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At least 379 records · Page 21Linked to original sources
PubMed1996

Mandibular incisors, alveolar bone, and symphysis after orthodontic treatment. A retrospective study.

The mandible of a deceased 19-year-old young woman who had been treated with an edgewise appliance was removed during autopsy. The overall tooth movements during the 19 months of treatment were reconstructed (treatment documents) and compared with the macroscopic, radiologic, and micromorphologic findings of the incisor/alveolar bone/symphysis complex of the dry mandible. The initial lateral cephalogram revealed an extremely narrow and high symphysis, with an incisor position straight above the thin bone. During treatment, the incisors had been moved to lingual (lingual root torque) and derotated. Morphologic evaluation of the dry mandible revealed lingual (oral) aspects of the roots reaching some millimeters out of the lingual alveolar bone and largely without cortical plate covering. Lateral dental contact radiographs of any bone/incisor segment showed the sagittal alveolar bone width to be smaller than the labiolingual (orobuccal) diameter of the incisor roots. A comparison of the approximate pretherapeutic alveolar bone height, which was assessed by measuring the distance from the cementoenamel junction to the most coronal margin of any root resorption in scanning electron microscopy, with that of the specimen showed a calculated bone loss on the lingual aspect extending from 2.3 to 6.9 mm. On the labial (buccal) aspect, bone loss was far less pronounced. These results suggest that in the case of a narrow and high symphysis, pronounced sagittal incisor movements and derotation during routine orthodontic treatment with a fixed appliance may be critical and lead to progressive bone loss of lingual and labial cortical plates.

Adult↗
PubMed1999

Rapid maxillary expansion with incisor intrusion: a study of vertical control.

This is a prospective study of 20 consecutively treated patients needing maxillary expansion and incisor intrusion. The patients were treated with a bonded maxillary expansion appliance, intrusion of the incisors with either a one-piece or three-piece base arch and anchorage augmented by the use of vertical-pull chincup therapy. Because rapid palatal expansion and intrusion of maxillary incisors both produce extrusion of posterior teeth, this study was undertaken to determine if a combination of controlled forces could prevent undesirable increases in vertical dimension. The maxillae were widened approximately 8 mm, the incisors were intruded 3 mm, the maxillary molars stayed the same or were intruded slightly, and the mandibular plane angle stayed essentially the same. In addition, A-point was retracted slightly and the occlusal plane was rotated in a counter-clockwise direction.

Cephalometry↗
PubMed2000

Correlation of asymmetric Notch2 expression and mouse incisor rotation.

Notch signaling defines an evolutionarily conserved cell communication mechanism, which enables neighboring cells to adopt different fates. Furthermore, Notch signaling may create boundaries that direct both the growth and patterning of the developing organs. Here we report on the expression of Notch receptors during the development of rodent incisors. Before the acquisition of their characteristic shape, incisors rotate antero-posteriorly and become asymmetric at their labial-lingual axis. Notch2 is expressed only in the anterior part of the developing incisors, well before their rotation, while Notch2 expression was symmetrical in the developing molars. This is the first demonstration of an asymmetric gene expression pattern during the rotation of the rodent incisors.

Animals↗
PubMed2003

Clinical outcomes for permanent incisor luxations in a pediatric population. II. Extrusions.

A longitudinal outcome study was undertaken to identify variables that significantly influenced outcomes for extruded permanent maxillary incisors of children and adolescents. Clinical and radiographic data was available for 35 patients (18 males, 17 females) representing 55 incisors. Mean age at the time of injury was 10.6 years (range: 7.1-17.8 years). Mean time elapsed to follow up was 1320 days (range: 423-2887 days). Survival analysis was used to identify variables significantly related to the prognosis of these teeth. The loss of an incisor following extrusion was uncommon as only one tooth (1/55) required extraction. There was no statistically significant difference in survival between severely extruded teeth and avulsions that had been stored in physiological media (P > 0.10). Pulp necrosis (PN) was the most common complication following injury (43%) and it most often occurred during the first year. Although not statistically significant, a trend towards increased PN was found with more severely extruded teeth (P = 0.20, relative risk = 2.08). Pulp canal obliteration (PCO) was the second most common outcome (35%). The degree of extrusion was proven to be significantly associated with the development of PCO (P = 0.03, relative risk = 0.33). Root resorption was an uncommon outcome (3/55). This study represents the first outcome data on extrusions to permanent maxillary incisors in an exclusively pediatric population.

Adolescent↗
PubMed1996

An investigation into the measurement of the working length of immature incisor teeth requiring endodontic treatment in children.

A study was undertaken to determine if a tactile technique, using absorbent paper points, could be used to estimate the working length of nonvital immature incisor teeth undergoing endodontic treatment. Two operators were involved in measuring 35 incisor teeth. The tactile technique was found to be valid and reliable. In 95% of the cases the estimated working length was within 1 mm of the radiographic diagnostic length. It is recommended that diagnostic radiographs are no longer necessary in the majority of cases involving endodontic treatment of incisor teeth requiring root end closure in children, for practitioners who are regularly carrying out endodontic treatment of immature incisor teeth. However, if a tooth has been on open drainage a diagnostic radiograph is still required.

Adolescent↗
PubMed2005

Complications following replantation of a primary incisor: a cautionary tale.

The replantation of avulsed primary incisors is contra-indicated. This case describes an 8-year-old child who six years previously had avulsed and had replanted a primary central incisor. At presentation, this tooth was retained, the permanent successor had failed to erupt and appearance of the adjacent lateral incisor was notably delayed. Investigation revealed a radicular cyst in relation to the replanted deciduous incisor together with severe displacement of the permanent tooth, which could not be saved.

Child↗
PubMed1982

Change in lip contour with maxillary incisor retraction.

Cephalometric analysis of the influence of hard tissue changes on lip contour in 41 cases showed the following effects. Patients with large palatal tilt angles showed larger changes in the nasolabial angle with incisor retraction. Nasolabial angle is increased with uprighting (lingual tipping) of the incisors. Horizontal movement of the incisor edge has an unpredictable relationship with change in the nasolabial angle. A ratio of 1:3.8 was found between lip retraction and incisor retraction.

Adolescent↗
PubMed1985

Stiffness of incisor segments of edgewise arches in torsion and bending.

A mechanical model dentition is used in a laboratory study to relate incisor segment third-order activation to actual torque induced upon engagement of maxillary Edgewise arches. A portion of the sample of stainless-steel aches was subjected to stress-relief heat treatment. Torsional stiffness values are calculated, and the accompanying vertical displacement force on the incisor segment is evaluated. The results seem to warrant the following conclusions. Broad ranges of incisor segment torque magnitudes may be obtained from rectangular orthodontic wires and arch designs presently in common clinical use. Torsional behavior is associated with the elastic shear modulus or modulus of rigidity, which is essentially the same for all stainless and chrome-cobalt alloys. Vertical extrusive force is generated as a secondary effect directly related to the torsional stiffness and torque activation. Compensation is possible through archwire adjustments to cause the wire to lie above the bracket slots of the incisor segment before activation of lingual root torque. Stress relief of rectangular stainless steel arches following placement of V-bends, twists, or loops did not have a significant effect on force values. Further investigation, modeling other configurations such as labiolingual movements of the six maxillary anterior teeth to determine the torsional stiffnesses for commonly-used arches could be worthwhile. Similarly, the quantification of torsional stiffnesses of arches fabricated in rectangular nickel-titanium, titanium-molybdenum, and braided stainless-steel wires may be of value.

Biomechanical Phenomena↗
PubMed1992

Mandibular incisor extraction--postretention evaluation of stability and relapse.

Pretreatment, posttreatment and 10-year postretention dental cast and lateral cephalogram records of 42 patients were evaluated. Each patient had undergone edgewise orthodontic treatment following removal of one or two mandibular incisors and various maxillary teeth. Seven of 24 patients (29%) in the single-incisor extraction group and 10 of 18 (56%) patients in the two-incisor extraction group demonstrated unacceptable mandibular incisor alignment at the postretention stage. This result was considerably more favorable than the results of previously reported premolar extraction cases (70% unacceptable alignment at postretention). Intercanine width decreased during treatment and continued to decrease postretention in most cases. Overbite and overjet remained acceptable. No associations could be found to predict the amount of relapse.

Cephalometry↗
PubMed1997

Lower molar and incisor displacement associated with mandibular remodeling.

The purpose of this study was to quantify the amount of alveolar modeling at the apices of the mandibular incisor and first molar specifically associated with appositional and resorptive changes on the lower border of the mandible during growth and treatment. Cephalometric data from superimpositions on anterior cranial base, mandibular implants of the Björk type, and anatomical "best fit" of mandibular border structures were integrated using a recently developed strategy, which is described. Data were available at annual intervals between 8.5 and 15.5 years for a previously described sample of approximately 30 children with implants. The average magnitudes of the changes at the root apices of the mandibular first molar and central incisor associated with modeling/remodeling of the mandibular border and symphysis were unexpectedly small. At the molar apex, mean values approximated zero in both anteroposterior and vertical directions. At the incisor apex, mean values approximated zero in the anteroposterior direction and averaged less than 0.15 mm/year in the vertical direction. Standard deviations were roughly equal for the molar and the incisor in both the anteroposterior and vertical directions. Dental displacement associated with surface modeling plays a smaller role in final tooth position in the mandible than in the maxilla. It may also be reasonably inferred that anatomical best-fit superimpositions made in the absence of implants give a more complete picture of hard tissue turnover in the mandible than they do in the maxilla.

Adolescent↗
PubMed1998

Mandibular lateral incisor-canine transposition, concomitant dental anomalies, and genetic control.

Mandibular lateral incisor-canine (Mn.I2.C) transposition is a rare developmental disturbance of tooth order characterized by positional interchange of the two teeth. In children with Mn.I2.C anomaly, the mandibular lateral incisor shows distal ectopic eruption and the adjacent canine subsequently erupts mesial to it. A sample of 60 orthodontic patients with Mn.I2.C transposition was studied using roentgenograms taken at the time of diagnosis. Two age-related phenotypes of the anomaly were identified: early-stage (median age, 9 years) and mature-stage (median age, 12 years). Mn.I2.C transposition occurred bilaterally in 10 subjects (17%) and favored female expression (sex ratio, M1:F3) and right-side occurrence (68% of unilateral cases). Statistically significant associations were found between Mn.I2.C transposition and increased frequency of tooth agenesis (M3, p < 0.01; MnP2, p < 0.01) and peg-shaped maxillary lateral incisors (p < 0.0001). The results from this study and the analysis of 50 previously published cases provide evidence that Mn.I2.C transposition is a disturbance of tooth order and eruptive position probably caused by genetic influences. The Mn.I2.C anomaly likely results from genetic mechanisms similar to those responsible for occurrences of its associated dental anomalies, such as tooth agenesis and peg-shaped maxillary lateral incisors. In an appendix, clinical orthodontic management of Mn.I2.C transposition is discussed, based on treatment data derived from the study sample.

Adolescent↗
PubMed2000

Incisor root resorptions due to ectopic maxillary canines imaged by computerized tomography: a comparative study in extracted teeth.

The purpose of the study was to analyze the ability of computerized tomography (CT) scanning to discriminate maxillary incisor root resorptions caused by ectopically erupting canines. Seventeen maxillary incisors were radiographed in vivo by CT scanning. Contiguous transverse CT scans with a slice thickness of 2 mm were exposed perpendicular to the long axis of the lateral incisors and through the crown of the adjacent, ectopically positioned maxillary canine. Each scan was analyzed and the resorptions on the roots of the laterals were graded according to the maximum depth of the cavity. After the lateral incisors were extracted they were clinically inspected, photographed in different light settings and views, and probed at the contact area between the laterals and the canines. The assessment of the extent of resorption in 4 stages on the CT images compared with the in vitro observations of the extracted roots showed a high degree of agreement for the extent of loss of root substance for all teeth. We conclude that CT scanning performed with good technique accurately reveals tooth root resorption. The presence and influence of the inherent artifacts of tooth root resorption on CT scans are discussed.

Artifacts↗
PubMed2001

Effect of reverse curve mushroom archwire on lower incisors in adult patients: a prospective study.

This prospective clinical study was undertaken to analyze adult skeletodental changes induced by a reverse curve mushroom archwire during the initial stage of treatment. Lateral cephalograms from before treatment and immediately after bite opening were evaluated from 8 female adult patients who were undergoing lingual orthodontic treatment. Before treatment the patients had a mean overbite of 3.9 mm. Six linear and 5 angular measurements were selected for cephalometric analysis. The mean change in the cephalometric parameters was subjected to paired t-tests to determine whether the change was significant. There was a highly significant overbite reduction (-1.9 mm, P < .001) leaving a postintrusion overbite of 2.0 mm. The lower incisors were intruded 1.5 mm (P < .001) and the lower incisor edge was in an approximately stable sagittal position (L1 to NPg = -0.2 mm, NS). Some lower incisor proclination (L1 to MP = 1.2 degrees) was seen, which was not of significance. The mandibular molars were not significantly extruded. After bite opening the mandibular plane angle was not significantly altered. Consequently, the lower anterior face height was not significantly increased. The results of this study revealed that the use of reverse curve mushroom archwire is capable of intruding the lower incisors with minimal side effects on the posterior teeth.

Adult↗
PubMed2005

Winged maxillary central incisors with unusual morphology: a unique presentation and early treatment.

Winged incisors are a well-recognized clinical finding. In this report, the disorder is briefly reviewed and a unique case of winging of the two maxillary central incisors having unusual morphology in an eight-year six-month-old boy is presented. The two winged maxillary central incisors were derotated using an anterior sectional wire inserted into a pair of twin brackets, one bonded to each of the two central incisors, and reciprocal anchorage.

Accidental Falls↗
PubMed1998

Microvascular system of the rat incisor enamel organ. A scanning electron microscopic study of vascular corrosion casts.

The rat incisor is a commonly used model in studies of tooth eruption, amelogenesis and effects of mechanical loading on the dental and periodontal tissues. The purpose of this study was to assess the three-dimensional architecture of the microvascular bed of the rat incisor enamel organ, to describe the direction of blood flow, and to provide a histometric assessment of the vascular categories that can be statistically analyzed. Vascular corrosion casts were prepared and examined by scanning electron microscopy. The microvasculature of the labial periodontal space was arranged in three distinct layers. The inner layer in direct relation to the enamel organ consisted of a capillary network which was drained by short venules at the cemento-enamel junction. The intermediate layer consisted of arterioles oriented parallel to the long axis of the incisor mainly mid-labially, branching off smaller arterioles to the capillary network. The outer layer was formed by flattened sinusoid vessels of larger caliber. Blood supply was from the anterior superior alveolar artery branches through the arterioles into the capillary network. Drainage was postero-laterally along the cemento-enamel junction via short venules which emptied into the sinusoid vessels, finally to flow through Volkmann's canals into the alveolar bone via small venules. The findings demonstrate that the microvasculature of the rat incisor enamel organ has an exceptionally high level of physiologically-adapted structural organization.

Analysis of Variance↗
PubMed2002

Pulpal anaesthesia for mandibular central incisor teeth: a comparison of infiltration and intraligamentary injections.

AIM: This study compared the anaesthetic efficacy of infiltration and intraligamentary injections in the permanent mandibular central incisor. METHODOLOGY: Twelve healthy volunteers received each of the following methods of anaesthesia for one of their mandibular central incisors over four visits. 1 Labial infiltration of 1.0 mL. 2 Lingual infiltration of 1.0 mL. 3 Labial infiltration of 0.5 mL plus lingual infiltration of 0.5 mL. 4 Intraligamentary injection of (118 mL. Two percent lidocaine with 1: 80 000 adrenaline and 30 gauge needles were used throughout. Electrical pulp testing was performed before injection and every 2 min up to 30 min after the injection. Injection discomfort was recorded on a 100-mm visual analogue scale. Data were compared with ANOVA, Student's t-test and chi2 tests. RESULTS: Anaesthesia varied between techniques(F = 9.3, P < 0.001). The incidence of anaesthesia at any time was as follows: 50% success for labial infiltration; 50% success for lingual infiltration: 92% success for combined labial and lingual infiltration; 0% success for intraligamentary injections (chi2 = 20; P < 0.001). The mean (+/-SD) VAS score for intraligamentary injection discomfort was 28 +/- 12 mm, for buccal infiltrations 17 +/- 8 mm and for lingual infiltrations 16 +16 mm. Intraligamentary injections were more uncomfortable than buccal (t = 3.7: P < 0.01) and lingual infiltrations (t = 2.67: P < 0.05). CONCLUSIONS: The most reliable method of the techniques investigated for obtaining pulpal anaesthesia in mandibular permanent central incisors was a combination of labial and lingual infiltration. Intraligamentary injections were unreliable and were more uncomfortable than infiltrations in the mandibular central incisor region.

Adult↗
PubMed2004

Evaluation of pulpal blood flow after tooth splinting of luxated permanent maxillary incisors.

Laser Doppler flowmetry (LDF) is a non-invasive method to assess pulpal blood flow (PBF). Dental injury has been associated with losses of pulpal sensibility. The purpose of this study was to assess whether LDF could be used to detect short- and long-term changes of PBF values of luxated permanent maxillary central incisors after repositioning and splinting. In 18 trauma patients, a single maxillary incisor treated by repositioning and splinting, and the respective contralateral homologous tooth were investigated by LDF to assess local PBF values. Perfusion units (PU) were taken in four sessions: on the day of splint removal, and 12, 24, and 36 weeks after splint removal. Analysis of the luxation type-related PBF measurements revealed intrusion type-related PBF values to be associated with a significant decrease in PBF values (P < 0.05), while lateral luxation and extrusion type-related PBF values showed no significant difference between the session-related values (P > 0.05). PBF measurements did not change over time for the contralateral incisors (P > 0.05). Teeth affected by an intrusion-type luxation injury remained unresponsive to sensitivity testing at follow up, while 3 (60%) developed grey discoloration of the crown. LDF may become useful in the detection of ischemic episodes of luxated maxillary central incisors after repositioning and splinting. Further studies are warranted to assess the validity of post-traumatic 'ischemic episodes' by comparing it to histological tooth pulp changes.

Adolescent↗
PubMed2000

Treatment of a Class I malocclusion with a carious mandibular incisor and no Bolton discrepancy.

Occasionally orthodontists must plan treatment for a patient with extensive caries or a traumatic injury to one mandibular incisor. If the patient has a Bolton discrepancy, one treatment option could involve extraction of the affected mandibular incisor. However, if the patient does not have a Bolton discrepancy and a mandibular incisor is extracted, the treatment becomes more complicated. This case report will present and discuss the ramifications of extracting one mandibular incisor in a patient without an anterior tooth-size discrepancy. The CDABO Student Case Selection Committee chose this case for publication.

Adult↗