Sympathetic nervous system contributes to orthodontic tooth movement by central neural regulation from hypothalamus.

Orthodontic tooth movement (OTM) is a specific treatment of malocclusion, whose regulation mechanism is still not clear. This study aimed to reveal the relationship between the sympathetic nervous system (SNS) and OTM through the construction of an OTM rat model through the utilization of orthodontic nickeltitanium coiled springs. The results indicated that the stimulation of SNS by dopamine significantly promote the OTM process represented by the much larger distance between the first and second molar compared with mere exertion of orthodontic force. Superior cervical ganglionectomy (SCGx) can alleviate this promotion effect, further proving the role of SNS in the process of OTM. Subsequently, the ability of orthodontic force to stimulate the center of the SNS was visualized by the tyrosin hydroxylase (TH) staining of neurons in ventromedial hypothalamic nucleus (VMH) and arcuate nucleus (ARC) of the hypothalamus, as well as the up-regulated expression of norepinephrine in local alveolar bone. Moreover, we also elucidated that the stimulation of SNS can promote osteoclast differentiation in periodontal ligament cells (PDLCs) and bone marrow-derived cells (BMCs) through regulation of receptor activator of nuclear factor-κB ligand (RANKL)/osteoprotegerin (OPG) system, thus promoting the OTM process. In conclusion, this study provided the first evidence for the involvement of the hypothalamus in the promotion effect of SNS on OTM. This work could provide a novel theoretical and experimental basis for further understanding of the molecular mechanism of OTM.

Comment on: An analysis of the first and second mandibular molar roots proximity to the inferior alveolar canal and cortical plates using cone beam computed tomography among Saudi population.

[No Abstract Available].

Contribution of capsaicin-sensitive innervation to the continuous eruption of the rat mandibular incisors.

A major component of tooth innervation is made of capsaicin-sensitive primary afferents (CSPA). These fibers play a key role in tooth pain and inflammation; little is known, however, about the role of CSPA in tooth eruption. The aim of this study was to examine the role of the capsaicin-sensitive afferents in the process of eruption of intact rat incisors. CSPA fibers in several rat groups, were subjected to one of the following experimental procedures: systemic chemical ablation, systemic ablation followed by chemical sympathectomy and localized activation. The observed effects on incisor eruption were compared to those made on controls. The total amount of eruption in control/naïve rats, measured over a total period of 144 h, was 3.18 ± 0.07 mm and decreased to 2.43 ± 0.08 mm (n = 7; p < 0.001) following systemic ablation of CSPA. Further decrease to 2.24 ± 0.08 mm (n = 7; p < 0.001) was noticed when chemical sympathectomy was added to CSPA ablation. The average rate of eruption was 1.7 ± 0.25 mm following CSPA activation, compared to an average of 0.8 ± 0.07 mm for controls (n = 7; p < 0.001). Capsaicin sensitive fibers play an important role in tooth homeostasis, and intact neural supply is required for tooth growth under normal conditions.

Reduced Depth Technique with the Posterior Superior Alveolar Block.

Purpose: The posterior superior alveolar (PSA) block is one of many techniques used to provide profound anesthesia for invasive dental procedures. This technique has a long history, with a high success rate, but is not without complication risks. The purpose of this study was to determine if pulpal anesthesia of the maxillary second molar could be achieved using a posterior superior alveolar block with a reduced depth of penetration of 10 mm compared to the current suggested depth of 16 mm.Methods: Using a cold refrigerant, a thermal test was conducted using the buccal surface of a maxillary second molar of 43 participants. Positive neural responses were obtained from 100% of the participants (n=43) during the pretest. Each participant received a posterior superior alveolar block using a short (20mm), 27-gauge needle with the penetration depth reduced to 10mm. Post-test neural responses of these molars were evaluated using same cold thermal test technique.Results: Study results demonstrated that the reduced depth technique for the PSA block was successful in 88% (n=38) of the participants; pulpal anesthesia of the maxillary second molar had been achieved. Furthermore, there were zero positive aspirations and zero hematomas observed in the participants.Conclusion: The reduced needle depth technique showed promise in achieving desired results of pulpal anesthesia coupled with decreasing risk and complications associated with the PSA block. Additional blinded, randomized clinical studies are recommended to achieve evidence-based support for this reduced depth PSA block technique.

Protection of Inferior Alveolar Neurovascular Bundle in Alveolar Bone Operation.

PURPOSE: The aim of this study was to investigate the protection of the inferior alveolar neurovascular bundle in alveolar bone operation in conditions such as chronic osteomyelitis and cementoma. PATIENTS AND METHODS: The study enrolled 7 cases, 4 with chronic osteomyelitis and 3 with cementoma with pain. Computed tomography scan and 3-dimensional reconstruction were performed for the diseases. Data were processed by ProPlan CMF 1.3 software. The edge of lesion was defined and the inferior alveolar nerve was marked. Template was designed to guide the osteotomy line. Piezosurgery was used for osteotomy, with the avoidance of nerve canal. Current perception threshold (CPT) was performed to evaluate the nerve function after operation. RESULTS: The CPT difference of the affected side before and after operation showed no statistically significant differences compared with that of the unaffected side (P = 0.0556). CONCLUSIONS: Digital template protects the inferior alveolar neurovascular bundle with the aid of piezosurgery during alveolar bone resection, which obtained satisfying clinical results. As powerful assistive tools of functional surgery, digital template and piezosurgery achieve both the purposes of treatment and function.

The Anesthetic Effect of Anterior Middle Superior Alveolar Technique (AMSA).

Anesthesia of the soft and hard tissues of the maxilla may require up to 5 injections. Thus, the aim of this study was to evaluate the anesthetic efficacy of the anterior middle superior alveolar (AMSA) and supraperiosteal injection techniques during subgingival scaling and root planing (SRP). Thirty individuals with periodontitis were scheduled for SRP on the buccal aspect of teeth in the anterior maxilla. Before SRP, on a randomly chosen side of the maxilla, the supraperiosteal injection was performed in 1 session, while the AMSA injection was conducted in the contralateral side of the same patient in another session. Immediately after each SRP session, patients rated their pain perception during the procedure with a visual analog scale. No statistically significant differences in mean pain ratings during SRP were found after both anesthetic techniques (P > .05). This preliminary study demonstrated that the AMSA and supraperiosteal injection techniques provided similar anesthetic comfort during SRP. The AMSA injection could be an alternative to anesthetize the buccal aspect of maxilla, without the undesirable effects on facial structures such as the upper lip, nostrils, and lower eyelids. However, further randomized clinical trials with larger samples are necessary to confirm such results.

Morphological and morphometric analysis of the shape, position, number and size of mental foramen on human mandibles.

OBJECTIVE: To provide anatomical information on the position, morphological variations and incidence of mental foramen (MF) and accessory mental foramen (AMF) as they are important for dental surgeons, anesthetists in nerve block and surgical procedures, to avoid injury to the neurovascular bundle in the mental foramen area. METHODS: Our study was conducted on 150 adult dry human mandibles from the osteological collection of the Department of Anatomy of the Faculty of Medicine, University of Sarajevo. The location and shape of the MF and the presence of the AMF were studied by visual examination. The size and position of the MF were measured using a digital vernier caliper. SPSS, version 17 software was used for the statistical analysis. RESULTS: Bilateral mental foramina were presented in all 150 mandibles. In the majority of mandibles, the MF was located between the first and second premolar (20.3%) or on the level of the root of the second premolar (60.3%), midway between the inferior margin and the alveolar margin of the mandible. Most of the mental foramina were oval in shape (83.3%). An AMF was present in four mandibles (2.7%) on the right side. CONCLUSION: This study may be a very useful new supplement to data on variations in the incidence, position, shape and size of mental and accessory mental foramina, which may help surgeons, anaesthetists, neurosurgeons and dentists in carrying out surgical procedures successfully.

Mandibular bone block harvesting from the retromolar region: a 10-year prospective clinical study.

PURPOSE: The aim of this prospective study was to evaluate the outcome of bone block harvesting from the external oblique ridge with the MicroSaw, assess the volume of the harvested block, and identify possible morbidity and complications related to the procedure. MATERIALS AND METHODS: Bone blocks were harvested from the external oblique line of the mandible according to the MicroSaw protocol. The bone blocks were split into two thinner blocks with a diamond disk according to the split bone block (SBB) technique for biologic grafting procedures. RESULTS: In all, 3,874 bone blocks were harvested from the external oblique line of the mandible in 3,328 patients. Four hundred nineteen patients (12.59%) underwent bilateral bone block harvesting, and 127 patients (3.82%) had more than one block harvested from the same area during the study period. In 431 cases (11.12%), only one block was required, so the second was repositioned to reconstruct its donor site. The average harvesting time was 6.5 ± 2.5 minutes, and a mean volume of 1.9 ± 0.9 cm³ was obtained (maximum 4.4 cm³). In 168 (4.33%) cases, the alveolar nerve was exposed, leading to sensory problems lasting up to 6 months. In 20 cases (0.5%), minor nerve injury resulted in hypesthesia or paresthesia that lasted for up to 1 year in most patients. No major nerve lesions with permanent anesthesia were observed. Sixty-one (1.58%) donor sites showed primary healing complications, most in smokers (80.4%). Reentry of 16 reimplanted harvested areas was performed between 6 and 40 months later, showing a well-regenerated and healed external oblique ridge. CONCLUSION: This study demonstrated that relatively large volumes of bone block graft can be retrieved in the mandible with a low complication rate. Reimplantation of half of the bone block offers the possibility for complete regeneration of the donor site.

Effect of Buffered 4% Lidocaine on the Success of the Inferior Alveolar Nerve Block in Patients with Symptomatic Irreversible Pulpitis: A Prospective, Randomized, Double-blind Study.

INTRODUCTION: Medical studies have suggested that buffering local anesthetic may increase the ability to achieve anesthesia. The purpose of this study was to determine the effect of 4% buffered lidocaine on the anesthetic success of the inferior alveolar nerve (IAN) block in patients experiencing symptomatic irreversible pulpitis. METHODS: One hundred emergency patients diagnosed with symptomatic irreversible pulpitis of a mandibular posterior tooth randomly received a conventional IAN block using either 2.8 mL 4% lidocaine with 1:100,000 epinephrine or 2.8 mL 4% lidocaine with 1:100,000 epinephrine buffered with sodium bicarbonate in a double-blind manner. For the buffered solution, each cartridge was buffered with 8.4% sodium bicarbonate using the OnPharma (Los Gatos, CA) system to produce a final concentration of 0.18 mEq/mL sodium bicarbonate. Fifteen minutes after administration of the IAN block, profound lip numbness was confirmed, and endodontic access was initiated. Success was defined as no or mild pain (≤54 mm on a 170-mm visual analog scale) on access or instrumentation of the root canal. RESULTS: The success rate for the IAN block was 32% for the buffered group and 40% for the nonbuffered group, with no significant difference (P = .4047) between the groups. Injection pain ratings for the IAN block were not significantly (P = .9080) different between the 2 formulations. CONCLUSIONS: For mandibular posterior teeth, a 4% buffered lidocaine formulation did not result in a statistically significant increase in the success rate or a decrease in injection pain of the IAN block in patients with symptomatic irreversible pulpitis.

Multivariate assessment of site of lingual nerve.

Injury to the lingual nerve can cause debilitating symptoms. The nerve lies in the retromolar region and its anatomical site can vary within patients and according to sex, age, and dentate status. To our knowledge, no previous studies have recorded its course from multiple bony landmarks and examined the association between age, dentate status, and sex, in the same sample. We dissected 30 white cadavers and took primary and secondary reference points from the internal oblique ridge. We measured the distance to the lingual nerve in sagittal, vertical, and horizontal planes, and recorded the position where the nerve was closest to the lingual plate. We dissected 46 hemimandibles (23 male, mean age 79 years, range 52-100) of which 26 were from the left side. Mean (SD) sagittal, vertical, and horizontal distances from the primary reference point were 9.29 (3.41)mm, 9.15 (3.87)mm, and 0.57 (0.56)mm, respectively. Mean (SD) vertical and horizontal distances from the secondary point were 7.79 (5.45) mm and 0.59 (0.64)mm, respectively. The proximity of the nerve to the lingual plate varied widely (range -13.00 to 15.17mm from the primary reference point). Dentate status was significant for the sagittal measurement from the primary point, and the vertical measurement from the secondary point. Differences in age, sex, or site of the contralateral nerve were not significant (n=16 pairs). Our findings suggest that the site of the nerve is consistent between and within subjects for sex and age, but not for dentate status. The association between the nerve and the lingual plate varied, which suggests that care must be taken when operating in the area.

Evaluation of the treatment modalities for neurosensory disturbances of the inferior alveolar nerve following retromolar bone harvesting for bone augmentation.

SUBJECTS: The purpose of this study was to evaluate the treatment modalities for neurosensory disturbances (NSDs) of the inferior alveolar nerve occurring after retromolar bone harvesting for bone augmentation procedures before implant placement. METHODS: One hundred four patients, of which 49 and 55 exhibited vertical or horizontal alveolar ridge defects in the mandible and maxilla, respectively, were enrolled. Nineteen patients underwent block bone grafting, 38 underwent guided bone generation or autogenous bone grafting combined with titanium mesh reconstruction, and 47 underwent sinus floor augmentation. Using a visual analog scale, we examined subjective symptoms and discomfort related to sensory alteration within the area of the NSDs in these patients. NSDs were clinically investigated using a two-point discrimination test with blunt-tipped calipers. In addition, neurometry was used for evaluation of trigeminal nerve injury. We tested three treatment modalities for NSDs: follow-up observation (no treatment), medication, and stellate ganglion block (SGB). RESULTS: A week after surgery, 26 patients (25.0%) experienced NSDs. Five patients received no treatment, 10 patients received medication, and 11 patients received SGB. Three months after surgery, patients in the medication and SGB group achieved complete recovery. Current perception threshold values recovered to near-baseline values at 3 months: recovery was much earlier in this group than in the other two groups. SGB can accelerate recovery from NSDs. CONCLUSIONS: Our results justify SGB as a reasonable treatment modality for NSDs occurring after the harvesting of retromolar bone grafts.

Panoramic radiography and cone-beam computed tomography findings in preoperative examination of impacted mandibular third molars.

BACKGROUND: Preoperative radiographic examination of impacted mandibular third molars (IMTM) is essential to prevent inferior alveolar nerve injury during extraction. The purpose of this study was to evaluate the correlation between cone-beam computed tomography (CBCT) and digital panoramic radiography (DPR) findings in preoperative examination of IMTM. METHODS: This retrospective study included 298 teeth in 191 individuals. The relationship between the inferior alveolar canal (IAC) and the IMTM (buccal, lingual, interradicular or inferior), the position of the IMTM with respect to the IAC (contact, no contact), the morphologic shape of the mandible in the IMTM region (round, lingual extended, lingual concave), the type of IMTM (vertical, horizontal or angular) and the number of roots of the IMTM were evaluated on CBCT images. DPR images were evaluated for the number of roots of the IMTM and for the most common radiographic findings indicating a relationship between the IAC and the IMTM (darkening of the roots, diversion of the IAC, narrowing of the IAC and interruption of the white line). Data were statistically analyzed with Cramer V coefficient, Kappa statistic, chi-square and Fisher's exact test. RESULTS: There was a significant difference in number of roots detected on DPR versus CBCT images. There was a significant association between the type of IMTM and the morphologic shape of the mandible on CBCT images. Darkening of the roots and interruption of the white line on DPR images were significantly associated with the presence of contact between the IMTM and the IAC on CBCT images. CONCLUSIONS: Panoramic radiography is inadequate, whereas CBCT is useful to detect multiple roots of IMTM. When darkening of the roots and interruption of the white line are observed on panoramic images, there is increased likelihood of contact between the IMTM and the IAC. CBCT is required in these cases.

Selective ß2-adrenergic Antagonist Butoxamine Reduces Orthodontic Tooth Movement.

Recently, involvement of the sympathetic nervous system in bone metabolism has attracted attention. ß2-Adrenergic receptor (ß2-AR) is presented on osteoblastic and osteoclastic cells. We previously demonstrated that ß-AR blockers at low dose improve osteoporosis with hyperactivity of the sympathetic nervous system via ß2-AR blocking, while they may have a somewhat inhibitory effect on osteoblastic activity at high doses. In this study, the effects of butoxamine (BUT), a specific ß2-AR antagonist, on tooth movement were examined in spontaneously hypertensive rats (SHR) showing osteoporosis with hyperactivity of the sympathetic nervous system. We administered BUT (1 mg/kg) orally, and closed-coil springs were inserted into the upper-left first molar. After sacrifice, we calculated the amount of tooth movement and analyzed the trabecular microarchitecture and histomorphometry. The distance in the SHR control was greater than that in the Wistar-Kyoto rat group, but no significant difference was found in the SHR treated with BUT compared with the Wistar-Kyoto rat control. Analysis of bone volume per tissue volume, trabecular number, and osteoclast surface per bone surface in the alveolar bone showed clear bone loss by an increase of bone resorption in SHR. In addition, BUT treatment resulted in a recovery of alveolar bone loss. Furthermore, TH-immunoreactive nerves in the periodontal ligament were increased by tooth movement, and BUT administration decreased TH-immunoreactive nerves. These results suggest that BUT prevents alveolar bone loss and orthodontic tooth movement via ß2-AR blocking.

Does wearing dentures change sensory nerve responses under the denture base?

BACKGROUND: The standard textbook on complete dentures suggests the necessity of relief for the incisive and posterior palatine foramina of denture wearers to prevent the impingement of the nerves and vessels passing through these foramina. However, concrete evidence of the effect of dentures on the sensory function of the nerves underlying dentures is lacking. OBJECTIVE: The study aim was to investigate the influence of denture-induced compression on sensory nerve responses to stimulations. MATERIALS AND METHODS: Only partially edentulous patients of maxillary Kennedy class II who wear dentures (WD) or who never wear dentures (ND) were recruited as participants. The WD and ND groups had 15 participants with a mean age of 66.9 years and 22 participants with a mean age of 60.2 years, respectively. Current perception thresholds (CPTs) at 2000, 250 and 5 Hz, corresponding to A-beta, A-delta and C fibres, respectively, were measured by the Neurometer(®) NS3000 device and compared between groups. The data were analysed by the t-test, the paired t-test and analysis of covariance adjusted for age, sex and thickness of the mucosa. RESULTS: The CPTs showed large differences at 2000 Hz but no differences at the other frequencies when the WD and ND groups were compared. Only the CPT of the edentulous side at 2000 Hz was significantly different between groups. CONCLUSION: Wearing removable partial dentures contributes to changes of responses to stimulations in the large fibre of the sensory nerve underlying the maxillary alveolar ridge.

Electrophysiologic evaluation of inferior alveolar nerve regenerated by bifocal distraction osteogenesis in dogs.

BACKGROUND: Bifocal distraction osteogenesis has been shown to be a reliable method for reconstructing missing bone segments. However, there are no reports regarding inferior alveolar nerve regeneration during bifocal distraction. In the present study, the authors evaluated the function of inferior alveolar nerve regenerated by bifocal distraction after segmental resection in the mandibles of dogs. METHODS: Using a bifocal distraction osteogenesis method, the authors produced a 10-mm mandibular defect and distracted the transport disk at a rate of 1 mm/day. The regenerated inferior alveolar nerve was evaluated by electrophysiologic analysis that was performed on all dogs after euthanasia at 3, 6, and 12 months after the first operation. RESULTS: At 6 and 12 months, stable evoked potential measurements were obtained from the nerves throughout the study on electrophysiologic analyses. CONCLUSIONS: The authors' results indicate that the inferior alveolar nerve regenerated by bifocal distraction osteogenesis functioned electrophysiologically at 6 months after the first operation. Although our research is still at the stage of animal experiments, future application in humans is considered to be possible.

Vertical splitting of the mandibular body as an alternative to inferior alveolar nerve lateralization.

The aim of this study was to present and evaluate a modified technique to inferior alveolar nerve lateralization (IANL) that allows the placement of longer implants in the posterior mandibular region. One hundred and forty-three consecutive patients were enrolled in this study; these patients had between 1.8 and 8mm residual crestal height above the mandibular canal. Vertical splitting of the mandibular body was performed using piezoelectric surgery followed by bone expansion and insertion of special conical implants of 10 and/or 12mm in length. Two hundred and sixty-nine osteotomies were performed and 636 implants were inserted, with a survival rate of 99% at the end of 12 months. Immediately postoperative there was an alteration of sensation in the lip/chin area in 8.5% of cases; 4.1% regained full sensation within 10-14 days, 2.6% after 8 weeks, and 0.7% had persistent paresthesia that did not affect their daily activities. Progressively increasing pain and numbness was present in 1.1%; the implants were removed 6 months postoperatively. This is a relatively simple procedure that has no limitations in clinical situations with minimal bone height. It allows for greater implant stability, and the risk of neurological disturbance is minimal.

Oral rehabilitation of an edentulous patient using two-segment le fort I repositioning and implant-supported fixed prostheses.

Anteroposterior (AP) deficiencies present a restorative treatment challenge. Complex, multidisciplinary planning is necessary for the success of the treatment. This clinical report describes an approach to managing a complex complete oral rehabilitation of an edentulous patient with skeletal transverse and AP deficiencies with a history of facial trauma to the left zygomaticomaxillary complex. This was further complicated by a hopeless remaining dentition and pneumatization of the maxillary sinuses. Treatment included initial bony augmentation of the vertically and horizontally deficient maxilla, dental implant placement, provisional restoration in a Class III malocclusion with bilateral posterior crossbite, and Le Fort I osteotomy with transverse widening and advancement to correct the skeletal deficiency. Definitive restoration was accomplished with implant-supported fixed prostheses that provided ideal facial balance and occlusion.

Clinical anatomy of the lingual nerve and identification with ultrasonography.

Our objective was to investigate the pathway of the lingual nerve and find out whether it can be identified using ultrasonography (US) intraorally. It is a dominant sensory nerve that branches from the posterior division of the mandibular aspect of the trigeminal nerve, and is one of the two most injured nerves during oral surgery. Its anatomy in the region of the third molar has been associated with lingual nerves of variable morphology. If surgeons can identify its precise location using US, morbidity should decrease. We searched published anatomical and specialty texts, journals, and websites for reference to its site and US. Cadavers (28 nerves) were dissected to analyse its orientation at the superior lingual alveolar crest (or lingual shelf). Volunteers (140 nerves) had US scans to identify the nerve intraorally. Our search of published books and journals found that descriptions of the nerve along the superior lingual alveolar crest were inadequate. We found no US studies of the nerve in humans. Dissections showed that the nerve was above (n=6, 21%) and below (n=22, 79%) the crest of the lingual plate. US scans showed 140 lingual nerves intraorally in 70 volunteers. The nerve lay either above or below the superior lingual alveolar crest, which led us to develop a high/low classification system. US can identify the lingual nerve and help to classify it preoperatively to avoid injury. Our results suggest that clinical anatomy of the lingual nerve includes the superior lingual alveolar crest at the third and second molars because of its surgical importance. US scans can successfully identify the nerve intraorally preoperatively.

Accessory neurovascular foramina on the lingual surface of mandible: incidence, topography, and clinical implications.

CONTEXT: It was suggested that the accessory neurovascular foramina of the mandible might be of significance in relation to the effectiveness of local anesthesia following the routine inferior alveolar nerve block. AIMS: To investigate the incidence of neurovascular foramina over the lingual surface of the mandible in South Indian population. SETTINGS AND DESIGN: The study was conducted at the department of anatomy. MATERIALS AND METHODS: The study included 67 human adult dry mandibles, the exact ages and sexes of which were not known. The location and number of neurovascular foramina were topographically analyzed. STATISTICAL ANALYSIS USED: Descriptive statistics. RESULTS: The foramina were observed in 64 mandibles (95.5%) and were often multiple in most of the cases. They were located between the two medial incisors in 8 mandibles (1.9%), between the medial and lateral incisor in 34 mandibles (50.7%; 25-bilateral; 7-right; 2-left), between the lateral incisor and canine in 7 mandibles (10.4%; 2-bilateral; 3-right; 2-left), between the canine and first premolar in 6 cases (8.9%; 3 on each side). Foramina were also present around the genial tubercle in 56 mandibles (83.6%). Among them, 52 mandibles showed a single foramen just above the genial tubercle, 34 mandibles had foramina below the tubercles, 13 mandibles had foramina on the right side of genial tubercle and 17 were having on the left side. CONCLUSION: Since the anatomical details of these foramina are important to various fields of dentistry and oncology, the present investigation was undertaken. The clinical significance and implications are emphasized.