SEARCH · Search PubMed
Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Cranio-mandibular dysfunction therapy of a moderate Angle Class III malocclusion with retroclined incisors with anterior crossbite and pronounced crowding was based not on extraction of the first premolars but on protrusion of the incisors and the extraction of one lower incisor.
The purpose of the present study was to discern possible relationships between dental parameters and the horizontal inclination of the condyle path. Two test groups of orthodontically untreated individuals with non-physiological incisor relationships, one group with enlarged and the other with reverse overjet, were selected for the study. An opto-electronic apparatus was employed to measure the horizontal inclination of the condyle path. The dental parameters were set by clinical examination and by measuring plaster casts. Both groups exhibited significant distribution deviations in the inclination of the condyle path and in the following parameters: "occlusal contacts of the front teeth during protrusion", "overbite", "resulting overjet", and "sagittal and vertical distance of the incisal edge of the lower incisors to the zero point of the upper incisors". Statistically no correlation between the dental parameters and the inclination of the condyle path was discerned. The influence of muscular guidance is in large measure the determining factor for the large variations in the TMJ registrations, and especially in their quantitative evaluation. The results were the same even when tracings were repeated a number of times with the same patient.
The influence of the level of experience of the laryngoscopist on the duration of laryngoscopy, the forces exerted on the tongue and on the maxillary incisors during laryngoscopy, were investigated. Five groups (anaesthetists, residents in anaesthesia, nurse anaesthetists, surgeons and medical students), each consisting of 15 individuals, participated in the study. An intubation manikin was used with a laryngoscope modified so that the forces applied during laryngoscopy could be measured. The mean duration of laryngoscopy in these groups was 23.4 sec, 17.6 sec, 27.1 sec, 26.8 sec and 42.7 sec, respectively. The maximally applied forces on the tongue were 71.7 N, 60.5 N, 65.9 N, 74.2 N and 69.7 N, respectively. The maximally applied forces on the maxillary incisors were 49.9 N, 36.3 N, 41.1 N, 58.3 N and 53.9 N, respectively. These results indicate the level of experience has a significant influence on the duration of laryngoscopy but seems to have little influence on the forces applied to the tongue and the maxillary incisors.
OBJECTIVE: Molar-incisor hypomineralization (MIH) is common in many countries and it has significant impact on treatment need. The aim of the present study was to assess developmental enamel defects with an emphasis to MIH in children from four primary schools in Benghazi, Libya. METHODS: Permanent first molars of a total of 378 (188 females) 7.0-8.9-year-old children were examined for demarcated opacities, diffuse opacities and hypoplasia in their schools using a portable light, a mirror, and a probe. A subgroup of children attending two of the four schools and having all incisors and first molars erupted (N = 154) was examined for enamel defects in these teeth. RESULTS: Eleven children (2.9%) had MIH. The mean value of demarcated opacities in their first molars was 1.5. MIH lesions were found only in 1.1% of the children's first molars (tooth prevalence) and all lesions were mild. Six children (1.6%) had diffuse opacities and 3 (0.8%) had hypoplastic defects in their first molars. Fourteen out of 154 children (9%) who had both incisors and molars examined had some kind of developmental enamel defect: 11 children (7.1%) had demarcated opacities, 3 (1.9%) had diffuse opacities, and none had hypoplasia. CONCLUSION: MIH was rare in Benghazi, Libya. The prevalence was clearly lower than in comparable studies performed in Italy or in Nordic countries, where, according to the earlier reports, MIH is seen in every fifth or sixth child. Our result may be valuable when so far mostly unknown etiology behind MIH is investigated.
AIM: The aim of this study was to analyze the relative contribution of torque and protrusion to the change in incisor inclination in the treatment of Class II, Division 2 malocclusion with fixed appliances. Furthermore, the extent of incisor intrusion was to be evaluated. The second part of the study was aimed at documenting the stability of the therapeutic outcome in terms of inclination and intrusion within the framework of a follow-up examination. PATIENTS AND METHOD: The study sample comprised 25 adult patients, and the follow-up sample eleven patients. The intrusion and change in inclination of the incisors as well as their stability were analyzed by evaluating and superimposing lateral cephalograms taken before and after treatment as well as after retention. RESULTS: Although the mean value of inclination at the end of the therapy was in accordance with the standard value (102 degrees), there was a marked interindividual variation. In the maxilla, the mean torque component was 58%, and the mean protrusion component 42%. In the mandible, the torque: protrusion ratio was 37%:63%. The mean intrusion was 1 mm in both dental arches. The follow-up examination showed that the intrusion was relatively stable. In cases where the change in inclination relapsed, the ratio of protrusion to torque was almost equal to that previously used to induce the change during the course of treatment. CONCLUSION: It is concluded that therapy with torque movement and intrusion offers a more stable result in adults than protrusion movement alone.
Tissue inhibitors of metalloproteinases (TIMPs) possess multiple functions, in addition to their matrix metalloproteinase (MMP) inhibitory activity. The continuously growing incisor of mouse possesses a stem cell compartment at the apical end of the epithelium (the apical loop) and thus provides an excellent tool to analyze the mechanisms of organogenesis and cytodifferentiation. To understand the functions of TIMPs in tooth development, we have analyzed the gene expression and protein localization of TIMP-1, -2, and -3 during mouse incisor development, from embryonic day 13 (E13) to postnatal day 3 (P3). TIMP-1 was present on the basement membrane during early developmental stages. At P2, TIMP-1 was strongly detected along the apical loop, transiently disappeared from the basement membrane in the cytodifferentiation zone, and later reappeared at the distal end of functional ameloblasts. Expression of TIMP-2 protein was restricted to the outer part of the apical loop throughout the examined stages. At P2, TIMP-2 was present on the basement membrane at the outer part of the apical loop. The dental follicle also expressed Timp-2, and the corresponding protein was abundant within the extracellular matrix. Timp-3 mRNA was highly expressed in the mesenchyme surrounding the apical loop. During matrix formation, Timp-3 was expressed by subodontoblasts, and the protein was detected in this layer and between odontoblasts. Distinct temporal and spatial expression patterns of TIMPs suggest divergent functions of these factors in incisor organogenesis.
BACKGROUND: The treatment of traumatized patients plays a significant role in the everyday life of oral and maxillofacial surgeons as well as of dentists. Traumas of incisor teeth account for a considerable part. These traumas are often followed by lawsuits. The aim of this retrospective analysis was to highlight aspects of these lawsuits of special significance and to show the consequences for surgeons and general practitioners. MATERIAL AND METHODS: A total of 398 medical expert opinions were evaluated. Moreover, an online search of databases for relevant court decisions was performed. Analysis was initially based on formal aspects of the cases and reports. It was later supplemented by a differentiated assignment of the questions addressed by the courts to the expert consultants. RESULTS: In 97 (24%) medical expert opinions traumas of the incisor teeth were the main subject. In 35% the trauma was caused by traffic accidents followed by assaults. In one-third the medical expert opinion was commissioned by accident insurance companies. The compensation for pain and suffering was between 1500 and 2000 euros per lost tooth. CONCLUSION: Traumas of incisor teeth are often followed by litigations. Clinicians performing first treatment should ensure that documentation of clinical and radiological findings is detailed and complete. This documentation plays a decisive role in medical expert opinions.
The frontier between the enamel organ and the dental papilla, the future dentino-enamel junction, undergoes coordinated modifications. The mineralization of the extracellular matrix starts within the predentine, which is a prerequisite for the formation of the first enamel crystallites in vivo. We investigated the dentino-enamel junction using the embryonic mouse incisor as a model. Our data showed that the notion of the dentino-enamel junction should not be restricted to the thin interface classically described. A temporo-spatial survey from the epithelio-mesenchymal junction to the dentino-enamel junction delineated a clear sequence of events characterized by the early deposition of electron-dense granules, followed by the appearance of patches of stippled material at the dentino-enamel junction. The first tiny enamel crystallites appeared in the vicinity of this material which presented a well-ordered alignment. The comparison of data obtained in vivo on 17-, 18-, 19-d-old embryonic incisors with those obtained in vitro using 15-d-old embryonic incisors cultured for 7 d emphasizes the relevance of this sequence. Helicoidal growing crystals were observed in cultured tooth germs but never in vivo.
This study consisted of analyzing clinical records of fifty cases treated for correction of Class I malocclusion with varying degrees of bimaxillary protrusion and anterior mandibular crowding. Thrity of these cases required extraction of all four first premolars. Parameters characterizing changes in position of mandibular incisors during treatment with edgewise appliances and during retention and shortly afterward were studied. All the parameters indicated rather similar changes for the nonextraction and the extraction groups. The relapse of anterior mandibular crowding was significantly larger (p less than or equal to 0.05) in the nonextraction group. The IMPA and interincisal angle changed significantly more in the extraction group. Upon testing for validity of the mesiodistal to faciolingual indices, it was determined that they predicted stability of the achieved alignment of mandibular incisors. There were, however, individual cases in both groups which did not follow the central tendency. It was observed that the mesiodistal diameters of mandibular incisirs were somewhat larger in the extraction cases. There was only one pair of parameters that showed a moderately high intercorrelation (r equals 0.68); that was between correction of the anterior crowding and relapse of the intercanine expansion. It was observed that the more correction took place, the more readily expanded canines would relapse. An over-all impression is that the mandibular incisors change little in their position to each other and relative to the other structures of the mouth. The question remains: Is this due to our ability to control them well, or due to an inability to move and maintain them in their new position?
1. From this study, it was found that in cases treated by the Begg technique one can anticipate greater retraction of the anterior dental units in nonextraction (see article) cases, in both types of premolar extraction cases, and in cases, involving extraction of first molars plus first premolars than would be expected on the basis of root surface area resistance values. 2. There is a likely explanation for this. Molars were maintained upright and allowed to move bodily only while incisors were not only moved bodily but often partially tipped as well. 3. The actual mean anterior retraction in first molar extraction cases exhibited a close approximation to the expected mean anterior retraction values in relation to root surface resistance values. 4. Second premolar extraction is one answer to overretraction and has the added edge of creating even less incisor retraction than second premolar extraction. 5. It was also found that the extraction of premolars alone did not result (see article) in a significant change in the increased eruption of the third molars into functional occlusion. A very significant improvement in the rate of sucessful third molar eruption was found in first molar extraction cases and in cases involving extraction of first molars plus first premolars. 6. The mean ages of the patients in the various treatment categories at the start of treatment were similar enough to each other to suggest that age at the start of treatment had no bearing on the success rate of third molar erup tion. Extraction-site selection seemed to be the dominating factor in successful third molar eruption. 7. It was found that the group of cases that exhibited the least amount of anterior retraction also inhibited the least amount of anterior relapse and, conversely, the group of cases exhibiting the greatest amount of anterior retraction also exhibited the greatest amount of anterior relapse. (see article) 8. The nonextraction cases, with no extraction space to close, were treated in the shortest mean time, while the eight-tooth (first molar plus first premolar) extraction cases having the greatest amount of extraction space required the greatest amount of mean treatment time.9. In conclusion, it can be said that changing the location of the extraction site resulted in a change in relative root surface areas of the opposing anchor units in the anterior and posterior segments. There was a definite and predictable change in the amount of anterior retraction achieved by varying the location of the extraction site. This should be considered in the diagnosis, so that a desired treatment goal for the final position of the incisors within the facial profile can be achieved.
Class II, Division 2 malocclusions show several common characteristics. One of the features is the presence of a deep overbite ("deckbiss"), which can be the result of an excessive eruption of the maxillary central incisors. This study tested the theory that the deep overbite, together with the apparent entrapment of the mandible, may be partly due to the bending of the maxillary central incisors or the presence of the Collum angle. In a comparison between the group of patients with Class II. Division 2 malocclusions and the control group, it was determined that the former group exhibited significantly larger Collum angles than the latter group (p < 0.005). It is suggested that in describing the maxillary incisor angulation in this type of malocclusion, the long axis of the crown, rather than the long axis of the tooth connecting the incisal edge to the apex, be used as a measure of their position.
Changes in the nasolabial angle of the soft-tissue profile were assessed quantitatively in a serial cephalometric study of fifty treated subjects and forty-three untreated subjects, all of whom had Class II, Division 1 malocclusions. Correlations, simple and multiple regression analyses, and multifactorial analysis of variance were used to examine the changes in the nasolabial angle owing to incisor superius retraction and associated skeletal displacements. There were no significant changes in nasolabial angle because of growth. However, the greater the maxillary incisor retraction, the greater was the increase in nasolabial angle. Increase in the nasolabial angle showed a significant correlation with treatment-related increase in the vertical dimension of the lower face. The soft-tissue profile followed closely the underlying skeletal framework. Extraction and nonextraction treatment procedures did not show significant differences in the changes of the nasolabial angle. Results permit prediction of the changes in nasolabial angle owing to incisor superius retraction in orthodontic treatment.
A technique based on pulsed laser hologram interferometry was used to study the dynamics of incisor extrusion. Maxillary central incisors of four subjects were loaded with forces acting along the long axis of the tooth, and the resulting motions were measured noninvasively in three dimensions. The incisor translations and rotations were used to determine centers of rotation. The experimentally determined centers of rotation are shown to depend on tooth root geometry and are found to lie at a vertical level coincident with the centroid of the root.
This article presents five cases of an unusual dental anomaly--transposition of mandibular canine and lateral incisor. While every one of the presented cases had its individual characteristics, there are certain common traits. For instance, deciduous canines are usually retained, and the anomaly is found concurrent with other dental problems, such as congenital absence of teeth or peg-shaped lateral incisors. Many transposition cases also have a severe arch length discrepancy, which in itself may be an etiologic factor. In two of our cases orthodontic management included extraction of the transposed lateral incisor, whereas in the remaining three cases teeth were left in their transposed positions. On the basis of the longitudinal records of one of our cases, we speculate that there are early signs of transposition in the making, signs which should be recognized and which could possibly make transposition preventable.
An investigation was carried out to study the efficiency of a new technique for semipermanent replacement of missing incisors. A flexible system allowing slight physiologic movement of the bridge units was created by bonding an acrylic tooth to the abutments by means of three orthodontic wires, as shown in Figs. 9 to 11. Between June, 1981, and December, 1982, fifty-three bridges of this type were inserted in a sample that was nonselected relative to overbite and overjet. It comprised fifty-one persons 10 to 22 years of age (mean, 16; SD, 3.9). During an observation period of 5 to 22 months (mean, 15; SD, 4.8) ten bridges came loose, giving a failure rate of 18.9% for the whole sample. All the loosened bridges were replacements for missing maxillary central incisors. The thirteen bridges replacing missing maxillary lateral incisors and two bridges inserted in the mandible functioned without problems. There was no correlation between failure rate and overjet and overbite. However, the functional occlusion was of importance. If there was antagonistic contact with the pontic during functional movements, the failure rate was 57.1%. If there was no such contact, however, the failure rate was only 5.4%. This difference was statistically significant. Accumulation of plaque was significantly higher around the abutments than on contralateral surfaces. However, no significant differences in gingival health were recorded. In two persons, dental caries was recorded on the abutment surface facing the pontic.(ABSTRACT TRUNCATED AT 250 WORDS)
Variability in tooth morphology can play a significant role in appliance design and the achievable results of orthodontic treatment. This investigation was undertaken to determine quantitatively the variation in three anatomic features of the maxillary central incisor. The three features are the crown-root angulation in a labiolingual direction, the angle formed by a tangent to the middle of the labial surface of the crown and the long axis of the crown from a proximal view, and the lingual curvature of the crown from a proximal view. Tracings of maxillary central incisors were made from two different sources. The first source consisted of radiograms of 98 extracted central incisors, and the second source was a group of 100 cephalometric radiograms which were part of pretreatment records of patients in the Orthodontic Department. The cephalometric radiograms included 25 Angle Class I, 25 Class II, Division 1, 25 Class II, Division 2, and 25 Class III malocclusions. The first measurement taken was the angle formed by the long axis of the crown and the long axis of the root. The second measurement was the angle formed by the long axis of the crown and a tangent to the midpoint of the labial surface of the crown. For the third measurement, the lingual curvature of the crown was described by a mathematical equation whose parameters were used for comparisons. The results revealed a wide range of variation in the three features measured. The mean crown-root angle for Class II, Division 2 malocclusions differed significantly from that for Class II, Division 1 and Class III malocclusions.(ABSTRACT TRUNCATED AT 250 WORDS)
Forces (2.5-15 mN) applied in a direction that opposed the eruption of rat maxillary incisors made these teeth sink into their sockets at a decreasing rate. Sometimes eruption subsequently restarted from this intruded position while the force was still applied. After the forces were removed, all the incisors extruded, rapidly at first than showing to normal rates of eruption. Forces (2.5-20 mN) applied in a direction that aided the eruption made the teeth rise in their sockets, initially rapidly, then slowing to a steady rate. After the forces were removed, the incisors sank back into their sockets at a decreasing rate. These responses could be separated into two components; rapid movements occurring immediately after applying or removing the forces and slower movements occurring at rates that were maintained as long as the force was applied, which could be regarded as eruption.
Measurements of eruption rates were compared with a computer analysis of measurements of eruption rates from stable and unstable reference points. In the computer analysis, when the measurements were made from unstable reference points, there were correlations between eruption rates and changes in tooth length and between unimpeded and impeded eruption rates. These correlations were not seen in measurements made from stable reference points. The measurements from unstable reference points had greater variances. These correlations were found in measurements made from the gingival margin of the unimpeded incisor but not in measurements from the margin of the impeded incisor. The measurements from the impeded incisor had a lower variance. The ability was demonstrated of these correlations and variance ratios to detect instability of reference points.