Neurexin 3 Regulates Synaptic Connections Between Central Amygdala Neurons and Excitable Cells of the Lateral Parabrachial Nucleus in Rats with Varicella Zoster Induced Orofacial Pain.

Introduction: Herpes Zoster in humans is the result of varicella zoster virus (VZV) infection. Injecting rats with varicella zoster virus produces pain similar to herpes zoster "shingles" pain in humans. . In a previous study, orofacial pain was induced by injecting the whisker pad of male rats with VZV and the pain response increased after attenuating neurexin 3 (Nrxn3) expression in the central amygdala. Neurons descend from the central amygdala to the lateral parabrachial nucleus and orofacial pain signals ascend to the lateral parabrachial nucleus. GABAergic neurons within the central amygdala regulate pain by inhibiting activity within the lateral parabrachial nucleus. Attenuating Nrxn3 expression in the central amygdala increased GABA release in the lateral parabrachial nucleus suggesting Nrxn3 controls pain by regulating GABA release. Nrxn3 can also control synaptic connections between neurons, and we hypothesized that Nrxn3 knockdown in the central amygdala would reduce the number of GABAergic synaptic connections in the lateral parabrachial nucleus and increase VZV associated pain. Methods: To test this idea, the number of synaptic connections between GABAergic cells of the central amygdala and excitatory or dynorphin positive neurons within the lateral parabrachial nucleus were quantitated after infusion of a virus expressing synaptophysin. Synaptophysin is a synaptic vesicle protein that labels neuronal synaptic connections. These connections were measured in rats with and without whisker pad injection of VZV and knockdown of Nrxn3 within the central amygdala. Orofacial pain was measured using a place escape avoidance paradigm. Results: GABAergic synaptic connections were reduced in the lateral parabrachial nucleus after Nrxn3 knockdown. Rats with a reduction in the number of connections had an increase in VZV associated orofacial pain. Immunostaining with the pain marker prodynorphin indicated that the reduction in GABAergic connections was primarily associated with prodynorphin positive neurons. Discussion: The results suggest Nrxn3 reduces VZV associated orofacial pain, in part, by enhancing synaptic connections between GABA cells of the central amygdala and pain neurons within the lateral parabrachial nucleus.

A Possible Association of Salivary Gland Tumors and Oral Lesions with Birt-Hogg-Dube Syndrome: A Systematic Review.

BACKGROUND: Birt-Hogg-Dube syndrome (BHDS) is an autosomal dominant syndrome with different skin, lung, and renal manifestations. It is diagnosed commonly in the third decade of life, and patients have an increased risk for pneumothorax and renal carcinomas. METHODS: Articles published in PubMed, and Medline from 1977 to September 2023, were included in the systematic review. Inclusion criteria were applied to case reports, case series, and a retrospective cohort study, describing clinical, histopathological, and genetic findings in patients with BHDS with oral and/or parotid lesions. RESULTS: Sixteen families/individuals with BHDS were identified for analysis. Patients ranged in age from 20 to 74 years, with an average of 49.4 years. Males were affected 52.2% of the time and females, 39.1%. Skin fibrofolliculomas were reported in 87% of cases, and oral lesions were documented in 47.8%. Parotid tumors were documented in 43.5% of patients, 30.4% of which were oncocytomas, 4.3% bilateral oncocytomas, and 4.3% "oncocytic carcinoma". CONCLUSIONS: Because BHDS is uncommon, its spectrum of clinical manifestations may be underrecognized, especially as the disease is mostly reported at advanced stage. And some of the patients with BHDS may have oncocytic parotid tumors and oral lesions. In this regard, patients presenting these lesions and other indications of BHDS should be considered for renal screening.

Liposomal Bupivacaine Suspension Can Reduce the Length of Stay of Patients Undergoing Open Reduction and Internal Fixation of Mandibular Fracture.

BACKGROUND: Poorly controlled postoperative pain results in prolonged length of stay (LOS). The use of liposome bupivacaine injectable suspension (LB) for postoperative pain control is a relatively recent practice. PURPOSE: The purpose of this study was to investigate the following. In patients undergoing open reduction and internal fixation of mandibular fracture(s), does the use of LB reduce LOS compared with regular bupivacaine? STUDY DESIGN, SETTING, SAMPLE: We implemented a retrospective cohort study of consecutive patients with mandibular fracture(s) presented to Grady Memorial Hospital in Atlanta, GA, from January 2021 to January 2022. Adult patients diagnosed with 1 or more isolated mandibular fracture(s) and treated by open reduction and internal fixation were included. We excluded patients with non-isolated mandibular fracture(s), isolated condyle, infected, previously treated fractures, and documented allergy to amide local anesthetics and/or its preservatives. PREDICTOR/EXPOSURE/INDEPENDENT VARIABLE: Primary predictor variable was local anesthetic (regular bupivacaine alone or LB/regular bupivacaine). MAIN OUTCOME VARIABLE(S): Primary outcome variable was LOS, defined as the number of days from surgical procedure until discharge. Secondary outcome variables were number of opioid prescription refill(s) and postoperative pain at discharge, determined with visual analogue scale. COVARIATES: The covariates were Demographics, American Society of Anesthesiologists classification, smoking, alcohol exposure, illicit drug use, etiology, location, laterality, number of fracture(s), surgical approach, and method of maxillomandibular fixation. ANALYSES: Univariate and bivariate analyses were calculated. Statistical significance was P < .05. RESULTS: Sixty-two subjects met the inclusion criteria (31 subjects in each group). The mean ages in LB/regular bupivacaine and regular bupivacaine alone groups were 33.3 (±12) and 35.1 (±15.6), respectively (P = .94), the mean LOS in days was 0.23 (±0.44) in LB/regular bupivacaine and 1.48 (±1.77) in regular bupivacaine alone (P= < .001), and the mean VAS pain scores for LB/regular bupivacaine and regular bupivacaine alone groups were 0.53 (±1.07) and 1.87 (±2.66), respectively (P = .02). Mean number of opioid prescription refill(s) was 0 in LB/regular bupivacaine and 1 in regular bupivacaine alone group, respectively (P = .01). CONCLUSION AND RELEVANCE: The use of LB/regular bupivacaine for mandibular fracture(s) results in decrease in LOS and number of opioid refills compared to regular bupivacaine alone.

PAQR8 and PAQR9 expression is altered in the ventral tegmental area of aged rats infected with varicella zoster virus.

Infection with varicella zoster virus (VZV) results in chicken pox and reactivation of VZV results in herpes zoster (HZ) or what is often referred to as shingles. Patients with HZ experience decreased motivation and increased emotional distress consistent with functions of the ventral tegmental area (VTA) of the brain. In addition, activity within the ventral tegmental area is altered in patients with HZ. HZ primarily affects individuals that are older and the VTA changes with age. To begin to determine if the VTA has a role in HZ symptoms, a screen of 10,000 genes within the VTA in young and old male rats was completed after injecting the whisker pad with VZV. The two genes that had maximal change were membrane progesterone receptors PAQR8 (mPRß) and PAQR9 (mPRε). Neurons and non-neuronal cells expressed both PAQR8 and PAQR9. PAQR8 and PAQR9 protein expression was significantly reduced after VZV injection of young males. In old rats PAQR9 protein expression was significantly increased after VZV injection and PAQR9 protein expression was reduced in aged male rats versus young rats. Consistent with previous results, pain significantly increased after VZV injection of the whisker pad and aged animals showed significantly more pain than young animals. Our data suggests that PAQR8 and PAQR9 expression is altered by VZV injection and that these changes are affected by age.

Does the Treatment Approach for Mandibular Condyle Fractures Impact Self-Perceived Quality of Life?

PURPOSE: There is no consensus in mandibular condylar fracture/s treatment. In medicine, quality of life (QOL) includes the individual's satisfaction toward their own health condition, disease, or treatment. The purpose of this study was to investigate self-perception QOL outcomes for patients who sustained mandibular condylar fracture/s. METHODS: This cross-sectional study surveyed patients at Grady Memorial Hospital in Atlanta, Georgia from November 2016 to June 2020. The study included patients who were at least 16 years old at the time of injury, diagnosed with mandibular condylar fracture/s, treated by close reduction or open reduction and internal fixation (ORIF), presented for 6-months post-operative follow-up, and had a valid phone number. The primary predictor variable was treatment approach. The primary outcome variable was mood. Covariates were demographics, injury details, and self-perception QOL questionnaire. Univariate, bivariate, and ordinal regression analysis were performed (P < .05 significance). RESULTS: A total of 108 patients met inclusion criteria. Response rate was 84.2%. Our data showed that patients who underwent ORIF treatment were statistically more likely to experience no or milder pain when chewing (tau = 0.390, P = .002), to not require pain medications (tau = 0.389, P = .002), to report larger maximum mouth opening (tau = 0.402, P = .0003), and to report better QOL (tau = 0.440, P = 7.407e-05). Ordinal regression analysis showed that patients who had undergone ORIF treatment were positively associated with better mood (estimate: -0.062; OR: 0.54; P = .29) and statistically significant associated with excellent QOL (estimate: -2; OR: 0.13; P = 3.99e-05). Patients who sustained class III Lindahl mandibular condyle fracture were statistically significantly associated with depressed mood (estimate: 1.46; OR: 4.33; P = .002). CONCLUSION: ORIF treatment was positively associated with better QOL when compared to closed reduction for mandibular condyle fracture.

Sex Differences in the Role of Neurexin 3α in Zoster Associated Pain.

Varicella zoster virus (VZV) induces orofacial pain and female rats show greater pain than male rats. During the proestrus phase of the estrous cycle the VZV induce pain response is attenuated in female rats. A screen of gene expression changes in diestrus and proestrus female rats indicated neurexin 3α (Nrxn3α) was elevated in the central amygdala of proestrus rats vs. diestrus rats. GABAergic neurons descend from the central amygdala to the lateral parabrachial region and Nrxn3α is important for presynaptic γ-Aminobutyric acid (GABA) release. Thus, we hypothesized that the reduced orofacial pain in male rats and proestrus female rats is the result of increased Nrxn3α within the central amygdala that increases GABA release from axon terminals within the parabrachial and inhibits ascending pain signals. To test this hypothesis Nrxn3 α expression was knocked-down by infusing shRNA constructs in the central amygdala. Then GABA release in the parabrachial was quantitated concomitant with measuring the pain response. Results revealed that knockdown of Nrxn3α expression significantly increases the pain response in both male rats and proestrus female rats vs. diestrus rats. GABA release was significantly reduced in the parabrachial of male and proestrus female rats after Nrxn3α knockdown. Neuronal activity of excitatory neurons was significantly inhibited in the parabrachial after Nrxn3α knockdown. These results are consistent with the idea that Nrxn3 within the central amygdala controls VZV associated pain by regulating GABA release in the lateral parabrachial that then modulates ascending orofacial pain signals.

Neurexin 3α in the Central Amygdala has a Role in Orofacial Varicella Zoster Pain.

Varicella zoster virus (VZV) is responsible for chronic pain. VZV injection has similarities to herpes zoster (HZ) "shingles" pain in humans. In this study orofacial pain was induced by injecting male rats with the human VZV. The amygdala and parabrachial have been implicated to control affective/motivational orofacial pain. Recently our lab reported neurexin 3α (Nrxn3α) is expressed in the central amygdala and parabrachial. GABAergic neurons descend from the central amygdala to the lateral parabrachial region and Nrxn3α is important for presynaptic (γ-Aminobutyric acid) GABA release. Thus, we hypothesized that lateral parabrachial neuronal activity and orofacial pain are controlled by Nrxn3α within the central amygdala. To test the hypothesis Nrxn3α expression was knocked down (i.e., using short hairpin RNA or shRNA) in the central amygdala and GABA release and neuronal activity were quantitated in the parabrachial concomitant with measurement of the VZV induced pain response. Results revealed that attenuating Nrxn3 expression within the amygdala reduces GABA release in the parabrachial and increases neuronal activity within the lateral parabrachial region. Attenuating Nrxn3 expression also increases VZV associated orofacial pain. Activating GABAergic neurons within the central amygdala with opsins increase GABA release in the parabrachial and reduced the pain response after Nrxn3 shRNA treatment. These results are consistent with the idea that Nrxn3 within the central amygdala controls VZV associated pain by regulating GABA release in the lateral parabrachial that then controls the activity of ascending pain neurons.

Self-perception and self-representation preference between 2-dimensional and 3-dimensional facial reconstructions among dentists, dental students, and laypersons.

STATEMENT OF PROBLEM: Computer-aided design (CAD) software can merge the intraoral digital scan with patient photographs or 3-dimensional (3D) facial reconstructions for treatment planning purposes. However, whether an individual perceives a 3D facial reconstruction as a better self-representation compared with a 2-dimensional (2D) photograph is unclear. PURPOSE: The purpose of this observational study was to compare self-perception ratings and self-representation preference of the 2D and 3D facial reconstructions among laypersons, dental students, and dentists. MATERIAL AND METHODS: Three populations participated in the study: laypersons, dental students, and dentists (n=20, N=60). Facial and intraoral features were digitized by using facial and intraoral scanners, and a complete-face smile photograph was obtained. Two simulations were performed for each participant: 2D (2D group) and 3D (3D group) reconstructions. In the 2D group, a maxillary digital veneer waxing from the left to the right second premolars was produced without altering the shape, position, or length of the involved teeth. A software program (Dental Systems; 3Shape A/S) was used to merge the maxillary digital waxing with the full-face smile photograph. One image was obtained for each participant. In the 3D group, a dental software program (Matera 2.4; exocad GmbH) was used to merge the intraoral and facial scans. Subsequently, 1 video of a 180-degree rotation of each 3D superimposition was obtained. Participants evaluated both superimpositions on a scale from 1 (least esthetically pleasing) to 6 (most esthetically pleasing). Finally, participants were asked which superimposition they preferred for a potential treatment outcome representation. RESULTS: All the ratings were esthetically pleasing (median group rating 5 or 6). When analyzed solely for differences across occupation groups, ratings for the 2D representation varied significantly across populations (Kruskal-Wallis chi-squared=13.241, df=2, P=.001), but the ratings for the 3D representation did not exhibit statistically significant differences (Kruskal-Wallis chi-squared=4.3756, df=2, P=.112). Ordinal logistic regression revealed no significant main effects but a significant effect of the population×image-type interaction on the esthetic rating. All participants felt well-represented in both the 2D and 3D representations. Also, 40% of dentists, 55% of dental students, and 50% of laypersons preferred the 3D reconstructions. Sex and occupation in general had no effect on the ratings. However, students tended to give higher ratings to the 3D representations of themselves. CONCLUSIONS: There is no evidence based on the current study that 2D and 3D representations were perceived differently, but representation preferences may depend on a person's occupation. When individuals rated 3D visualization higher than 2D visualization, they strongly preferred the 3D visualization for representing the treatment outcome.

The Evolving Landscape of the American Board of Endodontics Certification Process: What it Means for the Future of the Specialty.

INTRODUCTION: The American Board of Endodontics certification is an evolving process to ensure the continuing existence of the specialty of endodontics. Recent examination changes have resulted in greater numbers of Diplomates. To fully understand the implications of such changes and evaluate current Diplomates' views of the examination process, a specific set of questions was developed focusing on beliefs and perceptions, age relationships, test components, and hypotheticals for potential changes. An analysis of the examination process has never been reported in the literature, and, as such, the survey was designed to provide the endodontic community with critical information on the past, current, and potentially future examination process. METHODS: A Web-based survey consisting of 25 questions was e-mailed to 1522 Diplomates. RESULTS: A total of 736 Diplomates responded to the survey for a response rate of 48.4%. Descriptive statistics and regression analysis (p < .05) were used to explore relationships in the data. CONCLUSIONS: A lack of perceived importance of being board certified was a major barrier. Respondents opposed de-emphasizing literature, offering the oral examination in a videoconferencing virtual format, eliminating mandatory recalls, and entirely removing 1 component of the examination to increase the numbers of Diplomates. Respondents supported reviewing the case history portfolio examination on a rolling basis. Respondents disagreed that molar cases alone demonstrated clinical competency. Older Diplomates felt the strongest that the meaning of being a Diplomate has been diluted by the changes in the certification process. The authors believe the American Association of Endodontists, program directors, and the College of Diplomates must continually emphasize the importance and value of board certification as the process continues to evolve.

Layperson and Dental Professional Perception When Evaluating Their Own Virtually 2D or 3D Simulated Esthetic Discrepancies.

PURPOSE: To analyze the perceptions of laypersons, dental students, and dentists regarding disparities of the maxillary dental midline and the occlusal plane (OP) when analyzing their own 2D or 3D clinical simulation. MATERIAL AND METHODS: 20 participants per group volunteered (N = 60). Intraoral and facial scans, and a photograph were obtained from each participant. Two simulation groups were created: 2D and 3D groups, which were subdivided into two subgroups. In the first subgroup, the OP was modified by 1-degree increments without changing the maxillary midline. In the second subgroup, the OP was modified by the same increments, but the maxillary midline was altered to match the OP inclination. Participants were asked to rate the simulations on a 1-to-6 scale and a question survey. Ordinal logistic regression (OR) was used to analyze the ratings. RESULTS: Tilt of the OP had the strongest negative effect on the ratings which was further amplified by the dental midline inclination (OR = 0.122). Midline modification alone did not affect the ratings (OR = 0.744). 3D simulations had a stronger positive effect on the ratings compared to 2D simulations. For dental students, the positive rating effect of 3D simulations was similar to dentists. For laypersons, the positive rating effect of 3D simulations compared to the 2D simulations decreased relative to dentists. The survey revealed that 45% of the dentists, 80% of the students, and 50% of the laypersons preferred the 3D simulation. CONCLUSIONS: The type of dimensional representation affected the esthetic perception of all participants. 3D simulations obtained higher esthetic ratings for the same esthetic discrepancy than 2D simulations. However, all participants' ratings decreased with increased tilt of the OP and were further decreased with the inclination of the dental midline.

Comparison of a Dental Operating Microscope and High-resolution Videoscope for Endodontic Procedures.

INTRODUCTION: The purpose of this study was to compare a dental operating microscope (DOM) with a high-resolution videoscope (VS) in terms of depth of field (DOF), resolution, and effect on fine motor skills. METHODS: Two observers used test targets to measure the resolution and DOF of the DOM and the VS. In addition, 18 participants (12 dental students and 6 endodontic residents) performed an accuracy test on a manikin head using DOM, VS, or loupes. Each participant completed a posttest survey. RESULTS: The 3 magnifications of the DOM had higher resolutions and DOF (resolution: 32, 40.3, and 50.8 line pairs/mm; DOF: 15, 10, and 6 mm) than the VS (resolution: 20.1 line pairs/mm; DOF: 5 mm). Accuracy testing showed the DOM produced better results than the VS for both resident and student groups (P < .001); however, the VS was not significantly different than loupes. The residents performed better than the students using the DOM and the VS (P < .001). The students in general took 1.3 times longer than the residents to perform the accuracy test, irrespective of the magnification device used. The DOM and the VS required on average 1.9 and 2.8 times longer compared with loupes, respectively. Most participants reported a preference for the DOM with regard to visualization and ease of use. Comments also suggested that the VS has value in diagnosis and magnification in endodontics. CONCLUSIONS: Considering the findings from this study, the DOM stands out as the leading magnification tool in endodontics. However, the VS has potential in endodontic procedures and might be used as an adjunct to other visualization aids.

Periradicular Lesions in Cancellous Bone Can Be Detected Radiographically.

INTRODUCTION: The purpose of this study was to evaluate whether naturally occurring periradicular lesions confined to cancellous bone can be detected on periapical digital radiography and whether the size of the lesion had any effect on lesion detection. METHODS: One hundred twenty-nine roots were chosen based on cone-beam computed tomographic imaging and categorized as having no lesion, a lesion confined to cancellous bone, a lesion that encroaches on junctional corticocancellous trabeculae, or a lesion with cortical involvement. The largest buccolingual dimension of the lesions was measured on cone-beam computed tomographic imaging. Two observers separately viewed the corresponding periapical radiographs in their original version as well as in the edge-enhanced setting on MiPACS (LEAD Technologies Inc, Charlotte, NC). Observers were asked to evaluate and interpret the periapical radiographs as having a lesion present, absent, or "unsure." Evaluations of images were conducted at 2 times 1 week apart. Data were analyzed, and the level of significance was set at P = .05. RESULTS: Lesion size, not the degree of cortical involvement, significantly affected the observers' ability to accurately detect lesions. As the size of the lesion increased, the probability of correctly identifying a lesion increased (P = .0008). Lesions were correctly identified 97.6%, 94.1%, 91.6%, and 89.3% of the time, respectively, when in cortical bone, at the junction of corticocancellous bone, in cancellous bone, and when no lesion was present. Observers were "unsure" whether a lesion was present or absent 10.7% of the time. Only lesions in cortical bone significantly increased observers' certainty in making a diagnosis. CONCLUSIONS: This study concluded that lesions confined to cancellous bone can be detected radiographically at a high rate. Lesion size was positively correlated with correct lesion identification, whereas the degree of cortical involvement had no significant effect. This suggests that lesion size may be a better predictor for correct lesion identification than lesion location.

Esthetic dental perception comparisons between 2D- and 3D-simulated dental discrepancies.

STATEMENT OF PROBLEM: Intraoral scanners (IOSs), facial scanners (FSs), and computer-aided design (CAD) software programs have become powerful tools for treatment planning. However, discrepancies in perception regarding 2-dimensional (2D) or 3-dimensional (3D) simulations by dentists, dental students, and laypeople have not been analyzed. PURPOSE: The purpose of this observational study was to analyze the perceptions of laypersons, dental students, and dentists regarding disparities of the maxillary dental midline and the occlusal plane when analyzing the dental discrepancies on 2D- and 3D-clinical simulations. MATERIAL AND METHODS: A female model was digitized by using an FS, IOS, and a full-face smile photograph. Dental discrepancies were simulated by using a 2D photograph (2D group) and 3D scan (3D group) of the model. In both simulation groups, 2 subgroups were produced. The occlusal plane of the first subgroup was modified in 1-degree increments without changing the dental midline or the position of the maxillary dental incisors. In the second subgroup, the occlusal plane was modified by using the same increments, but the maxillary central incisors and dental midline were altered to match the inclination of the occlusal plane. A total of 300 participants (N=300) were asked to rate the 2D images (N=12) and 3D videos (N=12) on a 1-to-6 scale and answer a questionnaire. Ordinal logistic regression was used to analyze the ratings. RESULTS: The ratings decreased with the increased tilt of the occlusal plane, and the layperson group gave consistently higher ratings than the other 2 groups. For dentists, the odds of giving a higher versus lower rating decreased by almost a half for each degree of tilt. However, for students, that effect was diminished by a positive interaction term, and for laypersons, the effect was even less. Students gave similar ratings to dentists, but laypersons gave higher ratings. As the age of the participants increased, however, the ratings also increased. The use of 3D versus 2D images had a positive effect on the ratings, but the effect decreased for the student observers and decreased even further for laypersons. Furthermore, midline alteration led to higher ratings but also resulted in worsening of the odds ratio for the tilt. Seventy percent of the dentists, 57% of the dental students, and 52% of the laypersons preferred 2D simulations to 3D simulations. CONCLUSIONS: Dentists, dental students, and laypersons decreased their ratings with increased inclination of the occlusal plane; however, laypersons still graded all the 2D and 3D images as esthetically pleasant, giving consistently higher ratings than the dentists and dental students. Overall, 3D simulations obtained higher ratings than 2D images, but the positive effect decreased for the student observers and decreased even further for laypersons.

Color dimensions of additive manufactured interim restorative dental material.

STATEMENT OF PROBLEM: Interim dental restorations can be fabricated by using additive manufacturing (AM) technologies. Although dental restoration contours can be easily and accurately fabricated by using computer-aided design (CAD) procedures, protocols for creating predictable color dimensions of AM interim restorations are lacking. PURPOSE: The purpose of this in vitro study was to measure and compare color dimensions of different AM and conventional interim restorative materials. MATERIAL AND METHODS: Disks (N=420) were fabricated by using either conventionally (CNV group) or additively manufactured (AM group) materials. The CNV group was further divided into the subgroups CNV-1 (Protemp 4; 3M ESPE) and CNV-2 (Anaxdent new outline dentin; Anaxdent). AM subgroups included AM-1 (FreePrint temp; Detax), AM-2 (E-Dent 400; Envisiontec), AM-3 (NextDent C&B; NextDent), AM-4 (NextDent C&B MFH; NextDent), and AM-5 (Med620 VEROGlaze; Stratasys). Color measurements in the CIELab coordinates were made by using a spectrophotometer (VITA EasyShade Advance 4.0; VITA) with a standardized photography gray card as a background under room light conditions (1003 lux). Color difference (ΔE*) values were calculated by using the CIE76 and CIEDE2000 formulas. The data were analyzed by using the Kruskal-Wallis test with nonparametric pairwise comparisons. RESULTS: Owing to a software error, the spectrophotometer was unable to measure the color of any specimens in the AM-5 subgroup, which was consequently excluded from further analysis. Significant differences (P=.001) between 2 manufacturing groups were found based on the L* variable. All subgroups were significantly different from each other for all 3 variables (P<.001). Pairwise comparisons revealed that all groups were significantly different from each other, except for the AM-1 and AM-2 subgroups, compared with the CNV-1 subgroup for the L* color dimension. The ΔE* values calculated by using the CIE76 formula varied from 6.63 to 23.1 and by using the CIEDE2000 formula from 3.43 to 10.21, suggesting a perceptible and unacceptable color mismatch between the CNV and AM groups. CONCLUSIONS: None of the additively manufactured interim materials tested matched the conventional interim materials in all 3 CIELab color dimensions.

Accuracy of 3-dimensional-printed Endodontic Surgical Guide: A Human Cadaver Study.

INTRODUCTION: Cone-beam computed tomographic (CBCT)-based 3-dimensional-printed surgical guides, such as those used in implant placement and orofacial surgery, allow for accurate planning and performance of surgical procedures. The objective of this study was to evaluate the accuracy of CBCT-designed surgical guides for use during endodontic surgery. METHODS: A split-mouth design was conducted using 48 roots in a cadaver model. In the experimental group, using information from the preoperative CBCT scans and digital impressions, surgical guides were designed using Blue Sky Bio (Grayslake, IL) planning software and printed using a Form 2 3-dimensional printer (Formlabs, Somerville, MA). The guides were designed to allow for surgical access at 3 mm from the apex of each root with depth control to the lingual or palatal surface of the root. In the control group, surgical access was completed "freehand" by visually approximating measurements from the CBCT scan only. The planned and postoperative CBCT images were superimposed, and the deviation of the surgical access point from the planned target was measured using Invivo software (Anatomage, San Jose, CA). A 2-tailed t test and the Fisher exact test were conducted to compare the deviation in the experimental CBCT-guided group versus the control CBCT-approximated freehand group. RESULTS: The mean deviation for the guided group (1.743 mm) was significantly less than that of the approximated freehand group (2.638 mm, P < .001). Only in 11 of the 24 samples of the control group was surgical access considered clinically successful (within the apical area of the root), whereas all 24 of the experimental samples were considered clinically successful. CONCLUSIONS: Using a CBCT-designed printed surgical guide is a more accurate method for access to the apical portion of the root during surgical endodontics compared with a "freehand" CBCT-approximated method.

Effectiveness of Gutta-percha/Sealer Removal during Retreatment of Extracted Human Molars Using the GentleWave System.

INTRODUCTION: The goal of endodontic retreatment is to address the etiology responsible for failure. In order to achieve this, the contents of the previous treatment must be removed. The aim of this study was to compare the effectiveness of the removal of residual obturation material (gutta-percha and sealer) using side-vented needle, EndoVac, and GentleWave (Sonendo, Inc, Laguna Hills, CA) irrigation protocols. METHODS: Thirty freshly extracted mandibular molars were instrumented to a master apical file size of 20.06, obturated using continuous wave of condensation and AH Plus sealer (Dentsply Tulsa, Tulsa, OK), restored, and placed in phosphate-buffered saline for 7 days. Teeth were retreated using a crown-down method to a master apical file size of 20.04. Radiographs and micro-computed tomographic images were obtained to confirm the presence of residual obturation material. Teeth were randomly divided among the following treatment groups: a side-vented needle, EndoVac, or GentleWave. Following strict irrigation protocols, postirrigation micro-computed tomographic scans were obtained and used to calculate the percentage of the residual obturation removed. RESULTS: GentleWave removed more residual obturation material (26%) than the side-vented needle (16%) and EndoVac (9%); the differences between the GentleWave group and the other 2 groups were not statistically significant (P > .05). The difference between the side-vented needle and EndoVac was statistically significant (P = .04). CONCLUSIONS: None of the irrigation techniques were able to completely remove all of the residual obturation material from the canals. The side-vented needle and the GentleWave groups were able to remove on average more residual obturation material than EndoVac; however, the differences were not significant.

Perception of occlusal plane that is nonparallel to interpupillary and commissural lines but with the maxillary dental midline ideally positioned.

STATEMENT OF PROBLEM: How disparities in parallelism between the occlusal plane and the interpupillary (IP) or commissural facial front lines are perceived is unclear. PURPOSE: The purpose of this observational study was to examine the perceptions of laypersons, dental students, and dentists regarding disparities of the anterior occlusal plane (AOP) and posterior occlusal plane (POP) with respect to the IP and commissural line (CL) with the maxillary dental midline ideally positioned. MATERIAL AND METHODS: A model of a symmetric female face was digitally created with the IP and CL parallel and the facial midline coincident with the maxillary dental midline. Two groups of images were created, one with the POP modified in 1-degree increments, in which both the maxillary dental midline and the position of the maxillary central incisors were not manipulated, and the other with the POP modified in the same increments but with the position of both maxillary central incisors lengthened to follow the inclination of the occlusal plane. Participants (N=312) were asked to rate the images on a 1-to-6 scale. The Kruskal-Wallis medians test and ordinal logistic regression were used to analyze the ratings. RESULTS: Group median ratings for different occupations gradually decreased with increased inclination of the occlusal plane. Significant differences were found for inclinations from 2 to 5 degrees. Significant odd ratios were found for age and sex. CONCLUSIONS: Dental professionals detected smaller POP disparities. The dentist and dental student groups gave lower ratings in proportion to the amount of POP inclination. Laypersons gave lower ratings only after 3 degrees of POP inclination but still graded all the images as esthetically pleasant. Older people and men tended to give higher ratings to the same image.

A Novel Prefabricated Grid for Guided Endodontic Microsurgery.

INTRODUCTION: This study aimed to introduce a novel method using cone-beam computed tomographic (CBCT) imaging and prefabricated grids to guide apical access during endodontic microsurgery and to compare its accuracy with that of the nonguided method. METHODS: Forty-two roots from human cadaver jaws were selected. Twenty-one were randomly assigned to the experimental group (grid based) and their contralateral counterparts to the control group (nonguided). Preoperative CBCT images were used to design a drill path that intended to reach the palatal/lingual aspect of the roots without attempting to complete the osteotomy or to resect the entire root end. In the experimental group, prefabricated metal grids used during imaging and surgery acted as a reference in the design and drilling. Postoperative CBCT volumes were superimposed on the preoperative volumes, and the distances between the actual drill paths and the target points were measured. A dichotomized outcome of success versus failure was also recorded and compared. Statistical analysis was performed using the paired t test and Fisher exact test. RESULTS: The mean deviation of the drill paths from the target points was 0.66 mm ± 0.54 mm (mean ± standard deviation) for grid-based drilling and 1.92 mm ± 1.05 mm (mean ± standard deviation) for nonguided drilling (P < .001). Grid-based drilling was on average 1.27 mm (95% confidence interval, 0.81-1.72 mm) closer to the target point than nonguided drilling. The probability of successful drilling was also significantly higher with grids than without grids (P = .02). CONCLUSIONS: The proposed method of guided osteotomy and root-end resection using prefabricated grids was more accurate than the nonguided method.

Interobserver and Intraobserver Reliability of Cone-beam Computed Tomography in Identification of Apical Periodontitis.

INTRODUCTION: Accurate radiographic interpretation is of the utmost importance in the diagnosis and treatment of patients. Previous studies have indicated subjectivity in the radiographic interpretation of periapical tissues irrespective of using conventional radiography, digital radiography, or cone-beam computed tomographic (CBCT) imaging. No studies to date have evaluated the reliability of the interpretation of periapical tissues based on the size of periapical radiolucency (PAR). The purpose of this study was to assess the interobserver and intraobserver reliability of CBCT interpretation by observers from different specialties and different levels of experience when identifying PARs of various sizes. METHODS: Limited field of view CBCT scans were selected such that a variety of PARs with various sizes were included. Six observers with different levels of experience and fields of specialty evaluated periradicular tissues of 28 roots on the CBCT scans at 3 separate sittings each a month apart. RESULTS: The overall Fleiss kappa coefficient for interobserver reliability and intraobserver reliability was 0.88 and 0.85; the larger the PAR, the more reliable the radiographic interpretation. Increased experience level improved the intraobserver reliability. CONCLUSIONS: CBCT imaging appears to be a reliable method for the interpretation of PAR. The larger the PAR is the more reliable the radiographic interpretation.

Effect of Pregnancy on TMJ Nociception in Rats.

OBJECTIVE: Does TMJ nociception, as measured by a behavioral assay, differ during pregnancy, potentially due to the effect of sex steroids? METHODS: Thirty - two Sprague Dawlcy rats were randomly allocated to either mid- (EH 11) or late- (EH 17) pregnancy groups. The animals within each group were further allocated to a saline or CFA treatment. At EH 11 or EH 17, the animals were injected bilaterally into TMJ with either saline (15 µL.) or 1 µg/µL CFA (15 µL). Nociception was measured with a feeding assay (pellet recording) and analyzed by comparing in-tra-meal rates using a distance-based permutation method. RESULTS: CFA injection resulted in the animals eating longer in both the mid - pregnant and late-pregnant groups. Plasma estradiol was higher in the late - pregnant group versus the mid - pregnant group. Importantly, the CFA injected late-pregnant group ate for a shorter amount of time (i. e., shorter meal rate) than the CFA injected rats at mid - pregnancy. CONCLUSION: The reduced nociceptive response (shorter meal rate) in the CFA injected late - pregnant group may be due to greater estradiol versus the CFA injected mid - pregnancy rats. Thus, one potential reason why women report fewer TMJ symptoms during pregnancy is the higher level of circulating estradiol.