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Dental and Medical Problems 2022The thorough knowledge of the anatomy of mandibular premolars is an essential factor for a correct approach to endodontic treatment, concerning both non-surgical and...
BACKGROUND
The thorough knowledge of the anatomy of mandibular premolars is an essential factor for a correct approach to endodontic treatment, concerning both non-surgical and surgical treatment.
OBJECTIVES
Since there is no data on the Italian population in this context, the aim of this study was to evaluate, from a surgical perspective, the anatomy of mandibular premolars among the Italian population through a cone-beam computed tomography (CBCT) analysis, considering the morphology of their root canals according to Vertucci's classification and the prospect of their apices with regard to the vestibular bone plate and the proximity to the inferior alveolar nerve and the mental foramen as well as to evaluate the most appropriate distance from the apex in the radicular resection (3 mm or 5 mm).
MATERIAL AND METHODS
At total of 492 CBCT acquisitions (from 246 males and 246 females) were included retrospectively, evaluating 720 mandibular premolars. Age, gender, the tooth position in relation to the vestibular plate, the number of roots, the tooth length and the root length, the number of canals, the configuration of the root canal system according to Vertucci's criteria, C-shaped canals, the distance from the cementoenamel junction (CEJ) to the canal bifurcation, the number of apical foramina, and the distance from the apex to the inferior alveolar nerve or the mental foramen were evaluated.
RESULTS
The study highlighted the frequent anatomic variability of the root canal system. It found the presence of 1 root for first and second premolars in 97% and 99% of cases, of 2 roots in 2.7% and 0.7% of cases, and of 3 roots in 0.3% and 0.3% cases, respectively. In 92% of cases, the mental foramen was located below a second premolar, or between a first premolar and a second premolar; only in 8% of cases, it was located close to a first premolar, but never as close as to a second premolar.
CONCLUSIONS
Mandibular premolars show a truly surprising anatomical variability, especially for mandibular first premolars, which therefore requires adequate radiographic planning before providing any endodontic treatment, or especially endodontic retreatment or endodontic surgery. Taking into account proximity to the inferior alveolar nerve and the mental foramen, any surgical approach must be carefully planned. Frequently, a two-dimensional (2D) radiographic examination is not sufficient to fully understand the anatomical variability of these teeth.
Topics: Bicuspid; Female; Humans; Male; Mandible; Retrospective Studies; Spiral Cone-Beam Computed Tomography; Tooth Root
PubMed: 35766896
DOI: 10.17219/dmp/143546 -
The Angle Orthodontist Jan 2010To quantify the amount of perioral tissue changes following the extraction of four premolars in patients with bimaxillary protrusion who had nearly completed active... (Review)
Review
OBJECTIVE
To quantify the amount of perioral tissue changes following the extraction of four premolars in patients with bimaxillary protrusion who had nearly completed active growth.
MATERIALS AND METHODS
A literature search was conducted to identify clinical trials that assessed cephalometric perioral soft tissue changes in patients affected by biprotrusion and treated with extractions. Electronic databases (PubMed, ISI WoS Science Citation Index Expanded, and HubMed) were searched. Abstracts that appeared to fulfill the initial selection criteria were selected, and the full-text original articles were retrieved and analyzed. Only articles that fulfilled the final selection criteria were finally considered. Their references were also hand-searched for possible missing articles from the database searches.
RESULTS
Nine abstracts met the initial inclusion criteria and these articles were retrieved. From these, five were later rejected mostly because the sample dealt with growing subjects. Four articles remained and they showed that the upper and lower lips retracted and the nasolabial angle increased following premolar extraction. Upper lip retraction ranged from 2 mm to 3.2 mm, lower lip retraction ranged from 2 mm to 4.5 mm.
CONCLUSIONS
The lip procumbency improves following the extraction of four premolars and this improvement is predictable. However, the changes are small and do not dramatically modify the profile. A "dished in" profile is not to be expected. Individual variation in response is large.
Topics: Bicuspid; Cephalometry; Humans; Lip; Malocclusion; Maxillofacial Development; Serial Extraction
PubMed: 19852663
DOI: 10.2319/010709-16.1 -
Head & Face Medicine Sep 2022Previous studies have reported inconsistent effects of premolar extraction on the oropharynx and hyoid bones. Currently, no strong evidence is available regarding the... (Comparative Study)
Comparative Study
BACKGROUND
Previous studies have reported inconsistent effects of premolar extraction on the oropharynx and hyoid bones. Currently, no strong evidence is available regarding the effect of extraction on upper airway size. Hence, the aim of this study was to analyse the effects of first premolar extraction on the oropharynx and hyoid bone positions in female adult patients, and further explored differences in oropharynx and hyoid bone changes among skeletal patterns.
METHODS
The study population included 40 female adult patients who did not undergo extraction and 120 female adult patients who underwent extraction of four premolars; the including patients had four distinct sagittal and vertical skeletal patterns. Cone-beam computed tomography was performed before (T0) and after (T1) orthodontic treatment. Eight oropharynx variables and five hyoid bone variables were measured using Dolphin 3D Imaging software. Paired and independent t-tests were used to analyse measurements between timepoints and groups, respectively.
RESULTS
The oropharynx volume increased significantly in the extraction group; changes did not differ significantly between extraction and non-extraction groups. Oropharynx variables did not differ significantly at T0 among the four skeletal pattern groups. After orthodontic extraction treatment, the oropharynx volume increased significantly in the class I-norm and class I-hyper subgroups, but not in the class II-norm and class II-hyper subgroups. Significant increases were observed in the oropharynx volume and most constricted axial area from T0 to T1 in the moderate retraction group, but not in the maximum retraction group. Extraction patients exhibited significant posterior movement of the hyoid, particularly among maximum retraction patients.
CONCLUSIONS
In female adult patients, first premolar extraction tends to increase the oropharynx size and cause posterior movement of the hyoid bone, particularly in skeletal class I patients. For skeletal class II and hyperdivergent patients with a narrow oropharynx, first premolar extraction does not negatively influence oropharynx size or hyoid bone position. The differences of oropharyngeal changes between moderate retraction patients and maximum retraction patients were not significant.
Topics: Adult; Bicuspid; Bone and Bones; Cone-Beam Computed Tomography; Female; Humans; Hyoid Bone; Oropharynx; Retrospective Studies; Tooth Extraction
PubMed: 36064714
DOI: 10.1186/s13005-022-00334-1 -
The Angle Orthodontist Sep 2020To compare the amount of en-masse retraction with or without piezocision corticotomy, to assess the type of tooth movement, to evaluate root integrity after retraction,... (Randomized Controlled Trial)
Randomized Controlled Trial
OBJECTIVES
To compare the amount of en-masse retraction with or without piezocision corticotomy, to assess the type of tooth movement, to evaluate root integrity after retraction, and to record reported pain levels.
MATERIALS AND METHODS
This randomized, controlled clinical trial included 26 orthodontic patients requiring premolar extraction. The patients were divided into two groups: (1) an extraction with piezocision corticotomy group (PCG) and (2) an extraction-only group, which served as the control group (CG). Cone-beam computed tomography images were acquired before and 4 months after the initiation of en-masse retraction utilizing miniscrews. The following variables were assessed: the amount of en-masse retraction, incisor inclination, incisor and canine root resorption, and patient-reported pain.
RESULTS
Twelve and 11 participants completed the entire study in the PCG and CG, respectively. The amount of en-masse retraction was significantly greater in the PCG compared to the CG (mean = 4.8 ± 0.57 mm vs 2.4 ± 0.33 mm, respectively [P < .001]). There was also significantly less tipping and root resorption of incisors in the PCG (P < .05). The reported pain was significantly higher on the first day in the PCG compared to the CG (P < .001); however, it became similar between the groups after 24 hours.
CONCLUSIONS
Piezocision corticotomy enhanced the amount of en-masse retraction two times more with less root resorption. However, future studies are required to assess the long-term effects of this technique.
Topics: Bicuspid; Humans; Incisor; Orthodontic Anchorage Procedures; Root Resorption; Tooth Movement Techniques
PubMed: 33378476
DOI: 10.2319/092719-615.1 -
BMC Oral Health Jun 2022Previous studies have described and recorded abnormal root morphology; however, most of these studies were based on two-dimensional periapical or panoramic radiographs,...
BACKGROUND
Previous studies have described and recorded abnormal root morphology; however, most of these studies were based on two-dimensional periapical or panoramic radiographs, and only a few studies have quantified it. We aimed to combine two-dimensional periapical radiographs and three-dimensional cone-beam computed tomography (CBCT) to conduct qualitative judgments and quantitative analyses of normal and conical roots, and explore the clinical diagnostic method of normal and conical roots based on intraoral radiographs and CBCT.
METHODS
The conical root was identified visually on periapical radiographs as the clinical gold standard. All teeth were divided into the cone-rooted teeth (CRT) or normal-rooted teeth (NRT) groups. Furthermore, differences in root length (RL), root surface area (RSA), and root volume (RV) of conical and normal roots in the maxillary premolars on CBCT were compared. Receiver operator characteristic curves were generated, and the area under the curve (AUC) and cut-off values were calculated to evaluate the diagnostic value of RV, RSA, RV/RL, and RSA/RL.
RESULTS
The RSAs of NRT and CRT were 236.88 ± 27.93 mm and 207.98 ± 27.80 mm, respectively (P = 0.000). The mean RV in the CRT group was lower than that in the NRT group, and the difference was statistically significant (253.40 ± 41.98 mm vs. 316.93 ± 49.89 mm, P = 0.000). The RSA and RV of conical roots in single root premolars were 12.29% and 19.33% less than those of normal roots, respectively. The AUC values of RSA/RL and RV/RL were 0.87 and 0.89, respectively, and the best cut-off values were 19.61 for RSA/RL (if RSA/RL was < 19.61, the teeth were considered CRT) and 24.05 for RV/RL (if RV/RL was < 24.05, the teeth were considered CRT).
CONCLUSIONS
CBCT has significant diagnostic value in the clinical evaluation of conical roots. RSA/RL and RV/RL were the best parameters with the largest AUC and high sensitivity and specificity.
Topics: Bicuspid; Cone-Beam Computed Tomography; Humans; Tooth Root
PubMed: 35681195
DOI: 10.1186/s12903-022-02258-3 -
The Angle Orthodontist Jul 2023To compare mandibular relative anchorage loss (RAL) under reciprocal anchorage between first and second premolar extraction cases in bimaxillary protrusion mild crowding...
OBJECTIVES
To compare mandibular relative anchorage loss (RAL) under reciprocal anchorage between first and second premolar extraction cases in bimaxillary protrusion mild crowding cases treated using clear aligner therapy (CAT).
MATERIALS AND METHODS
Adult patients who met the following criteria were included: treated using CAT with bilateral mandibular premolar extractions and space closure using intra-arch reciprocal anchorage. RAL was defined as the percent molar mesial movement relative to the sum of molar mesial plus canine distal movement. Movements of the mandibular central incisor (L1), canine (L3), and first molar (L6) were measured based on superimposition of the pre- and post-treatment dentition and jaw models.
RESULTS
Among the 60 mandibular extraction quadrants, 38 had lower first premolar (L4) and 22 had lower second premolar (L5) extracted. L6 mesial movement was 2.01 ± 1.11 mm with RAL of 25% in the L4 extraction group vs 3.25 ± 1.19 mm with RAL of 40% in the L5 extraction group (P < .001). Tooth movement efficacy was 43% for L1 occlusogingival movement, 75% for L1 buccolingual inclination, 60% for L3 occlusogingival movement, and 53% for L3 mesiodistal angulation. L1 had unwanted extrusion and lingual crown torquing whereas L3 had unwanted extrusion and distal crown tipping, on which the power ridges or attachments had little preventive effect.
CONCLUSIONS
The average mandibular reciprocal RAL is 25% or 40% for extraction of L4 or L5, respectively, in CAT cases. A RAL-based treatment planning workflow is proposed for CAT extraction cases.
Topics: Humans; Bicuspid; Tooth Movement Techniques; Molar; Malocclusion; Orthodontic Appliances, Removable
PubMed: 37343197
DOI: 10.2319/102222-727.1 -
The Journal of Thoracic and... Jul 2018
Topics: Aorta; Aortic Valve; Bicuspid; Humans; Replantation; Tricuspid Valve
PubMed: 29730115
DOI: 10.1016/j.jtcvs.2018.03.089 -
The Angle Orthodontist Dec 2003Intrabony migration of impacted teeth is a rare dental anomaly, which occurs only in the permanent dentition of the lower jaw. The teeth involved in this phenomenon are... (Review)
Review
Intrabony migration of impacted teeth is a rare dental anomaly, which occurs only in the permanent dentition of the lower jaw. The teeth involved in this phenomenon are the mandibular lateral incisor, canine, and second premolar. Migration of the lateral incisor is usually in a distal direction, resulting in transposition with the canine. Migration of the canine is most frequently in a mesial direction, resulting in transmigration across the mandibular symphysis to the opposite side of the dental arch. The second premolar most often migrates distally, sometimes past the gonial angle and as far as the coronoid process. Surgical and orthodontic treatment options are presented for the three intrabony migrating teeth.
Topics: Bicuspid; Cuspid; Humans; Incisor; Mandible; Tooth Eruption, Ectopic; Tooth, Impacted
PubMed: 14719741
DOI: 10.1043/0003-3219(2003)073<0738:IMOIT>2.0.CO;2 -
American Journal of Physical... Aug 2019This study explores the outer and inner crown of lower third and fourth premolars (P , P ) by analyzing the morphological variation among diverse modern human groups.
OBJECTIVES
This study explores the outer and inner crown of lower third and fourth premolars (P , P ) by analyzing the morphological variation among diverse modern human groups.
MATERIALS AND METHODS
We studied three-dimensional models of the outer enamel surface and the enamel-dentine junction (EDJ) from μCT datasets of 77 recent humans using both an assessment of seven nonmetric traits and a standard geometric morphometric (GM) analysis. For the latter, the dental crown was represented by four landmarks (dentine horns and fossae), 20 semilandmarks along the EDJ marginal ridge, and pseudolandmarks along the crown and cervical outlines.
RESULTS
Certain discrete traits showed significantly different regional frequencies and sexual dimorphism. The GM analyses of both P s and P s showed extensive overlap in shape variation of the various populations (classification accuracy 15-69%). The first principal components explained about 40% of shape variance with a correlation between 0.59 and 0.87 of the features of P s and P s. Shape covariation between P s and P s expressed concordance of high and narrow or low and broad crowns.
CONCLUSIONS
Due to marked intragroup and intergroup variation in GM analyses of lower premolars, discrete traits such as the number of lingual cusps and mesiolingual groove expression provide better geographic separation of modern human populations. The greater variability of the lingual region suggests a dominance of functional constraints over geographic provenience or sex. Additional information about functionally relevant aspects of the crown surface and odontogenetic data are needed to unravel the factors underlying dental morphology in modern humans.
Topics: Adolescent; Adult; Anthropology, Physical; Bicuspid; Child; Child, Preschool; Dental Enamel; Dentin; Female; Humans; Imaging, Three-Dimensional; Male; Middle Aged; Multivariate Analysis; Odontometry; Tooth Crown; X-Ray Microtomography; Young Adult
PubMed: 31099892
DOI: 10.1002/ajpa.23858 -
The Anatomical Record Jan 1998Bone sialoprotein (BSP) and osteopontin (OPN), two major noncollagenous proteins (NCPs) in collagen-based mineralized tissues, have been implicated in mineral deposition... (Comparative Study)
Comparative Study
BACKGROUND
Bone sialoprotein (BSP) and osteopontin (OPN), two major noncollagenous proteins (NCPs) in collagen-based mineralized tissues, have been implicated in mineral deposition and cell- and matrix-matrix interactions during root development. However, their role in cementogenesis is still a subject of debate. Since distribution of proteins is indicative of function, we have analyzed their temporo-spatial appearance in relation to that of cementum collagen.
METHODS
Human premolars and rat molars at various stages of root development characterized by differing rates of formation were fixed in aldehyde and embedded in epoxy and LR White resin. Sections were processed for ultrastructural analysis and postembedding colloidal gold (immuno)cytochemistry.
RESULTS
Incubations with antibodies against BSP and OPN and with lectins recognizing prominent sugars in these proteins generally revealed similar labeling patterns in both human and rat teeth, with gold particles accumulating mainly in the interfibrillar spaces. The lectin Helix pomatia, specific for N-acetyl-D-galactosamine, was distinctive in that it consistently reacted with human cementum, but only sporadically labeled rat cementum. Regardless of both the species and the stage of root development, mineralization initiated in mantle predentin in association with distinct foci immunoreactive for BSP and OPN. In human teeth, the deposition of cementum collagen began before the start of dentin mineralization and thus prior to any detectable labeling for BSP and OPN. However, at early stages of root formation in the rat, cementum collagen appeared after BSP and OPN accumulated on the root surface, whereas at advanced stages the deposition of cementum collagen, BSP and OPN coincided.
CONCLUSIONS
The temporo-spatial differences in the appearance of BSP and OPN relative to cementum collagen correlate well with known differences in the speed of root elongation and explain the variable appearance of the dentino-cemental junction. The data reveal no causal relationship between BSP and OPN and the differentiation of cementoprogenitor cells and indicate that the distribution of collagen fibrils ultimately determines the amount and pattern of accumulation of these NCPs. There also is no consistent planar accumulation of BSP and OPN between dentin and cementum such as the cement lines found between "old" and "new" bone. It is concluded that the interlacement of collagen fibrils at the dentino-cemental junction, across which mineralization spreads, represents the primary attachment mechanism between cementum and dentin.
Topics: Adolescent; Animals; Bicuspid; Cementogenesis; Child; Dental Cementum; Female; Gold Colloid; Humans; Immunohistochemistry; Integrin-Binding Sialoprotein; Lectins; Male; Molar; Osteopontin; Rats; Rats, Wistar; Sialoglycoproteins; Species Specificity; Tooth Root
PubMed: 9458064
DOI: 10.1002/(SICI)1097-0185(199801)250:1<13::AID-AR3>3.0.CO;2-F