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Background: Mandibular malpositioning may result in an abnormal concentration of stresses within the temporomandibular joint (TMJ) in adult rats, which may further lead to a series of pathological changes, such as articular cartilage wear, subchondral bone sclerosis and osteophyte formation. However, the pathological and adaptive changes in condylar cartilage caused by different stress distributions are still controversial., Objective: The aim of this study was to observe the effect of sagittal changes in mandibular position on condylar cartilage by changing the occlusal vertical dimension (OVD) in adult rats., Methods: Fifteen-week-old female rats were divided into three groups: control (CON), increased OVD (iOVD) and loss of occlusion (LO) groups. An occlusal plate and tooth extraction were used to establish the animal model. TMJ samples of the experimental and CON groups were observed and investigated by bone morphological, histomorphological and immunohistochemical staining analyses at 3 days, 1 week, 2 weeks, 4 weeks and 8 weeks. Weight curves were plotted., Results: Micro-computed tomography showed that, compared with the CON group, cartilage destruction followed by repair occurred in both experimental groups, which was similar to the trend observed in haematoxylin-eosin staining. All experimental results for the iOVD group showed an approximately similar time trend. Compared with the iOVD group, the toluidine blue and immunohistochemical staining results in the LO group showed no obvious change trend over time., Conclusion: Compared with occlusal loss, an increase in OVD caused faster and more severe damage to condylar cartilage, and subchondral bone repair occurred later., (© 2024 John Wiley & Sons Ltd.)

Background: The temporomandibular joint (TMJ) disc plays a role in joint movement and in load absorbance and distribution. An experimental unilateral anterior crossbite (UAC) prosthesis induces mandibular condylar cartilage degeneration in rats. However, the changes in the articular disc are still unknown., Objective: To describe changes in the TMJ discs of UAC rats., Methods: The discs of fifty-four Sprague-Dawley rats, equally distributed into a UAC group and an age-matched sham-operated control group at 4, 12 and 20 weeks (n = 9), were evaluated by gross and histomorphological observation and by detection at the mRNA or protein expression levels of the markers related to the matrix elements., Results: No macro- or micro-morphological differences were observed between groups. However, there were catabolic degradative changes at the molecular level in the UAC group, showing a significant reduction in the mRNA and/or protein expression levels of many molecules. The reduction became worse with time (P < 0.05). The reduced molecules included: (a) those related to the extracellular matrix, such as type I collagen, decorin and fibromodulin; (b) those related to chondrogenesis, such as type II collagen and aggrecan; and (c) those related to osteogenesis, such as alkaline phosphatase and runt-related transcription factor 2. The mRNA expression of vascular endothelial growth factor did not change. In contrast, fibronectin, which can promote wound healing, and its N-terminal fragment, which can induce cartilage degradation, were accumulated (P < 0.05)., Conclusion: TMJ discs were stimulated to catabolic changes by the aberrant dental occlusion and seemed to go to inanimate with time., (© 2018 John Wiley & Sons Ltd.)

Temporomandibular joint (TMJ) displays a high remodelling capability. The current purpose was to investigate the differences between mandibular condylar remodelling responses of growing mice to installation and removal of unilateral anterior crossbite (UAC) prosthesis. Twenty-four mice were divided into one mock control group and two UAC groups. Unilateral anterior crossbite was created by installing a pair of prosthesis to left-side maxillary and mandibular incisors. Unilateral anterior crossbite was removed in removal group at 3 weeks but remained in UAC group. Temporomandibular joints were sampled at 7 weeks. Changes in condylar cartilage and subchondral bone were assessed by histology and in vivo micro-CT. Real-time PCR and immunohistochemistry were performed to evaluate expression changes in ADAMTS-5, MMP-3, MMP-9, MMP-13, IL-1, TNF-α, OPG and RANKL. Statistical analysis was performed at α = 0.05. Temporomandibular joint cartilage degradation was induced by UAC as previously reported but was reversed by removal of UAC. The dropped cartilage thickness, chondrocyte number and collagen II-positive area, the increased expression levels of Adamts-5, Mmp3, 9, 13, Tnf-α and Il-1β in cartilage, the decreased ratio of OPG/RANKL in both condylar cartilage and subchondral bone, the loss of TMJ subchondral bone and the increase in the TRAP-positive cells in subchondral bone were all reversed in the removal group (P < 0.05). The growing mouse TMJ condyle displays a high remodelling capability which can be degenerative and rehabilitative, respectively, in response to placement and thereafter removal of the aberrant prosthesis. Eliminating aberrant prosthesis is helpful to promote the degraded condyle to recover., (© 2015 John Wiley & Sons Ltd.)

Although a shortened dental arch has been reported to provide sufficient subjective chewing ability, the loss of molar occlusion significantly reduces trituration ability, and may result in an impaired digestive function including delayed gastric emptying. This study investigated the effect of the experimental loss of molar occlusion on gastric emptying rate. Thirteen healthy dentate males underwent two sessions of gastric emptying rate measurement after ingestion of the same test meal that contained ham, bread and an egg mixed with carbon-labelled octanoic acid. A test food was divided into nine equal portions, and each was consumed in 60 cycles of chewing. In one of the two sessions, the subjects wore an intraoral appliance devised to simulate the occlusal conditions of the shortened dental arches. Two parameters of gastric emptying; namely, the lag phase (T(lag)) and gastric half-emptying time (T(1/2)), were evaluated by means of a (13)C-octanoic acid breath test. Following the measurement of gastric emptying in each session, masticatory performance was evaluated by a conventional sieve test. Masticatory performance decreased significantly in case of loss of molar occlusion (78.1 +/- 11.1% versus 33.4 +/- 18.2%, P <0.001); however, no significant changes were observed in terms of the gastric emptying parameters (T(lag): 99 +/- 19 versus 105 +/- 34 min; T(1/2): 168 +/- 32 versus 178 +/- 48 min). Within the limitations of this study, it was concluded that reduction in food trituration caused by shortening of the dental arch does not significantly affect gastrointestinal digestive function.

The need and demand for replacement of missing posterior teeth may increase as the UK population is predicted to be at least partially dentate for life. Replacement with either fixed or removable prostheses may be indicated, and the tooth positional changes of adjacent or opposing teeth may require consideration. The objectives of this study are to: (1) Investigate the extent of overeruption associated with partially opposed posterior teeth; (2) Determine if overeruption is associated with tipping of the partially opposed tooth and examine the extent of tip. Ninety-one patients with either partially or completely unopposed posterior teeth were included in the study. For each group the extent of overeruption of the tooth was measured. Differences in the extent of overeruption and tipping were analysed. Correlations between the presence of partial tooth contact and the extent of overeruption and degree of tipping of the unopposed tooth were analysed. There was no significant difference in the extent of overeruption between the unopposed and partially opposed groups. The partially opposed teeth displayed a greater degree of tipping than the unopposed group. There was no significant correlation between the extent of overeruption and the degree of tipping, nor between the extent of overeruption and the presence of partial tooth contact. There was, a significant correlation between the degree of tooth tip and the presence of partial tooth contact. (1) Partial tooth contact does not appear to prevent or reduce overeruption; (2) Partially opposed teeth show an increased degree of tip relative to teeth with complete lack of occlusal contact. The findings suggest that partial tooth contact should not be relied on clinically to maintain vertical tooth position.

Floating-Harbor syndrome is a rare genetic disorder of unknown aetiology. It was described for the first time in 1973. The syndrome is characterized mainly by short stature, delay in speech development and characteristic facial features. This article describes a report of a case of the syndrome and emphasizes the oral aspects, including descriptions of soft tissues, teeth, occlusion, stage of dental development and findings on examination of the temporomandibular joint. The treatment provided and its outcome is also described. Hopefully this information will be compared with findings from other patients in the future to assist in clarifying the phenotype of the Floating-Harbor syndrome.

The morphologic characteristics of the dentition with maxillary prognathism and reversed occlusion were examined by a computer-assisted dental cast analysing system. Dental casts with normal occlusion, maxillary prognathism and reversed occlusion were selected and measured by a 3D shape measuring system. The dental arches and anteroposterior occlusal curves were approximated numerically by the polynomial expression with a fourth order and second order coefficients, respectively. The coefficients were analysed statistically. Maxillary dental arches with mandibular prognathism showed a more acuminate shape (V-shape) with a significant larger second order coefficient, while arches with reversed occlusion showed more angulate shapes (U-shape) with significantly smaller second order coefficients compared with arches with normal occlusions. However, a notable difference in the shape of the mandibular dental arches was not observed. The mandibular dental arches with maxillary prognathism were positioned backward relative to maxillary dental arches, while the arches with reversed occlusion were positioned forward. The anteroposterior occlusal curves with maxillary prognathism showed larger curvatures in maxilla and mandible, while the curves with reversed occlusion showed smaller curvatures in mandible comparing with the curves with normal occlusion. These results suggest that the present method could offer a useful and objective examination technique for the diagnosis of malocclusion.

The aim of this study was to investigate the relationships between occlusal curvature (OC) and frontal craniofacial morphology in patients with and without temporomandibular disorders (TMD), using frontal cephalograms and a sophisticated measuring device (XYZAX S400A). Thirty-seven female orthodontic patients (mean age 24.0 years) were divided into a TMD group (n = 25) and no-TMD group (n = 12). In the TMD group, the lateral OCs of the mandibular second premolar, and first and second molars were significantly deeper on the deviated side than on the non-deviated side, and the anteroposterior OCs of the mandibular second premolar and first molar were also significantly shallower on the deviated side. In the no-TMD group, however, there were no significant differences in OCs between deviated and non-deviated sides. The differences between right and left lateral OCs in the mandibular second premolar and first and second molars, as well as the anteroposterior OCs in the mandibular first and second molars, showed significant correlations with mandibular deviation in the TMD group. On the other hand, in the no-TMD group, there was no significant correlation between OCs and mandibular deviation. The above results suggest that OCs might try to compensate for mandibular deviation in patients with TMD.

The aim of this study was to investigate the relationship between orientation of craniofacial planes relative to the true horizontal and temporomandibular disorder (TMD), in normal occlusion. Fourteen university dental students, with full natural dentition and bilateral Angle Class I occlusion, who exhibited signs and symptoms of TMD, were compared with 14 age- and sex-matched healthy controls. Frontal and lateral photographs were taken in natural head position with the subject standing up, clenching a Fox plane and having a facial arch positioned. Photographs were examined by a standardized image analysis. Inter-pupillary axis, Frankfurt, occlusal and Camper planes were evaluated. In frontal view, the Frankfurt plane was right rotated relative to the true horizontal both in TMD subjects (P < 0.01) and controls (P < 0.05), but rotation was larger in TMD subjects (mean difference between groups, 1.1 degrees, 95% confidence interval, 95% CI, 0.2-2.0 degrees ). No significant deviation from the horizontal or difference between groups was observed for the interpupillary axis and occlusal plane. In lateral view, the Frankfurt plane was upward-orientated relative to the true horizontal in TMD group (mean angular deviation 2.8 degrees, 95% CI, 1.0-4.6 degrees ). The occlusal and Camper planes were downward-orientated in both groups (P < 0.0001), but inclination of occlusal plane tended to be smaller in TMD subjects (mean difference between groups, -3.8 degrees, 95% CI, -7.6-0.1 degrees ). Angles between any craniofacial planes did not significantly differ between groups. The findings show that in young adults with normal occlusion, a weak association exists between the orientation of craniofacial planes in natural head position and signs and symptoms of TMD. Furthermore, they suggest that, within this population, TMD might be mainly associated with head posture rather than with craniofacial morphology.

The aim of this study was to describe the distribution of occlusal contacts in subjects with signs or symptoms of temporomandibular disorder (TMD), and to assess whether any difference exists with healthy subjects. Twenty-five university dental students with complete natural dentition who exhibited TMD (13 females and 12 males, age from 19 to 30 years) and 25 age- and sex-matched controls entered the study. Occlusal contacts were evaluated in the intercuspal position and wax registrations were made in all subjects. Occlusal contacts were classified according to location and intensity. No differences were found between TMD and control groups for the overall number and distribution of contacts or for any side and intensity of contact. An intra-subject analysis showed that TMD subjects had significantly greater bilateral asymmetry in the number of contacts than controls. Median absolute difference of the number of contacts on right and left sides was 3 (95% CI, 2-4) in TMD subjects and 2 (95% CI, 1-2) in controls. In TMD subjects with mono-lateral TMD there was a significant concordance (88.9%) between the side of disorder and the side of higher number of contacts. These findings, while confirming that a significant relationship exists between distribution of occlusal contacts and TMD, further suggest that in young adults it may be primarily expressed by asymmetries in occlusal contact patterns. Existence and aetiology of any association of TMD with occlusal contacts should be further investigated.

The purpose of this study was to investigate the relationship between the disc positions of temporomandibular joints (TMJ), the vertical and lateral mandibular displacement (VMD and LMD, respectively) and age in female adolescents with signs and symptoms of the temporomandibular disorders (TMD). The VMD and LMD were assessed, using posteroanterior (PA) cephalograms. The disc positions were assessed by magnetic resonance imaging (MRI) and categorized as follows: normal disc position, functional disc displacement and functional disc dislocation. Excluding patients with osteoarthritis, the total number of subjects was 54 female adolescents who were grouped into three: the bilateral normal disc position group, the unilateral or bilateral functional disc displacement group, and the unilateral or bilateral functional disc dislocation group. We compared the extent of VMD and LMD between the three groups, and investigated their correlation with age. Results indicate that functional disc displacement and dislocation are related to mandibular displacement, and VMD did not correlate with age but LMD did correlate with age. This study suggests that the onset of disc displacement is related to the mandibular displacement and disturbs normal growth of the mandible three-dimensionally.

The purpose of this study was to evaluate whether the path of habitual mouth opening was influenced by anterior reverse bite malocclusion in children. Two groups of children with the primary dentition were chosen: (i) 10 children with anterior reverse bite (reverse bite group) and (ii) 10 with normal occlusion (normal occlusion group). Their habitual mouth opening movements were measured by an opto-electronic movement-analysing system with 6 d.f. at a sampling rate of 100 Hz. These movements were projected on the sagittal plane at the incisal and condylar points. To characterize the path, we used the angles between the path and the horizontal plane. In the initial stage of opening, the incisal path of the reverse bite group was displaced more posteriorly from the intercuspal position than that of the normal occlusion group. However, as opening continued, the direction of the path of the reverse bite group was more anterior than those of the normal occlusion group. During the entire opening movement, the condylar path of the reverse bite group was flatter than those of the normal occlusion group. In conclusion, it was demonstrated that anterior reverse bite in the primary dentition clearly affects the paths of habitual opening movements.

This study investigated mandibular displacements during clenching in the lateral mandibular position in relation to lateral occlusal relationships. Twelve healthy human subjects (mean=26.7 years) volunteered for this study. Acrylic occlusal devices were fabricated for the lower working-side canine, working-side second molar and balancing-side second molar in order to simulate a dominant canine guidance, working-side interference (WI), balancing-side interference (BI) and bilateral balanced occlusion (BO). Vertical displacements of the mandible were recorded by linear variable differential transformers during submaximal clenching in the right lateral position. The four experimental occlusal conditions were revealed to have a significant effect on mandibular displacement patterns (ANOVA, P < 0.001). A dominant canine raiser caused a mandibular elevation with the smallest displacement at the working-side premolar and the largest displacement at the balancing-side second molar. Clenching on a WI or BI caused a mandibular elevation with the smallest displacement at the working- or balancing-side second molar, respectively. A BO resulted in the smallest upward displacement among the four experimental conditions. These results suggest that the nature of reaction forces at the temporomandibular (TM) joints caused by the elevation of the mandible varies in a predictable manner depending upon lateral occlusal relationships.

To investigate the hypothesis of a functional coupling between the stomatognathic motor apparatus and the muscles of other body districts, as well as between occlusal conditions and neuromuscular performance, two groups of men (age range 20-26 years), with either normal occlusion (14 men) or malocclusion (15 men), sustained with their dominant arm a dumbbell weighing 80% of their maximum while maintaining different jaw positions: mouth open, without dental contact; mouth close, with light dental contact; maximum voluntary clench; maximum voluntary clench on two cotton rolls positioned on the posterior mandibular teeth; maximum voluntary clench on one cotton roll positioned on the right/left-side posterior mandibular teeth. Surface electromyography (EMG) of the biceps brachii muscle was performed, and the endurance time, mean root mean square (rms) potential, and mean median power frequency were computed. The mean potential and median power frequency were also computed for 2-s windows, and values as a function of time were interpolated by a linear regression analysis. Data were compared between groups and trials by using a factorial analysis of variance. The malocclusion group subjects could perform the exercise for a longer time span than the normal occlusion individuals (P < 0.005). During this endurance time their biceps brachii muscles contracted with different patterns: on average, in the malocclusion group they had a larger EMG amplitude (P < 0.005), and a shift of the power spectrum toward lower frequencies (P < 0.005). The factor 'jaw position' was significant only for the endurance time (P < 0.005). In both groups, the longest endurance time was found in the 'clench' trial, while the shortest in the 'right-side bite' trial. In conclusion, a morphologically altered occlusion does not always worsen the muscular performance of other body districts, and the use of occlusal supports (cotton rolls) is not always beneficial.

Dental abnormalities are common in chinchillas, although knowledge of the lesions responsible for the clinical signs is incomplete. Animals bred in the UK were examined to gain further knowledge of dental disease in this chinchilla population. Dental abnormalities, particularly those related to tooth elongation, were detected on careful external examination of 35 per cent of apparently healthy chinchillas. Incisor abnormalities were seen on clinical examination in 55 per cent of chinchillas presented because of clinical illness. In all but one case, this occurred secondarily to crown elongation of the cheek teeth or to the absence of opposing teeth, rather than being a primary skeletal problem. Clinical signs commonly attributed to malocclusion, such as ventral mandibular swelling, weight loss, dysphagia, altered chewing pattern and changed food preferences, were not specific to malocclusion, being seen associated with coronal spike formation, root elongation and advanced periodontal lesions. Caries and resorptive lesions rarely caused clinical signs in this population, but were identified during 37 per cent of postmortem examinations. Congenital absence of teeth, skeletal malocclusion and pathological loss of teeth all resulted in significant clinical signs, but were rare. It is concluded that provision of a diet with physical properties more closely matching that of wild chinchillas should improve the dental health of captive animals.

Dyskeratosis congenita is a rare multisystem condition involving mainly the ectoderm. It is characterized by a triad of reticular skin pigmentation, nail dystrophy and leukoplakia of mucous membranes. Oral and dental abnormalities may also be present. Complications are a predisposition to malignancy and bone marrow involvement with pancytopenia. The case of a 14-year-old girl is described who presented with several of the characteristic systemic features of this condition, together with the following oral features: hypodontia, diminutive maxillary lateral incisors, delayed dental eruption, crowding in the maxillary premolar region, short roots, poor oral hygiene, gingival inflammation and bleeding, alveolar bone loss, caries and a smooth atrophic tongue with leukoplakia. Although this condition is rare, dental surgeons should be aware of the dental abnormalities that exist and the risk of malignant transformation within the areas of leukoplakia.

The study group consisted of 19 subjects with positive overjet and overbite, and 17 subjects with skeletal open bite. Two bipolar surface electrodes were attached to the skin of the upper and lower lips. The mean integrated amplitude of the electromyographic (EMG) activity was obtained at the mandibular rest position with the lips in contact and with the lips apart. Subjects were divided into two groups based on positive or negative values of the difference in integrated EMG activity of the mentalis muscle between the two lip positions. Subjects displaying a negative value were classified as having competent lips and those displaying a positive value were classified as having incompetent lips. The EMG activity of the mentalis muscle was found to be more indicative of lip sealing as compared with the EMG activity of the depressor of the lower and the upper lips. The activities of the mentalis muscle at the mandibular rest position with the lips in contact and with the lips apart appear to offer an objective criterion for the evaluation of lip incompetence. In addition, the vertical dimension of the face, as well as the proclination of the incisors, appear to affect lower lip function.

Disc displacement is accepted as one of major findings in temporomandibular disorders (TMD). However, the associations of disc positions with morphological and positional changes of temporomandibular joint (TMJ) components and lateral pterygoid (LP), TMD clinical symptoms, and occlusion have rarely been discussed quantitatively. In this study, the morphological and positional changes of TMJ components and LP were assessed by means of magnetic resonance imaging (MRI) and tomography of the TMJ in 41 TMD and nine control (CN) subjects. Disc positions in TMD subjects were divided into normal position (NP) and anterior displacement with and without reduction (ADR+ and ADR-, respectively). From MRI scans and tomograms, the morphological and positional changes of TMJ components and LP were measured and compared among CN, NP, ADR+ and ADR- groups. Correlations between these measurements and the scored clinical symptoms and occlusal factors were analysed in TMD subjects. The results indicated that: (1) TMJ osseous structures and LP showed no significant difference among CN and the three TMD groups, except for a posterior seat of condyle and shorter/steeper condylar movement during jaw opening; (2) disc length and inclination were significantly shorter and steeper, respectively, in ADR+ and ADR-; (3) disc positions were not specified by clinical symptoms and occlusal factors, except for the dominant TMJ sounds in ADR+; (4) an uncoordinated movement of the condyle/disc complex was found in ADR+ and/or ADR-; (5) TMJ osseous structures and the disc were weakly associated with clinical symptoms and occlusal factors. However, the LP showed negative associations with palpable pain for both the TMJ and jaw muscles and the static occlusal factors. These findings suggest that TMJ internal derangements are more related to the positional changes or spatial relationships of TMJ components but less to the individual morphologies of TMJ osseous structures, disc and LP, as well as specific clinical symptoms and occlusal factors, which might be in disagreement with a large body of previous statements.

In order to study the relationship between morphological properties of the TMJ and the mathematically predicted force distribution in the TMJ, the geometric distribution of the joint space on top of the condylar surfaces was evaluated. Seven deep bite subjects and seven non-deep bite subjects were used, and the joint space in the maximum intercuspation and canine edge-to-edge positions was analysed in each group. Standardized images of the TMJ were taken with computed tomography (CT) using a mandible positioner. The comparative ratio of joint space (CRJS) between the maximum intercuspation and the canine edge-to-edge positions was calculated and summarized on the map of the mean morphological outline of the condyle. On the balancing-side condyle, the CRJS of small value was distributed mainly on the anterior edge of the condyle in the non-deep bite group, whereas, in the deep bite group, it was distributed on the centre of the condyle. On the working-side condyle, the small CRJS was distributed around the lateral pole of the condyle in the non-deep bite group, whereas, in the deep bite group, it was found around the posterior part of the condyle. The distribution pattern of CRJS on the upper surface of the condyle in the non-deep bite group was consistent with the results of previous studies on mathematical simulation of TMJ loading. From the results of this study, it was suggested that the distribution of mechanical loading on the TMJ in the eccentric mandibular position would be highly affected by the comparative ratio of joint space. As the comparative ratio of joint space would be highly affected by the condylar position, the analysis of the morphology of the TMJ in relation to mechanical joint loading, in a future investigation, should be carried out on specific mandibular positions in relation to the function of the TMJ to be studied.

In our previous study, it was reported that facial asymmetry due to mandibular lateral displacement (MLD) was significant in patients with temporomandibular disorders (TMD). In this study, dental asymmetry in TMD patients was investigated by means of PA cephalogram and study model. Lateral deviation of the midline of the mandibular occlusal table (PA-mid) and right-left difference of the molar relationship (Molar-Diff.) were examined, and their relationship with MLD was studied. PA-mid and Molar-Diff. were significantly correlated with MLD. In most cases, displaced side of the midline of the lower occlusal table was coincident with that of the mandibular skeletal midline. These results suggest that in TMD patients asymmetries in occlusal relationship of the midline of the mandibular teeth and molars were mainly due to a mandibular skeletal asymmetry and not merely due to a dental malposition on the alveolar basal bone. Many cases had a more distal occlusal relationship of the first molar on mandibular displaced side compared with that on the opposite side. A high incidence of Class II relationship was found (61.8% as a whole) and more remarkable on the mandibular displaced side. Midline discrepancy and right-left difference of the molar relationship seem to be important occlusal characteristics in patients with TMD.

In mandibulectomy patients with lateral discontinuity defect, the mandible is severely deviated and the occlusion is considered to be unstable. A thorough understanding of the mandibular occlusal position of these patients is important to achieve desirable results in their occlusal rehabilitation. This study compared the stability of the mandibular positions in occlusion, when the opening distance or the biting force was changed during mandibular movements, by simultaneously measuring four points on the mandible three-dimensionally. This study indicated that the mandibular positions in occlusion of these patients were extremely unstable as compared with those of the normal subjects and were considerably different from each other when the opening distance or the biting force was changed during mandibular movements.

Treatment effects of the Bionator functional appliance were studied on the pre- and post-treatment cephalograms of 49 Class II, Division 1 cases. After treatment, a significant more ventral localization of the anterior structures of the mandible was recorded in comparison with the pretreatment situation. The proclination of the maxillary incisors was reduced. No absolute inhibitory effect on maxillary growth was observed. In this study no significant differences in the measured treatment effects on cephalometric radiographs could be demonstrated in cases with a tendency to skeletal open bite from those with a tendency to skeletal deep bite according to the criteria used in this study.

A cross-sectional study of the contacts in maximum intercuspation was undertaken using a method to identify occlusal contacts, which is indicated as satisfactory by modern research. The aims were to describe in subjects with normal dentitions and normally functioning masticatory systems: (a) the general distribution of contacts; (b) the numbers in the various classes and types of occlusal contacts; (c) the numbers of teeth without contact. A randomized sample of 18 women and 20 men was used. Classical theoretical proposals for the numbers, distribution and nature of occlusal contacts were not supported. Wide variability was evident and asymmetry of distribution on the right and left sides of individual subjects was common. Contacts with stabilizing tendencies involved the mandibular supporting cusps in 79% of occurrences. Overall, the difference in the number of contacts with stabilizing effects was not significantly different from the number with unstabilizing tendencies. Contacts with mechanically unstabilizing effects did not produce clinically discernible, unfavourable sequelae in the dentitions. Because of the sparse number of stabilizing contacts, interventions involving the occlusal surfaces should maintain or improve on the number of such contacts in maximum intercuspation.

Cephalometric analyses have long been important diagnostic tools for the orthodontic specialist. Such analyses, as they pertain to adult skeletal problems and their consequent therapy, should also be a valuable adjunct for various dental specialties, e.g. the oral surgical clinician. However, because of the complexity of most analyses, it is difficult to glean the important values needed for most orthognathic cases. In this article an analysis is presented to aid the clinician in surgical diagnosis and treatment planning.

The relationship between number, distribution and intensity of occlusal tooth contacts and the craniomandibular functional status was investigated in 56 subjects aged 16-17 years. The photocclusion technique was used for the qualitative and quantitative evaluation of occlusal contacts, and a clinical examination was performed to assess the function of the stomatognathic system. According to a matched-pairs design two groups were formed, one consisting of individuals with signs of craniomandibular disorders, and the other consisting of functionally healthy adolescents. The pairs were matched according to morphological occlusal characteristics. The results of the present study emphasize the importance of occlusal contacts in relation to craniomandibular function. In particular the posterior occlusion appeared to be related to function, since statistically significant differences between the two groups were detected with regard to the number and load of contacts. Symmetry of intensity rather than symmetry of contact distribution per se seemed to be important in relation to craniomandibular function.

In an effort to explain the aetiology of early temporomandibular joint (TMJ) injuries, their incidence in children born by vaginal breech delivery and possible correlation with such deliveries were investigated. The study covered 156 children aged from 4 to 6 years, eighty-three of them born by vaginal breech delivery under application of the classical Mauriceau manoeuvre in seventeen cases and the Bracht manoeuvre in sixty-six. Seventy-three children delivered spontaneously in vertex presentation served as the control group. Signs of TMJ injury were found in 59.6% of the total group, the by-birth percentages being 67.5 in those after breech delivery and 50.7 in those after spontaneous delivery--the difference is statistically significant. The difference was even more significant for the more severe TMJ disorders, their percentages being in two groups respectively 48.2 and 29.7. In the children born by breech delivery the TMJ disorders were invariably attended by severe forms of distocclusion, among which the unilateral form deserves particular attention. The authors conclude that vaginal breech delivery is probably among the factors responsible for early TMJ abnormalities. They call the attention of paediatricians and obstetricians to this fact and urge examination of this joint as a very important part of oral examination in children born by vaginal breech delivery.

An association was sought between certain morphologic characteristics of malocclusion--Angle classification, over-bite, over-jet, open-bite, cross-bite and crowding--and the presence or absence of three cardinal symptoms of mandibular dysfunction--joint sounds, joint sensitivity to palpation and muscle sensitivity--in a sample of 369 Israeli school children. In addition, two additional independent variables, 'occlusal wear' and 'previous orthodontic treatment' were introduced into the statistical analysis. Occlusal wear and abnormal overbite were the only factors found to increase significantly the presence of dysfunction symptoms.

The complications and limitations in rehabilitating an adult woman with class II, division 1 malocclusion and posterior occlusal collapse is described with special consideration given to the aspects of time, the patient's personality and socio-economic situation. Fixed restorations were chosen for optimum function, comfort and to enhance the patient's emotional security. The importance of an individual treatment approach is stressed.