies were made on the lateral surface of the human maxilla. The materials consist of 128 cases of human fetuses ranging from the fourth to the tenth month and 306 cases of human juveniles and adults. The earliest month in which the loci with the scientific name (Nomina Anatomica) of the maxilla was observed was as follows; the frontal process, zygomatic process, anterior nasal spine and the nasal notch were first observed on the fourth fetal month. The infraorbital foramen and anterior lacrimal crest were first observed in some cases on the fourth fetal month and in all cases on the fifth fetal month. The infraorbital suture, lacrimal notch and alveolar process were first observed on the fifth to the sixth fetal month. The infraorbital sulcus and infraorbital canal were first formed on the fifth to the seventh fetal month. The following loci on the lateral surface of the maxilla which are related to the development of the maxillary teeth were first observed after birth as follows; the alveolar foramina were first observed in 3 to 7 years after birth and the maxillary tuberosity was first observed in 6 to 7 years after birth. The canine fossa was first observed in 6 years after birth. As far as the development of the maxilla is concerned, the frontal process and infraorbital margin were first observed and secondly the alveolar part was observed and finally the maxilla body which involved the maxillary sinus was formed.

Adolescent↗

PubMed1993

Significance of the contour of the lateral surface of the maxilla for planning osteotomy lines in orthognathic surgery.

The Le Fort I osteotomy is one of the most frequently used procedures in orthognathic surgery. The preoperative planning of a Le Fort I osteotomy usually involves a two-dimensional lateral radiograph. On the lateral radiograph, the movement of the maxilla in the sagittal and vertical planes can be simulated, and the position of the osteotomy line in relation to the occlusion can be determined. However, the lateral radiograph consists of two dimensions, whereas, during surgery, three dimensions have to be considered. The contour of the lateral surface of the maxilla and its individual regional variations are not reflected on the lateral radiograph. Therefore, this third dimension's influence on treatment planning is investigated. Discrepancies of the position of planned osteotomy cuts are described after the transfer from two to three dimensions. Discrepancies of the positions of reference points and lines are up to 3.3 mm. Therefore, it is not possible to transfer reference points and reference lines from the lateral radiograph to the maxilla nor to move the mobilized maxilla along the planned osteotomy lines in a precise manner. It is possible to indicate the general direction of the osteotomy lines. Results of this study show the necessity for the precise control of three-dimensional positioning of the maxilla during treatment planning, cast surgery, and actual surgery.

Cephalometry↗

PubMed2005

Interventions for replacing missing teeth: dental implants in zygomatic bone for the rehabilitation of the severely deficient edentulous maxilla.

BACKGROUND: Dental implants are used for replacing missing teeth. Placing dental implants is limited by the presence of adequate bone volume permitting their anchorage. Several bone augmentation procedures have been developed to solve this problem. Zygomatic implants are long screw-shaped implants developed as a partial or complete alternative to bone augmentation procedures for the severely atrophic maxilla. One to three zygomatic implants can be inserted through the posterior alveolar crest and maxillary sinus to engage the body of the zygomatic bone. A couple of conventional dental implants are also needed in the frontal region of the maxilla to stabilize the prosthesis. The potential main advantages of zygomatic implants could be that in some situations bone grafting may not be needed and a fixed denture could be fitted sooner. Another specific indication for using zygomatic implants could be the need of maxillary reconstruction after maxillectomy in cancer patients. OBJECTIVES: To test the hypothesis of no difference in outcomes between zygomatic implants with and without bone augmenting procedures in comparison with conventional dental implants in augmented bone for severely resorbed maxillae. SEARCH STRATEGY: We searched the Cochrane Oral Health Group's Trial Register, Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE and EMBASE. We handsearched several dental journals. No language restrictions were applied. Personal contacts and all known zygomatic implant manufacturers were contacted to identify unpublished trials. Most recent search: May 2005. SELECTION CRITERIA: Randomised controlled clinical trials (RCTs) including patients with severely resorbed maxillae who could not be rehabilitated with conventional dental implants, treated with zygomatic implants with and without bone grafts versus patients treated with conventional dental implants in conjunction with bone augmentation procedures having a follow up of at least 1 year. Outcome measures considered were: prosthesis and implant failures, side effects, patient satisfaction and cost effectiveness. DATA COLLECTION AND ANALYSIS: Screening of eligible studies, assessment of the methodological quality of trials and data extraction were to be conducted in duplicate and independently by two authors. Results were to be expressed as random-effects models using weighted mean differences for continuous outcomes and risk ratio for dichotomous outcomes with 95% confidence interval. Heterogeneity was to be investigated including both clinical and methodological factors. MAIN RESULTS: No RCTs or controlled clinical trials (CCTs) were identified. AUTHORS' CONCLUSIONS: There is the need for RCTs in this area to assess whether zygomatic implants offer some advantages over alternative bone augmentation techniques for treating atrophic maxillae.

Alveolar Ridge Augmentation↗

PubMed1999

The incidence, location, and height of maxillary sinus septa in the edentulous and dentate maxilla.

PURPOSE: This study evaluated the incidence, location, and height of antral septa and demonstrates their clinical implications. MATERIALS AND METHODS: One hundred ninety-four maxillary posterior regions, subdivided into four groups (group 1, 61 clinically examined atrophic ridges; group 2, 41 anatomically examined atrophic ridges; group 3, 42 radiographically [CT] examined atrophic ridges; and group 4, 50 CT examined dentate maxillary ridges), were examined for the incidence, location, and height of antral septa. RESULTS: The incidence of antral septa was significantly greater (P<.01) in atrophic edentulous regions (groups 1, 2, and 3) than in dentate regions (group 4). However, the septa were much lower (P<.01). In atrophic maxillae, about 70% of antral septa were located in the anterior (premolar) region. CONCLUSIONS: Antral septa are more commonly found in edentulous atrophic maxillae than in dentate maxillae. The septae in edentulous atrophic maxillae are shorter than those found in dentate maxillae. When present, maxillary sinus septae are more common anteriorly than posteriorly. CT scanning is the preferred radiographic method for detecting the presence (or absence) of sinus septae. Panoramic radiography has less sensitivity and specificity than CT scanning for the detection of sinus septa.

Adult↗

PubMed1996

Fractures of the atrophic, edentulous maxilla during Le Fort I osteotomy.

The incidence of unfavorable fractures of the maxilla during Le Fort I osteotomy was compared between patients with atrophic, edentulous maxillae and patients with normal dentate maxillae. Unfavorable fractures frequently occurred in atrophic, edentulous maxillae. The most common maxillary fracture involved the junction of the horizontal plate of the palatine bone and posterior part of the maxilla. Prevention strategies and treatment options are discussed.

Adolescent↗

PubMed1993

Reexamination of the immature hominid maxilla from Tangier, Morocco.

Reexamination of the immature Upper Pleistocene hominid maxilla from Mugharet el-'Aliya (Tangier), Morocco is undertaken in light of new evidence on the growth and development of Upper Pleistocene hominids. Metric and qualitative comparisons were made with 17 immature Upper Pleistocene maxillae, and with a recent Homo sapiens sapiens sample. No unambiguous criteria for aligning the maxilla with Neandertals were found, although one character, the degree of maxillary flexion on the zygoma, strongly suggests that this child could be a representative of H.s. sapiens. The probable lack of a canine fossa in Mugharet el-'Aliya 1, the primary criterion used previously to align it with Neandertals, cannot be accurately extrapolated to its adult form from this juvenile. The present evidence suggests that it is inappropriate to refer to this fossil as "Neandertal-like" or as a North African "neandertaloid." Thus, the Tangier maxilla should not be cited as evidence for the presence of Neandertal facial features in North Africa during the Upper Pleistocene.

Age Determination by Teeth↗