Preoperative assessment of the mandibular canal in implant surgery: comparison of rotational panoramic radiography (OPG), computed tomography (CT) and cone beam computed tomography (CBCT) for preoperative assessment in implant surgery.

PURPOSE: In this anatomical study, we compared the diagnostic accuracy of rotational panoramic radiography (OPG), computed tomography (CT) and cone beam computed tomography (CBCT) to the actual anatomical situation. MATERIALS AND METHODS: Dental images were taken of 10 human cadaver heads. Thereafter, they were prepared and measured. The height of the alveolar ridge to the mandibular canal was compared with the prior images taken. The deviation from the anatomical situation was calculated for each imaging technique. RESULTS: In the group of OPG images, there was a median of 2.3 mm distortion ranging from -0.2 to 5.7 mm in the vertical plane compared to the actual situation found during dissection. If steel balls were used during OPG, the median distortion was lowered to 0.2 mm, but the width of -1.6 to 3 mm was still quite extensive. CT images showed a mean distortion of -0.2 mm and a width of -1.5 to 1.3 mm. The mean distortion of the CBCT images was similar to the one found in CT, namely -0.3 mm with a range from -1.5 to 0.8 mm. CONCLUSIONS: The results show that OPG using steel balls as a calibration reference seems reliable in a standard situation. In more difficult cases, modern three-dimensional techniques should be used to additionally determine available bone volume.

Immediate rehabilitation of the edentulous mandible with screw type implants: results after up to 10 years of clinical function.

OBJECTIVES: The aim of this prospective case series was to evaluate the results of an immediate loading concept using four Xi VE S plus implants in the edentulous mandible, after a period of up to 10 years of clinical function. MATERIAL AND METHODS: Thirty patients were treated with four implants each placed interforaminally and provisionally restored within 1 week. Radiographic bone levels, condition of the peri-implant mucosa, implant survival and success were recorded annually from implant insertion (baseline) up to 10 years after final restoration. RESULTS: A total of 120 Xi VE S plus implants were placed in the interforaminal region. A significant coronal bone loss of 1.80 mm (SD ± 0.65) was recorded within the first 8 years of function (P < 0.001). Within the next years no further significant increase of bone resorption was observed. The mean values of the plaque, calculus, bleeding and mucosal indices and probing depth remained low throughout this period. All implants were inserted with an insertion torque of more than 32 N cm. Two losses (1.7%) occurred prior to permanent restoration (1 and 3 months post-insertion), resulting in a survival rate of 98.3% over the entire observation period. Four implants were recorded as failures due to excessive bone resorption, resulting in an overall success rate of 95%. CONCLUSIONS: The results of this study indicate that in selected patients immediate restoration of dental implants in the edentulous mandible will achieve a clinically predictable outcome.

Histology and intramandibular course of the inferior alveolar nerve.

The morphology of the inferior alveolar nerve is a very important factor for all surgical procedures in the mandibular region. The aim of this anatomical and histological study was to describe the intramandibular course and the microscopic histology of the inferior alveolar nerve in the dissected human cadaver. Twenty partially dentulous hemimandible specimens from human cadavers were dissected and embalmed, and the findings were interpreted by standard and histological imaging. The result of this study showed that the inferior alveolar nerve comprises two larger nerves that are separately wrapped in perineural sheaths and spirally twisted around each other. The mental nerve exits through the mental foramen in the premolar region and the dental nerve continues from the premolar region as the incisive nerve in the incisive canal. These findings provide relevant data for clinical dentistry, especially when planning oral and dental operative treatment procedures in the mandibular region.

Surgical factors influencing mesiodistal implant angulation.

OBJECTIVES: The aim of this experimental study was to identify relevant surgical parameters influencing the mesiodistal angular deviation of dental implants. MATERIAL AND METHODS: Pilot drillings of 2 mm diameter were performed in bovine ribs with a parallelometer. The subsequent preparation of the implant socket was performed freehand. Utilizing six different implant systems, at least 80 drillings per system of different diameters were performed. The pilot drillings were marked with 2 mm steel pins and cephalometric radiographs were taken. The mesiodistal angle between the longitudinal implant axis and the marked pilot drillings was measured and evaluated by a blinded investigator. To evaluate the influence of the surgeons' experience, their drillings were compared with those of a group of unexperienced surgeons. Additionally, the influence of drilling speed and size of bur steps on drilling accuracy were evaluated. RESULTS: The difference between the lowest value of 0.91 degrees of mesiodistal angular deviation found for 3i implants and the highest of 1.36 degrees for Ankylos implants was of low statistical significance (P=0.065). Drillings of experienced surgeons showed less deviation compared with those of a beginners group (P<0.0001). Higher deviations were measured when a bur size was skipped. Drillings performed at high speed showed significantly higher deviations than those with fewer rewinds per minute. CONCLUSION: In order to achieve precise implant angulation, all bur diameters available should be used. Utilizing low drilling speeds results in less mesiodistal deviation. The surgeon's experience seems to be the most relevant factor in precise implant placement.

Fetal microchimerism is not involved in the pathogenesis of lichen sclerosus of the vulva.

OBJECTIVES: The aim of this study was to investigate a possible relationship between fetal cell microchimerism and lichen sclerosus of the vulva. We searched for the presence of male cells and DNA in vulval tissue samples. METHODS: Paraffin-embedded skin biopsy samples from 15 women affected with vulval lichen sclerosus who gave birth to at least one son were analyzed for the presence of microchimeric male cells using fluorescence in situ hybridization (FISH) and fluorescent PCR. We included three lichen sclerosus samples originating from women without male offspring, six vulval specimens without pathological finding originating from autopsies and seven male gingival specimens as controls. RESULTS: Nucleated cells containing Y-chromosome specific sequences were neither detected at any site of the lesions nor in normal vulval specimens by using FISH. These results were confirmed by the use of PCR amplification demonstrating only DNA sequences specific for the X chromosome. No female microchimerism was detected in the male gingival samples. CONCLUSION: Despite the limited number and size of the samples, we conclude that persistent male fetal cells are not involved in the pathogenesis of lichen sclerosus of the vulva, since we consistently could not detect Y-chromosome specific sequences by using two molecular techniques.

Influence of PRP on autogenous sinus grafts. An experimental study on sheep.

Since platelet -rich plasma (PRP) has been introduced to the field of oral surgery, it has become a widely accepted additive for bone regeneration treatment. The aim of this study was to evaluate the regenerative capacity of PRP in a sinus graft study on sheep. Twelve adult sheep underwent a bilateral sinus floor elevation procedure with cancellous bone from the iliac crest. Unilaterally, PRP was administrated to the bone graft. After 4 (six sheep) and 12 weeks (six sheep), bone biopsies were obtained from each site. With histomorphometric analysis we evaluated both the percentage of newly formed bone within the grafted site and the percentage of the contact area between the grafted bone and the newly formed bone. After 4 weeks the mean proportion of newly formed bone on the control side was 26.1%, whereas it was 29.2% on the test side. After 12 weeks it was 46.9% on the control side and 51.1% on the test side. The area of contact between the graft and the newly formed bone was 73.0% on the control side and 78.5% on the test side after 4 weeks, and 87.2% on the control side and 90.1% on the test side after 12 weeks. A statistical analysis did not reveal significant differences between the control and the test side. The results of the present experimental study show a regenerative capacity of PRP of quite low potency. Further basic research is needed to investigate more profoundly the possibilities of PRP in bone regeneration.

Assessment of differential blockade by amitriptyline and its N-methyl derivative in different species by different routes.

BACKGROUND: Increasing the duration of local anesthesia and/or creating greater differential blockade (i.e., selective block of pain-transmitting nerve fibers) has been attempted by modifying currently available agents. Most drugs show a different profile depending on the model or species studied. This study was designed to investigate the differential nerve-blocking properties of amitriptyline and its quaternary ammonium derivative in rats and sheep. METHODS: The Na+ channel-blocking properties of N-methyl amitriptyline were determined with the patch clamp technique in cultured GH(3) cells. Various functions (motor, nociception, proprioception-ataxia) were compared in rats (spinal and sciatic nerve blockade) and sheep (spinal blockade) with amitriptyline, N-methyl amitriptyline, lidocaine, and bupivacaine (partially from historical data). RESULTS: In vitro testing revealed N-methyl amitriptyline to be a potent Na+ channel blocker similar to amitriptyline but with a much longer duration of action. All drug concentrations tested in both the sciatic nerve model and the spinal block model produced no significant differential blockade in rats. Three of six rats in the 20-mM N-methyl amitriptyline group showed residual blockade 4 days after sciatic nerve injection. However, in the sheep spinal model, amitriptyline and in particular N-methyl amitriptyline displayed significant differential blockade at most time points. Sheep data for lidocaine and bupivacaine seemed to be more comparable to the clinical experience in humans than did rat data. CONCLUSIONS: Amitriptyline and N-methyl amitriptyline are potent Na+ channel blockers and show greater differential blockade in sheep than in rats. This differential blockade in sheep is greater than that produced by lidocaine or bupivacaine.

In-patient comparison of immediately loaded and non-loaded implants within 6 months.

According to the Brånemark protocol, a stress-free healing period is one of the most emphasised requirements for implant integration. Recent studies have encouraged a progressive shortening of the healing period and immediate loading has been proposed for the edentulous mandible. This prospective study evaluated the clinical outcomes of 14 immediately loaded FRIALIT-2(R) implants compared with 28 non-loaded controls in an in-patient study. The results were based on clinical stability and on changes of bone level from implant placement to abutment connection 6 months after insertion. In the course of our investigation, seven patients with edentulous mandibles have been treated with 43 implants following an immediate-loading protocol. Six FRIALIT-2(R) implants were placed in the interforaminal region located at positions 34, 33, 32, 42, 43, 44. Bone level in relation to implant margin was measured and recorded. In order to obtain an in-patient comparison of immediately loaded and non-loaded implants, the ones at 33 and 43 were chosen to be immediately loaded by a Dolder-bar retained overdenture. The implants in position 32, 34, 42 and 44 were covered and left to heal. After a healing period of 6 months, second stage surgery was carried out. The clinical criteria to be checked at this point were survival, Periotest values and marginal bone level at the loaded and non-loaded implants. The mean Periotest value was -2.7 for the loaded and -5.6 for the non-loaded implants. The Mann-Whitney U-test showed that the difference was highly significant (P < 0.001). The mean bone level changes at prosthetic delivery were 0.9 mm resorption for the loaded implants and 0.33 mm for non-loaded implants. The difference was highly significant (P < 0.001). No implant failures were observed up to the prosthetic restoration 6 months post insertion. The results of this investigation allowed for direct comparison of implant survival and clinical results between immediately loaded implants and standard implants. Clinical bone changes at the 6-month evaluation demonstrated significantly higher crestal resorption around loaded implants. This fact was confirmed by higher median Periotest values (-3 vs. -6) of immediately loaded implants. According to the outcome of this study, immediate loading of two interforaminal implants with a Dolder-bar resulted in an intimate bone apposition comparable with implants with submerged healing. Nevertheless, the coronal bone level as well as clinical stability (PTV) were significantly lower in the case of the immediately loaded implants. Future studies will be necessary to evaluate marginal bone resorption, Periotest values and clinical success rates of mandibular immediately loaded implants in the long-term.

Immediate loading of single-tooth implants in the anterior maxilla. Preliminary results after one year.

According to the standard protocol, a load-free healing period is one of the most emphasized requirements for implant integration. Recent studies have encouraged a progressive shortening of the healing period for single-tooth implants and immediate loading has been proposed for the aesthetic zone in the maxilla. The present study evaluated clinical outcomes of immediately loaded FRIALIT-2 Synchro implants 12 months after placement in the maxillary incisal region. In the course of our investigation, nine patients have been treated following an immediate loading protocol. The stepped-screw type implants were inserted with an increasing torque up to 45 Ncm, thus measuring the primary stability of the implants. All implants were immediately restored with unsplinted acrylic resin provisional crowns and the patients provided with occlusal splints. Regular controls were performed at monthly intervals, intraoral radiographs were taken directly after implant placement, 6 and 12 months post insertion. The survival rate, clinical stability (Periotest) and radiographic coronal bone defects (CBD) were evaluated at delivery of the definitive superstructures (CBD 6) and 6 months later (CBD 12). Twelve FRIALIT-2 Synchro stepped screws of 3.8, 4.5 and 5.5 mm diameter and 13 and 15 mm length were placed in the incisal maxillary region. The median Periotest value 6 months post insertion was -2 with a minimum of -5 and a maximum of +2. The mean coronal bone level changes (CBD) at 6 and 12 months were 0.45 and 0.75 mm. No implant failed up to 12 months after insertion, resulting in a 100% survival rate. The presented results showed promising data for immediately loaded single-tooth implants in the anterior maxilla. Periotest values were within the range published for submerged implants. The radiographic coronal bone resorption after 6 and 12 months was even less than evaluated for implants placed in a standard two-stage procedure. It is evident that successful immediate loading protocols require a careful and strict patient selection aimed at achieving the best primary stability and avoiding any excessive functional or non-functional loading. Additional research needs to be done to provide data in situations where problems of poor bone quality, multiple implants or augmentation procedures must be overcome.

Coping with stress: its influence on periodontal disease.

BACKGROUND: Various forms of stress behavior were documented and in patients with periodontitis their relationship with periodontal disease was investigated. METHODS: Eighty-nine patients with different forms of chronic periodontitis were included in this retrospective case-control study. They were all undergoing periodontal treatment at the Department of Dental Prosthetics, University of Graz, or a private dental practice. The control group consisted of 63 persons employed in health care at the Clinic of Graz. All participants completed a stress coping questionnaire of 114 items and 19 actional and intrapsychic stress coping modes. The questionnaire served as a psychodiagnostic survey aimed at collecting data on stress coping strategies. Clinical attachment loss (CAL) served as the clinical parameter. RESULTS: With the help of a factor analysis with a factorization and Varimax rotation, 5 factors were extracted from the 19 subtests. The reliability of the questionnaire was less than 0.70 only for subtests "escape" and "pharmaceutical drugs." Otherwise the internal consistency ranged between 0.74 and 0.92, and the retest reliability between 0.72 and 0.84. Subsequent assessment with the t test for independent random samples at the 5% level showed that patients differ significantly from controls in regard of factor 2 (active coping, P = 0.40) and 3 (distractive coping, P = 0.033), and that they differ very significantly from controls in regard of factor 4 (defensive coping, P = 0.000) and 5 (coping through aggression and pharmaceutical drugs, P = 0.007). In the statistical analysis of factors with regard to the severity of periodontal disease, the patients were divided into 2 groups (mild to moderate and severe). The t test for independent random samples showed significance for factor 4 (defensive coping) in that patients with a defensive coping style had greater attachment loss (pF4 = 0.04). CONCLUSIONS: The data corroborate the thesis that periodontitis patients with inadequate stress behavior strategies (defensive coping) are at greater risk for severe periodontal disease. However, further investigations are required to confirm the significance of inappropriate coping styles with respect to the advancement of periodontal disease.

Evaluation of implants placed with barrier membranes. A restrospective follow-up study up to five years.

This follow-up study evaluated clinical and radiographic parameters of dental implants placed in combination with guided bone regeneration with barrier membranes. All implants functioned well up to 60 months after insertion. Forty-one patients, with a total of 72 augmented implants, who participated in a regular maintenance protocol, were investigated. Annual Periotest values (median value, - 3) revealed stable periimplant conditions and sustained osseointegration. At 6 months and annually thereafter up to five years, the radiographic evaluation yielded mean bone losses of 0.8, 1.25, 1.39, 1.42, 1.42 and 1.39 mm, respectively, with a range from 0 to 3.5 mm. No implant failures or losses were recorded. The results demonstrated stable periimplant conditions up to five years after membrane-protected osseous regeneration, with no significant differences in the radiographic bone level in regard to region, jaw or bone graft. Premature membrane exposure resulted in a significantly higher crestal bone loss up to 24 months. The newly formed bone appeared to be able to withstand functional loading for up to 60 months in a predictable manner.

Primary wound healing after lower third molar surgery: evaluation of 2 different flap designs.

OBJECTIVES: Wound dehiscences after lower third molar surgery potentially extend the time of postsurgical treatment and may cause long-lasting pain. It was the aim of this prospective study to evaluate the primary wound healing of 2 different flap designs. METHODS: Sixty completely covered lower third molars were removed. In 30 cases, the classic envelope flap with a sulcular incision from the first to the second molar and a distal relieving incision to the mandibular ramus was used, whereas the other 30 third molars were extracted after preparation of a modified triangular flap first similarly described by Szmyd. Wound healing was controlled on the first postoperative day, as well as 1 and 2 weeks after surgery. RESULTS: The overall result was a total of 33% wound dehiscence. In the envelope-flap group, wound dehiscences developed in 57% of the cases. This represents a relative risk ratio of 5.67, with a 95% CI from 1.852 to 12.336. With the modified triangular-flap technique, only 10% of the wounds gaped during wound healing. CONCLUSION: This study confirms evidence that the flap design in lower third molar surgery considerably influences primary wound healing. The modified triangular flap is significantly less conducive to the development of wound dehiscence.

Effects of capsaicin on KCl-induced blood flow and sensory nerve activity changes in the tooth pulp.

Potassium ion-containing solutions have been shown to initially excite then depress intradental nerve activity (INA) when applied into deep dentinal cavities. The INA reflects activity originating in intradental A fibers. Application of KCl to deep dentinal cavities also induces an increase in pulpal blood flow (PBF). Capsaicin is known to exert a highly selective desensitizing effect on polymodal C-fiber nerve endings. These C fibers are generally believed to release vasoactive substances in response to stimulation. In order to determine if KCl exerts its vascular effect via activation of capsaicin-sensitive nerve fibers, we examined blood flow and sensory nerve responses to KCl obtained before and after capsaicin desensitization. The A-fiber nerve activity was determined by using INA recording technique. Blood flow was measured simultaneously from the same tooth using laser Doppler flowmetry. Local application of 0.25 M KCl to a deep dentinal cavity induced a brief spike burst and an increase in PBF of 76.0 +/- 14.6% (n = 8). Repeated applications of 0.25 M KCl caused a consistent increase in the peak PBF amplitude (n = 8). Local application of 100 microM capsaicin to a deep dentinal cavity caused an increase in PBF of 116.8 +/- 26.3% (n = 8) lasting 12-18 min, but capsaicin application did not appear to evoke any INA response. The amplitude of PBF in response to capsaicin application declined during repeated applications. Following repeated applications of capsaicin the PBF response to KCl was significantly reduced (9.9 +/- 4.3%, n = 8).(ABSTRACT TRUNCATED AT 250 WORDS)