Dental Quadrant Research Articles

Exploring the Learning Curve of Dental Implant Placement Using a Task-Autonomous Robotic System Among Young Dentists From Different Specialties-A Pilot Module Study.

The learning curve effect of dynamic computer-assisted implant surgery (D-CAIS) was observed among inexperienced novice surgeons. The learning curves can provide valuable information for novice surgeons and valid comparisons between new and conventional techniques. Recently, robotic computer-assisted implant surgery (R-CAIS) has shown promise as a novel dental implant surgical technique for both partially and edentulous patients. However, its learning curve remains unknown. The aim of this study was to explore the learning curve of dental implant placement surgery with a task-autonomous robotic system among young dentists with different specialties. Four young dentists (mean age: 25.3 ± 1.5 years at the beginning of their first attempt) with equal representation of males and females and with different specialties participated in this study. None of the participants had prior experience in R-CAIS. Each operator placed eight implants over eight attempts using a semi-active task-autonomous robotic system. Among the eight implants, four were straight lateral incisor implants, and four were 30°-tilted premolar implants. The implants were placed in each dental quadrant of the maxillary and mandibular jaw modules. The operation time was recorded. Coronal, apical, and angular deviations between the planned and actual sites of implant placement were measured by merging preoperative and postoperative cone-beam computed tomography (CBCT) scans. The data were analyzed with repeated-measures ANOVA (α = 0.05). The mean time for implant placement was associated with the number of attempts (p < 0.01). The time taken for the second attempt was significantly shorter than that of the first attempt (33.26 vs. 30.47 min; p < 0.001) then it plateaued. Three-dimensional (3D) angular (p = 0.31), coronal deviation (p = 0.26), and apical deviation (p = 0.06) did not differ significantly among attempts. The mean values and standard deviations of 3D coronal deviation, 3D apical deviation, and 3D angular deviation were 0.71 ± 0.31 mm, 0.72 ± 0.30 mm, and 0.94 ± 0.58°, respectively. Neither the position of the jaw (p > 0.59) nor the tilt angle of the implant (straight or 30°-tilted, p > 0.85) was related to implant placement accuracy. Dentists quickly learned the basic workflow of R-CAIS and thus facilitated the clinicians in the mastery of implant placement on edentulous jaw modules, leading to a comparable operating speed and high precision. Moreover, the accuracy of placement of straight and tilted implants in both the maxilla and mandible with R-CAIS was satisfactory.

The association of severely worn dentition resulting from betel nut chewing with temporomandibular disorders: a cross-sectional study

BackgroundMost studies support parafunctions play an important role in temporomandibular disorders (TMD), whereas the association between tooth wear and TMD remains controversial. Betel nut chewing as a parafunction is popular in South and Southeast Asia. We therefore investigated the association of severely worn dentition resulting from betel nut chewing with TMD.MethodsA cross-sectional analysis of 408 control participants (male: 380, female: 28, 43.62 ± 9.54 years) and 408 participants with betel nut chewing related severely worn dentition (male: 380, female: 28, 43.73 ± 8.93 years) who received dental and TMD checkup according to Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) in Health Management Center, Xiangya Hospital was performed. Betel nut chewing related severely worn dentition meant all the natural teeth had moderate to severe tooth wear [Tooth Wear Index (TWI) ≥ 2)] including ≥ 2 severe wear teeth (TWI ≥ 3) due to betel nut chewing. Multivariable logistic regression analysis was used.ResultsAfter adjusting for age, gender, betel nut chewing related severely worn dentition, oral submucosal fibrosis, number of missing teeth, number of dental quadrants with missing teeth, visible third molar and orthodontic history, variables of age, gender and betel nut chewing related severely worn dentition were significant for overall TMD. Multivariable analysis showed betel nut chewing related severely worn dentition was significantly associated with intra-articular TMD [odds ratio and 95% confidence intervals: 1.689 (1.271–2.244), P = 0.001] in a betel nut chewing dose-dependent manner.ConclusionBetel nut chewing related severely worn dentition was associated with intra-articular TMD.

Minimally invasive non-surgical therapy (MINST) in stage III periodontitis patients: 6-month results of a split-mouth, randomised controlled clinical trial

ObjectivesTo determine if minimally invasive non-surgical therapy (MINST) outperforms classical non-surgical periodontal therapy for stage III periodontitis with primarily suprabony (horizontal) type defects.Materials and methodsIn a split-mouth randomised controlled trial, 20 patients’ dental quadrants were randomly assigned to MINST or classical non-surgical treatment. The primary outcome variable was the number of sites with probing pocket depth ≥ 5 mm and BOP. Treatment method, tooth type, smoking status, and gender were evaluated using a multivariate multilevel logistic regression model.ResultsAfter 6 months, the percentage of sites with PD ≥ 5 mm and BOP that healed (MINST = 75.5%; control group = 74.1%; p = 0.98), and the median number of persisting sites (MINST: 6.5, control group: 7.0; p = 0.925) were similar in both groups. In the test and control groups, respectively, median probing pocket depths (2.0 mm vs. 2.1 mm) and clinical attachment level (1.7 mm vs. 2.0 mm) changed significantly (p < 0.05) but similarly. Significantly less gingival recession occurred in the MINST group’s deep molar pockets compared to the control group (p = 0.037). Men (OR = 0.52, p = 0.014) and non-molars (OR = 3.84, p 0.001) had altered odds for healing of sites with PD ≥ 5 mm and BOP.ConclusionsMINST reduces gingival recession associated with molar teeth, although it performs similarly to traditional non-surgical therapy in treating stage III periodontitis with predominately horizontal-type defects.Clinical relevanceMINST performs similarly to non-surgical periodontal therapy in stage III periodontitis with predominantly suprabony defects.Trial registrationClinicaltrials.gov (NCT04036513) on June 29, 2019.

Association of congenitally missing teeth with adult temporomandibular disorders in the urban health checkup population

BackgroundCongenitally missing tooth is the most common dental abnormality which leaves spaces in the arch, leads to numerous forms of malocclusion due to the Bolton index discrepancy and is even associated with abnormal craniofacial morphology. Even though the roles of malocclusion and tooth loss in temporomandibular disorders (TMD) development remain controversial, basic researches have found some common molecules are involved in osteoarthritis and dental agenesis. However, the association of congenitally missing teeth with TMD is unknown. We hence investigated the association of congenitally missing teeth with TMD.MethodsA cross-sectional analysis of 586 control participants (male: 287, female: 299, 38.33 ± 11.65 years) and 583 participants with non-third molar congenitally missing teeth (male: 238, female: 345, 39.13 ± 11.67 years) who consecutively received routine dental and TMD checkup according to Diagnostic Criteria for Temporomandibular Disorders Axis I in Health Management Center, Xiangya Hospital was performed. Logistic regression analysis was used to study the association of congenitally missing teeth with TMD.ResultsThe congenitally missing teeth group included 581 hypodontia and 2 oligodontia participants. The congenitally missing anterior teeth participants, the congenitally missing posterior teeth participants and participants with both congenitally missing anterior and posterior teeth accounted for 88.34%, 8.40% and 3.26% of the congenitally missing teeth group respectively. Congenitally missing teeth group had greater ratios of females and orthodontic history. Participants with congenitally missing teeth had a significantly higher prevalence of overall TMD (67.24%) in comparison to control participants (45.90%). After adjusting age, gender, presence of congenitally missing teeth, number of congenitally missing teeth, number of non-congenitally missing teeth, number of dental quadrants with missing teeth, visible third molar and orthodontic history, the variables of age, gender, presence of congenitally missing teeth and number of dental quadrants with missing teeth were significant for overall TMD. Multivariable logistic regression analysis showed congenitally missing tooth was significantly related with overall TMD [odds ratio (OR):1.689(1.080–2.642), P = 0.022], intra-articular TMD [OR: 1.711(1.103–2.656), P = 0.017] and pain-related TMD [OR: 3.093(1.321–7.239), P = 0.009].ConclusionCongenitally missing tooth is a risk factor for TMD. When treating the congenitally missing teeth population, TMJ evaluation and multidisciplinary strategies are necessary.

Discoloration of stretched colored elastomeric modules : An in vivo study.

As the demands on esthetic orthodontic devices continue to increase, discoloration of colored elastomeric modules is still a concern for patients and orthodontics. Thus, we performed an in vivo study evaluating discoloration of stretched colored elastomeric modules (i.e., white, gray, and pink). In all, 90elastomeric modules of three different colors (white, gray and pink; 30elastics from each color) were placed around brackets. The elastomeric modules were distributed and arranged randomly in the patients' four dental quadrants, and were removed after 1, 2, and 4weeks. Color measurements were made before and after insertion into each patient's mouth. Digital images were taken with the camera of amobile phone (iPhoneX, Cupertino, CA, USA), and the variations in color were characterized using the Commission Internationale del'Eclairage (CIE) color space system (L*a*b*) offered by Photoshop (Adobe, San Jose, CA, USA). Analysis of variance (ANOVA) and least significant difference (LSD) tests were used for statistical analyses. The white elastomeric modules were most prone to discoloration, followed by the pink and then finally by the gray colored modules. The amount of discoloration resulting from arandom diet practiced by the patients increased gradually (but was not significant) for all elastomeric modules studied and reach apeak after 2weeks for the white and gray elastomeric modules, while discoloration of the pink elastomeric modules plateaued after 1week. Colored elastomeric modules (e.g., white, gray, and pink) discolor to variable degrees over time. Thus, patients should be advised that the consumption of food and drinks may result in discoloration of the elastomeric modules.

Therapeutic dentistry in prehistoric Maryland—New analyses from the Hughes (18MO1) archeological site

Late Woodland period prehistoric human remains recovered from the Hughes site (18MO1) in the 1930s were only recently submitted for bioarcheological analysis. These remains represent 20 individuals exhibiting varying degrees of preservation and representation. Among the remains are several teeth suspected of undergoing antemortem dental modification. All of the examined dental cavitations were deep, and some show excavation all the way to the pulp. Dental remains representing three individuals (two adult females and a child) were examined to define etiology of altered occlusal cavitations in these teeth. The findings provide evidence of prehistoric, therapeutic dentistry in the Middle Atlantic region of the eastern United States. Two mandibles and a maxillary right dental quadrant representing three individuals were analyzed utilizing radiographs, visible and alternate light source macro photography, and scanning electron microscopy in three modes of detection. All three specimens showed signs of both radial and concentric tool marks to varying degrees in both enamel and dentin borders of carious lesions. The shape of the cavitations do not follow normal pathological patterns of undisturbed occlusal decay in teeth. Further, evidence is presented that the excavative tool motion changes from rotational drilling to radial scooping the further posterior the cavitation is located in the oral cavity. Lastly, it is proposed that the reason for these modifications was therapeutic dentistry.

Positional trueness of abutments by using a digital die-merging protocol compared with complete arch direct digital scans and conventional dental impressions

Statement of problemComplex prosthodontic treatments frequently require capturing an accurate impression of abutment teeth throughout the dental arch. Intraoral digital scanning has been reported to be accurate within single dental quadrants; however, the positional trueness of complete arch intraoral digital scans is not well understood. PurposeThe purpose of this in vitro study was to compare the positional trueness of a complete arch digital scan generated by digitally merging portions of a direct digital scan from an intraoral scanner (IOS) with a digitized polyvinyl siloxane (PVS) complete arch impression. Material and methodsA 3D printed reference cast was scanned with a desktop scanner, and reference standard tessellation language (STL) data sets were obtained. The reference cast was used to generate 4 nonmerged (NM) groups and 2 die-merged (DM) groups. In the NM groups (n=10), a direct digital scan of the reference cast was made with an IOS (NM-IOS), the PVS impression of the reference cast was digitized by using a cone beam computed tomography (CBCT) scanner (NM-PVS-CBCT) or a desktop scanner (NM-PVS-DESK), and the gypsum cast made from the PVS impression was digitized by using a desktop scanner (NM-STONE). In the DM groups (n=10), individual dies were cropped from the complete arch digital scan from the NM-IOS group and merged with the digital scans from the NM-PVS-DESK and NM-PVS-CBCT groups to generate the DM-PVS-DESK and DM-PVS-CBCT groups, respectively. Deviation was measured as the absolute value of the distance from a reference position on the reference cast. The Kruskal-Wallis and Dunn pairwise comparison tests were used to compare the difference in deviation between the groups (α=.05). ResultsThe NM-STONE and NM-PVS-DESK groups demonstrated the highest positional trueness, with global deviations of 19.6 and 17.7 μm, respectively, with no statistically significant difference (P>.999). However, both the NM-IOS and NM-PVS-CBCT groups differed significantly from the NM-STONE group (P<.001 and P=.003, respectively) and the NM-PVS-DESK group (P<.001 and P=.004, respectively). In the DM groups, the DM-PVS-CBCT group presented a higher deviation than the DM-PVS-DESK group. ConclusionsComplete arch digital scans of PVS impressions digitized with a desktop scanner exhibited less positional deviation than those digitized with a CBCT scanner or complete arch digital scans generated with an IOS. Complete arch digital scans generated with an IOS and CBCT scanner result in more deviations in the posterior regions, and their positional trueness may not be sufficient to construct an accurate digital scan. Generating a complete arch digital scan by digitally merging portions of a direct digital scan from an IOS with a digitized PVS complete arch impression is a suitable alternative to the contemporary workflow of digitizing a stone cast with a desktop scanner.

Ergonomic Risk Assessment of Oral and Maxillofacial Surgeons - RULA Applied to Objective Kinematic Data.

The prevalence of musculoskeletal disorders is high in oral and maxillofacial surgeons (OS) due to their static and contorted working positions. Hence, the aim of this study was to conduct posture analyses in this specific group of dental professionals using the Rapid Upper Limb Assessment (RULA). In total, 15 (12m/3 f) OS participated in this study. An inertial motion capture system (Xsens) was used to collect kinematic data during a simulated workflow. Computer-based routines calculated the RULA score for the extracted joint angles at each defined time point. Then, an analysis of the time-dependent RULA scores by body regions was conducted. Key variables were the relative occurrence of specific RULA scores during the complete workflow, individual subtasks, and for treatment of each of the four different dental quadrants. The subtasks and dental quadrants were compared using the Friedman test. The total median RULA score represented a high risk for OS during their work (7), including the temporal component (OS spent 77.54% of their working time with a RULA score of 7). The wrists and hands, elbows, lower arms, and the neck were exposed to postures with the highest risk for musculoskeletal strain. For OS, both the right and the left assisting hand were heavily strained while working on the first dental quadrant caused the most unfavorable postures for OS.

Artificial intelligence implementation in tooth identification from X-ray images

Development of a convolutional neural network that can precisely and quickly identify teeth from x-ray images, without using neighbouring structures as a frame of reference. Using a database of 11403 x-ray images that were precisely annotated by dental professionals we have trained, validated and tested a convolutional neural network (CNN) that can identify teeth according to their position in the oral cavity. Four “levels” were tested, the first one being classification according to the type of the tooth morphologically. This consisted of 4 categories: incisor, canine, premolar and molar. The second “level” added the differentiation between types of incisors, premolars and molars. This “level” had 8 categories, imitating a dental quadrant. The third “level” added maxillary or mandibular origin and a total of 16 categories. Finally, the fourth “level” had 32 categories, meaning every tooth had its own. The first level offered an 97.83% accuracy on unseen data. The second level offered 92.13%. “Level” three offered 91.14%. The fourth level, while being the most demanding, offered a 91.13%. The results were the best in the 4 category “level” and the least successful in the 32 category “level”. Interestingly, the difference between the 32 and 16 category level was not significant at all. The developed CNN can identify the morphological type of the tooth with a very high accuracy rate. This opens a door into implementation of artificial intelligence in rapid analysis and cross referencing in (forensic) dental medicine. This study has been supported as a part of the Croatian Science Foundation under the project IP-2020-02-9423.

Tooth extraction without discontinuation of oral antithrombotic treatment: A prospective study.

To identify which variable, among those related to surgeries, to patients, or to antithrombotic treatments, could be considered as a bleeding indicator, and to analyze effectiveness of the local hemostatic protocols used, incidence of bleeding and healing index, depending on the number of extracted teeth, and patient antithrombotic treatment. Patients who underwent tooth extractions without interruption or reduction of antithrombotic treatment were prospectively followed. The exact two-tailed Fisher test was used to investigate the relationship between presence/absence of bleeding and type of hemostatic material. The effect of variables on the probability of bleeding and healing index was assessed by means of a multivariate logistic regression. Two hundred and fifty-four procedures were analyzed. The incidence of bleeding was 15.75%. Severe bleeding occurred in only 6 patients (2.34%). The number of involved dental quadrants and pre-surgical antibiotic treatments were found to be positively related with bleeding. The use of vasoconstrictors during surgery resulted in a reduction of healing index scores. Tooth extractions in patients on antithrombotic treatment were found to be free from significant bleeding although the involvement of more than 1 quadrant in the same procedure should be avoided.

Computed tomographic findings of dental disease in domestic rabbits (Oryctolagus cuniculus): 100 cases (2009-2017).

To characterize the CT findings and epidemiological features of acquired dental disease in rabbits. 100 client-owned rabbits (Oryctolagus cuniculus). Medical records were searched to identify rabbits that underwent skull CT for any reason from 2009 to 2017. History, signalment, and physical examination findings were recorded. The CT images were reevaluated retrospectively for evidence of dental disease and graded according to a previously described system (from 1 [no evidence of disease] to 5 [severe dental disease]) for acquired dental disease in rabbits, and an overall (mean) grade was assigned. Descriptive analyses were performed. Factors were assessed for associations between dental disease grade and malocclusion stage. Common findings included premolar or molar tooth curvature in transverse (n = 100 rabbits) and sagittal (95) planes, apical elongation of premolar or molar teeth (99), sharp dental points (93), deformation of the mandibular canal (82), and periodontal ligament space widening (76). Acquired dental disease was classified as grade 1 (n = 2 rabbits), 2 (60), 3 (14), 4 (4), or 5 (20). Most CT findings were significantly correlated with each other. Agreement of grades was fair between left- and right-sided quadrants and between maxillary and mandibular quadrants. Age was associated with increasing dental disease grade and malocclusion stage (proportional ORs, 1.21 and 1.32/y, respectively). Fair agreement in disease grades between dental quadrant pairs indicated a degree of asynchrony in the development of dental disease. Findings suggested premolar or molar tooth curvature in a sagittal plane, subtle elongation at premolar or molar tooth apices, and mandibular canal deformation should be added to the grading system.

Effect of one and two sessions of antimicrobial photodynamic therapy on clinical and microbial outcomes of non-surgical management of chronic periodontitis: A clinical study.

Background This study aimed to compare the effect of one and two sessions of antimicrobial photodynamic therapy (aPDT) as an adjunct to scaling and root planing (SRP) on clinical and microbial parameters in patients with chronic periodontitis.Methods This study was conducted on 20 patients. The dental quadrants of patients were randomly assigned to SRP at baseline (group 1), SRP at baseline and one month (group 2), SRP plus aPDT at baseline (group 3) and SRP plus aPDT at baseline and one month (group 4). Probing depth (PD), clinical attachment level (CAL) gain, and bleeding on probing (BoP) were measured at baseline, and one and three months later. F. nucleatum counts were determined by PCR. ANOVA was used for the comparison of these variables between the groups. Results In all the groups, PD reduction and CAL gain increased significantly at 1- and 3-month intervals compared to baseline (P=0.001). At three months, the difference in PD between groups 1 and 3 was statistically significant (P=0.014). CAL gain between groups 2 and 4 at one month (P=0.016) and three months (P=0.001) wasstatistically significant. Reduction in F. nucleatum counts was not significant between the four study groups (P>0.05). Conclusion A combination of two sessions of aPDT and SRP could improve CAL gain; however, further long-term studies are necessary in this regard.

A Retrospective Study of the Incidence and Management of Complications Associated With Regional Nerve Blocks in Equine Dental Patients.

Regional anesthesia of the equine head is commonly performed to allow oral extraction of diseased teeth in the standing horse. The use of 4 blocks (infraorbital nerve, maxillary nerve, mental nerve, and mandibular nerve) is well documented for desensitization of dental quadrants for oral surgery for exodontia, but descriptions of associated complications are limited. A total of 270 regional nerve blocks were performed on 162 equine patients in a second opinion referral hospital setting. Criteria for inclusion in the study included a 24-hour stay in hospital, that the blocks be performed by one clinician and at minimum, a 2-week follow-up examination be performed. A total of 8 complications were identified in 7 patients representing a 2.96% incidence of complication. Complications included supraorbital hematoma (3), local hematoma (2), lingual self-trauma (2), and nerve block failure to desensitize (1). Treatment and management of complications are discussed. Complications associated with regional anesthesia may be reduced by reducing anesthetic volumes, precise needle placement, familiarity with the facial anatomy relevant to nerve blocks, adequate restraint, aseptic technique, postprocedural muzzling, and the use of a newly opened bottle of local anesthetic.

Comparison of dental and chronological age based on CBCT-generated panoramic images and reconstructed 3D images

Objective: The aim of the present study was the comparison of the known chronological age of the studied subjects by dental age evaluated according to the developmental stages of seven permanent teeth in the lower left dental quadrant and to determine how much the child's dental age differs from its chronological age. Methods: Radiographs of 579 patients (288 boys and 291 girls), aged 3-16 years, from the database of the Radiological Clinic of the Second Medical Faculty of Charles University and the Motol University Hospital in Prague were reviewed. The patients were examined for different indications by cone beam computed tomography (CBCT). The evaluation of the developmental stages of the teeth was performed from generated panoramic images and reconstructed three-dimensional (3D) images. The developmental stages of the teeth were evaluated by Demirjian's method for dental maturity based on seven teeth of the lower left dental quadrant (Demirjian et al. 1973). The evaluated variables were mineralization and development of the dental crown, length of the root, and closure of the apical foramen. Results: The difference between chronological and dental age was -0.16 (standard deviation (SD) 1.68, p-value 0.7) in boys and -0.10 (SD 1.65, p-value 0.27) in girls, on average. These results confirm that the method is accurate. Low SD values express the precision of the evaluation. Conclusion: Use of reconstructed 3D images makes the evaluation of the maturation of teeth more accurate in comparison to the use of generated panoramic images. The development of teeth (with exception of third molars) was complete at the age of 16 in 97.3% of the studied subjects.

Radiographic Evaluation of the Presence/Agenesis of Third Molars in a Mexican Child Population

In the human being, third molar is the tooth that exhibits more variants during its embryologic development, usually causing diverse anomalies and discomfort when erupting to the oral cavity. It has been pointed out that the prevalence of third molar agenesis is between 9 to 37%. The aim of the present comparative cross-sectional study was to radiographically assess the presence/absence of third molar germs (G3M) in a sample of pediatric patients of Mexican origin. A total of 513 panoramic radiographs were analyzed from patients attending the Pediatric Dentistry Postgraduate Program ( San Luis Potosí University, México), during the years 2011 to 2017. Inclusion criteria were patients between 7 and 18 years old, any gender; children with antecedents of a third molar extraction, previous orthodontic treatment, or with an associated congenital or systemic condition were excluded. Total prevalence G3M agenesis was calculated. Then, statistical comparisons of agenesia proportions per dental quadrant, gender, and age group were performed. 245 panoramic radiographs corresponded to the female gender, while 268 belonged to the male gender. The total prevalence of G3M agenesia was estimated in nearly 56%, and the 7-8 years old group exhibited the highest proportion; however, when this age group was excluded from the analysis, such prevalence decreased to 27.3%. Both mandibular quadrants showed higher proportions of G3M agenesia. There were no significant differences between genders. The total prevalence reported in the present study was found to be well above regarding the international parameters. It is quite possible that lack of radiographic visualization of G3M had been inaccurate in some cases due to the common absence of calcification traces from those teeth during early ages (7-8 years old). The adjusted analysis provided a prevalence value more in line with the recognized standards in the dental literature.

Association Between Missing Posterior Teeth and Occurrence of Temporomandibular Joint Condylar Erosion: A Cone Beam Computed Tomography Study.

To determine a possible association between asymptomatic temporomandibular joint (TMJ) condylar erosion and the number of missing posterior teeth and their location, as well as the number of dental quadrants with missing posterior teeth. This case-control study involved 210 patients (male to female ratio = 98:112) aged 16-74 years, with 105 asymptomatic patients with TMJ condylar erosion and a control group of 105 patients without TMJ condylar erosion. Cone beam computed tomography images were evaluated to classify the severity of TMJ condylar erosion as grade 0 (absence of erosion), grade I (slight erosion), grade II (moderate erosion), or grade III (extensive erosion). The number of missing posterior teeth (mean ± standard deviation [SD]; 2.7 ± 2.4 vs 0.7 ± 1.2) (P < .001), number of dental quadrants with missing posterior teeth (1.5 ± 1.3 vs 0.6 ± 0.9) (P < .001), and bilateral location of missing posterior teeth (41 ± 39.0 vs 10 ± 9.5) (P < .001) were all significantly higher in patients with erosion than in those without erosion. The condylar erosion grade was significantly associated with the number of missing posterior teeth (odds ratio [OR] = 1.24; P = .006), the number of dental quadrants with missing posterior teeth (OR = 1.36; P = .006), and the bilateral occurrence of missing posterior teeth (OR = 3.03; P = .002). The findings from this study suggest a possible association between TMJ condylar erosion grades and the number of missing posterior teeth, the number of quadrants with missing posterior teeth, and the bilateral occurrence of missing posterior teeth.

Regional Nerve Blocks for Equine Dentistry.

Regional nerve blocks are necessary to facilitate equine oral surgery in the standing sedated patient. Step-by-step instruction on how to perform common regional nerve blocks are discussed, including infraorbital, maxillary, middle mental, and inferior alveolar nerve blocks. Regional nerve blocks are critical when performing dental procedures in the standing horse.1 The infraorbital and maxillary nerve blocks provide anesthesia of the infraorbital nerve, which is a branch of the maxillary nerve. Both nerve blocks provide adequate anesthesia for all maxillary dental procedures.1 When the infraorbital nerve block is utilized, care must be taken to advance the needle into the infraorbital foramen in order to appropriately anesthetize the caudal maxillary teeth. Mandibular dental procedures require anesthesia of the inferior alveolar nerve, which is a branch of the mandibular nerve. Local anesthesia at the level of the mental foramen will result in anesthesia of ipsilateral incisors and canines, while anesthesia at the level of the mandibular foramen will anesthetize the entire ipsilateral mandibular dental quadrant. All nerve blocks should have the injection site aseptically prepared prior to the procedure. The 4 most common dental nerve blocks are described step by step.

Condylar Erosion in Patients With Chronic Temporomandibular Joint Arthralgia: A Cone-Beam Computed Tomography Study

The objective of this study was to assess the association between temporomandibular joint (TMJ) condylar erosion and chronic TMJ arthralgia. Based on a sample size estimation, this case-and-control study involved 198 patients 16 to 73years old recruited from a routine clinical practice (99 cases, patients with chronic TMJ arthralgia and mean pain duration of 16.4months; 99 controls, asymptomatic patients without a history of orofacial pain). The clinical diagnosis of arthralgia was made according to the Research Diagnostic Criteria for Temporomandibular Disorders. Cone-beam computed tomographic (CBCT) images were evaluated for the presence or absence of erosive osseous changes of the TMJ condyle. Severity of TMJ condylar erosion was classified as grade 0 (absence of erosion), grade I (slight erosion), grade II (moderate erosion), or grade III (extensive erosion). Logistic regression analysis was used to assess the association between chronic TMJ arthralgia and condylar erosion, adjusting for age, gender, number of missing posterior teeth, and number of dental quadrants with missing posterior teeth. TMJ condylar erosion was found in 59.6% of cases and 21.2% of controls. There was a significant association between TMJ arthralgia and degree of condylar erosion (P < .001). The odds ratio that a TMJ with condylar erosion grade II might belong to the TMJ arthralgia group was strong (3.1:1; 95% confidence interval [CI], 1.17 to 8.09) and significant (P= .023). Significant increases in risk of TMJ arthralgia occurred with condylar erosion grade III (7.7:1; 95% CI, 3.09 to 19.18; P < .001). The study provides evidence of an association between TMJ condylar erosion and chronic TMJ arthralgia.

Varicella Zoster Virus and Internal Root Resorption: A Case Report

Herpes zoster is a viral infection caused by the reactivation of the varicella zoster virus. One of the less well-recognized maxillofacial complications is tooth root resorption. To our knowledge, this is the first case report about internal resorption associated with varicella zoster virus involving different dental quadrants. A 38-year-old woman presented with internal resorption of maxillary canine and first premolar tooth roots on the right quadrant and generalized internal resorption of second molars of both mandibular quadrants. The patient's medical history showed mild oral lichen planus and infection with varicella zoster virus (chickenpox) with severe clinical manifestations 5 years previously. The patient developed diabetes mellitus type I and hypothyroidism a short time after varicella zoster virus infection, and by the time of infection with this virus, oral lichen planus had progressed from the reticular pattern to the generalized severe erosive form. Viral etiology could also be considered in these diseases. The root canals of the affected teeth were debrided, irrigated, and dried, and calcium hydroxide paste was placed in the root canals for a week during the first treatment session. The root canals were obturated during the second session. Six-month follow-up showed improvement of oral lichen planus and resolution of widening of periodontal ligament of the affected teeth, with follow-up radiographs revealing no periapical problems. It appears some cases of internal root resorption classified as idiopathic might have viral etiology. Therefore, it is recommended that patients be questioned about a history of chickenpox and herpes zoster.

The Dynamics of Supernumerary Tooth Development Are Differentially Regulated by Sprouty Genes

In mice, a toothless diastema separates the single incisor from the three molars in each dental quadrant. In the prospective diastema of the embryo, small rudimentary buds are found that are presumed to be rudiments of suppressed teeth. A supernumerary tooth occurs in the diastema of adult mice carrying mutations in either Spry2 or Spry4. In the case of Spry2 mutants, the origin of the supernumerary tooth involves the revitalization of a rudimentary tooth bud (called R2), whereas its origin in the Spry4 mutants is not known. In addition to R2, another rudimentary primordium (called MS) arises more anteriorly in the prospective diastema. We investigated the participation of both rudiments (MS and R2) in supernumerary tooth development in Spry2 and Spry4 mutants by comparing morphogenesis, proliferation, apoptosis, size and Shh expression in the dental epithelium of MS and R2 rudiments. Increased proliferation and decreased apoptosis were found in MS and R2 at embryonic day (ED) 12.5 and 13.5 in Spry2(-/-) embryos. Apoptosis was also decreased in both rudiments in Spry4(-/-) embryos, but the proliferation was lower (similar to WT mice), and supernumerary tooth development was accelerated, exhibiting a cap stage by ED13.5. Compared to Spry2(-/-) mice, a high number of Spry4(-/-) supernumerary tooth primordia degenerated after ED13.5, resulting in a low percentage of supernumerary teeth in adults. We propose that Sprouty genes were implicated during evolution in reduction of the cheek teeth in Muridae, and their deletion can reveal ancestral stages of murine dental evolution.