Vertical Facial Dimensions Research Articles

L’oligodontie : stratégie thérapeutique à partir de 30 cas

Hypodontia is defined as the absence of at least six permanent teeth due to the hypodevelopment of tooth germs. The prevalence is weak and varies according to the ethnic origin. This familial abnormality is due to various mutations or polymorphisms of genes. It may be associated with other dental abnormalities. In children, it is responsible for growth, mastication, and phonation disorders, hypo-alveolia and lingual interposition in the toothless sites. We report the management of 30 patients presenting with oligodontia. The diagnosis was made on clinical and paraclinical data. The vertical and transversal facial dimensions, the three facial proportions, labial morphology, the number and localization of teeth, and occlusion were analyzed for future orthognathic and implant rehabilitation. The occlusion was studied transversally and vertically on dental casts. Rehabilitation with implant supported dental prostheses was chosen when conditions were met. The therapeutic protocol could include up to four chronological phases: the early prosthetic phase, the orthodontic phase, the surgical phase, and the implant and prosthetic phase. The 30 patients' age (13 male and 17 female patients) ranged from six to 20 years. An average of 15 dents were missing (6 to 28). Except for one case, all the third molars were missing. In 66% of the cases, the second molar was missing, in 33% for the first molar. In 66% of the cases, two lateral maxillary incisors were missing. There were no premolars in 50% of the patients. Agenesis of premolars and molars induced posterior bone insufficiency in the mandibula. Dysmorphosis was always present with vertical growth disorders. Six patients were not given orthodontic treatment because they did not have enough teeth. Orthognathic surgery was used in 14 cases (46.7%). Seventeen patients (56.7%) underwent apposition graft. In three patients, a high position of the alveolar nerve required nerve derivation. Implants were inserted in 14 patients (46.7%). The total number of implants was 155. Rehabilitation with implant supported dental prostheses is a good treatment for oligodontia. It requires an interdisciplinary approach (including a maxillo-facial surgeon, an orthodontist, a dentist, and a prosthesis specialist). The patient's motivation as well as that of his family is crucial.

Overbite and Vertical Facial Dimensions in Terms of Muscle Balance

Abstract No Abstract Available. * From the Division of Orthodontics, College of Dentistry, University of California. Read before the Internation Association for Dental Research, Chicago, March 19, 1944.

Treatment effects of mini-implants for en-masse retraction of anterior teeth in bialveolar dental protrusion patients: A randomized controlled trial

The purpose of this randomized controlled trial was to quantify the treatment effects of en-masse retraction of anterior teeth with mini-implants as anchor units in bialveolar dental protrusion patients undergoing extraction of all 4 first premolars. A total of 40 patients (mean age, 17.5 years; SD, 3.2 years) were randomly assigned either to group 1 (G1), anterior space closure with mini-implants as anchor units, or group 2 (G2), anterior space closure with conventional methods of anchorage (without mini-implants). Skeletal, dental, and soft-tissue changes were analyzed in both groups on lateral cephalograms taken before retraction and after space closure. Student paired and unpaired t tests were used to analyze the treatment changes in the 2 groups. For the skeletal parameters, a statistically significant decrease in the facial vertical dimensions was seen in G1, but the variables in G2 showed no significant differences (P >0.05). Anchorage loss, in both the horizontal and vertical directions, was noted in G2, whereas G1 showed distalization (anchorage gain) and intrusion of molars. Although the soft-tissue response was variable, facial convexity angle, nasolabial angle, and lower lip protrusion had greater changes in G1. No differences were found in the amount of upper lip retraction between the groups (P >0.05). Mini-implants provided absolute anchorage to allow greater skeletal, dental, and esthetic changes in patients requiring maximum anterior retraction, when compared with other conventional methods of space closure. The treatment changes were favorable. However, no differences in the mean retraction time were noted between the 2 groups.

Vertical Facial Dimensions Linked to Abnormal Foot Motion

Twenty-two children from Jiutepec, Mexico, were studied to determine whether a correlation exists among foot motion, the position of the innominates, and vertical facial dimensions (ie, the distances between the outer corners of the eyes [the exocanthions] and the ipsilateral outer margins of the lips). Three null hypotheses were constructed and tested using the one-sample t test. Hypothesis A: there is no relationship between abnormal foot pronation and hip position; Hypothesis B: there is no relationship between hip position and vertical facial dimensions; and Hypothesis C: there is no relationship between abnormal foot pronation and vertical facial dimensions. The three null hypotheses were rejected. An ascending foot cranial model was theorized to explain the findings generated from this study: 1) due to the action of gravity on the body, abnormal foot pronation (inward, forward, and downward rotation) displaces the innominates anteriorly (forward) and downward, with the more anteriorly rotated innominate corresponding to the more pronated foot; 2) anterior rotation of the innominates draws the temporal bones into anterior (internal) rotation, with the more anteriorly rotated temporal bone being ipsilateral to the more anteriorly rotated innominate bone; 3) the more anteriorly rotated temporal bone is linked to an ipsilateral inferior cant of the sphenoid and superior cant of the maxilla, resulting in a relative loss of vertical facial dimensions; and 4) the relative loss of vertical facial dimensions is on the same side as the more pronated foot.

Longitudinal study of facial skeletal growth completion in 3 dimensions

Previous authors have suggested that transverse facial skeletal growth is completed before either anteroposterior or vertical growth and that anteroposterior growth is completed before vertical growth. Our purpose in this study was to examine this concept. Twenty-four subjects (11 male, 13 female) who had annual lateral and posteroanterior cephalograms up to and including age 17 or 18 and again at age 25 or older were identified from the Iowa Facial Growth Study. Transverse, anteroposterior, and vertical facial dimensions were measured longitudinally into adulthood by using key skeletal landmarks. Descriptive statistics were calculated, and nonparametric Wilcoxon signed rank tests were performed separately for the sexes to determine the age at which each anteroposterior, vertical, and transverse growth variable reached adult size. For both sexes, an overlap exists at any age in the amount of growth completed for the various measurements in the transverse, anteroposterior, and vertical dimensions. Although some transverse measures (cranial width and interjugal width) attain adult size before any anteroposterior or vertical ones, there is evidence of continued growth for other transverse parameters (interzygomatic width and intergonial width). A similar overlap is seen in the anteroposterior and vertical dimensions. A distinct separation, by time and dimension, is not seen in the amount of facial growth completed during development. Instead, a dramatic spread and an overlap of growth curves are observed throughout the developing years.

Three-dimensional bimetric maxillary distalization arches compared with a modified Begg intraoral distalization system

The purpose of this study was to compare the dentofacial effects of two intraoral molar distalization techniques [three-dimensional bimetric maxillary distalization arches (3D-BMDA) and a modified Begg intraoral distalization system (MBIDS)] in subjects requiring maxillary molar distalization. Twenty-one patients (12 females and 9 males, mean age pre-treatment: 14.7 +/- 1.50 years) were treated with the 3D-BMDA and 17 (14 females and 3 males, mean age pre-treatment: 14.4 +/- 1.43 years) with the MBIDS. Measurements were recorded from lateral cephalometric radiographs taken at two different points in time: at the start of treatment for the MBIDS group and prior to distalization for the 3D-BMDA group (T1) and post-distalization (T2). Student's t- and paired t-tests were used to determine differences between and within the groups. The total amount of distalization for the 3D-BMDA and MBIDS groups was similar (3.55 and 3.27 mm, respectively). However, there were statistically significant differences in the length of the distalization period (3.4 and 6.5 months, respectively) and the amount monthly of distalization (1.11 and 0.54 mm, respectively). The most significant differences were observed in the mandibular dental arches and vertical facial dimensions. Anchorage loss in the mandible was greater in the 3D-BMDA group, whereas increases in facial dimensions were greater in the MBIDS group. Both 3D-BMDA and MBIDS techniques were found to be effective to obtain distal movement of the maxillary molars. In order to achieve successful results, the side-effects of each treatment modality on dentofacial structures need to be taken into consideration.

Effects of the reciprocal mini-chin cup appliance

The aim of this prospective study was to evaluate the dentofacial effects of the reciprocal mini-chin cup (RMCC) appliance in subjects with pubertal growth and development potential (group 1) and in subjects that had completed this period (group 2). Eighteen patients (13 females, five males) with an Angle Class II division 1 and nine patients (six females, three males) with a Class II division 2 malocclusion, with mandibular dentoalveolar retrusion and optimal vertical facial dimension were included. A control group consisting of 14 subjects (nine females, five males) with pubertal growth and development potential was constructed for comparison with group 1. In both treatment groups a RMCC was used. A Class I molar relationship was achieved in an average period of 5.11 months in group 1 and 10.57 months in group 2. From lateral cephalometric tracings, beside the angular and linear parameters, eight parameters that determined the ratio of the skeletal and dental effects of RMCC were measured and statistically evaluated. A paired comparison t-test was used to assess the differences in each group and a Student's t text to evaluate the differences between the groups. In both groups, no effect of RMCC was found on either the maxilla and/or the sagittal position of the mandible. In group 1, lower anterior face height was increased more compared with group 2; the mandibular plane angle increased and the mandible developed mostly in the vertical dimension. While a Class I molar relationship and correction of the overbite and overjet were achieved in both groups, a greater correction of overjet was found in group 1. Retrusion of the upper incisors without extrusion, protrusion, or proclination of the lower incisors, distalization of the upper molars, mesialization and extrusion of the lower molars and mesialization of the mandibular dentoalveolar structures were observed in both groups. Contributions to the correction of overjet and molar relationship were mostly dentoalveolar in both groups.

Evaluation of changes in the vertical facial dimension with different anchorage systems in extraction and non-extraction subjects treated by Begg fixed appliances: a retrospective study

The aim of the study was to evaluate and compare the effects of mesial movement of the maxillary and mandibular molars on the facial vertical dimensions following orthodontic treatment. Patients with an Angle Class I malocclusion were treated by four first premolar extractions and Begg fixed appliances (moderate and maximum anchorage groups), while those with an Angle Class II malocclusion were treated by Begg intraoral distalization mechanics without extractions (distalization group). Following treatment, the patients were grouped according to the mesial movement of the mandibular first molars and compared with an Angle Class I control group. All groups comprised 15 patients, their mean pre-treatment ages were 14.95 years for the moderate (13 females, 2 males), 14.88 years for the maximum (13 females, 2 males), 14.41 years for the distalization (10 females, 5 males), and 14.38 years for the control (13 females, 2 males) groups. Lateral cephalometric measurements were performed at two time points (T(1): pre-treatment/control, T(2): post-treatment/control). A paired t-test was used for within-group comparisons and non-parametric Kruskal-Wallis and Dunn's multiple-comparison tests to determine any differences. The increases in anterior and posterior face heights were similar between groups. The mandibular plane angle (SN/GoGn) was increased in all treatment groups, while it decreased in the control group. Although SN/GoGn increased more in the distalization and less in the moderate anchorage groups, these differences were not statistically significant. The change in SN/GoGn was significantly different only between the distalization and control groups. Facial vertical dimensions were not significantly affected by the amount of mesial movement of the molar teeth.

A controlled clinical trial of the effects of the Twin Block and Dynamax appliances on the hard and soft tissues

The aim of this controlled trial was to identify and quantify skeletal, soft tissue and dental changes during treatment, and immediately post-treatment with Twin Block (TB) or Dynamax appliance using the techniques of three-dimensional (3D)optical surface laser scanning, cephalometric, and clinical measurements. Sixty-two Caucasian subjects, 36 males aged 11-14 years and 26 females aged 10-13 years were enrolled in the study. The patients were placed in two groups, matched for gender and age and subsequently allocated randomly for treatment with either a TB or Dynamax appliance. Active treatment lasted 9 months followed by 3 months' post-treatment observation. Laser scanning and clinical measurements were taken at 3-monthly intervals and final cephalometric records after 12 months. Statistical analysis was performed using Wilcoxon's matched-pairs signed-rank tests. The non-compliance rates were the same for both groups (9 per cent), but a greater incidence of breakages was found in the Dynamax group. The TB was found to produce slightly more antero-posterior skeletal change, median ANB reduction, TB=2 degrees, Dynamax 1.1 degree (P=0.006), and similar forward movements of the chin and was associated with larger increases in the vertical facial dimension, median total anterior face height increase; TB=3.2 mm, Dynamax = 2.8 mm (P=0.03). The soft tissue vertical cephalometric increases were 3.6 mm with the TB, 2.0 mm with the Dynamax (P=0.036), and with laser scanning 5.05 and 2.6 mm, respectively, a difference which is likely to be more clinically relevant. The median post-treatment changes in soft tissue pogonion were -0.65 mm in the TB and +0.22 mm in the Dynamax group. The optical surface scanning mark and measure system is a valid method for quantifying soft tissue changes.

Tooth Wears and Dentoalveolar Compensation of Vertical Height

ABSTRACTThe present study aims to determine differences in vertical facial dimensions as a result of dental wear.The study consisted of 20 subjects with vertical tooth wear. The mean age of sample was 52.4 years. The control group consisted of 20 dental school students. The mean age of control group was 22 years (subjects with severe malocclusion or tooth wear were not included). All subjects' cephalometric and panoramic radiographs were taken from natural head posture. Dentoalveolar height was recorded as in the maxilla and in the mandible on the both cephalometric and panoramic radiograph. Result of the cephalometric measurements showed that significant differences lower face height (ANS-Me), lower dentoalveolar height (Ii- MP) between the groups (p <0,001). Upper dentoalveolar height (Is-PP) and total face height (N-Me) was greater than control group (p<0,01).According to the result of panoramic measurement dentoalveolar compensatory of samples was greater than control group in mandibuler premolar area (p<0,05).We found out that dentoalveolar structure is compensating the loss of vertical height when there is the severe occlusal tooth wears.

Myosin heavy chain isoform composition of human masseter muscle from subjects with different mandibular plane angles

Abstract Aim To investigate the presence of myosin heavy chain isoforms in human masseter muscle and to describe any differences in orthognathic surgery patients with different mandibular plane angles. Method Biopsies were obtained from the anterior border of the superficial masseter muscle in 18 patients undergoing various orthognathic procedures. Myosin heavy chain isoforms were isolated and analysed by SDS-PAGE gel electrophoresis. Steiner’s mandibular plane angles were measured from pretreatment lateral cephalometric radiographs and used to classify the vertical dimension of each subject. Results Despite the fact that there was wide individual variation, there appeared to be no direct association between the presence of myosin heavy chain isoforms and specific vertical facial patterns. Type I myosin heavy chain isoform was the most common isoform found in all subjects. More Type IIA myosin heavy chain isoforms were observed in dolichofacial subjects. There were no differences between genders in myosin heavy chain expression. Conclusion A wide variation of myosin heavy chain isoforms exists in the masseter muscle of individuals with different mandibular plane angles. Further investigations involving larger sample sizes and the incorporation of bite-force measurements may help to clarify the relationship between mandibular muscle characteristics and the vertical facial dimension.

The Importance of Masticatory Muscle Function in Dentofacial Growth

Masticatory muscle function and its influence on craniofacial growth have been investigated in animal experiments and clinical studies. These investigations commonly show that the elevator muscles of the mandible influence transverse and vertical facial dimensions. Increased loading of the jaws associated with masticatory muscle function increases sutural growth and stimulates bone apposition, resulting in greater transverse growth of the maxilla and broader bone bases for the dental arches. Furthermore, an increase in masticatory muscle function is often associated with an anterior growth-rotation pattern and well-developed angular, coronoid, and condylar processes in the mandible. One interesting point that has not been thoroughly discussed is that individuals with strong masticatory muscles have a more homogeneous facial morphology, in contrast to individuals with weak masticatory muscles who show great interindividual variation in their vertical facial dimensions. Thus, individuals with strong masticatory muscles usually have a hypodivergent facial type, although not all individuals with hypodivergent facial form have strong masticatory muscles. The literature supports the hypothesis that a certain level of masticatory muscle strength may be sufficient for normal vertical craniofacial growth, though it is not a prerequisite.

First or second premolar extraction effects on facial vertical dimension.

If the concept of mesial movement of molars to reduce the "wedge effect" and decrease facial vertical dimension (FVD) is valid, it is important to investigate the effect of first (P1) and second premolar (P2) extraction on FVD. This study compares the mesial movement of molars and changes in FVD between P1 and P2 extraction groups in Class I malocclusion with a hyperdivergent facial type. We compared 27 cases with maxillary and mandibular P1 extractions (group 1) and 27 cases with maxillary and mandibular P2 extractions (group 2). To determine FVD changes due to treatment and to compare differences between two groups, paired t-test and independent t-test were performed, respectively. Group 2 showed more mesial movement of the maxillary and mandibular first molars and less retraction of the maxillary and mandibular central incisors than group 1 (P < .05). Both groups showed increased anterior facial height (P < .05), but there were no statistically significant differences in angular and proportional measurements between pre- and posttreatment. There was no significant difference in the amount of FVD change between groups 1 and 2 except in the maxillomandibular plane angle and SN to palatal plane angle (P < .05). These results suggest that there is no decrease in FVD regardless of the maxillary and mandibular P1 or P2 extraction. Therefore, the hypothesis that P2 extraction in hyperdivergent facial types will result in mesial molar movement and decrease FVD by reducing the wedge effect is invalid.

Three-dimensional assessment of the relative contribution of genetics and environment to various facial parameters with the twin method

The purpose of this prospective study was to help distinguish the relative contributions of heredity and environment to the external facial features and to assess the relative strength of the genetic influence on anteroposterior and vertical facial parameters, by using 3-dimensional optical surface scanning and the inferential twin method. The subject group consisted of 10 pairs of monozygotic twins (5 male, 5 female, mean age 11.9 years), 10 pairs of same-sex dizygotic twins (3 male, 7 female, mean age 12.1 years), and 6 mixed-sex dizygotic twin pairs. Two methods of analysis were used on the 3-dimensional scans. Interlandmark measurements of 28 facial parameters were recorded, and the mean intrapair differences for each parameter were compared between the monozygotic and dizygotic groups. The second method used the analysis of surface shape for all twin pairs. This technique characterizes the face by using 9 surface shapes distinguished visually by color, allowing a qualitative description of the differences between monozygotic and dizygotic twin pairs. Analysis of the 28 facial parameters showed significant ( P< .05) genetic determination for midfacial parameters, especially left eye width, intercanthal width, nose height, and nose width. Analysis of surface shape showed the strongest genetic determination for a triangular area of the midface encompassing the orbital rims, intercanthal area, and nose. The concordance for vertical and anteroposterior facial parameters was found to be greater in monozygotic twins than in dizygotic twins. The concordance for vertical facial dimensions of the middle and lower anterior parts of the face was found to be greater than that for anteroposterior facial dimensions in monozygotic twins.

Lip curve changes in females with premolar extraction or nonextraction treatment.

Changes in lip curvature resulting from treatment have been largely ignored in orthodontic literature. The focus instead has been primarily directed at retraction of the vermilion border and changes in the nasolabial angle. This study, therefore, was designed to retrospectively analyze changes in the upper and lower lip curves associated with growth and treatment. The lateral cephalometric records of 137 female orthodontic patients were digitized. Sixty-two were treated with premolar extractions and 75 without extractions. The overall extraction group was further divided into subgroups on the basis of the chosen extraction sequence, which included extraction of 4/4, 4/5, or 5/5. Statistical analysis revealed no significant differences in changes in lip curve depth between the two overall samples, relative to either of the two reference lines. This would suggest that an appropriately selected plan, whether extraction or nonextraction, should allow treatment to be carried out without negative effects on the curvature of the lips. Calculation of correlation coefficients and regression analysis suggested that the inherent properties and morphology of the soft tissues themselves are probably the greatest determinants of lip curve behavior with treatment. The midface soft tissues appear to be less dependent on changes in the underlying hard tissues than do the lower face soft tissues. Pretreatment upper and lower incisor positions and angulations and the underlying vertical facial dimension appear to play more significant roles in the behavior of the lower lip than the upper lip.

Biomechanical considerations in themanagement of the vertical dimension

The vertical dimension may be altered purposefully or unintentionally during therapy by dental extrusion, intrusion, growth modification, or orthognathic surgery. Vertical changes result in the mandible rotating either open or closed with corresponding alterations in interarch dental relationships, facial esthetics, and lip and tongue function. The biomechanics involved in the treatment of patients who exhibit an anterior open bite or a deep overbite related to excessive or deficient vertical facial dimensions are discussed.

Biomechanics of deep overbite correction

Correction of deep overbite can be accomplished in different ways depending on the treatment goals chosen for individual patients. The 2 primary methods of correction are intrusion of anterior teeth or extrusion of posterior teeth. Successful intrusion of the incisors depends on careful control of the force system used. Low force magnitude, force constancy, a properly selected single point of force application, and control of force direction are all important factors to consider. The design of the intrusion arch may be continuous, or a 3-piece intrusion arch may be selected depending on the needs of the patient. Alternatively, extrusion of posterior teeth may be indicated in patients who are still actively growing and who have short vertical facial dimensions.

Maxillary Distraction Osteogenesis: A Two-Dimensional Mathematical Model

Patients with cleft lip and palate with severe maxillary retrusion usually have a mandible with anterior-superior autorotation and subsequent overclosure and loss of the vertical facial dimension. Maxillary distraction osteogenesis can correct the sagittal maxillomandibular relationship and should simultaneously reestablish vertical dimension through maxillary vertical height increase and clockwise rotation of the mandible to restore facial balance. We present a two-dimensional mathematical model in the sagittal plane, which reestablishes sagittal and vertical skeletal deficiencies and proper occlusal alignment for planning maxillary advancement with distraction osteogenesis in patients with cleft lip and palate. The model is illustrated in a case of a 13-year-old boy with a complete bilateral cleft lip and palate and severe maxillary retrusion. The two-dimensional mathematical model described in this article allows the surgeon and orthodontist to calculate in a simple and accurate way the ideal distraction vector to advance the maxilla to its desired position.

Contribution of jaw muscle size and craniofacial morphology to human bite force magnitude.

The existence of an interaction among bite force magnitude, jaw muscle size (e.g., cross-sectional area, thickness), and craniofacial morphology is widely accepted. Bite force magnitude depends on the size of the jaw muscles and the lever arm lengths of bite force and muscle forces, which in turn are dictated by craniofacial morphology. In this study, the relative contributions of craniofacial morphology and jaw muscle thickness to the bite force magnitude were studied. In 121 adult individuals, both magnitude and direction of the maximal voluntary bite force were registered. Craniofacial dimensions were measured by anthropometrics and from lateral radiographs. The thicknesses of the masseter, temporal, and digastric muscles were registered by ultrasonography. After a factor analysis was applied to the anthropometric and cephalometric dimensions, the correlation between bite force magnitude, on the one hand, and the "craniofacial factors" and jaw muscle thicknesses, on the other, was assessed by stepwise multiple regression. Fifty-eight percent of the bite force variance could be explained. From the jaw muscles, only the thickness of the masseter muscle correlated significantly with bite force magnitude. Bite force magnitude also correlated significantly positively with vertical and transverse facial dimensions and the inclination of the midface, and significantly negatively with mandibular inclination and occlusal plane inclination. The contribution of the masseter muscle to the variation in bite force magnitude was higher than that of the craniofacial factors.

Craniofacial structure of Japanese and European-American adults with normal occlusions and well-balanced faces

The purpose of this study is to compare two groups of adults from different races who were selected on the basis of having normal (“ideal”) occlusions and well-balanced faces. The lateral cephalometric radiographs of 54 Japanese adults (26 men and 28 women) were compared with a sample of 125 adults (44 men and 81 women) of European-American ancestry. The samples were chosen by orthodontists of the same racial background as the sample selected. Each lateral cephalogram was traced and digitized, and differences between cephalometric measurements between groups were analyzed with completely randomized t tests. In comparison to the European-American sample, the Japanese sample, in general, was smaller in anteroposterior facial dimensions and proportionately larger in vertical facial dimensions. The facial axis angle was more vertical in Japanese subjects, indicating a more downward direction of facial development. On average, the subjects in the Japanese sample were more protrusive dentally, with a more acute nasolabial angle and a greater tendency toward bilabial protrusion. These differences, evident even in groups with so-called “well-balanced faces”, indicate that fundamental variation exists in the craniofacial structure of Japanese and European-Americans. The results of this study support the premise that a single standard of facial esthetics is not appropriate for application to diverse racial and ethnic groups. (Am J Orthod Dentofac Orthop 1996;110:431-8.)