Screening and medical evaluation of adults: contraindications for invasive dental procedures.

Implant and preprosthetic surgeries aim to restore normal anatomical contours, function, comfort, esthetics, and oral health. Systemic screening of a patient prior to implant and/or biomaterial insertion is critical to patient well being and success of the surgical procedure(s). It is no longer appropriate to limit the general contraindications to the malfunction of major organs and systems and not consider the devastating long-term effects of an unhealthy lifestyle (smoking, inadequate diet, etc.). Modern standards of care should not systematically exclude patients with relative or marginal health conditions without exploring the possibilities of improving and stabilizing those conditions. Based on the classification of the American Society of Anesthesiology, a number of absolute and relative contraindications are presented. Treatments are proposed for optimizing some marginal health conditions and stabilizing unbalanced physiological function prior to surgery. A knowledge of the fundamentals of internal medicine is an important prerequisite for predictable implant and preprosthetic surgery. This paper reflects the opinion of a physician and dentist who has been actively involved in implant and preprosthetic surgery for the past quarter of a century in both private and university hospital practice.

Tripodal mandibular subperiosteal implant: basic sciences, operational procedures, and clinical data.

A tripodal mandibular subperiosteal dental implant is a three piece cast metal framework that fits on the residual ridge beneath the periosteum and provides support for a dental prosthesis by means of posts or other mechanisms protruding through the oral mucosa. This implant is indicated in patients with advanced atrophy of the mandible where the unstable alveolar bone has completely disappeared, leaving in place the more stable basal bone with specific anatomical contours. The authors present their experience of 317 cases carried out in three different centers related to this implant modality and underline the importance of the basic anatomic, physiologic, and medical knowledge required to optimize the results.

Telescopic retained overdentures in mentally handicapped and schizophrenic patients--a retrospective study.

For a long time the dental treatment of choice for mentally handicapped patients was extraction of teeth due to the lack of oral hygiene. Recent studies show the possibilities of restorative and prosthodontic treatment even in this group of patients. The records of 58 patients of a psychiatric clinic treated with 84 telescopic overdentures were examined. The highest survival rates after 7 years were in the light mentally retarded group with 86% and the overdentures with 3 anchor teeth with 81%. Schizophrenic patients and overdentures with only one anchor tooth presented only 29% and 37% survival respectively. It can be concluded that the number of anchor teeth and the kind of mental illness should be considered when planning treatment for mentally handicapped patients with overdentures.

The multi-modal prosthetic treatment of mentally handicapped patients--necessity and challenge.

The dental treatment of 573 mentally handicapped patients, over a period of twelve years from 1984 to 1996, is reported. The patients suffered from different varieties of mental retardation and/or schizophrenia, classified according to the International Statistical Classification of Disease N'. 10 of the World Health Organization. 189 patients were equipped with different types of removable prostheses which were followed to determine the survival time and the predictability of the prosthetic treatments. The findings showed greater risk factors related to long term hospitalised Schizophrenic patients and those with edentulous atrophic mandibles. 90% of the full-arch overdentures in the maxilla were in situ after 5 years in comparison with only 30% in the mandible. 81% of overdentures, retained telescopically by 3 teeth survived, while only 30% of overdentures anchored over a single tooth were still in place. These findings showed acceptable success rates of comprehensive restoration procedures for handicapped patients.

Patient screening and medical evaluation for implant and preprosthetic surgery.

Implant and preprosthetic surgeries aim to restore normal anatomic contours, function, comfort, aesthetics, and oral health. As such, they are not life-saving procedures. The prime concern must therefore be to not undermine the patient's overall health and safety. It is then that every step must be taken to select the appropriate treatment plan and maximize the longevity of the implanted system, including the overlying prostheses. One important category into which a number of possible complications may fall is the inadequate systemic screening of patients prior to implant and biomaterial insertion. Without wishing to enter into the whole human pathology, it is no longer appropriate to limit the general contraindications of implantology to the traditionally considered malfunctions of the pancreas, liver or hematopoietic system and to ignore the devastating long-term effect of smoking or inadequate dietary habits. There are, in fact, a number of systemic problems that may create major risk factors. On the other hand, modern standards of care should not systematically exclude the use of implant surgery on patients with relative or marginal health conditions without exploring the possibilities of improving and stabilizing those conditions. As newer techniques of general anesthesia and intravenous sedation are more frequently used on an ambulatory basis, allowing implant surgeons to take their patients into various degrees of consciousness or deep sedation, the patient screening should also take into consideration factors related to this form of management. An arbitrary guideline for patient selection may be based on the classification of the American Society of Anesthesiology. This guideline restricts (with very few exceptions) intraosseous implants and implant-related graft surgeries on patients who fall into ASA1 or ASA2 categories of the classification. In the domain of subperiosteal implants for treatment of advanced atrophy of the mandible, the body response seems to be much less dramatic than to endosseous devices or to grafted sites. The cortical histoarchitecture and metabolism are, by far, less affected by organ disorders than are endosseous structures. This article presents a number of absolute contraindications and analyzes a series of relative contraindications for which the doctor's judgment remains the decisive factor. In this latter case, it proposes treatment patterns that could optimize certain marginal health conditions or stabilize unbalanced biological functions prior to or at the time of surgery. As life expectancy in the industrial countries is continuously increasing, a greater number of elderly patients are equipped with implant-supported prosthetics. The effort must therefore be focused on keeping a regular and watchful eye on their general health and screening for possible geriatric conditions responsible for long-term implant failure. Will a minimum knowledge of internal medicine be a prerequisite for future academic implant education?

[Intravenous sedation in implantology]. / Sédation intraveineuse en implantologie.

Local or block anesthesia can be used satisfactorily in many implant procedures. However, when advanced implant techniques or pre-prosthetic reconstruction surgery of the maxillofacial bones are required, local or regional anesthesia is insufficient. The "day-hospital" concept is a rational approach which meets the requirements for anesthesia and deep sedation with criteria for patient safety and comfort while guaranteeing optimal operating conditions. Intravenous sedation, both "conscious" and "deep" sedation, is a very well adapted form of anesthesia for implant recipients. Local or block anesthesia is enhanced or reinforced prior to surgery by the intravenous administration of a sedative and anxiolytic agent (single-drug concept), such as a benzodiazepine, associated or not with a morphinomimetic agent and an antihistaminic substance (multiple-drug concept). The main goal is to maintain spontaneous respiration while obtaining postoperative amnesia of the entire procedure. Mandatory use of a pulse oximeter has greatly contributed to improved safety of intravenous sedation, essentially indicated for operations not lasting more than 2 and a half hours in patients in good general health (scoring 1 or 2 in the American Society of Anesthesiology (ASA) classification) and with a low risk of postoperative complications. This concept requires an adapted technical facility. The operating theatre should have all the equipment necessary for cardiovascular, neurological and respiratory emergency care. The postoperative recovery room should also be equipped with cardiovascular monitoring devices and be able to accommodate an intensive care unit. Under these strict rules, short duration surgical procedures (< 150') can be performed : 1) with the best conditions of medical safety, 2) with improved operating conditions for the implant surgeon (the patient responds immediately to vocal orders when necessary) while asepsis is maintained as easily as with general anesthesia, 3) with better conditions for postoperative care and patient comfort (the anesthetist is continuously present). 4) better psychological conditions for the patient who will be discharged the same day, 5) with total amnesia of the entire surgical procedure, 6) elimination of a usually disproportionately long hospitalization. Day hospitalization also helps contain health care costs by cutting out the need for overnight care and accommodation. We underline the safety of current intravenous sedation techniques and present two series of data related to the use of this technique by an anesthetist and an operating surgeon in a day hospital from 1986 to 1995.

[Implant rehabilitation of distal mandibular atrophy using a blade implant]. / Rehabilitation implantaire des atrophies mandibulaires distales par l'implant ramique.

After a brief revision of the anatomy of the posterior mandible and its natural resorption pattern, the ramus plate-form implant would be the implant of choice for the rehabilitation of this region. This "site specific" implant is inserted on the top of the crest and superficially impacted within the residual alveolar bone at the distal segment of the horizontal branch and guided to climb parallel to the anterior aspect of the ascending ramus. Its form and specific dimensions are perfectly compatible with the frequently limited quantity of available bone above the nerve canal in patients with advanced atrophy of the posterior mandible. It provides a predictable abutment for the implant-supported or dento-implant-supported prostheses of the posterior mandible.

Sinus grafting related to implantology. Statistical analysis of 15 years of surgical experience (1979-1994).

Sinus cavities are often a major obstacle to the placement of dental implants in the posterior maxilla, especially when early tooth loss has occurred. Several grafting procedures aimed at reducing the expanded volume of these pneumatic cavities have been routinely utilized since 1979. Essentially, these techniques have consisted of recreating the necessary viable bone volume at the floor of sinus cavities by placing different bone substitute materials to allow for the insertion of endosseous implant devices. The progress achieved in the refinement of the surgical procedures and the knowledge acquired in the field of patient screening and selection, choice of biomaterials, management of complications, etc., have made sinus graft surgery highly codified and predictable. A comprehensive statistical study by multifactorial procedures was carried out to establish a Burt Contingency Chart. This chart visualizes the frequencies of all the "modality combinations" among the selected "qualitative parameters" and, by a " factorial analysis", the "multiple correlations", so that the "statistical affinities" that may exist among the same variables can be determined. This critical study endeavors to search for and reveal the favorable clinical, biologic and scientific parameters necessary for the success of sinus graft surgery on short-, medium-, and long-term bases (more than nine years). It is a particularly homogenous study, since all the operative procedures have been carried out exclusively by the author under standardized conditions. The wide variety of biomaterials utilized by the author since 1979 shows the development of bone substitute biomaterials as they have been introduced into the market during the past 15 years. The large number of patients treated, the variety of grafting materials, the important success rate obtained, and the long duration of patient follow-up have been instrumental in enabling us to establish scientifically significant results. Autogenous bone and its combinations with calcium- and phosphorus-containing biomaterials remain undoubtedly the best all-purpose biomaterials. The synthetic biomaterials have their own specific indications according to their stable (non-resorbable) or unstable (resorbable) nature and their rates of metabolic "turnover". Differently treated bones from the tissue bank (if not contaminated or immunologically questionable) behave in a fashion not unlike autogenous bone. Root-form implants are by far the best implants in the reconstructed sinus sites, while other implant types (subperiosteal implants, etc.) inserted beneath the reinforced osseous sinus floor, buccal wall, and pyramidal process, also have their indications.

[The periosteum: the "umbilical cord" of bone. Quantification of the blood supply of cortical bone of periosteal origin]. / Le périoste: "Cordon ombilical" de l'os quantification de la vascularisation corticale osseuse d'origine périostée.

The Periosteum or periosteal membrane is a continuous composite fibroelastic covering membrane of the bone to which it is intimately linked. It consists of multipotent mesodermal cells (11, 15). Although the bone cortex is the main beneficiary of the principal anatomical and physiological functions of the periosteal membrane, the behaviour of the entire bone remains closely influenced by the periosteal activity. These principal functions are related to the cortical blood supply, osteogenesis, muscle and ligament attachments. Through its elastic and contractile nature, it participates in the maintenance of bone shape, and plays an important role in metabolic ionic exchange and physiological distribution of electro-chemical potential difference across its membranous structure. It has also been suggested that the periosteum may have its own specific proprioceptive property. This presentation will study the histo-anatomy and physiology of the periosteum and will discuss in detail its main functions of cortical blood supply and osteogenesis (fig. 1 and 2). It will also present the third intermediary report on a current study of the quantification of cortical vascularisation of femoral bone via the periosteum, using an isotonic salt solution of 85Strontium. The afferent-efferent (arterio-venous) flows of this solution in the thigh vascular system of guinea pigs were measured by gamma spectrometry after a series of selective macro and micro injections of radioactive salt into the femoral arterial system were carried out. Each vascular territory was meticulously selected and the injections were made according to size, starting with the larger vessels, with or without ligatures of neighbouring vessels, going progressively to smaller and smaller vessels not exceeding 100m in diameter.(ABSTRACT TRUNCATED AT 250 WORDS)

[A panorama of current materials for osseous application in maxillofacial surgery and oral implantology]. / Panorama des matériaux actuels pour apport osseux en chirurgie maxillo-faciale et implantologie orale.

Many materials are used in bone reconstruction. According to their physico-chemical structure, their activity is based on one of the three main mechanisms of bone repair: osteogenesis, osteoconduction, osteo-induction. The materials can be classified in two categories: tissues and substitution biomaterials. Tissues may be living ones (mainly, autograft) or non living ones (mainly, allograft or xenograft). Among the substitution biomaterials, we find synthetic materials (calcium based ceramics, vitreous ceramics and bioglasses, polymers) and composite materials made of a mixture of synthetic and natural materials or a mixture of different synthetic materials or a mixture of different synthetic materials. At last, membranes provide a new technic in bone reconstruction. They come from natural origin (human or animal) or synthetic origin (resorbable or non resorbable).

[Risks and regulations related to materials used in implantology and maxillofacial surgery]. / Risques et réglementations relatifs aux matériaux utilisés en implantologie et chirurgie maxillo-faciale.

In the present paper, the authors call in mind the definitions of biocompatibility and the essential qualities required for biomaterials. The materials mostly used in implantology and maxillofacial surgery are numerous alloys, bioceramics, resorbable and non-resorbable polymers, and finally osseous substitutes of human or animal origin. As to synthetic and non-living materials, the risks in patients are generated by the degradation products. These may induce tissular reactions of inflammatory or immune origin owing to toxic effects. Concerning osseous substitutes, rejections are mostly of immune origin, for allografts and in particular for xenografts. Infections may be another major risk and in spite of all precautionary measures viral infections by hepatitis B, HIV and transmissible spongiform encephalopathy are not yet got under total control. It is just in these domains that one can state juristic lacks which national and european organisation of standardisation and homologation have to cover during the next few years.

Anatomy and histophysiology of the periosteum: quantification of the periosteal blood supply to the adjacent bone with 85Sr and gamma spectrometry.

The periosteum or periosteal membrane is a continuous composite fibroelastic covering membrane of the bone to which it is intimately linked. Although the bone cortex is the main beneficiary of the principal anatomical and physiological functions of the periosteal membrane, the behavior of the entire bone remains closely influenced by periosteal activity. These principal functions are related to the cortical blood supply, osteogenesis, and muscle and ligament attachments. Through its elastic and contractile nature, it participates in the maintenance of bone shape, and plays an important role in metabolic ionic exchange and physiologic distribution of electro-chemical potential differences across its membranous structure. It has also been suggested that the periosteum may have its own specific proprioceptive property. This paper presents a study of the anatomy and histophysiology of the periosteum, and discusses in detail its main functions of cortical blood supply and osteogenesis. It also presents the third intermediary report on a current study of the quantification of cortical vascularization of femoral bone via the periosteum, using an isotonic salt solution containing 85 Strontium. The afferent-efferent (arterio-venous) flows of this solution in the thigh vascular system of guinea pigs were measured by gamma spectrometry after a series of selective macro- and micro-injections of radioactive salt into the femoral arterial system was carried out. Each vascular territory was meticulously selected and the injections were made according to size, starting with the larger vessels, with or without ligatures of neighboring vessels, going progressively to smaller and smaller vessels with diameters not exceeding 100 microns. The principal technical difficulty at this stage of experimentation was related to the identifying and acquiring of appropriate microcatheters. The study also includes a series of measurements after blockage of the transmuscular blood flow and the corresponding periosteal vascular system by selective ligation of the thigh muscles. The results clearly show the fundamental predominance of periosteal blood circulation to the bone cortex (70 to 80% of the arterial supply and 90 to 100% of venous return) compared with centromedullary vascularization. A quantitative formula related to the general blood circulation in the bone cortex and marrow, taking into account the two pathways, is presented. Although the application of these results (which concern a long-bone site in an animal) to the alveolar and maxillo-mandibular periosteum requires the conception of an appropriate human experimental model, the extrapolation of the findings seems plausible in the case of the mandible, where the osseous structures and the vascular network are comparable with those found in long bone. However, in the maxilla, where the general blood supply is more intense and anastomotic, the periosteal contribution may legitimately be considered less important than the centro-medullary circulation. Finally, the presentation analyzes the physio-pathology of an experimentally damaged periosteum either directly (by thermodestruction, squashing, and chemodestruction), or indirectly (by muscular pull and tear), leading to the inevitable chain reaction, i.e., "ischemia-necrosis-atrophy and partial regeneration" of the underlying bone and very frequently compromising the survival of an implant that had been placed within it. The report emphasizes the importance of impeccable soft tissue and periosteum management at the time of implant surgery and indicates a number of technical precautions that should be observed in order to avoid periosteal damage.

Fate of bioresorbable poly(lactic acid) microbeads implanted in artificial bone defects for cortical bone augmentation in dog mandible.

The fate was examined of poly(lactic acid) microbeads implanted in large artificial defects created in cortical bone of dog mandibles. Two poly(lactic acid) polymers--poly(L-lactic acid) (PLA 100) and poly(DL-lactic acid) (PLA 50)--were used to make microbeads by solvent evaporation with poly(vinyl alcohol) as surfactant. Histological observation of non-decalcified mandibular bone showed that no real bone regeneration existed in the experimental bone defects 18 months after PLA 100 microbeads implantation. The same observation was made 6 months after implantation of PLA 50 microbeads. PLA 100 and PLA 50 microbeads appeared unable to induce regeneration of cortical bone defects of dog mandible, in contrast to previous observations in man for PLA 50 large implants. The failure is tentatively assigned to the presence of poly(vinyl alcohol) at the surface of microbeads.

Maxillary sinus: anatomy, physiology, surgery, and bone grafting related to implantology--eleven years of surgical experience (1979-1990).

The sinus is a pneumatic cavity of the facial skeleton within maxillary bone. It is very closely linked to the alveolar crest, the resorption of which, especially when tooth loss occurs, could cause a serious obstacle to oral implantology. It is therefore of great importance for this obstacle to be removed by adequate surgical procedures aimed at reducing the expanded volume of this cavity either partially or totally. Several grafting techniques involving autogenous bone (either alone, mixed with a bone-substituting biomaterial, or with insertion of only a biomaterial) are now available. The biomaterials include an increasing variety of treated bone from a bone bank. This paper will endeavor to outline the basic scientific and clinical knowledge required for this important surgery and will also stress the grave dangers that lie behind complications that may result from the inadequate practice of surgery by untrained operators.