Extraction Of Molar Teeth Research Articles

Perioperative Auricular Electroacupuncture Has No Effect on Pain and Analgesic Consumption After Third Molar Tooth Extraction

Auricular acupuncture (AA) has been shown to alleviate acute and chronic pain. We investigated the effects of auricular electroacupuncture (AE) on pain and analgesic drug consumption in the first 48 h after unilateral mandibular third molar tooth extraction under local anesthesia in a prospective, randomized, double-blind, placebo-controlled study in 149 patients. Patients received either AA with electrical stimulation (AE, n = 76) or without (AA, n = 37) electrical stimulation at an alternating frequency of 2/100 Hz or a sham AE with metal plates instead of needles and no electrical stimulation, no-needle (NN, n = 36) at the AA points 1 (tooth), 55 (Shen men) and 84 (mouth) during the entire study period. Regularly rated pain intensity (five-point verbal rating scale), consumption of acetaminophen 500 mg tablets and additional rescue medication with mefenamic acid 500 mg were assessed. The median fraction of time when pain was rated as moderate or worse (upper and lower quartile): AE: 33% (12%, 64%), AA: 22% (6%, 56%), NN: 30% (7%, 53%) did not differ significantly among the treatment groups. There were no significant differences in mean number of acetaminophen 500 mg tablets (range): AE: 5.2 (0-12), AA: 4.6 (0-11), NN: 5.4 (0-10) or percentage of patients requiring additional mefenamic acid: AE: 19%, AA: 18%, NN: 19%. We conclude that neither AE nor AA alone reduce either pain intensity or analgesic consumption in a molar tooth extraction model of acute pain.

P-Stim™ auricular electroacupuncture stimulation device for pain relief

Acupuncture is now accepted as a complementary analgesic treatment. Auricular acupuncture is a distinct form of acupuncture. Electrical stimulation of acupoints (electroacupuncture) increases the effects of acupuncture. Recently, an auricular electroacupuncture device, the P-Stim™, has become available. Clinical studies in outpatients have investigated the P-Stim in chronic musculoskeletal pain and its use for minor surgery. In chronic cervical or low back pain, auricular electroacupuncture was more effective than conventional auricular acupuncture. The results in acute pain were controversial. Auricular electroacupuncture reduced pain and remifentanil consumption during oocyte aspiration when compared with conventional auricular acupuncture or a sham treatment. However, after third molar tooth extraction, auricular electroacupuncture and auricular acupuncture failed to reduce either postoperative pain or analgesic consumption. Further large-scale studies are required to evaluate the analgesic efficacy of auricular electroacupuncture.

Clinical and Anatomical Study of Retromolar Foramen and Canal

The retromolar canal is a rare anatomic variation of the mandible. The neurovascular content of the mandibular retromolar canal is very important for surgical procedures involving the retromolar area and there has been a lack of information on this subject. This study consists of anatomic research of the retromolar foramen and canal, planned after an impacted third molar tooth extraction operation in which we encountered a retromolar neurovascular bundle. Eighty sides of 40 mandibles were evaluated and the presence of the retromolar foramen and its relation to the last teeth, the transverse and sagittal distances of the retromolar trigone, and the distance of the retromolar foramen to the last socket of the arch were measured. The neurovascular bundle includes striated muscle fibers, thin myelinated nerve fibers, numerous venules and a muscular artery. Of the 40 mandibles included in this study, retromolar foramens were found in 10 (25%). The presence of the retromolar foramen is not dependent on the last teeth of the arch. The dimensions of the retromolar trigone were measured and the presence of the retromolar foramen was found to be nonrelevant to the dimensions of the retromolar trigone. Retromolar foramen distance from the distal edge of the last socket of the arch was found to be 11.91 +/- 6.71 mm and 4.23 +/- 2.30 mm, respectively, from the second and third molars. This study therefore clearly establishes the incidence and importance of the retromolar canal. This study shows that the retromolar foramen and canal can be seen occasionally in routine dental surgery. Due to the neurovascular bundle passing through it, the retromolar canal and foramen must be kept in mind in all anesthetic and surgical approaches regarding the retromolar area and mandible.

A comparative study of cone-beam computed tomography and conventional panoramic radiography in assessing the topographic relationship between the mandibular canal and impacted third molars

To evaluate the diagnostic accuracy of cone-beam CT compared with panoramic images in predicting neurovascular bundle exposure during extraction of impacted mandibular third molars. Cone-beam CT and panoramic images of 142 impacted mandibular third molars were prospectively evaluated to assess tooth relationship to the mandibular canal. These interpretations were then correlated with intraoperative findings. The sensitivity and specificity of the 2 modalities in predicting neurovascular bundle exposure at extraction were calculated and compared. The diagnostic criterion for panoramic images was defined using multivariate logistic regression analysis. In predicting the exposure, the sensitivity and specificity were 93% and 77% for cone-beam CT, and 70% and 63% for panoramic images, respectively. Cone-beam CT was significantly superior to panoramic images in both sensitivity and specificity. Cone-beam CT was significantly superior to panoramic images in predicting neurovascular bundle exposure during extraction of impacted mandibular third molar teeth.

Retromolar intubation – a simple alternative to submental intubation

There are special considerations when securing the airway peri-operatively in patients with panfacial trauma. Orotracheal intubation is not feasible when intra-operative intermaxillary fixation is planned for restoration of dental occlusion [1]. Nasotracheal intubation, an alternate technique of securing airway, is contra-indicated in certain conditions such as fracture of the base of the skull or fracture of the naso-orbital-ethmoid complex [2]. In such patients, submento-tracheal intubation has been described as an alternative to short-term tracheostomy for securing the airway peri-operatively [3, 4]. Disadvantages of submento-tracheal intubation include superficial wound infection, haemorrhage, trauma to the sublingual ducts and orocutaneous fistula [4]. Retromolar intubation is a non-invasive technique and avoids both submento-tracheal intubation and tracheostomy in the majority of patients. In 15 patients with panfacial trauma, where orotracheal intubation was not feasible and nasotracheal intubation contra-indicated, retromolar intubation was attempted to avoid tracheostomy. First, orotracheal intubation was performed with a flexometallic tracheal tube using a standard general anaesthesia technique. The orotracheal tube was then placed in the retromolar space behind the last upper and lower erupted molar teeth. The tube was then fixed by a wire ligature to the molar/premolar tooth along the upper or lower maxilla in a ‘figure of eight’ fashion. (The fixation should not be too tight as the flexometallic tube wire can be deformed). Retromolar intubation was successful in 12 patients and intra-operative intermaxillary fixation was easily carried out. At the end of the surgical procedure the wire fixation was cut and mouth opening was adequate. The wire ligature around the tracheal tube was removed and the tube moved back to a standard orotracheal position, and the trachea then extubated. In three patients, the retromolar space was inadequate and the tracheal tube could not be placed there. In these patients submento-tracheal intubation was performed. The adequacy of the retromolar space can be determined by introducing an index finger into the patient's mouth and asking him or her to close the mouth. No compression on the finger indicates an adequate space. The technique of Martinez et al. [5] to increase the retromolar space by extraction of the third molar tooth and performing a semilunar osteotomy involves destruction of the bony anatomy. This bone may otherwise have been useful for fixation devices and the technique is impractical [6]. If necessary, a tracheal tube smaller than the standard size for the patient can be used for retromolar intubation. One minor disadvantage of this is that the tube can interfere with the surgical field.

Neuroleptics Antagonize Nalbuphine Antianalgesia

To evaluate the role of σ receptors in the sexually dimorphic antianalgesic effect of agonist-antagonist κ opioids, 2 neuroleptics, haloperidol, a σ receptor antagonist, and chlorpromazine, which has minimal effect at σ receptors, were administered with the agonist-antagonist κ opioid nalbuphine in patients with postoperative pain. Before surgical extraction of bony impacted mandibular third molar teeth, patients received haloperidol (1 mg), chlorpromazine (10 mg), or placebo by oral administration. After surgery, the pain intensity did not differ significantly between the 3 treatment groups, suggesting lack of analgesic effect produced by either haloperidol or chlorpromazine. All patients were then administered nalbuphine (5 mg, intravenous). As previously reported, the group that did not receive a preoperative neuroleptic exhibited sexually dimorphic analgesia, with women experiencing greater analgesia than men. Antianalgesia was also observed, with men experiencing late onset increased pain compared with baseline, starting approximately 1 hour after nalbuphine administration. Both neuroleptics blocked nalbuphine antianalgesia, resulting in enhanced analgesia and elimination of the sex differences. Because chlorpromazine and haloperidol enhanced nalbuphine analgesia and eliminated sexual dimorphism, the receptor at which neuroleptics act to antagonize the “antianalgesia” might be a common site of action to both drugs. Perspective This study demonstrates that neuroleptics can block the antianalgesic effect of agonist-antagonist κ opioids. These findings could help inform the development of novel analgesics.

Reasons for Third Molar Teeth Extraction in Jordanian Adults

To assess reasons for third molar teeth extractions in a sample of Jordanian dental patients and to evaluate the association of extractions with other independent variables. The study sample was comprised of dental patients in North Jordan who had third molar extractions. Data were collected from 36 dentists who were instructed to administer questionnaires to their adult patients undergoing third molar extractions and then to record the primary reason for those extractions. The data in this study was analyzed using a descriptive summary and chi square statistics. Dentists performed 810 extractions for 648 patients. The reasons for the extractions were: dental caries and its consequences about 42%, eruption problems 39%, periodontal diseases about 7%, and approximately 9% of extractions were a result of the dentist's choice. The percentage of extractions due to dental caries significantly increased with increasing age. However, significant numbers of teeth were extracted due to eruption problems (51%-69%) in young adults. For 46+ year olds, 23% of extractions were caused by periodontal diseases. Extraction due to dental caries was distributed equally among the sexes. Persons with irregular tooth brushing and fewer dental visits had significantly more third molar teeth extracted due to caries and periodontal diseases compared to persons with regular tooth brushing and dental visits.

Central giant cell reparative granuloma of the mandible caused by a molar tooth extraction: Special reference to the manuever of drilling the surgical field

Central giant cell reparative granuloma (CGCRG) is an uncommon benign, reactive osseous lesion usually located in the mandible and maxilla. Although it is histologically benign, it may be locally destructive. There is still controversy on its development and growth pattern. Surgery is the treatment traditionally recommended. In this article, we presented a 12 year-old girl CGCRG of the mandible caused by a molar tooth extraction and discussed its histopathological, clinical, radiological and therapeutic features in the light of the current literature. Also we described our additional surgical maneuver 'drilling the surgical field' after the removal of the lesion.

Bone–implant contact at calcium phosphate‐coated and porous titanium oxide (TiUnite™)‐modified oral implants

Calcium phosphate (CP)-coated implants are usually referred to as having osteoconductive properties, whereas titanium implants with a native oxide layer are considered less osteoconductive. Often smooth titanium oxides (TOs) are compared to relatively rough CP structures. The objective of this study was to evaluate osteoconduction by comparing bone-implant contact at a relatively smooth, highly crystalline CP coating with a structured, porous TO (TiUnite)-modified surface. Ten adult Hound Labrador mongrel dogs were used. Four titanium implants (Nobel Biocare) with CP-coated (2) or TO-modified (2) surfaces were installed 12 weeks following mandibular premolar and molar teeth extraction. The implants were alternated within and between jaw quadrants in consecutive animals. Mucosal flaps were advanced and sutured leaving the implants in a submerged position. The animals were injected with fluorescent bone labels at 3 and 4 weeks postsurgery, and pre-euthanasia to monitor progress of bone formation. The animals were euthanized at 8 weeks postsurgery and block biopsies were prepared for histologic and histometric analysis. There were no remarkable differences in bone formation and apparent bone-implant contact comparing the TO-modified and CP-coated surfaces. However, the measured average bone-implant contact was 71% and 57% (P=0.027) for TO-modified and CP-coated implants, respectively. We conclude that the TO surface exhibits osteoconductive properties exceeding that of the CP surface. One or several of the chemical and physical properties of the TO surface may result in the remarkable bone formation along its surface. This study indicated that crystallinity and/or chemistry may be important.

Dental emergency rates at an expeditionary medical support facility supporting Operation Enduring Freedom.

The purpose of this study was to report the dental emergency rate and the distribution of cause of dental emergencies at an Expeditionary Medical Support +25 medical facility during a 6-month deployment in support of Operation Enduring Freedom. A retrospective cohort analysis of 1,972 soldiers stationed at Seeb Air Base, Sultanate of Oman, was accomplished from a phased deployment from March to September 2002. Procedures were divided into 11 categories: endodontic, extraction of teeth other than third molars, extraction of third molar teeth, restoration of teeth (caries), restoration of broken teeth (not caries), orthodontic bracket/wire problem, sensitive teeth, temperomandibular pain, periodontal, oral pathology, and prosthodontic. One hundred thirty-five dental emergency visits were recorded, corresponding to a rate of 137 dental emergencies per 1,000 soldiers per year. Most of the emergencies (34.8%) were due to caries. Pain from third molars was the second most common reason for visiting the dental clinic (19.3%).

Connective tissue growth factor expressed in rat alveolar bone regeneration sites after tooth extraction

Objective: To understand bone regeneration process after tooth extraction could be a clue to develop a new strategy for alveolar bone reconstruction. Recently, accumulated evidences support that connective tissue growth factor (CTGF) is implicated in tissue repair of many tissues. In this study, we investigated the spatial and temporal expression of CTGF in the rat tooth extraction sockets. Design: Five weeks old wild type male rats (weighing 120 g) were used for this experiment. Expression of CTGF was determined by immunohistochemistry and in situ hybridization in the rat upper molar tooth extraction sockets at 2, 4, 7, 10 and 14 days after tooth extraction. Results: CTGF was expressed strongly in the endothelial cells migrating into the granulation tissue at the bottom of the sockets during 4 days after tooth extraction. During the reparative process, no apparent chondrocyte-like cell appeared in the sockets, while osteoblast-like cells proliferated in the sockets with low CTGF expression at 7, 10, 14 days after extraction. As expected, no staining was observed with the preimmune rabbit IgG and CTGF sense probe. CTGF may play an important role in angiogenesis and granulation tissue formation specifically at early healing stage after tooth extraction to initiate alveolar bone repair. Conclusion: CTGF was expressed at early healing stage of the rat tooth extraction wound.

Atypical Stafne Bone Cavity

A patient was referred to the Department of Oral and Maxillofacial Surgery for extraction of the lower-left third molar tooth. There had been one episode of pericoronitis 5 years previously, since which there had been no symptoms. A panoramic radiograph showed a partially erupted mesioangularly impacted third molar without associated disease. Clinically no inflammation was present, and in the absence of specific indications for its removal, the tooth was left in situ. However, the radiograph revealed a radiolucency in the contralateral side of the mandible, below the fully-erupted lower-right third molar. The radiolucency measured approximately 2.5 cm £ 2.0 cm and was rhomboidal in shape. It extended from the apices of the lower-right second and third molars to the lower border of the mandible and was well defined with a corticated smooth but irregular margin (Fig. 1). The roots of the teeth were not resorbed and the periodontal ligament space and lamina dura appeared normal. The lesion was asymptomatic, and all teeth in the lower-right quadrant proved vital on electric pulp testing. Further radiographic views, a lower 908 occlusal and postero-anterior jaws were taken but did not add any further information. The most likely diagnosis was a Stafne bone cavity, but because of the unusual shape and extent, axial computed tomography (CT) (volume scan, 3 mm slices) was performed, and this showed a well-defined lingual defect in the posterior aspect of the right side of the mandible (Fig. 2). The buccal cortex was thinned and expanded and possibly perforated, though this last feature could not be differentiated from partial volume artefact. The cavity was partially filled by soft tissue that appeared to be continuous with the submandibular gland, but contained areas of a lower density, similar to the density of parotid gland. However a benign soft tissue tumour could not be excluded Based on these investigations the patient was informed of the likely diagnosis of Stafne bone cavity, and review to observe the lesion and thus confirm the diagnosis was recommended. However, aware of the unusual features, the patient was keen to obtain a definitive diagnosis and requested biopsy despite the proximity of the inferior alveolar nerve and the risk of nerve injury. Under general anaesthesia an intraoral buccal mucoperiosteal flap was raised and buccal bone removed with a bur. The cavity was found to be filled with salivary gland tissue and an incisional biopsy performed. Histopathological examination revealed an un-inflamed salivary gland with a normal duct and lobular structure and mild adipose replacement. At higher power the gland was found to be composed almost exclusively of serous acini with occasional clusters of mucous acini, consistent with the distal pole of the submandibular gland. A final diagnosis of Stafne idiopathic salivary gland inclusion was made (Fig. 3). Two months postoperatively the patient had some residual but resolving paraesthesia of the right mental nerve and did not return for further followup.

A comparative study of sevoflurane sedation with nitrous oxide sedation for dental surgery

Abstract. This study compares the use of inhalation sedation using sevoflurane (group S) with inhalation sedation using nitrous oxide (group N) in patients undergoing bilateral extraction of third molar teeth under local anaesthesia. The study was designed as a cross-over study. Seventeen ASA I, day surgery patients were studied. Patients were randomly allocated to receive either 8 l/min 50% nitrous oxide in oxygen (group N) or same flow of 1% sevoflurane (group S) for the first procedure. Each patient then had the alternate method of sedation for the second procedure. There were no significant differences between the methods in patient co-operation and surgeon's satisfaction with sedation. Psychomotor tests were comparable in both groups. The patients were significantly more sedated in the group S compared to group N ( P=0.004). Significantly more patients complained of an unpleasant odour group S ( P< 0.01) but none withdrew from the study for this reason. No adverse cardiorespiratory effects resulted from sevoflurane or nitrous oxide sedation. Both methods gave good amnesia during the procedure. There was high acceptance of both methods and the patients rated the technique as equally satisfactory. We conclude that inhalation sedation with sevoflurane is a suitable alternative method to nitrous oxide sedation.

The clinical effectiveness of implants placed immediately into fresh extraction sites of molar teeth.

Studies concerning immediate implantation describe its use in the anterior and premolar regions. However, its clinical effectiveness in immediately replacing molar teeth has rarely been challenged. The purpose of this study was to evaluate the survival rate of implants placed immediately after extraction of molar teeth to support a fixed ceramo-metal prosthesis. From 1989 to 1996, 56 immediate implants were placed in 43 patients following extraction of 51 molars; 46 molars were replaced by 1 implant and 5 molars replaced by 2 implants. All implants were restored with fixed prostheses (4 single crowns and 52 splinted). Mean follow-up period was 15 months (range, 4 to 60 months). The influence of the following parameters on implant failure was evaluated: gender, arch, smoking, pre-extraction vertical bone loss, implant length, and severity of complications between the two stages of surgery. The 5-year cumulative survival rate (5-year CSR) was 89%. The 5-year CSR among men was 84% compared to 93.5% among women. The maxillary 5-year CSR was 82% and the mandibular 92%. Among non-smokers (50 implants), the 5-year CSR was 90% compared to 83% among smokers (6 implants). Complications were evident in 8 (6 minor, 2 major) out of 50 non-failing implants compared to 2 (minor) of the 6 failing implants. No differences were evident in the other study variables. Immediate implantation in the molar region is an alternative, predictable surgical treatment. Immediate implantation in the posterior mandible has a better prognosis than in the posterior maxilla.

Action of naloxone on gender-dependent analgesic and antianalgesic effects of nalbuphine in humans

Previously, we have shown that the κ-opioid analgesic nalbuphine, when administered at a low dose to treat postoperative pain after extraction of impacted third molar teeth, produced a marked increase in pain in men, whereas in women the effect of this dose was similar to placebo. In the current study, employing the same postoperative model, we found that coadministration of naloxone, which had no analgesic action administered alone, not only reversed the expected pain-enhancing effect of nalbuphine in men, but produced a similar degree of long-lasting analgesia in both sexes. This result further suggests that, at the dose employed, although naloxone antagonizes the pain-enhancing effect, it does not antagonize the analgesic effect of nalbuphine. Although observed only in men, this antianalgesic action also might be present in women but offset by a similar degree of analgesia, thus explaining the lack of analgesia in women produced by this dose of nalbuphine alone. Such action would suggest that the previously reported gender differences in κ-mediated analgesia might, in fact, be explained by a gender difference in κ-mediated antianalgesia. By avoiding side effects associated with μ-opioid analgesics, this drug combination might become an important new pharmacological therapy for pain relief.

Neutrophils in the molar tooth extraction wound in the rat: a transmission electron microscope (TEM) study.

Neutrophils have been ascribed a number of functions from ultrastructural studies of healing wounds. All of the wounds so far examined have been relatively aseptic. This study investigates, by TEM, the structure of neutrophils in healing molar tooth sockets in rats. Prior to epithelial coverage, a dense infiltrate of neutrophils separated the viable wound tissues from the overlying debris and bacteria. The more deeply situated neutrophils contained many granules and only occasional phagosomes. More superficial neutrophils contained fewer granules and phagosomes with engulfed bacteria undergoing lysis. The most superficial neutrophils were degenerate, lacked granules and often contained viable bacteria. There were varying numbers of neutrophils containing granules in the blood clot, granulation tissue, wound epithelium and adjacent tissue. No extracellular neutrophil granules nor extracellular discharge of granules was found. These findings differ from those of previous ultrastructural studies of relatively aseptic healing wounds. Ultrastructurally, the only function of neutrophils in healing tooth extraction wounds appears to be phagocytosis of bacteria, which supports a role in the prevention of infection.

歯の喪失が高次脳機能に及ぼす影響に関する行動学的，組織学的研究

The purpose of the present study was to investigate changes in spatial learning and memory in mice after extraction of maxillary and/or mandibular molar teeth, in addition to investigating the neural mechanisms underlying that change.Male ddY mice, 30 weeks old, were used. In each experimental group, the molar teeth on both sides were extracted as follows: Maxillary, mandibular, both maxillaryand mandibular, and no extraction group as control. Spatial learning and memory were measured by performance in an 8-arm radial maze 1, 7 and 20 weeks followingextraction. Following completion of these behavioral tests on all four groups, histological investigation was carried out by pyramidal cell count of tissue samples (Nissl staining) from the frontal section in CA 1, CA 3 and CA 4 of the hippocampus.The experimental group showed significantly slower search times and an increase in error rate, compared to the control group. The experimental groupshowed a significant decrease in the number of hippocampal pyramidal cells compared to the control group. A further decline in both spatial memory and the number of cells was observed, especially in the maxillary molar loss group.In conclusion, it was found that spatial memory and neurological changes of the brain were impaired by the loss of tooth after a long time.

The effect of acupuncture on pain and swelling after day case molar teeth extraction under general anaesthesia

Pain following third molar teeth extraction can be severe and for day case patients, pain can worsen after leaving hospital. The objective of this study was to establish whether acupuncture could reduce post-operative pain and swelling. A total of 40 patients undergoing third molar teeth extraction were randomly allocated to two groups. The acupuncture group received acupuncture before and during general anaesthesia whilst the control group received general anaesthesia alone. Visual analogue scores for pain were measured in recovery and at 2, 18 and 72 h post-operatively, together with measurement of percentage reduction in mouth opening and assessments of swelling. Visual analogue scores at 18 h were significantly reduced from 24.5 mm in the control group to 12.5 mm in the acupuncture group ( P<0.05). The two groups were comparable in all other measurements. The study indicates that, in this group of patients, acupuncture can be useful in reducing post-operative pain on the day after surgery.

Post-extraction bleeding--an aid to diagnosis? Case report.

Haemophilia A, the most common of bleeding disorders is characterized by bruising and spontaneous bleeding into the joints but may remain undiagnosed if present in the mild form. A case is discussed where episodes of bruising and joint swelling as a child were misdiagnosed as rheumatic fever and the bleeding disorder was diagnosed following recurrent episodes of bleeding after extraction of an upper molar tooth.

Trabecular bone formation in the healing of the rodent molar tooth extraction socket.

The aim of this study was to investigate the nature of the template structure on which trabecular bone formation occurs during healing of the rodent tooth extraction socket, a well studied bone healing system. The presence of collagen type II mRNA has previously been described in the healing socket, although the formation of the protein or cartilage has not been observed. However, recent evidence from developmental and other bone healing studies indicates that collagen type III may be important in forming the preliminary scaffold on which bone trabeculae are formed. The maxillary right molar teeth were removed from rats under general anaesthesia and the animals killed at various times afterward. The tissues were examined using histological, in situ hybridization, and immunohistochemical staining techniques. It was concluded that collagen type IIA mRNA was produced by osteoblast cells of the socket, but that collagen type II, if present, would account for less than 0.01% of the total proteins extracted. During bone formation, Sharpey's fibers were seen radiating from the peripheral bone toward the center of the socket. These optically active collagen fibers were inserted into the forming bone trabeculae and were recognized by antibodies raised against collagen type III. The arrangement and composition of these fibers therefore suggest that they form a preliminary framework on which deposition of woven bone trabeculae occurs.