Evaluation of Infraorbital Foramen Position Using Cone-Beam Computed Tomography in a Cohort of Central Gujarat, Indian Population

OBJECTIVE

The location of infraorbital foramen varies between geographic locations. Thus, population-specific information is required to facilitate the prediction of its exact location.

METHODS

 A cross-sectional study was conducted on 100 cone beam computed tomography (CBCT) sections to evaluate the distance between the infraorbital foramen and incisal edge of the maxillary central incisor, the occlusal plane of the maxillary second premolar, and the alveolar crest over the maxillary second premolar using CBCT in Central Gujarat, Indian population. Descriptive statistical analysis was performed to calculate means and standard deviations for each measured parameter. The statistical significance level was defined at p<0.05.

RESULTS

The distance between the infraorbital foramen and incisal surface of the maxillary central incisor was (mean ± standard deviation) R=49.39 ± 3.12 mm and L=49.49 ± 3.29 mm, the occlusal plane of the maxillary second premolar was R=39.02 ± 2.65 mm and L=39.49 ± 2.53 mm, and the alveolar crest over the maxillary second premolar was R=32.64 ± 2.67 mm and L=31.64 ± 2.33 mm. There was no significant difference in the mean values of all variables between genders and age groups (p>0.05). The distance between the infraorbital foramen and the alveolar crest over the maxillary second premolar was greater on the right side (p<0.05).

CONCLUSION

The results of this study were analogous to those observed in a cohort of the Turkish population but varied from those observed in a cohort of the Sri Lankan population. Hence, more population-specific studies are required.

Domestic cat embryos reveal unique transcriptomes of developing incisor, canine, and premolar teeth

Division of the dentition into morphologically distinct classes of teeth (incisors, canines, premolars, and molars) and the acquisition of tribosphenic molars facilitated precise occlusion between the teeth early in mammal evolution. Despite the evolutionary and ecological importance of distinct classes of teeth with unique cusp, crest, and basin morphologies, relatively little is known about the genetic basis for the development of different tooth classes within the embryo. Here we investigated genetic differences between developing deciduous incisor, canine, and premolar teeth in the domestic cat (Felis catus), which we propose to be a new model for tooth development. We examined differences in both developmental timing and crown morphology between the three tooth classes. Using RNA sequencing of early bell stage tooth germs, we showed that each of the three deciduous tooth classes possess a unique transcriptional profile. Three notable groups of genes emerged from our differential expression analysis; genes involved in the extracellular matrix (ECM), Wnt pathway signaling, and members of multiple homeobox gene families (Lhx, Dlx, Alx, and Nkx). Our results suggest that ECM genes may play a previously under-appreciated role in shaping the surface of the tooth crown during development. Differential regulation of these genes likely underlies differences in tooth crown shape and size, although subtle temporal differences in development between the tooth germs could also be responsible. This study provides foundational data for future experiments to examine the function of these candidate genes in tooth development to directly test their potential effects on crown morphology.

Strain Measurement within an Intact Swine Periodontal Ligament

The periodontal ligament (PDL) provides support, proprioception, nutrition, and protection within the tooth–PDL–bone complex (TPBC). While understanding the mechanical behavior of the PDL is critical, current research has inferred PDL mechanics from finite element models, from experimental measures on complete TPBCs, or through direct measurement of isolated PDL sections. Here, transducers are used in an attempt to quantify ex vivo PDL strain. In-fiber Bragg grating (FBG) sensors are small flexible sensors that can be placed within an intact TPBC and yield repeatable strain measurements from within the PDL space. The objective of this study was to determine: 1) if the FBG strain measured from the PDL space of intact swine premolars ex vivo was equivalent to physical PDL strains estimated through finite element analysis and 2) if a change in FBG strain could be linearly related to a change in finite element strain under variable tooth displacement, applied to an intact swine TPBC. Experimentally, individual TPBCs were subjected to 2 displacements (n = 14). The location of the FBG was determined from representative micro–computed tomography images. From a linear elastic finite element model of a TPBC, the strain magnitudes at the sensor locations were recorded. An experimental ratio (i.e., FBG strain at the first displacement divided by the FBG strain at the second displacement) and a finite element ratio (i.e., finite element strain at the first displacement divided by the finite element strain at the second displacement) were calculated. A linear regression model indicated a statistically significant relationship between the experimental and finite element ratio (P = 0.017) with a correlation coefficient (R²) of 0.448. It was concluded that the FBG sensor could be used as a measure for a change in strain and thus could be implemented in applications where the mechanical properties of an intact PDL are monitored over time.

A Systematic Review with Meta-Analysis

The aim of the current meta-analysis was to assess the impact of methodological variables in performing fracture strength tests of upper premolars. Medline (Pubmed), Embase and Google Scholar were screened for studies performing ex vivo fracture strength tests of intact upper premolars or premolars with 0, 1 or 2 walls lost. The outcome variable for each study was the maximum breaking load expressed in Newton (kg × m/s²). Methodological variables (i.e., simulation of the periodontal ligament, load inclination, tip position, tip diameter and thermocycling) were registered to perform subgroup analyses and meta-regression. Overall, 25 studies and 78 study groups were included in the meta-analysis. Intact premolars (17 study groups) were not significantly influenced by any of the methodological variables considered. Subgroup analysis for load inclination (30°/45° vs. 90°/150°) was significant for premolars with 0 (10 study groups), 1 (6 study groups) and 2 (45 study groups) walls lost; thermocycling was significant for premolars with 1 and 2 walls lost. A strong methodological heterogeneity across studies evaluating the fracture strength of upper premolars was highlighted, especially when 0, 1 or 2 walls were lost. Further studies are needed to standardize the methodology used in order to allow for across-studies comparisons.

An assessment of root stage of canine and premolar teeth at alveolar eruption

OBJECTIVE

The primary aim was to evaluate the degree of root development of permanent canines at the time of alveolar eruption. We also aimed to assess whether differences in the degree of root development at alveolar eruption exist between permanent canines and premolars and between maxilla and mandible.

DESIGN

A cross-sectional study.

SETTING

Barts and The London School of Medicine and Dentistry, Queen Mary University of London.

PARTICIPANTS

Two hundred dental panoramic radiographs taken as part of routine dental care.

METHODS

Radiographs were assessed for canine and premolar root development stage and eruption level with calibration and repeat measurements undertaken.

RESULTS

Two hundred and sixty teeth were identified as being at the level of alveolar eruption. The majority of maxillary canines reached alveolar eruption when root formation was complete. Most premolars and mandibular canines reached alveolar eruption when roots were three-quarters developed. At alveolar eruption, canines were statistically more mature than premolars (p<0.001) and maxillary teeth were more mature than mandibular teeth (p<0.05).

CONCLUSIONS

Root development appears to be particularly advanced for maxillary permanent canines, being essentially root-complete at alveolar eruption, while premolars and mandibular permanent canines appear to have three-quarters root development at this stage. This information may be used to inform whether and when to extract primary teeth for orthodontic reasons.

Extraction or Nonextraction in Orthodontic Cases: A Review

Orthodontic treatment helps bring teeth in alignment. There is always debate whether tooth should be extracted or not for treating crowding. The present article highlights various advantages and disadvantages of extraction.

CBCT-based assessment of the anatomic relationship between maxillary sinus and upper teeth

Objectives

To describe the relationship between maxillary sinus (MS) and upper teeth based on cone beam computed tomographic scans (CBCT).

Materials and methods

Based on CBCT maxillary imaging data of 147 patients, distance between MS and apices of canines and posterior maxillary teeth were assessed. Distances between tooth roots and sinus were classified into three groups: distant (>2 mm), close (<2 mm) or in contact with MS. Teeth with apical lesions and uncommon root configurations were excluded.

Results

In total, 1075 teeth of maxillary canines, upper premolars and upper molars were included in this study. Teeth most often in contact with MS were the second (89%) and first (81%) maxillary molar without any significant difference (p = 0.19). Roots most often in contact with MS were the mesiobuccal and distobuccal root of the second molar (85% and 76%; p = <0.01) followed by the palatal root of the first molar (73%). A fifth of the upper canines are situated less than 2 mm from MS.

Conclusions

More than four out of five upper molars (first and second) are in a close relationship to the MS. Knowledge of the anatomical relationship between posterior maxillary teeth and the MS is important for diagnosis and treatment in this area.

Pre-autotransplantation alveolar process augmentation and premolar autotransplantation as a treatment method for single tooth replacement in adolescents

The treatment of young patients with missing teeth and an atrophied alveolar process after trauma or agenesis of a tooth can be challenging. The aim of this study was to evaluate autotransplantation of a premolar after pre-autotransplantation alveolar process augmentation (PAPA) as a treatment option for these patients. A retrospective cohort study was implemented to analyse the PAPA procedure and subsequent autotransplantation procedure. Alveolar process augmentation was performed using different types of autologous bone grafts. Subsequent autotransplantation of one or more premolars was performed approximately 4 months later. Nine patients with a mean age of 12 years were included. Twelve premolars were transplanted after a PAPA procedure: seven in the maxillary incisor region, four in the mandibular premolar region, and one in the mandibular incisor region. Initially all transplanted teeth functioned well. However, one mandibular premolar that was transplanted in the maxillary incisor region was lost because of resorption after 6 years of follow-up. The other 11 transplanted teeth functioned well. The mean follow-up was 6 years (range 3-13 years). The results showed that autotransplantation can be facilitated by PAPA with a high chance of success. It can therefore be a valuable addition to other existing treatment options.

Influence of dental crown topography on fracture resistance of premolars with MOD preparation and subjected to different restorative protocols

To evaluate whether dental crown topography influences the fracture resistance of premolars treated endodontically and with MOD preparation subjected to different restorative protocols. Sixty-four human premolars with one or two roots in equal numerical proportions (n) were selected and randomly divided into four groups (n = 8): (S = single-rooted; D = double-rooted) SS: sound single-rooted; SNR: endodontics (E) + MOD cavity preparation; SR: E + MOD + resin restoration (RS); SP: E + MOD + RS + horizontal zirconia post (ZP); DS: sound double-rooted; DNR: E + MOD; DR: E + MOD + RS; and DP: E + MOD + RS + ZP. After allocation to the groups, the samples were thermocycled and then subjected to the fracture resistance test. Failures after the fracture test were classified as irreparable (with pulp floor fracture) or reparable (without pulp floor fracture). Data were analysed using one-way anova and the Tukey test (α = 0.05). Single-rooted premolars were more resistant to fracture than double-rooted premolars. The restorative treatment using a horizontally transfixed zirconia post improved fracture resistance, resembling that of a healthy tooth.

Delayed Development of Maxillary Second Premolar: Case Report and Literature Review

Delayed tooth development (DTD) is the development progress of a tooth germ that takes place later due to local or general causes. This case report reviews a 16-year-old Asian adolescent whose bilateral upper second premolar germs were at Nolla's 6 stage as shown on a panoramic radiograph. It is unusual that tooth germs of the maxillary second premolar are developed after 11 years of age. To reduce the chance of misdiagnosis, clinicians should consider the possibility of DTD if a tooth germ does not present in radiographs.

Validated Finite Element Models of Premolars: A Scoping Review

Finite element (FE) models are widely used to investigate the biomechanics of reconstructed premolars. However, parameter identification is a complex step because experimental validation cannot always be conducted. The aim of this study was to collect the experimentally validated FE models of premolars, extract their parameters, and discuss trends. A systematic review was performed following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Records were identified in three electronic databases (MEDLINE [PubMed], Scopus, The Cochrane Library) by two independent reviewers. Twenty-seven parameters dealing with failure criteria, model construction, material laws, boundary conditions, and model validation were extracted from the included articles. From 1306 records, 214 were selected for eligibility and entirely read. Among them, 19 studies were included. A heterogeneity was observed for several parameters associated with failure criteria and model construction. Elasticity, linearity, and isotropy were more often chosen for dental and periodontal tissues with a Young’s modulus mostly set at 18–18.6 GPa for dentine. Loading was mainly simulated by an axial force, and FE models were mostly validated by in vitro tests evaluating tooth strains, but different conditions about experiment type, sample size, and tooth status (intact or restored) were reported. In conclusion, material laws identified herein could be applied to future premolar FE models. However, further investigations such as sensitivity analysis are required for several parameters to clarify their indication.

A Randomized Control Trial Comparing Buccal Infiltration of 4% Articaine with Buccal and Palatal Infiltration of 2% Lignocaine for the Extraction of Maxillary Premolar Teeth

Introduction

The use of articaine has been claimed to obviate the need for routine palatal local anesthetic injections on account of its better diffusion through soft and hard tissues as compared to other local anesthetic agents.

Objective

The objective of the study is to evaluate the efficacy of 4% articaine (with 1:100,000 adrenaline) infiltrated only buccally in the extraction of maxillary premolars for orthodontic reasons.

Materials and Methods

A double-blind randomized clinical trial with a split-mouth design, where each patient (n = 100) was part of two groups, was conducted. Experimental Group 1: single buccal infiltration of 4% articaine with 1:100,000 adrenaline (Septanest™ with adrenaline 1:100,000 by Septodont). Control Group 2: routine buccal and palatal infiltrations of 2% lignocaine with 1:200,000 adrenaline (Lox™ 2% with adrenaline 1:200,000 by Neon). The parameters studied were time to onset of anesthesia, pain during the extraction procedure (not during the injecting of the local anesthetic), and frequency of extra amount of local anesthetic injected.

Results

The difference was not statistically significant (P > 0.05) between the two groups with respect to all three parameters. This proves that a single buccal infiltration of articaine can be used as an alternative to lignocaine for the extraction of the maxillary premolar teeth in most of the cases.

Conclusion

This proves that a single buccal infiltration of articaine can be used as an alternative to lignocaine for the extraction of the maxillary premolar teeth in most of the cases.

Comparison of soft and hard tissue changes between symmetric and asymmetric extraction patterns in patients undergoing orthodontic extractions

BACKGROUND

Orthodontic treatment modalities and biomechanics are important factors influencing soft and hard tissues.

OBJECTIVES

The aim of this study was to compare soft and hard tissue changes after implementing asymmetric and symmetric extraction patterns.

MATERIAL AND METHODS

A retrospective cross-sectional study was conducted using the orthodontic files of 62 patients from the dental clinics of a tertiary care hospital. Patients were divided into 2 groups, each of 31 patients. Group 1 referred to the symmetric extraction patterns (SEP), whereas group 2 regarded the asymmetric extraction patterns (AEP). The Wilcoxon signed-rank test was used to determine differences between the initial and final cephalometric parameters. The Mann-Whitney U-test was used to compare the treatment changes between SEP and AEP. The SEP and AEP groups were divided into subgroups for further analyses. The Kruskal-Wallis test was used to determine significant differences in the cephalometric changes among the different subgroups. In order to further establish inter-group differences, a pairwise comparison between the subgroups was made using the Mann-Whitney U-test.

RESULTS

In the symmetric group, the preand post-treatment values for all soft tissue variables, upper incisor-sella-nasion plane angle (UI-SN), lower incisor mandibular plane angle (L-IMPA), and Frankfurtmandibular plane angle (FMA) showed significant differences (p ≤ 0.05). In the asymmetric group, none of the soft tissue parameters showed any significant difference in the preand post-treatment values; however, FMA and L-IMPA differed significantly (p ≤ 0.05). The parameters UI-SN and FMA as well as all soft tissue variables except Z-angle (Z), were significantly different between the SEP and AEP groups. The medians and interquartile ranges (IQRs) of the cephalometric changes among the subgroups were compared using the Kruskal-Wallis test. All soft tissues parameters except Z showed significant differences.

CONCLUSIONS

The symmetric extraction patterns leads to a greater change in the patient's profile, whereas asymmetric extractions can be carried out to remedy occlusal discrepancies without the risk of profile flattening. While employing premolar extractions aiming to reduce the facial height, due consideration with respect to biomechanics must be given.

Factors influencing dental arch form

Dental arch length, bilateral intermolar distance, morphology of the anterior teeth, and bilateral intercanine distance have been reported as factors influencing the determination of dental arch form. However, studies evaluating the factors that influence the determination of the above-mentioned components are limited. Therefore, to verify these points, the present study aimed to examine factors influencing the determination of dental arch form using statistical methods.Data obtained from sample dental casts were analyzed using principal component and cluster analyses. By principal component analysis, 23 sets of information were summarized into three components for the maxilla and four for the mandible. As a result of cluster analysis using principal component scores, the maxillary and mandibular dental arches were classified into four forms, respectively.Dental arch length is an important indicator of dental arch size and is influenced by the bilateral interincisor distance of the maxilla and mandible, and the mesiodistal crown width of the incisors and premolars. In the mandible, canine width also affects dental arch length. Dental arch width also influences the determination of dental arch form. However, the distance between the anterior teeth and the distance between the molars are independent and have no effect on each other.

Scintigraphic evaluation of cheek teeth in clinically sound horses

Dental disorders are one of the top-ranking clinical domains in equine practice. Scintigraphy has emerged as a useful diagnostic imaging modality for equine dental diseases. There is a paucity of the normal scintigraphic uptake and its correlation with age. This prospective, cross-sectional, descriptive and pilot-designed study aimed to describe the radioisotope uptake (RU) patterns of the reserved crown and periodontal bone of the maxillary and mandibular cheek teeth (CT) in clinically sound horses and to evaluate the age effect on RU. For this purpose, 60 horses that underwent a bone scintigraphy for reason unrelated to head were included and divided equally into four age groups. Regions of interests (ROIs) were positioned around alveolar and periodontal bone of each maxillary and mandibular CT including their reserve crown, and a reference ROI positioned at the mandibular ramus. The count per pixel of each ROI was measured using a dedicated software and the RU ratio relative to the reference region was calculated. The results showed that the maxillary and mandibular CT had a standard RU pattern, where it increased from rostral to caudal, and peaked in the middle of dental arcades and decreased slightly towards the last CT. The maxillary CT had a higher RU compared with the mandibular CT, and there was no significant difference in the maxillary and mandibular CT uptake between age groups. This information may aid veterinarians evaluating potentially abnormal dental scintigraphy.

Prevalence of Premolars with Dens Evaginatus in a Taiwanese and Spanish Population and Related Complications of the Fracture of its Tubercle

Objective:

Dens evaginatus (DE) is an odontogenic developmental anomaly that can be defined as a supernumerary tubercle structure that extends from the occlusal surface of the affected tooth. Tubercular fracture or attrition of the tubercle, invaded by pulp tissue, may cause various pulpal diseases, such as pulpitis, pulp necrosis, and periapical periodontitis. This study aimed to determine the prevalence of premolars with DE in Taiwanese and Spanish study populations and to report associated dental complications.

Methods:

This study was based on the clinical examination of volunteers of Spanish and Taiwanese origin, recruited among the undergraduate dentistry students at CEU-Cardenal Herrera University, Valencia, Spain. Informed consents were obtained from students identified with DE. Additional examinations were performed, including vitality test, percussion, palpation, and radiographs, to diagnosis the status of the pulp and periapical tissue.

Results:

The prevalence of DE among Taiwanese students was 4.08%, compared to 0% in the Spanish Caucasian group. In the Taiwanese group, the occurrence of DE in premolars was more common in the mandibular (78.9%) compared to the maxillar region (21.1%). In 84% of the cases, DE-affected teeth were found bilaterally. The mandibular second premolar was the most commonly involved tooth (57.8%). When investigating the complications related to DE among six affected Taiwanese students, it was found that two teeth (10.5%) had received pulp treatment, one of them prior to complete root formation.

Conclusion:

DE appears to be more prevalent in people of Mongoloid origin and rare in those of Caucasian origin. The wear or fracture of DE may affect pulpal tissue, leading to incomplete root growth.

Mandibular premolar migration: two case reports

Premolar migration is an infrequent and unusual phenomenon. Although several cases of distal premolar migration have been reported in the literature, the management of these cases is often challenging and to date, there are no agreed guidelines regarding best practice. This report describes two cases of distal migration of a lower second permanent premolar with sequential panoramic imaging mapping the progress of the teeth as they migrated distally. Cone Beam Computerised Tomography was subsequently used in one case to locate the migrated premolars' precise position. We report on one case which was managed with the surgical removal of the migrated premolar and one case which has been managed conservatively to date, largely due to patient wishes. Alternative treatment strategies are also discussed in the following case report.

Assessment of the relationship between the maxillary sinus floor and the upper posterior root tips: Clinical considerations

AIM

The purpose of the present study was to evaluate the relationship between the maxillary sinus floor and the upper posterior root tips in the Colombian population using cone-beam computed tomography.

METHODS

A total of 1656 roots were analyzed (1104 molars and 552 premolars), classified as types I (outside the maxillary sinus) and II (inside the maxillary sinus).

RESULTS

The results showed that the palatal root of the maxillary first molar was most frequently found inside the antrum.

CONCLUSIONS

Understanding the relationship between the maxillary sinus floor and the upper posterior root tips is important to the clinician when performing conventional or surgical endodontic treatment and conventional surgery procedures in order to minimize or avoid the risk of damaging the maxillary sinus.

Brain activation patterns during unilateral premolar occlusion

OBJECTIVE

To observe the characteristics of brain activation during unilateral premolar occlusion.

METHODS

Functional magnetic resonance imaging was collected from 10 healthy volunteers during occlusion of the left first premolar (L1), left second premolar (L2), and right first premolar (R1). The brain activation patterns were analyzed, and the primary sensorimotor cortex, supplementary motor area, insula, thalamus, and prefrontal cortex were chosen as regions of interest.

RESULTS

Single premolar occlusion activated the precentral gyrus, postcentral gyrus, cerebellum, thalamus, frontal lobe, hippocampus, cingulate gyrus, and parietal lobe. The brain areas showing activation during single premolar occlusion were similar to those activated by chewing. The activation pattern of L1 was more similar to that of L2 than R1. No significant left and right hemisphere differences in signal intensity were detected within the regions of interest.

CONCLUSION

Brain activation patterns from two ipsilateral premolars were more similar than the pattern from a contralateral premolar.

Vertical root fractures of endodontically treated posterior teeth: A histologic analysis with clinical and radiographic correlates

Vertical root fractures (VRFs) usually develop slowly, unnoticed by the patient until clinical signs and symptoms become apparent. In endodontically treated teeth, a VRF is a typical cause for extraction. The objective of the present study was the histologic analysis of VRFs in extracted, endodontically treated premolars and molars. In addition, clinical and radiographic findings of these VRF-affected teeth were retrospectively evaluated. Thirty extracted teeth with a clinically diagnosed VRF were embedded in methylmethacrylate. Serial ground sections (perpendicular to the longitudinal axis of the root) were stained with toluidine blue and basic fuchsin. The specimens were photographed and assessed with regard to the vertical and horizontal extent as well as to the course of the VRF. Most VRFs ran from the cervical to the apical region (81.3%). In the axial plane, 50% of VRFs traversed the root completely from buccal to oral. Another 40.6% of VRFs were limited to the buccal root portion. 84.4% of the evaluated roots presented an isthmus. Overall, the VRF was associated with the isthmus in 56.3%, but bypassed the isthmus in 28.1%. The most frequently observed clinical findings included pain (in 60% of the evaluated cases), presence of a fistula (46.7%) and an isolated periodontal pocket with ≥6 mm probing depth (40%). A periapical radiolucency (53.3%) was the most frequent radiographic finding in VRFs. “J-shape” lesions were seen in eight cases (26.7%).

Buccally impacted maxillary canines increase the likelihood of root separation in adjacent first premolars

OBJECTIVE

To investigate the influence of maxillary impacted canines on the root morphology of adjacent premolars in a Chinese population.

SUBJECTS AND METHODS

A sample of 370 Chinese subjects with maxillary canine impaction and 370 control subjects were collected in this study. CBCT data of all subjects were collected and analyzed. The prevalence of separate-rooted maxillary premolars was compared between subjects with and without impacted canines. Then, the prevalence of separate-rooted maxillary premolars was compared between subjects with buccal canine impaction (BIC) and those with palatal impaction (PIC).

RESULTS

The prevalence of separate-rooted first premolars was significantly higher in the canine impaction group (P = 0.046), but the prevalence of separate-rooted second premolars was not different (P = 0.780). Furthermore, a significant higher prevalence of first premolar root separation was found on the impacted site in the BIC subgroup (P < 0.001), but not in the PIC subgroup (P = 0.508). Also, the prevalence of separate-rooted first premolars in the BIC subgroup was significantly higher than that of the control group (P = 0.008), but not so for the PIC subgroup (P = 0.097).

CONCLUSIONS

Buccally impacted maxillary canines are associated with an increased prevalence of root separation in the adjacent maxillary first premolars. This is likely because that buccally impacted canines encroach on the space needed for root development of the first premolars.

Root canal anatomy of mandibular first premolars in an Emirati subpopulation: A laboratory study

Objective:

The purpose of this study was to determine the root canal anatomy of mandibular first premolar teeth in an Emirati subpopulation using a decalcification and clearing method.

Materials and Methods:

One hundred permanent mandibular first premolar teeth extracted for orthodontic purposes from an Emirati subpopulation from the United Arab Emirates were used for this study. They were subjected to decalcification and clearing. The tooth length, the canal orifice shape, mesial invagination, canal pattern, the location of apex, presence of lateral canals, and intercanal communications were determined.

Results:

The most common canal pattern was the Vertucci Type I (65%) followed by Type V (14%) and Type IV (13%). The most common type of canal orifice seen was the oval shape (36%) followed by the round shape (25%). Mesial invaginations were seen in 44% of the teeth. The mean tooth length was 19.9 mm, and apical deltas were seen in 24% of teeth.

Conclusion:

The Vertucci Type I canal pattern was the most prevalent in the mandibular first premolars while the occurrence of multiple canals was noted in 35% of this population.

Incidental finding of two rare developmental anomalies: Fusion and dilaceration: A case report and literature review

A number of developmental anomalies of morphology are there. However, as compared to the more common oral diseases like caries or periodontal problems, they account for a relatively lower number. When present, they may pose various problems of esthetic, function, malocclusion, or possible disposition to other oral problems. Hence, though rare, their timely diagnosis is very vital in proper treatment planning to avoid unseen complications during extractions, endodontic or orthodontic treatment. The present case is of a patient reporting with two very rare developmental anomalies, that is, fusion and root dilaceration, in contralateral sides of the same patient. To the knowledge of the author, reportedly it is the first such case. The terminologies, etiology, and epidemiology of both these anomalies are also discussed.

[Three years retrospective clinical evaluation of endodontically treated premolars restored by cast ceramic onlays]

OBJECTIVE

This study aimed to evaluate the success and survival rate of endodontically treated premolars restored by ceramic onlays by comparing restored by quartz fiber posts and metal ceramic crowns.

METHODS

Ninety-four patients with 126 endodontically treated premolars were enrolled in this study and divided into 4 groups according to the remaining axial walls and restorative methods. The observation time was 36 months. The success and survival rates of the restorations, as well as causes of failures, were analyzed.

RESULTS

At the final follow-up, the success and survival rates of the mild defect endodontically treated premolars were restored by quartz fiber posts and the crowns were at 96.3% and 98.1%; the success and survival rates of the severe defect premolars restored by quartz fiber posts and crowns were at 88.5% and 96.2%. The success and survival rates of the mild defect premolars restored by cast ceramic onlays were both at 96.6%, the success and survival rates of the severe defect premolars restored by cast ceramic onlays were at 94.1% and 100%, respectively. The success and survival rates of the different groups were no significant difference (P>0.05).

CONCLUSION

Based on the results and within the limits of this study, cast ceramic onlays is a very reliable method to restore endodontically treated premolars.

Prevalence of Impacted Pre-Molar Teeth in College of Dentistry, King Khalid University, Abha, Kingdom of Saudi Arabia

BACKGROUND

An impacted tooth is one which fails to reach the occlusal plane even after two-third's of its root completion. Though the etiology is multi-factorial, most common reason is crowding of teeth with lack of space for eruption. Mandibular third molars are the most commonly impacted teeth. Very few studies have been done to assess the prevalence of impacted premolar teeth.

MATERIALS AND METHODS

This study had been undertaken at College of Dentistry, King Khalid University, Abha, Kingdom of Saudi Arabia to report the prevalence of impacted premolar teeth and its relation to age group and gender. This retrospective study involved 3800 panoramic radiographs of subjects aged 18-45 years who had presented to the College of Dentistry, King Khalid University, Abha, Kingdom of Saudi Arabia, for oral care during the period from February 2009 to February 2011. All panoramic radiographs were taken with standardized equipment and specifications.

RESULTS

The study sample comprised of 3800 panoramic radiographs. A total of 45 impacted premolar teeth were identified (1.2%) (P = 0.89). The male to female ratio with impacted premolars was 35:10 (3.5:1). Age Group 1 (i.e., 20-25 years) had the highest prevalence of premolar tooth impaction (75.5%) and this decreased with increasing age. Of the 45 impacted premolars, mandibular premolars were most commonly encountered (75.6%), followed by impacted teeth in the mandibular arch (24.4%). The ratio of mandibular to maxillary third molar impaction was 3:1.

CONCLUSION

(1) The prevalence of impacted premolar teeth is more in mandibular arch than in the maxillary arch, (2) females had higher prevalence of impacted teeth than men, (3) age group 25-30 years had high rate of prevalence of impacted premolars.

SHARONLAY - A new onlay design for endodontically treated premolar

Root-canal-treated teeth are structurally compromised as a result of loss of tooth structure due to caries, iatrogenic cavity preparation, and dehydration. Given that a direct relationship exists between the amount of remaining tooth structure and the ability to resist occlusal forces, it is vital to provide a restoration allowing cuspal coverage as soon as possible following completion of the root canal treatment. A decision to provide a full crown or an onlay depends on the remaining tooth structure; if the cuspal width to length ratio is 1:2 or more, an onlay can be placed. When the ratio is less than 1:2, a full crown has to be planned. In single-rooted teeth requiring post-endodontic restoration cast post and core or a prefabricated post can provide resistance to fracture with comparable results. However, in case of premolars contradictory to the practice of providing only cuspal coverage through Onlays, it would in addition require cervical reinforcement also to counter horizontal forces acting in cervical region. A new onlay design SHARONLAY patented design with I.P. no 1956475 dated 27/04/2010 with a post extending into the radicular portion of the premolar providing the required reinforcement in a conservative manner and protecting it against both vertical and horizontal forces is proposed herewith.

[Inversion of unerupted second deciduous molar and second premolar: a case report]

Impacted teeth are usually involved in permanent dentition but not in primary dentition. This paper reports a clinical case of unerupted mandibular second deciduous molar inferior to the second premolar.

Location and dimensions of access cavity in permanent incisors, canines, and premolars

Background:

Ideal access cavity assures unobstructed straight-line access to the apical third of the root canal and preserves tooth structure.

Aim:

The aim of the study was to determine the location and dimensions of access cavity with straight-line access in incisors, canines, and premolars and to evaluate the largest diameter of their root canals in the mesiodistal and vestibulooral direction.

Materials and Methods:

Twenty extracted teeth of each group were randomly selected and digitally radiographed from the mesiodistal and vestibulooral direction. Position of the straight-line access midline in relation to anatomical landmarks (incisal edges, fissures, and cusps) was recorded. The largest diameters in mesiodistal and vestibulooral direction were measured. Relative frequencies of access position and mean and standard deviation of both diameters were calculated.

Results:

For the anterior teeth, the predominant location of straight-line access was from incisal edge, except for maxillary central incisors, where location was equally distributed between incisal edge and oral surface. In mandibular premolars, the straight-line access was positioned vestibular from central fissure. In mesiodistal direction, the largest diameter was found for maxillary central incisors and canines (1.54 mm), while the smallest diameter was found for mandibular incisors (0.64 mm). In vestibulooral direction, the largest diameter was found for maxillary first premolar (5.28 mm), while the smallest diameter was found for maxillary lateral incisor (1.39 mm).

Conclusions:

Knowledge of location and size of access cavity facilitates achieving balance between straight-line access to the apical third of the root canal and preservation of tooth structure.

Positional changes of the third molar in orthodontically treated patients

OBJECTIVE AND RATIONALE

Over the years, the effects of the third molars eruption on the dental arches have been studied extensively. Still, literature provides less data regarding the effects of the orthodontic treatment on the third molars position. The aim of our study was to assess the positional changes of the third molars relative to the occlusal plane and to the second molar long axis, changes occurred during orthodontic treatment performed with or without premolar extractions.

METHOD

This study included 20 orthodontic treated patients: 10 of them with premolar extractions and 10 without premolar extractions. The pretreatment and post treatment panoramic radiographs were analyzed, and the angles between the third molar long axis and the occlusal plane and between the long axis of the third molar and the long axis of the second molar were measured.

RESULTS

Changes in third molar position, from pretreatment to post treatment, for the two groups of patients were evaluated by using the Student's t-test. The results of the statistical analysis revealed an improvement in third molars position, the best results were seen in the lower third molars, in the group of patients treated with premolar extractions.

Fracture resistance and pattern of the upper premolars with obturated canals and restored endodontic occlusal access cavities

We studied whether obturing canals and restoring endodontic occlusal access cavities on upper premolars could provide acceptable resistance and pattern to fracture. Eighteen upper premolars were divided equally into 3 groups. Group 1 consisted of intact controls; group 2 had access cavities and root canal preparations; group 3 as in group 2 but obturated with gutta-percha and AH26, and the access cavity restored with glass ionomer and composite. Specimens were submitted to compressive strength testing using the Hounsfield Universal H50KM testing machine with a load cell of 2000 Newtons and a crosshead speed set at 1.0 mm/min until fracture. The results from the compressive strength tests showed that intact controls (1105.83±90.93 MPa) and restored premolars (936.67±44.67 MPa) were significantly different from premolars with unrestored access cavities 568.33±105.49 MPa. There was no significant difference between intact controls and restored premolars. The predominant fracture pattern for intact teeth was an oblique fracture. For premolars that had endodontic access cavities, restored or unrestored, the most common fracture pattern was a vertical fracture. The restoration of occlusal access cavities with glass ionomer and composite provided fracture resistance close to that of intact controls, but when restored teeth fractured, they were predominantly non-restorable.

Dens evaginatus on maxillary first premolar: Report of a rare clinical case

Dens evaginatus (DE) is an odontogenic developmental anomaly that can be defined as a tubercle or protuberance from the involved surface of the affected tooth consisting of an outer layer of enamel, a core of dentin, and may contain a slender extension of pulp tissue. Early diagnosis and management of DE is important in order to prevent occlusal interference, compromised esthetics, carious developmental grooves, periodontal problems due to excessive occlusal forces, or irritation of the tongue during speech and mastication. DE usually affects the mandibular second premolars as an accessory cusp or a protuberance between the buccal and lingual cusps. Reports of DE on maxillary premolar are rare in the literature. We report one such extremely rare case of DE on maxillary first premolar.

Prevalence of taurodontism in premolars and molars in the South of iran

Background and aims

The study was undertaken to assess the prevalence of taurodontism and related systemic condi-tions and gender differences in premolars and molars of patients attending Shiraz Faculty of Dentistry.

Materials and methods

In this cross-sectional study, panoramic radiographs of 510 randomly selected patients were evaluated by a maxillofacial radiologist for the apically displaced pulp chamber. Detailed medical and family history of the patients was obtained.

Results

The prevalence of taurodontism in 510 panoramic views was 5.5% of patients. Females had significantly higher prevalence of taurodontism than men (P>0.05) and mandibular second molar was the most affected tooth.

Conclusion

Taurodontism was relatively common in population under study. A family history of other anomalies should be checked for affected patients.