Effect of hyaluronic acid on the osseointegration of dental implants.

The mechanism of osseointegration is related to many factors, including the quality of the bone, the biocompatibility and surface characteristics of the implant material, the surgical technique, and functional loading. The purpose of this study was to investigate the effects of hyaluronic acid gel on the osseointegration of implants placed in defined areas of the mandible in rabbits. Hyaluronic acid is known to have an osteoinductive effect during regeneration of bony defects, and we thought that it might also have a favourable effect on osseointegration, a specialised mechanism to heal bone. Ten New Zealand rabbits aged 10 weeks and weighing 2.5-3.0kg were used, and sites for implants that were far enough from the apices of the teeth in the mandibular molar area were chosen. Two cavities were prepared in each rabbit, one (anterior) for the control implant, and one (posterior) for the implant with hyaluronic acid gel (Medical Instinct GmbH, Bovenden). New bone and the osteoid matrix content around the dental implants were evaluated histologically and histomorphometrically two months after the operation, and no significant difference was found between the two groups.

Radiographic and histological evaluation of persistent periapical lesions associated with endodontic failures after apical microsurgery.

AIM: To determine the histology of persistent periapical lesions associated with nonsurgical endodontic treatment failures and to compare radiographically the sizes of periapical lesions and the presence or absence of the radiopaque lamina with the histological findings. METHODOLOGY: Ninety-three anterior teeth designated for apical microsurgery were included in the study. After taking standard radiographs of all cases using the parallel technique, the films were scanned and evaluated for the size of periapical radiolucent lesions and the presence or absence of radiopaque lamina by two calibrated observers. Biopsy specimens were obtained during apical microsurgery and examined under light microscopy by oral pathologists. Histological analysis established diagnoses of granuloma, cyst, abscess and scar tissue. Interobserver agreement was evaluated by the kappa test, and the relationship between histological diagnosis and lesion size was analysed by the Pearson's chi-square test. RESULTS: The 93 specimens consisted of 72% periradicular granulomas; 21.5% radicular cysts, including two keratocysts; 4.3% abscesses; and 2.2% scar tissue. Cystic prevalence increased as the size of the periapical lesion increased; however, there was no correlation between the presence of a radiopaque lamina and histological diagnosis of cyst. CONCLUSIONS: Neither radiographic size nor presence of an associated radiopaque line alone was sufficient to determine the type of lesion. Histological examination is required in order to reach to a definitive diagnosis.

The outcome of apical microsurgery using MTA as the root-end filling material: 2- to 6-year follow-up study.

AIM: To evaluate the influence of various predictors on the healing outcome 2-6 years after apical microsurgery (AMS) using MTA as the root-end filling material. METHODOLOGY: A total of 90 anterior teeth with asymptomatic persistent periradicular periodontitis of strictly endodontic origin that failed after either nonsurgical or surgical treatment were included. Surgery was completed under local anaesthesia using a standardized clinical protocol. Clinical and radiographic measures as well as the follow-up period were used to determine the healing outcome. For statistical analysis of the predictors, the outcome was dichotomized into healed cases and nonhealed cases. Odds ratios were calculated, and Pearson chi-square or Fisher's exact tests were used to analyse the data. RESULTS: Clinical and radiographic assessment of AMS revealed that 80% were healed, 14.4% were nonhealed, whilst 5.6% were judged to be uncertain. None of the various predictors investigated had a significant influence on the outcome of AMS. CONCLUSIONS: The results of this clinical study demonstrated that 80% of cases that received apical microsurgery healed when using MTA as the root-end filling material.

Biomechanical evaluation of a new design titanium miniplate for the treatment of mandibular angle fractures.

The optimal management of mandibular angle fractures remains controversial. The aim of this experimental study was to test the stability and resistance to mechanical force of a new titanium miniplate design. Thirty fresh sheep hemimandibles, sectioned at the angle region, were used to evaluate two plating techniques. One group received fixation via a new design single non-compression titanium miniplate and the second group via a six-hole straight non-compression titanium miniplate. A custom-made biomechanical test model was used for the samples. Each hemimandible was subjected to compressive and tensile forces using an Instron machine. The biomechanical forces (N) that caused 4-mm displacement or fixation loosening were compared. Comparison between the groups showed that fixation with the new design miniplate had more resistance to lateral compression forces than with a six-hole straight miniplate (P<0.009). Moreover, the new design miniplate fixation displayed more resistance to vertical compression and tensile forces (P>0.46 and P>0.61, respectively). The study demonstrated that mandibular fracture fixation with the new design non-compression titanium miniplate offered greater resistance to lateral displacement forces and may also provide increased resistance to vertical compressive and tensile forces than a conventional six-hole straight miniplate.

Clinical accuracy of two electronic apex locators in teeth with large periapical lesions.

AIM: To evaluate in vivo the accuracy of two electronic apex locators (EALs) in determining the position of the apical foramen of teeth with large periapical lesions and persistent intracanal exudate. METHODOLOGY: Thirty-three maxillary anterior teeth assigned for periapical surgery were selected. Following the preparation of standard endodontic access cavities, electronic working lengths were determined using the ProPex and Apex Pointer apex locators. During endodontic surgery, the actual root canal length of each tooth was measured by positioning a K-file at the most coronal border of the major foramen. Root canal treatments combined with apical surgery were then completed. Data were analysed with paired t-tests. RESULTS: ProPex and Apex Pointer were accurate (within ± 0.5 mm) 97% and 94% of the time. No significant differences were detected between the apex locators (P = 0.325). CONCLUSIONS: Despite the presence of exudate in the root canals, the position of the major foramen in teeth with large periapical lesions can be determined with high level of precision either by ProPex or Apex Pointer. Both EALs can be used safely in working length determination of teeth with large periapical lesions, which have persistent intracanal exudate.

5-fluorouracil increases the number and complexity of premature complexes in the heart: a prospective study using ambulatory ECG monitoring.

The cardiac toxicity of LV5FU2 (de Gramont) regimen which is a widely used chemotherapy regimen in gastrointestinal system cancers is not well defined. We aimed to evaluate the impact of this regimen on cardiac rhythm. Two Holter ECG recordings were obtained in all patients with gastrointestinal system cancers treated with LV5FU2 regimen as first-line chemotherapy (one before and the second during the first 24 h of chemotherapy). Records were reviewed for the heart rate, rhythm, atrial premature complexes (APC), ventricular premature complexes (VPC), grades according to Lown-Wolf grading system and ST segment changes. Holter ECG recordings were evaluated in 27 patients. In the baseline evaluation, neither clinical symptom nor ST segment changes were observed. During the treatment period, chest pain was observed in two patients without any cardiac enzyme and ST segment changes. Moreover, a decrease in mean heart rate, and an increase in the number and complexity of premature complexes secondary to treatment were observed. The mean heart rate, APC per hour and VPC per hour (+/-SD) before vs. during treatment were, respectively, 93.1+/-16.4 vs. 81.6+/-12.7 (p=0.001), 18.9+/-54.0 vs. 45.3+/-53.8 vs. (p=0.049) and 12.7+/-29.6 vs. 38.1+/-42.1 (p=0.002). LV5FU2 regimen leads to a decrease in mean heart rate and a significant increase in APC and VPC which may lead to serious arrhythmias. These effects must be better understood for a safer administration of this useful and widely used drug regimen.

Expression of the RB protein, allelic imbalance of the RB gene and amplification of the CDK4 gene in metaplasias, dysplasias and carcinomas in Barrett's oesophagus.

In the present study, the role of allelic loss at the retinoblastoma gene (RB), expression of the retinoblastoma protein (pRb) and amplification at the CDK4 gene in the metaplasia--dysplasia--carcinoma sequence in Barrett's oesophagus (BO) was investigated. Samples of metaplastic specialised epithelium (SE; n = 28), low-grade dysplasia (LGD; n = 21), high-grade dysplasia (HGD; n = 19) and invasive adenocarcinoma (CA; n = 35) derived from 36 oesophagectomy specimens were included. Of the cases that were informative for the RB gene (n = 27), loss of heterozygosity (LOH) was found in none of the 22 SE, in none of the 14 LGD, in 1 of the 12 HGD (8.3%) and in 5 of the 27 CA (18.5%). Immunohistochemically, an enhanced expression of pRb protein in LGD, HGD and CA as compared with SE was found in most cases. In 4 carcinoma samples, however, a marked reduction (3 cases) or complete absence (1 case) of pRb protein expression was found. Two out of these 4 CA samples showed LOH in the RB gene whilst one case was heterozygous and one case was homozygous. In contrast to the positive controls used, CDK4 amplification was not detectable by means of differential PCR in any of the samples under investigation. The present study indicated that allelic loss of the RB gene occurs late in the metaplasia--dysplasia--carcinoma sequence in BO. Immunohistochemically determined loss of pRb protein expression may indicate LOH of the RB gene. CDK4 gene amplification does not seem to play a role in the development of oesophageal adenocarcinoma.

Worsening of left ventricular diastolic dysfunction during exercise causes decreased exercise tolerance in hypertension.

BACKGROUND: Exercise tolerance is reduced in hypertension. Hypertension affects left ventricular (LV) diastolic filling by causing abnormal relaxation and decreasing compliance. HYPOTHESIS: This study was designed to determine whether worsening of LV diastolic dysfunction during exercise causes decreased exercise tolerance in hypertension. METHODS: Left ventricular diastolic filling parameters were examined at mitral valve by Doppler echocardiography at rest and at peak exercise in hypertensive patients and were compared with those of age- and gender-matched normotensive individuals. Treadmill exercise stress test was performed according to the Bruce protocol and the exercise time was recorded. RESULTS: Exercise time was significantly shorter in the hypertensive group than that in the normotensive group (320 +/- 29 vs. 446 +/- 38 s, p 0.03). The hypertensive group demonstrated abnormal relaxation pattern of diastolic mitral inflow at rest, which became pseudonormal at peak exercise (E/A velocity ratio, rest 0.86 +/- 0.06 vs. exercise 1.19 +/- 0.09, p < 0.001). The diastolic mitral inflow pattern remained normal at peak exercise in the normotensive group. The deceleration time and the pressure half time of early mitral inflow at peak exercise were significantly shorter in the hypertensive group than those in the normotensive group (deceleration time, 182 +/- 20 vs. 238 +/- 22 ms, p 0.02: pressure half time, 54 +/- 5 vs. 70 +/- 12 ms, p 0.01). CONCLUSIONS: This study demonstrates that reduced exercise tolerance in hypertension is associated with worsening of diastolic dysfunction during exercise consistent with an increase in left atrial pressure.

A left atrial paraganglioma patient presenting with compressive dysphagia.

Paragangliomas are rare neoplasms of neural crest origin arising in the chromaffin (pheochromocytoma) and chemoreceptor (chemodectoma) tissues. Only a few cases of paragangliomas have been reported in the heart. Most of the cardiac paragangliomas are located in, or adjacent to, the left atrium. The biological activity indicative of catecholamine production has rarely been shown in cardiac paragangliomas. Patients with cardiac paragangliomas may present with hypertension, or with various obstructive or compressive symptoms, depending on the location of the tumour. A left atrial paraganglioma compressing the esophagus causing dysphagia is presented. A 37-year-old female patient underwent work-up for dysphagia to solids. Transesophageal echocardiography showed the presence of a large mass in the dilated left atrium. The tumour was removed completely intact and was a benign noncatecholamine-secreting paraganglioma. The patient's dysphagia was relieved. The clinical perspectives of cardiac paraganglioma and cardiac dysphagia are discussed.

Periodontal healing after intentional auto-alloplastic reimplantation of injured immature upper front teeth.

BACKGROUND/AIMS: Conventional endodontic treatment results in high complication quota when performed in immature teeth. Intentional reimplantation with extraoral insertion of an endodontic implant (auto-alloplastic reimplantation) is an alternative. METHOD: In a retrospective study, the healing of 40 teeth reimplanted intentionally according to this method in patients aged 7 to 15 years was evaluated. Clinical tests (palpation, percussion sound, periotest values) and radiographical examinations were used to determine the type of periodontal healing (inflammatory resorption/periodontitis apicalis; replacement resorption/ankylosis; normal healing). RESULTS: Mean lifetime of the replanted teeth was 59.2+/-42.5 months, estimated survival time on the basis of the Kaplan-Meier analysis was 99.5 months. 17 teeth (42.5%) were classified as failures, mostly due to inflammatory resorption or periodontitis apicalis. Further investigations demonstrated that success rate and retention period of intentionally replanted teeth depend on the preoperative condition of the pulp. Teeth with preoperative infection suffered frequently from inflammatory resorption or periodontitis apicalis after being replanted (14 of 28 teeth). Estimated survival time according to Kaplan-Meier was 75.5 months. In contrast, inflammations or progressive resorptions were not observed in teeth without preoperative infection of the pulp. All these 12 teeth showed normal periodontal healing and regular tooth mobility. In the absence of any pathology in clinical or radiological findings after an average functional period of 72.3 months, the prognosis can be presumed excellent. Estimated survival time of 148.3 months according to Kaplan-Meier differs significantly from survival time of teeth infected preoperatively. CONCLUSIONS: From the results of this investigation, it may be concluded that an infection of the pulp - due to delay of treatment or attempts at endodontic therapy - should be avoided before intentional replantation of immature front teeth with pulp necrosis. Periodontal healing of the autologous root is not impaired by the insertion of posts made of Al2O3-ceramics or titanium. The inserted posts do not ankylose. Orthodontic movement of auto-alloplastically replanted teeth is possible.

Sensory disorders after separation of the nasopalatine nerve during removal of palatal displaced canines: prospective investigation.

During a prospective study after separation of the nasopalatine nerve at the foramen incisivum during exposure or removal of impacted and palatal displaced maxillary canines, 59 patients were examined neurologically for 4 weeks postoperatively over an investigation period of 18 months. During the first week after the operation, subjective as well as objective sensory disorders were found in all of the patients, but after 4 weeks at the most no neurological deficit could be detected in any patient.

Investigations on a cell culture medium for storage and transportation of avulsed teeth.

Non-physiologic storage of avulsed teeth leads to a high incidence of root resorption, resulting in poor prognosis. This study investigated the suitability of specially composed cell culture media for storage of extracted teeth for up to 48 hours. Autoradiographic investigations revealed that the proliferative activity of periodontal ligament (PDL) cells of teeth stored in cell culture medium for up to 48 hours increased with storage time. Studies on proliferation of PDL cells after storage of teeth in different media for up to 24 hours demonstrated that the proliferative activity is dependent on the composition of the medium. Immunohistochemical investigations with markers for cell proliferation revealed that pulp cells of extracted immature teeth show numerous proliferations after storage for up to 24 hours in a special cell culture medium but few proliferations after storage in Hanks Balanced Salt Solution (HBSS). The investigations indicate that a special cell culture medium can preserve cell viability of PDL cells adhering to extracted teeth for at least 48 hours. The in vitro results are confirmed by a case presented: After storage of two upper central incisors for 36 hours in the cell culture medium the teeth could be successfully reimplanted after extraoral insertion of titanium posts into the root canal (auto-alloplastic reimplantation). Clinical and radiological follow-up examinations for 12 months revealed normal periodontal healing.

Use of intraventricular dispersion of the peak diastolic flow velocity as a marker of left ventricular diastolic dysfunction in patients with atrial fibrillation.

The aim of this study was to evaluate the use of intraventricular dispersion of the peak diastolic flow velocity as a marker of left ventricular diastolic dysfunction in patients with atrial fibrillation. Regional diastolic flow velocity patterns at 1, 2, and 3 cm away from the mitral tip toward the apex were simultaneously recorded with the mitral flow velocity pattern by using pulsed Doppler echocardiography in 24 patients with atrial fibrillation before electrical or medical cardioversion. Echocardiographic examination was repeated after 10 to 30 days (ie, at the time of recovery of left atrial mechanical functions) after cardioversion of atrial fibrillation in all patients. Thirteen patients were found to have diastolic dysfunction; the remaining 11 patients with a normal E/A ratio constituted the control group. Afterward, the data recorded before the cardioversion were analyzed for each patient. In subjects with normal diastolic function, the peak diastolic flow velocity (PDFV) at the mitral tips also was maintained at the positions 1 to 3 cm away from the tip in the left ventricular cavity (PDFV at the mitral tips: 0.84 m/s, PDFV at 3 cm: 0.85 m/s; P =.34). In contrast, the regional PDFV progressively decreased toward the apex in patients with diastolic dysfunction (PDFV at the mitral tips: 0.82 m/s, PDFV at 3 cm: 0.63 m/s; P =.0004). Only 77% of the initial velocity was maintained at 3 cm away from the mitral tips in patients with diastolic dysfunction, whereas almost 100% of the initial velocity was preserved in patients with normal diastolic function (P <.001). These findings suggest that the assessment of the intraventricular decrease in mitral PDFV may be used as a reliable marker of diastolic dysfunction in patients with atrial fibrillation.

[Extrafollicular variant of centrally located adenomatoid odontogenic tumor]. / Extrafollikulare Variante eines zentral gelegenen adenomatoiden odontogenen Tumors.

An adenomatoid odontogenic tumor has been reported which was not connected with any impacted or displaced tooth. The clinical and radiographical results were consistent with a non-odontogenic cyst, but in this case the pathohistological examination revealed string-like and partly cross-linked cells of odontogenic epithelium as well as solid aggregates of epithelia, possessing gland-like structures at their centers. Furthermore, small deposits of PAS-positive materials could be seen which could be interpreted as non-mineralized dentine with a tubular basic structure. The therapy consisted of completely enucleating the tumor. Any recurrence of malignant degeneration has not yet been reported.

Transplantation of displaced and dilacerated anterior teeth.

The therapy of dilacerated permanent anterior teeth usually involves surgically removing the tooth. Subsequently, orthodontic methods for closing the space or keeping it open are preferred until the patient reaches an age when definitive implantological or prosthetic treatments may be used. Anterior tooth transplantation should be considered as an alternative to surgically extracting the tooth. This study describes a period of investigation covering 3 years during which neither replacement resorption nor inflammatory resorption was diagnosed in the five transplanted teeth. The clinical tooth mobility was similar to that of the adjacent teeth. In spite of the vertical loss of bone shown radiographically no pathologically enlarged pockets or recessions have been found. It is not yet possible to make any comments on the prognosis for the long term.