Clinical application of the blink reflex with stimulation of the mental nerve in lesions of the inferior alveolar nerve.

We evaluated the clinical usefulness of a new modification of the blink reflex (BR) test with electrical stimulation of the innervation area of the mental nerve (MN). We studied the MN BR in 28 patients with traumatic lesions of the inferior alveolar nerve and compared the results with the clinical sensory examination. Within 3 months of the trauma, the MN BR was abnormal in 18 of 20 nerves. In lesions older than 3 months, the test was often normal (in 9 of 11 nerves) despite subjective sensory symptoms and mild clinical signs. Anatomic obstacles to nerve regeneration also gave rise to abnormal MN BR in two patients examined 2 and 4 years after the trauma. The MN BR responses were often absent after violently traumatic lesions, whereas milder injuries commonly produced only latency prolongation of the reflex components. The MN BR is a useful objective method in the diagnosis of sensory loss in the distribution of the MN.

Electrophysiologic evidence for extremely late sensory collateral reinnervation in humans.

We present a patient in whom unexpectedly late sensory recovery occurred over 5 years after removal of a 3-cm piece of the right inferior alveolar nerve (IAN) in tumor surgery of the mandible. For a year after surgery, the distribution of the mental nerve, the terminal branch of the IAN, was totally anesthetic. Thereafter, a gradual subjective sensory recovery occurred centripetally from the surrounding skin distributions. Five years after surgery, findings in electrophysiologic tests were consistent with a total lesion of the right IAN. Two years later, electrophysiologic tests gave, for the first time in humans, objective evidence for sensory collateral sprouting in trigeminal distribution.

A follow-up study of radiographic findings in the mandibular condyles of orthodontically treated patients and associations with TMD.

Our earlier studies have shown that some radiographic structural findings in the mandibular condyles are more common in orthodontically treated populations than in normal populations. To test the hypothesis that these findings are stable, we studied condylar findings in panoramic radiographs longitudinally in 39 subjects and in 39 sex- and age-matched controls. The subjects had condylar findings at the end of orthodontic treatment at about 15 years of age; no such findings were seen in the controls. The subjects and controls were re-examined radiographically about 12 years after the posttreatment radiographic examination. We also tested the hypothesis that radiographic condylar findings are associated with temporomandibular disorders (TMD). No statistically significant differences were found between subjects and controls in terms of reported subjective TMD symptoms. Clinically, the subjects had temporomandibular joint (TMJ) crepitation significantly more frequently (27%) than controls (8%) (p < 0.05). Crepitation correlated with some reported symptoms and clinical signs, suggesting that osteoarthrosis might have been an important etiological factor for TMD in the present subjects. At the follow-up examination, radiographic condylar findings were seen in 25 subjects and in four controls (p < 0.001). The condylar findings varied greatly between the time of orthodontic treatment and follow-up in the subjects. The findings had become more severe in 49% of the subjects, more often in females than in males (p < 0.05), whereas in 28% of the subjects the condylar findings had disappeared. Although the radiographic findings after orthodontic treatment fluctuated with age, in most adolescents with changes in their condyles, these findings remained constant or became more severe.(ABSTRACT TRUNCATED AT 250 WORDS)

ITI titanium plasma-sprayed screw implants in the treatment of edentulous mandibles: a follow-up study of 39 patients.

The outcomes of 153 ITI titanium plasma-sprayed screw implants were studied in 39 patients. Four implants were placed in the edentulous mandible between the mental foramina and used as support for a denture prosthesis. Thirteen implants in six patients had been lost during the follow-up time of 3 to 10 years (mean 5.6 years). The mean annual bone resorption was 0.25 mm (SD 0.29 mm; range 0 to 1.37 mm). Bone loss was smaller in patients with prosthetic loading applied within 7 postoperative days than in those with delayed prosthetic treatment. No evidence of bone loss was seen around 37 (26.4%) implants. The cumulative and overall success rates for titanium plasma-sprayed implants were 80.8% and 91.5%, respectively. The corresponding figures for the patients were 86.8% and 94.9%.

A panoramatomographic study of the teeth and jaws of Finnish university students.

A random sample of panoramic radiographs was taken of 1027 (386 male and 641 female) university students. All the students were born between 1965 and 1971. The following were examined: caries, apical radiolucencies, endodontically treated teeth, marginal and vertical bone loss, third molars, supernumerary, missing, and persisting teeth, bone structure, condyles, maxillary sinuses and soft tissue calcifications. In the inter- (of two examiners) and intra-examiner variation Kappa indices varied between 0.15 and 1.00, and agreement percentages from 52, to 100. Kappa index was poor (0.15) in evaluation of the bone structure. The mean DMFT index for the students was 8.4. A sound dentition was found in 6.6%, and 48.4% of the students were free of caries. The mean number of carious lesions was 1.1. There were 50 retained roots (49 from primary teeth). 76.6% of the students had one or more unerupted wisdom teeth and 22.7% had radiologic changes typical of pericoronitis in the region of the mandibular third molars. 16.2% of the students had at least one missing wisdom tooth. Bone structure was normal in 92.4% of the students, idiopathic osteosclerosis being the most common divergence (3.5%). Arthrotic changes in the condyles were found in 9% of the students. In eight cases there was erosion of the condyles, which was diagnosed as arthritis. Styloid ligament calcifications were found in 21.5% of the students. In the maxillary sinuses, male students exhibited changes 1.7 times more often than female students (26.3% in males and 15.1% in females).

The mental nerve blink reflex in the diagnosis of lesions of the inferior alveolar nerve following orthognathic surgery of the mandible.

The purpose of this study was to evaluate the diagnostic value of a new modification of the blink reflex test with stimulation of the distribution of the mental nerve in iatrogenic lesions of the inferior alveolar nerve. The test was performed on 23 patients undergoing orthognathic surgery of the mandible, most of them (20) with bilateral sagittal split osteotomies. The function of the inferior alveolar nerve was studied preoperatively, and 2 weeks, 2 months, 6 months and 1 year postoperatively with both mental nerve blink reflex test and clinical neurosensory testing. The objective electrophysiological test proved to be useful in the diagnosis and follow-up of sensory impairment of the inferior alveolar nerve. The results of the mental nerve blink reflex test and clinical neurosensory testing were closely related. The results of the two tests did not differ statistically significantly in the two first postoperative examinations. The positive predictive value of the mental nerve blink reflex test was better than that of clinical neurosensory testing: an initially abnormal reflex response predicted persistent subjective sensory symptoms after one year more reliably than did altered sensation at the first two examinations. Irrespective of the possible coexistent sensory symptoms and signs, a normal mental nerve blink reflex within 2 months after operation also predicted a reasonably good sensory recovery at 1 year.

Odontogenic myxoma--a radiographic study of 21 tumours.

Radiological features of 21 odontogenic myxomas found in 14 women and 7 men were analysed. Ten of the tumors were unilocular and 11 were multilocular. Unilocular lesions were mostly located in the anterior and multilocular in the posterior areas of the jaws. Intralesional trabeculation was seen in all multilocular but only in 3 unilocular lesions. Because radiological appearance of myxoma may be essentially similar with many other lesions of the jaws careful radiological examination is mandatory for planning of proper treatment.

Dosimetry and image quality of four dental cone beam computed tomography scanners compared with multislice computed tomography scanners.

OBJECTIVES: The aim of this study was to evaluate the radiation dose and image quality of four dental cone beam CT (CBCT) scanners, and to compare them with those of two multislice CT (MSCT) scanners. METHODS: Tissue doses were measured using a tissue-equivalent anthropomorphic RANDO Head Phantom((R)) with thermoluminescence dosemeters (TLD). An RSVP Head Phantom(TM) with a specially designed cylindrical insert was used for comparison of image quality and absorbed dose. Image quality was evaluated in the form of contrast-to-noise ratio (CNR) and modulation transfer function (MTF). RESULTS: Using standard imaging parameters, the effective doses varied between 14 microSv and 269 microSv (International Commission on Radiation Protection (ICRP) 1990) and 27 microSv and 674 microSv (ICRP 2008) with the CBCT scanners, and between 350 microSv and 742 microSv (ICRP 1990) and 685 microSv and 1410 microSv (ICRP 2008) with the MSCT scanners. The CNR of the CBCT and MSCT scanners were 8.2-18.8 and 13.6-20.7, respectively. Low-dose MSCT protocols provided CNRs comparable with those from CBCT scanners. The 10% MTF of the CBCT scanners varied between 0.1 mm(-1) and 0.8 mm(-1), and was 0.5 mm(-1) for all the MSCT protocols examined. CONCLUSIONS: CBCT scanners provide adequate image quality for dentomaxillofacial examinations while delivering considerably smaller effective doses to the patient. Large variations in patient dose and image quality emphasize the importance of optimizing imaging parameters in both CBCT and MSCT examinations.

Accuracy of linear measurements using dental cone beam and conventional multislice computed tomography.

OBJECTIVES: The aim of this study was to evaluate the accuracy of linear measurements obtained with dental cone beam CT (CBCT) and multislice CT (MSCT) by altering radiation doses using pre-operative planning of the placement of oral implants as a model. METHODS: A human cadaver mandible was examined in two edentulous areas and one dentate area using CBCT and MSCT. The mandible was examined both dry and immersed in sucrose solution isointense with soft tissue. Two readers measured four linear distances twice from each section. The mandible was cut into 4 mm thick slices at three marked places. These slices were microradiographed and used as the gold standard for measurements from each section. RESULTS: The intraclass correlations between the intra- and interobserver readings obtained with the different methods showed almost perfect matches. The measurement error (ME) showed significant differences between the methods studied (P = 0.022): the mean ME was 4.7% for CBCT and 8.8% for MSCT of the dry mandible, 2.3% and 6.6%, respectively, for the mandible immersed in sucrose solution and 5.4% for low-dose MSCT. Lowering the MSCT radiation dose to less than a quarter of its conventional original value did not significantly affect the ME. CONCLUSIONS: CBCT is a reliable tool for implant-planning measurements when compared with MSCT. In this study, a considerable radiation dose reduction could be achieved with low-dose MSCT examinations without a major loss of measurement accuracy.

The 3DX multi image micro-CT device in clinical dental practice.

OBJECTIVES: To evaluate the usefulness of 3DX multi-image micro-CT device in clinical dental practice. METHODS: Images of 198 examinations performed with a 3DX device during a 6 month period in a private dental practice were evaluated retrospectively for the benefit of additional information compared with panoramic or intraoral radiographs. RESULTS: The main indication for the use of 3DX micro-CT was planning of dental implant placement in 49% of the examinations. Diagnosis or exclusion of dental infection or peri-implantitis represented 28% of the examinations and tooth, root or foreign body localization represented 13%. Temporomandibular joint (TMJ) imaging and cyst or tumour diagnosis represented 7.5% and 2.5% of the examinations, respectively. In implant planning and tooth, root or foreign body localization examinations, the required information was obtained in every case except three implant planning examinations, in which the exact measurements were hampered by artefacts caused by root fillings and retrograde fillings or metal posts. When compared with conventional radiography, additional radiographic information was obtained in 51% of the micro-CT examinations performed to confirm or exclude dental infection or peri-implantitis. Micro-CT also showed the bone structure of TMJs precisely. CONCLUSIONS: The 3DX micro-CT device visualizes bony anatomical structures precisely, which makes it a reliable tool for, for example, planning of implant treatment. The device is highly suitable for diagnosing dental infections. Dental restorations may cause disturbing artefacts and in 4.5% of the examinations the small imaging area resulted in re-examination.

Tyrosine derived polycarbonate membrane is useful for guided bone regeneration in rabbit mandibular defects.

Standardized bilateral through-and-through defects (12x6 mm) were created extraorally in the mandibular angle of 18 New Zealand White rabbits. Animals were divided in to three groups (n=6) according to the intended healing time. On the left side, defects were covered with a poly(desaminotyrosyl-tyrosine-ethyl ester carbonate) (PDTE carbonate) membrane wrapped around the inferior border of the mandible and fixed with bioabsorbable sutures. On the right side, the defects were filled with a mesh made of bioactive glass 13-93 and 3 wt% chitosan. The defects were covered with the same membranes. Periosteal flap was sutured over the membrane. Radiographically, bone ingrowth was seen in all specimens at 12 weeks postoperatively. At 24 weeks, completely ossified area remained approximately at the same level as at 12 weeks, but the non-ossified area decreased to almost zero. However, the bioactive glass mesh did not improve the results. Nevertheless, enveloping the defect with PDTE carbonate membrane seemed to play a crucial role in new bone formation. Based on these results, we conclude that tyrosine polycarbonate is a promising new material for guided bone regeneration.

Radiological variations in mandibular condyles of Finnish students, one group orthodontically treated and the other not.

Panoramatomograms of 968 students (355 males and 613 females) aged between 19 and 25 years were evaluated with special emphasis on the mandibular condyles. Two-hundred-and-thirty-five students (24.3 per cent) had been treated orthodontically. Radiographic variations in the condyles were significantly more common in the orthodontically treated group as a whole and in males (n = 71, P < 0.001), but not in females (n = 164). No age correlation in the frequency of condylar variations was found in either group. In terms of individual severe variation, flattening of the articular surface (P < 0.001) and subcortical sclerosis (P < 0.01) were more common in the orthodontically treated students. In the untreated subjects (284 males and 449 females), females had more variations (9.3 per cent) in their condyles than males (3.7 per cent P < 0.001). In the orthodontically treated students the percentages with condylar variations were 21.1 per cent in males and 16.5 per cent in females (N.S.).

Cross-sectional tomograms obtained with four panoramic radiographic units in the assessment of implant site measurements.

OBJECTIVES: The aim of this study was to evaluate the ability of four panoramic X-ray units to produce cross-sectional images and to assess the effect of interexaminer and intraexaminer variations on the results. METHODS: Cross-sectional tomograms of a human cadaver mandible were taken from two edentulous and one dentate area using four different X-ray units: OP-100 Ortho Trans (Instrumentarium Imaging Co, Tuusula, Finland), Proscan (Planmeca Co, Helsinki, Finland), Cranex-Tome and Scanora (Soredex, Orion Co, Espoo, Finland). Four different linear distances were measured from each radiograph. The mandible was then cut into 4 mm thick slices at three marked places. These slices were microradiographed and used as the gold standard for measurements made from each cross-sectional tomogram. RESULTS: Of all measurements only the thickness of the mandible in the radiographs taken with the OP-100 differed significantly (P < 0.021) from the gold standard. In the interexaminer variation, the agreement was 85% and Kappa index 0.68. In the intraexaminer reproducibility, the agreement was 76.7% and Kappa indices 0.52 and 0.50. CONCLUSIONS: The X-ray units studied were found to be similar in terms of image performance and the produced images were acceptable for dental implant placement planning. Interexaminer and intraexaminer variations can be large and the main source of error can be the interpreter him or herself.

Function of masticatory system after surgical-orthodontic correction of maxillomandibular discrepancies.

Thirty-two subjects were interviewed about their pre- and post-treatment symptoms of craniomandibular disorders (CMD) and examined for signs of CMD at follow up 2-5 years after surgical-orthodontic treatment for maxillomandibular discrepancies. Symptoms of CMD were among the main reasons for seeking treatment in 31% of the patients. Patients with retrognathic mandibles had significantly more severe symptoms than patients with mandibular prognathism before treatment. After treatment, the severity of subjective symptoms had decreased for the patients as a whole, and significantly in the subjects with originally severe symptoms. Ten subjects out of 12 reported a decrease in the occurrence of headache. The clinical findings of CMD after surgery were usually mild. The importance of occlusal adjustment and rehabilitation as final steps after surgical-orthodontic treatment is stressed.

Clinical aspects of oral implantology.

During the past few decades the use of implants in dentistry has increased markedly. Endosteal titanium implants are now most commonly used for replacement of single teeth and partial and full dentition. The success rates reported for osseointegrated implants depend on the type of implant and the criteria of success. Results are better for the mandible than the maxilla. Patient selection, careful planning of surgical and prosthetic treatment, and atraumatic, aseptic surgical procedures are essential for successful results. This article reviews various implant methods used in our Department and gives examples of treatment in particular clinical situations.

Radiographic structural findings in the mandibular condyles of young individuals receiving orthodontic treatment.

Radiographic findings in mandibular condyles were studied from the pre- and post-treatment panoramic radiographs of 625 orthodontic patients. The subjects' mean age was 11 years at the start and 14 years at the end of active orthodontic treatment. Radiographic condylar findings were seen in 14 (2%) subjects before treatment and in 54 subjects (9%) after treatment (p < 0.001). In age-related controls (n = 783) condylar findings were seen in 3% (p < 0.001). The condylar finding was 'flattening only' in half of the patients and in one-third of the controls with condylar findings. Activator treatment was associated with condylar findings (p < 0.05). Condylar findings increased with age in the orthodontically treated subjects (p < 0.05) but not in the unselected population controls. This may mean that condyles become more sensitive with age in children. Increase with age may be partly due to the radiographic interpretation, since minor condylar findings are difficult to observe in young children, and partly due to differences in treatment modalities and the duration of treatment.

Radiographic characteristics in mandibular condyles of orthodontic patients before treatment.

Pretreatment panoramic radiographs and patient files of 625 orthodontic patients (269 males and 356 females), aged 4-15.9 years (mean 11.0, SD 1.7) were evaluated with special emphasis on the mandibular condyles and malocclusions. Radiographic characteristics in the mandibular condyle were seen in 14 children (2.2 per cent), comprising six boys (2.2 per cent) and eight girls (2.3 per cent). There were no statistically significant differences between orthodontic patients before treatment and normal population controls (n = 410,229 males and 181 females, mean age 11.4 years, SD 1.8). No statistically significant difference in the frequency of condylar characteristics was found between younger (under 12) and older (over 12) children. Angle Class II molar relationship was the only type of morphological malocclusion associated (P < 0.05) with condylar characteristics. The means of several cephalometric measurements in the children with condylar characteristics were close to those of children with harmonious skeletal relationships.

The effect of PUVA on langerhans cells in rat oral epithelium photosensitized with systemic methoxsalen or topical trioxsalen.

BACKGROUND/PURPOSE: Ultraviolet-A radiation (UVA) of the oral mucosa after photosensitization with either systemic methoxsalen (8-MOP) or topical trioxsalen (TMP), i.e. mouth-PUVA, has been reported to be successful in the treatment of oral lichenoid lesions. In the case of PUVA treatment of skin disorders, local immune suppressive effects have been demonstrated, and the antigen presenting epithelial Langerhans cells (LCs) have been shown to be especially sensitive to ultraviolet treatments. Our aim was to compare the photobiological effects of PUVA in oral mucous membrane (OMM) using topical TMP or systemic 8-MOP photosensitization. METHODS: Rat OMM photosensitized with topical TMP or systemic 8-MOP was treated with PUVA using UVA doses of 1-8 J/cm2. The LCs were demonstrated in epithelial sheets of the treated OMM with ATPase staining. RESULTS: Both treatments caused a sim ilar, dose-dependent depletion of ATPase-positive LCs, with a maximal depletion of 80% or 73% with 8 J/cm2 at 2 days after irradiation as photosensitized with TMP or 8-MOP, respectively. This contrasts with earlier published findings in human skin, where topical TMP is an order of magnitude greater a sensitizer than 8-MOP, and PUVA-induced depletion of LCs occurs maximally 5 days after irradiation. CONCLUSION: The depletion of LCs of rat OMM after PUVA treatment is greater using topical TMP compared to systemic 8-MOP, but the difference is significantly smaller than reported earlier in human skin.

Evaluating function of the inferior alveolar nerve with repeated nerve conduction tests during mandibular sagittal split osteotomy.

PURPOSE: This article evaluates a new intraoperative recording technique for measuring the sensory nerve conduction velocity (SNCV) of the human inferior alveolar nerve (IAN) during orthognathic surgery of the mandible to assess the effects of intraoperative strain on function of the IAN. MATERIALS AND METHODS: The new test was successfully applied in 10 patients during bilateral sagittal split osteotomy of the mandible (20 IANs). The recordings were made with active wire electrodes at foramen ovale and stimulation was done at the mental foramen with two monopolar needle electrodes. The sensory nerve action potentials (SNAP) were recorded intraoperatively at three stages: 1) before the split, 2) after splitting of the mandible and possible mobilization of the IAN from the proximal bone fragment, and 3) at the end of the operation after fixation of the proximal and distal fragments with screws. RESULTS: The SNCV values (mean 64.1 m/sec) were obtained in all 20 nerves at stage 1, with no significant differences between the sides in latency or amplitude of the SNAPs. The sNAPs remained stable in the IANs not exposed during the operation. In the remaining nerves, the most obvious and statistically significant changes indicating nerve injury occurred between stages and 1 and 2. Partial transsection and mobilization of the IAN were equally potent in bringing about abnormal results in objective neurophysiologic tests as well as subjective sensory disturbances. The results of the intraoperative SNCV recordings correlated well with the findings of the mental nerve blink reflex tests conducted 2 weeks after the operation, whereas comparison of the results of clinical neurosensory testing with the intraoperative events and SNCVs were more inconsistent. CONCLUSIONS: Recording of the SNCV offers a useful objective tool for the examination of the IAN both intraoperatively and in clinical diagnosis.

Dental infections in association with cerebral infarction in young and middle-aged men.

The association between dental infections and cerebral infarction was investigated in a case-control study involving 40 patients with ischaemic cerebral infarction under the age of 50, and 40 randomly selected community controls matched for sex and age. Poor oral health, as assessed by two indices measuring the severity of infections of teeth and periodontium, or by the presence of subgingival calculus or the presence of suppuration in the gingival pockets, were more common in male patients than in male controls, but no difference was observed in females. If severe dental infections were combined with other probable bacterial infections there were altogether 16 patients (40%) but only two controls (5%) who had suffered from a probable bacterial infection within 1 month or at the time of the stroke or when examined as a control (P less than 0.01). Our results suggest an association between bacterial infection and ischaemic cerebrovascular disease in patients under 50 years of age. Severe chronic dental infection seems to be an important type of infection associated with cerebral infarction in males.