Haemostatic effect and tissue reactions of methods and agents used for haemorrhage control in apical surgery.

AIM: To compare the haemostatic effect and tissue reactions of different agents and methods used for haemorrhage control in apical surgery. METHODOLOGY: Six standardized bone defects were prepared in the calvaria of six Burgundy rabbits. Five haemostatic modalities were tested for their haemostatic effect and tissue reactions, and were compared with untreated control defects: Expasyl + Stasis, Expasyl + Stasi + freshening of the bone defect with a bur, Spongostan, Spongostan+ epinephrine, and electro cauterization. The haemostatic effect was analysed visually and compared using Wilcoxon's signed rank test. Two groups of three animals were evaluated histologically for hard and soft tissue reactions related to the different haemostatic measures, after 3 and 12 weeks of healing respectively. RESULTS: Expasyl + Stasis and electro cauterization proved most effective in reducing bleeding (P < 0.05), but were accompanied by unfavourable tissue reactions, as indicated by the presence of necrotic bone, inflammatory cells and the absence of bone repair. These adverse tissue reactions did not recover substantially over time. However, adverse reactions were not observed when the superficial layer of bone had been removed with a rotary instrument. In contrast, Spongostan + epinephrine showed only a moderate haemostatic effect, but elicited also only mild adverse tissue reactions. CONCLUSIONS: Haemostasis in experimental bone defects is most effectively accomplished by using Expasyl + Stasis or electro cauterization. However, the bone defects should be freshened with a rotary instrument before suturing so as not to compromise healing.

Teaching and assessment of implant dentistry in undergraduate and postgraduate education: a European consensus.

This paper constitutes a summary of the consensus documents agreed at the First European Workshop on Implant Dentistry University Education held in Prague on 19-22 June 2008. Implant dentistry is becoming increasingly important treatment alternative for the restoration of missing teeth, as patients expectations and demands increase. Furthermore, implant related complications such as peri-implantitis are presenting more frequently in the dental surgery. This consensus paper recommends that implant dentistry should be an integral part of the undergraduate curriculum. Whilst few schools will achieve student competence in the surgical placement of implants this should not preclude the inclusion of the fundamental principles of implant dentistry in the undergraduate curriculum such as the evidence base for their use, indications and contraindications and treatment of the complications that may arise. The consensus paper sets out the rationale for the introduction of implant dentistry in the dental curriculum and the knowledge base for an undergraduate programme in the subject. It lists the competencies that might be sought without expectations of surgical placement of implants at this stage and the assessment methods that might be employed. The paper also addresses the competencies and educational pathways for postgraduate education in implant dentistry.

Effect of treatment delay upon pulp and periodontal healing of traumatic dental injuries -- a review article.

Based on an analysis of the literature concerning parameters influencing the prognosis of traumatic dental injuries, few studies were found to have examined possible relationships between treatment delay and pulpal and periodontal ligament healing complications. It has been commonly accepted that all injuries should be treated on an emergency basis, for the comfort of the patient and also to reduce wound healing complications. For practical and especially economic reasons, various approaches can be selected to fulfill such a demand, such as acute treatment (i.e. within a few hours), subacute (i.e. within the first 24 h), and delayed (i.e. after the first 24 h). In this survey the consequences of treatment delay on pulpal and periodontal healing have been analyzed for the various dental trauma groups. Applying such a treatment approach to the various types of injuries, the following treatment guidelines can be recommended, based on our present rather limited knowledge of the effect of treatment delay upon wound healing. Crown and crown/root fractures: Subacute or delayed approach. Root fractures: Acute or subacute approach. Alveolar fractures: Acute approach (evidence however questionable). Concussion and subluxation: Subacute approach. Extrusion and lateral luxation: Acute or subacute approach (evidence however questionable). Intrusion: Subacute approach (evidence however questionable). Avulsion: If the tooth is not replanted at the time of injury, acute approach; otherwise subacute. Primary tooth injury: Subacute approach, unless the primary tooth is displaced into the follicle of the permanent tooth or occlusal problems are present; in the latter instances, an acute approach should be chosen. These treatment guidelines are based on very limited evidence from the literature and should be revised as soon as more evidence about the effect of treatment delay becomes available.

Osseointegration of subperiosteal implants using bovine bone substitute and various membranes.

An earlier study revealed incomplete osseointegration of individually made titanium subperiosteal implants covered by ePTFE membranes and fixated to the rabbit tibial bone surface. In addition, the newly-formed bone was dominated by large marrow spaces. In this subsequent study, subperiosteal implants were also fixated on the bone surface of both tibia of 9 Copenhagen White rabbits. Bio-Oss particles were packed densely covering the entire implant surface. One of 3 different membranes covered the implant and the particles. The membranes used were the degradable Polyglactin 910 mesh, a degradable bilayer collagen membrane and the non-degradable ePTFE membrane. Undecalcified sections were prepared for histologic evaluation after a 12 weeks' observation period. All 18 subperiosteal implants were completely osseointegrated. In addition, the marrow spaces were reduced compared to our previous study. The Bio-Oss particles proved to be biocompatible and osteoconductive. The ePTFE membranes revealed neither signs of collapse nor adjacent infiltration of inflammatory cells. The Polyglactin 910 mesh and the bilayer collagen membranes collapsed slightly. There were signs of resorption of the surface of the newly-formed bone under the degradable membranes. The cause of resorption can not be documented.

A 41-year history of a mandibular subperiosteal implant.

The subperiosteal implant was originally described in the 1940s. The inadequate long-term results of subperiosteal implants are in contrast to the excellent results documented for endosseous osseointegrated oral implants. Consequently, subperiosteal implants and other soft-tissue-anchored implants should not be used presently. Furthermore, these implants are seldom seen today, because they generally were removed rather shortly after placement. The present report documents a full 41-year history of a mandibular subperiosteal implant inserted in 1957 by focusing upon the consequences of not removing an implant in spite of continuous periods of complications during 4 decades. Implant exposure, inflammation, infection, and fistula formation occurred persistently. Total implant removal was refused by the patient in 1973. After 25 years without control, tremendous resorption of the mandible was observed in 1998. Consequently, the entire implant was then removed. Placement of osseointegrated oral implants was impossible without extensive autogenous bone grafting. The present report has demonstrated that regular control of patients with subperiosteal implants is mandatory. Furthermore, subperiosteal implants should definitely be removed, if continuous periods of complications occur.

Infraposition of ankylosed permanent maxillary incisors after replantation related to age and sex.

The extent of infraposition of replanted and subsequently ankylosed permanent incisors was examined in a longitudinal study of 52 patients. Study cast models were made during the follow-up period. Infraposition was evaluated on frontal photos of the study cast models taken parallel with the occlusal plane. The extent of infraposition was defined as the difference between the position of the incisal edge of the replanted incisor and the adjacent non-injured incisor in apico-coronal direction, measured with a digital caliper at 50x magnification of the negatives. The precision of this measuring procedure was 2.9% and the accuracy 2.0%. Marked infraposition was identified if the tooth was traumatized before the age of 16 in boys and before the age of 14 in girls. In addition, infraposition was observed when ankylosis developed in patients aged 20-30 years, with a yearly mean infraposition rate of 0.07 mm/year (range: 0.02-0.21 mm/year) in males and 0.07 mm/year (range: 0.00-0.12 mm/year) in females. The latter findings supported the concept of slow continuous eruption of the teeth. This phenomenon may have implications not only for the treatment of traumatized teeth but also for the treatment of tooth loss by osseointegrated implants, which represent an analogue to the ankylosed replanted tooth.

Incomplete bone regeneration of rabbit calvarial defects using different membranes.

The present study describes the use of a degradable and a non-degradable material for guided bone regeneration. Forty rabbits were divided into 5 groups. Bicortical defects 15 mm in diameter were prepared in rabbit calvaria. A titanium microplate was placed over the defect to prevent collapse of the membrane. The calvarial defects of 2 groups were covered by an outer expanded polytetrafluoroethylene (ePTFE) membrane respectively by a Polyglactin 910 membrane. Bicortical ePTFE membranes or Polyglactin 910 membranes were used in 2 other groups. The defects were not covered by membranes in the control group. Undecalcified sections were prepared for histologic evaluation after an observation period of 8 weeks. Complete bone healing of the defects was not observed in any of the specimens. The Polyglactin 910 material lacks physical strength, resulting in collapse of the membrane and brain tissue herniation into the defects. Subsequently, bone regeneration was impaired. The cellular reactions due to degradation of the material were minor and did not interfere with bone healing. Defects covered bicortically by ePTFE membranes revealed the largest amount of regenerated bone. The ePTFE membrane induced a severe cellular reaction, but no inhibition of bone regeneration was noted.

Unbiased stereological methods used for the quantitative evaluation of guided bone regeneration.

The present study describes the use of unbiased stereological methods for the quantitative evaluation of the amount of regenerated bone. Using the principle of guided bone regeneration the amount of regenerated bone after placement of degradable or non-degradable membranes covering defects in rabbit calvaria was compared. Forty rabbits were divided into 5 groups. A titanium microplate was placed over the defect to prevent collapse of the membrane. The non-degradable expanded polytetrafluoroethylene membrane and the degradable Polyglactin 910 material were both placed unicortically and bicortically. Undecalcified sections were prepared for stereologic evaluation after an observation period of 8 weeks. Complete bone healing of the defects was not observed in any of the specimens. Unbiased stereologic estimates revealed 48% bone regeneration in defects covered by 2 ePTFE membranes, and 12% in defects covered by 2 Polyglactin 910 membranes. Defects covered by 1 ePTFE or 1 Polyglactin 910 membranes revealed 10% or 18% bone regeneration, respectively. The control group regenerated 14%. The major difference of the estimates was caused by real difference between specimens, i.e. biologic variation, whereas only minimal variance was added by the stereologic estimation procedure.

Effect of platelet-derived growth factor-BB on bone formation in calvarial defects: an experimental study in rabbits.

The effect of recombinant human platelet-derived growth factor-BB (rhPDGF-BB) on bone healing was examined in calvarial defects in rabbits. Bicortical circular (critical size) defects were prepared in the calvarial bone of 16 rabbits. The defects were closed on the dural side and covered externally with expanded polytetrafluoroethylene membranes to prevent interference with osteogenesis within the defect by the surrounding tissue and to keep the growth factor in place. A single dose of methylcellulose gel (4.4%) with (n = 8) or without rhPDGF-BB (50 micrograms/ml) (n = 8) was applied to the defects, and the bone formation was evaluated after 8 weeks. Healing of defects in both groups was characterized by the presence of newly formed bone along the edges of the original defect and by a central area of fibrous connective tissue. The newly formed bone in the rhPDGF-BB treated defects had a trabecular structure; in contrast, a more compact structure was found in the control defects. In the rhPDGF-BB-treated defects, the bone ingrowth was 51.8 +/- 7.1% compared to 30.5 +/- 3.3% in the control defects. Furthermore, the amount of mineralized tissue was increased 112% in the rhPDGF-BB group. The amount of bone marrow was increased 75% in the rhPDGF-BB-treated defect. The porosity of cortical lamella in the newly formed bone was 84% higher in the rhPDGF-BB-treated defects compared to the control. These results show that administration of a single dose of rhPDGF-BB stimulates bone formation in critical size calvarial defects.

Tissue reaction and material characteristics of four bone substitutes.

The aim of the present study was to qualitatively and quantitatively compare the tissue reactions around four different bone substitutes used in orthopedic and craniofacial surgery. Cylinders of two bovine bone substitutes (Endobon and Bio-Oss) and two coral-derived bone substitutes (Pro Osteon 500 and Interpore 500 HA/CC) were implanted into 5-mm bur holes in rabbit tibiae. There was no difference in the amount of newly formed bone around the four biomaterials. Interpore 500 HA/CC resorbed completely, whereas the other three biomaterials did not undergo any detectable biodegradation. Bio-Oss was osseointegrated to a higher degree than the other biomaterials. Material characteristics obtained by diffuse reflectance infrared Fourier transform spectrometry analysis and energy-dispersive spectrometry did not explain the differences in biologic behavior.

Anchorage of TiO2-blasted, HA-coated, and machined implants: an experimental study with rabbits.

The purpose of this study was to evaluate the histometrical and biomechanical anchorage of TiO2-blasted implants and TiO2-blasted implants coated with hydroxyapatite. The control implants were machined. Twenty-six rabbits had a total of 156 implants placed in the proximal part of the tibia. Each rabbit had a machined, a TiO2-blasted, and a TiO2-blasted, HA-coated implant placed in each tibia. After a healing period of 3 and 12 weeks, respectively, the implants placed in the right tibia were used for removal torque test, and the implants placed in the left tibia were used for histomorphometrical measurements. Preoperatively, implants from the same batches were examined topographically with a TopScan 3D system. The TiO2-blasted implants demonstrated significantly higher removal torque values than the machined implants, and they also had a significantly more irregular surface. Furthermore, significantly higher bone-to-implant contact length fractions were measured adjacent to the TiO2-blasted implants in contrast to the machined implants. The advantages of a TiO2-blasted surface were more pronounced after 3 weeks than after 12 weeks. The results demonstrated that it was possible to influence the anchorage of implants by altering the surface structure morphology. The new method with TiO2 blasting on the titanium surface improves the anchorage of implants but is not yet practicable for HA coating.

Healing of experimentally created defects: a review.

Within cranio-maxillofacial surgery and orthopedic surgery a bone graft or a bone substitute is required to recontour or assist bony healing in repair of osseous congenital deformities, or in repair of deformity due to trauma or to surgical excision after elimination of osseous disease processes exceeding a certain size. An autogenous bone graft is the optimal material of choice, however its use is problematic due to donor site morbidity, sparse amounts and uncontrolled resorption. Immunological responses and risk of viral contamination of allogenous and xenogenous bone materials make the use of these materials questionable. Healing and degradation of alloplastic materials are inconsistent with subsequent restricted use. The principle of guided tissue regeneration excluding soft tissue cells from a certain area is not alone sufficient to insure complete bony healing. Recombinant bone morphogenetic proteins have with success been added as adjuncts to already known biomaterials. In the future, inductive materials together with a suitable carrier and a biodegradable membrane may be the choice of bone substitute used within cranio-maxillofacial and orthopaedic surgery.

Osseointegration of subperiosteal implant via guided tissue regeneration. A pilot study.

The principle of guided tissue regeneration was applied in an attempt to generate bone to cover a subperiosteal implant. Titanium frame works, casted on individual impressions of the anterior surface of the tibia of 4 Copenhagen White rabbits, were stabilized to the tibia by microscrews, and half of them were covered by an expanded polytetrafluoroethylene augmentation membrane. The observation period was 12 weeks. Guided bone regeneration partly covering the implants was seen at all experimental sides; on the control sides the implants were mainly embedded in fibrous tissue. Studies are in progress with the aim of reducing marked marrow space formation observed in all the regenerated areas.

Repair of the lingual nerve after iatrogenic injury: a follow-up study of return of sensation and taste.

PURPOSE: To evaluate the return of sensation and taste after surgical repair of the lingual nerve in patients who had experienced lingual nerve sectioning. PATIENTS AND METHODS: Average follow-up was 3.7 years with a range of 1.1 to 4.6 yrs. The patients' assessment of tongue sensation and taste was registered. Clinical testing for sensibility included light touch, prick, sharp/dull discrimination, heat (45 degrees C), cold (0 degree C), anterior/posterior localization of touch, perception of direction of touch movement, and two-point discrimination. The sense of taste was tested with sweet (saccharose 5%), sour (citric acid 5%), salt (saline 5%), and bitter (chinin-hydrochloride 0.5%). RESULTS: Three patients rated their tongue sensation on the affected side as normal, another three scored subnormal, and one felt no sensibility. Likewise, four patients thought that their sense of taste was normal, two were undecided, and one felt no sense of taste on the affected side. The ability to differentiate the quality of taste on the operated side of the tongue was validated in four of 24 tests. Conversely, on the healthy side of the tongue, two of 24 tests proved negative for taste perception. CONCLUSION: There was a notable difference in the patients' assessment of normality of tongue sensation versus the result of neurological testing. Likewise, there was a remarkable difference between the patients' subjective impression of gustatory capability and their ability to diagnose the quality of taste on testing.

Unicortical critical size defect of rabbit tibia is larger than 8 mm.

The critical-size defect is important as an experimental model to test bone repair materials. Guided tissue regeneration is an established method for tissue regeneration within periodontal surgery. Bony defects covered by a membrane are allowed to be filled by bony tissue. Healing of 8-mm unicortical trephine defects was tested in Copenhagen White rabbit tibia using 3 different membranes. The critical-size defect in Copenhagen White rabbit tibia is larger than 8 mm, because control defects 8 mm in diameter healed spontaneously. However, it is anatomically not possible to create defects larger than 8 mm in an adult Copenhagen White rabbit tibia.

Immediate implant placement using a biodegradable barrier, polyhydroxybutyrate-hydroxyvalerate reinforced with polyglactin 910. An experimental study in dogs.

The purpose of this study was to evaluate the use of a biodegradable membrane of polyhydroxybutyrate-hydroxyvalerate copolymer reinforced with polyglactin 910 fibers, as an occlusive barrier over implants placed into fresh extraction sockets. Ten dogs had the 3rd and 4th mandibular premolars extracted bilaterally. Each dog had 4 Astra Dental Implants placed directly into the fresh extraction sockets. The top of the fixtures was placed at the same level as the top of the buccal cortical bone. The two implants in the right side were covered with the hydrolyzable polyester material (polyhydroxybutyrate-hydroxyvalerate reinforced with polyglactin 910 fibers; PHB-HV/PG), and the 2 implants in the left side were controls without occlusive membranes. Soft tissue dehiscences were registered for half of the implants in the test side but were not noted in the control side. The histomorphological measurements after 12 weeks showed that the mean distance from the top of the fixtures to the first bone-to-implant contact was significantly greater than for the control side. The membrane-covered implants without dehiscences showed also significantly less bone fill compared with the control side. Inflammatory cell infiltrates were seen adjacent to all PHB-HV/PG membranes, and frequently the membrane material was surrounded by a fibrous tissue capsule. The polyester membranes used in this study interfered with the marginal bone healing adjacent to the immediately placed implants. An increased inflammatory reaction and significantly less marginal bone healing was registered in the membrane side compared with the control side.

Benign cementoblastoma. A review and five new cases.

This article includes five new cases of benign cementoblastoma. The study includes a review on 66 previously published cases that we consider to be bonafide cases. It is considered that benign cementoblastoma continues to be an infrequent entity that particularly affects young patients under the age of 30. The sex distribution shows a slight tendency for being more common in females. The most frequently effected area is the mandibular molar-premolar region. Pain, expansion and, radiographic radiopacity surrounded by a peripheral radiolucent halo are the most striking features. Treatment and prognosis are also discussed. Histopathologic conditions and factors to be considered with respect to differential diagnosis conclude the report.

Evaluation of guided bone generation around implants placed into fresh extraction sockets: an experimental study in dogs.

Immediate placement of implants into fresh extraction sockets would have the principal advantage of decreasing the recommended period of healing. It also would result in a guided placement of the implant, and it could reduce the resorption of the alveolar bone in the extraction area. However, when an implant is placed immediately into an extraction socket, it may not engage the walls of the socket near the crest of the alveolar ridge. With the presence of a bone defect around an implant, ingrowth of soft tissue could compromise the achievement of osseointegration in the crestal bone area. The objective of this study was to evaluate the crestal bone healing response adjacent to implants placed immediately into fresh extraction sockets with and without covering membranes. Eight adult mongrel dogs had the third and fourth mandibular premolars extracted bilaterally. Thirty-two submerged titanium hollow-screw implants were inserted immediately into the extraction sockets. On the right side, the implants were covered with an expanded polytetrafluorethylene membrane, whereas the left side served as a control. One dog was killed after 2 weeks, one after 4 weeks, and six after 12 weeks. Soft tissue dehiscence developed over 10 implants (12-week dogs) covered with membranes. Dehiscence was noted histologically over three contralateral control implants. When soft tissue dehiscence occurred and the membrane was left exposed without oral hygiene during healing, the degree of bone integration was significantly less than in the control sites without membranes.(ABSTRACT TRUNCATED AT 250 WORDS)