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Issue: 04/2017
Patients with general Medical risk factors

Assessing risk factors in implantology

Prof. Dr. Dr. Bilal Al-Nawas

Why read this contribution?

To enable you to reliably assess risk factors for implant healing and the patient’s general condition.

Summary: Whereas a few years ago contraindications were mentioned in the case of general diseases, this term has narrowed down to risk assessment. The aim is to compare the possible benefit of additional quality of life with possible risks. A greater significance is assigned to complications of the underlying disease than the loss of the implant which was often examined in the study. Adequate planning and information of the patient regarding specific risks and alternative therapies are essential. A special role is thus assigned to directly identifying the patient’s past medical history and a joint decision-making process.

Keywords: Implant loss; general disease; patient’s past medical history; Diabetes mellitus; osteoporosis; bisphosphonate; vitamin D; infection; coagulation dysfunction


Quotation: Al-Nawas B: Patienten mit
Allgemeinerkrankungen. Z Zahnärztl Implantol 2017; 33: 284?290. DOI 10.3238/ZZI.2017.0284?0290 [Patients with general diseases]


The demographic change is one of the key challenges of our profession, as our day-to-day work practice reflects. With an increasing age of the patient, the risk factors also rise, as expected, whereby in „large-scale surgery“ age itself plays an independent risk factor for perioperative mortality [27]. In implantology, age does not only involve a poorer implant prognosis [20], nevertheless our attention should not only focus on the implant forecast, but also on possible consequences for the patient’s general condition [1]. For example, bleeding complications triggered by an implantological intervention can pose a vital threat to the compromised patient. The patient under bisphosphonate medication views the possible development of a bone necrosis as more relevant than the issue of the implant forecast. In particular in the case of patients with underlying general diseases it is therefore essential to balance general risks vis-à-vis the benefit of additional quality of life as a central aspect of medical care. The question whether implants will heal in the case of a certain general disease is important, but in consideration of the underlying general disease by no way a central issue.

The patient’s general past medical history plays a fundamental role in day-to-day practice. The term „patient’s past medical history“ is often misleadingly understood as completing a structured questionnaire. It is easily underestimated that the patient’s past medical history stands for an interview which in many cases reveal valuable information by “listening, observing and inquiring”. The structured questionnaire cannot be more than the basis for such an interview. It should also be viewed critically that really validated questionnaires are lacking in dentistry [8]. The questionnaire alone is not at all deemed to suffice in dental surgery. In particular in the surgical-implantological environment an active investigation of the physical stress load and coagulation-modifying medication is urgently recommended. In older studies additional relevant risk factors were identified amongst about 12% of the patients in a dental surgery [7]. Allergies, high blood pressure, Diabetes mellitus, cardiac disorders and thyroid diseases ranked at the top of the list.

The questionnaire thus represents an appropriate basis for the interview on the patient’s past medical history; however, it may not replace this interview.

Important findings are often revealed by directly asking the patient about specific prescription medication used.

When treating patients suffering from general diseases, possible life-threatening complications of the underlying disease often play a more significant role than the implant prognosis.

Implant prognosis

When observing the possible problems within the scope of implant-supported rehabilitation, it is necessary to initially discuss osseointegration and soft-tissue healing. All diseases and medication which may influence not only soft-tissue and bone healing, but also the immunological reaction are of significance. It seems that modern implant systems are able to reliably heal, thus making high success rates possible even in the case of risk patients. These success rates are, however, often based on a particularly gentle procedure.

The second aspect to be observed is the long-term prognosis. This might be worse as a result of the underlying disease itself, e.g. in the case of an immune defence disorder. In addition, it is often noticed that only a reduced awareness is ascribed to the significance of oral hygiene in the case of the patients faced with a burdening serious general disease. With regard to implantological care these aspects should be essentially included in the planning procedure.

An adequate risk analysis is therefore fundamental and must be essentially included in informing the patient and obtaining the patient’s consent to treatment. Under these prerequisites the implant-supported rehabilitation with restricted prognosis can also represent a significant gain in additional quality of life. In the event of a false indication, however, complications in connection with the implantological intervention can have a life-threatening character.

Underlying disease and medication should be evaluated with regard to their influence on immune defence, soft tissue and bone healing properties.

Patients with serious general diseases often reflect deficits in oral hygiene.

The possible additional benefit in terms of quality of life has to be seen in comparison to the risk of complications.

It is necessary to inform the patient of this assessment of risks; this will result in the patient’s participation in making the final decision.

Diabetes mellitus

Diabetes mellitus is one of the most frequent „widespread diseases“ and was even initially deemed to be a contraindication for endosseous implants. This has surely relativised considerably over the past years. In particular patients suffering from Diabetes mellitus frequently complain of the loss of teeth and the reciprocal effect on parodontitis is also well documented. In an implantological respect acute blood sugar imbalance as emergency case has to be seen as a distinction from perioperative changes and the consequences for the implant prognosis. Appointments for treatment of insulin-dependent patients with Diabetes mellitus are often scheduled in the morning hours with the request to take the normal meals in the morning. That allows the surgical intervention to be planned in the majority of cases in a well controllable period with regard to the patient’s blood sugar level.

The consequence for bone metabolism is more difficult to assess. A distinction has to be made between the disturbed osseointegration and the possibly more critical long-term outcome. In a systematic review of great interest which supplied the basis for the DGI S3-Clinical Practice Guidelines, the authors were given the opportunity to present the latest scientific data [18]. In implantology the HbA1c value has established itself as an objective parameter as to how well the blood sugar is controlled. A parameter value > 10 % is considered to be „poorly controlled“. A significantly reduced osseointegration was manifested in this group. After one year the implant stability amongst all patients was similar irrespective of the blood sugar parameter readings. The question as to whether peri-implant inflammations are to be expected in the long term among patients with poorly controlled Diabetes mellitus is discussed with a heterogeneous approach in literature and thus seems to play a rather subordinate role. A consensus is deemed to be equally unlikely with regard to implant survival as discussions have revealed. In the majority of long-term studies patients suffering from Diabetes mellitus did not reflect a higher implant loss rate in the long-term overview. Whether the duration of diabetes plays a role in terms of the implant prognosis is also controversial. It is noticeable that with regard to the issue of augmentation in the case of Diabetes mellitus there are hardly any solid data. Clinically seen no peculiarities arise for the circumscribed augmentation (sinus lift, GBR), whereas cases of extensive augmentation in patients with Diabetes mellitus are poorly documented in scientific papers. The favourable effect of a peri-operative antibody prophylaxis in the case of patients suffering from Diabetes mellitus is relatively uniquely documented.

On this basis the authors of the S3-Clinical Practice Guidelines draw the following conclusions [31]:

„Dental rehabilitation with tooth implants in the case of patients suffering from Diabetes mellitus represents a reliable and predictable procedure.“

„Prior to commencing treatment the treating dentist should request information on the patient’s medication doses. Patients with poorly controlled Diabetes mellitus seem to document a delayed osseointegration after the implantation.“

„Based on a delayed osseointegration the indication for an immediate and early loading should be critically reviewed.“

„As patients with Diabetes mellitus have a higher risk for peri-implantitis, a risk-adapted follow-up care after inserting the implants should take place.“

„There is evidence that an adjuvant therapy with the prophylactic administration of an antibiotic and the application of a chlorhexidine mouth rinse improves the successful outcome of treatment.“

Bone metabolism –
osteoporosis, vitamin D

The bone metabolism is of central significance in connection with the implant healing period. An impaired bone metabolism is – at least theoretically – regularly seen in connection with implant losses. The vitamin D level has been discussed in detail in the past as an alimentary variable and possible influencing factor in the implant healing period. This issue is currently being examined in two essays. The influence of the vitamin D level was surprisingly low on the premature implant loss in a study conducted with over 800 patients; a decent observation of more early losses but statistically significant differences was not noticed [14]:

9 (2.2 %) with serum levels of vitamin D > 30 ng/mL

16 (3.9 %) in patients with 10–30 g/mL

2 (9.0 %) at < 10 ng/mL

The data for augmentations in which no significant influence of the vitamin D level was shown reflect a similar limited significance [23]. The practical effect of a modified vitamin D level or even the intervention by substitution seem to play a rather subordinate role in the case of osseointegration. Nevertheless, it should be taken into consideration that the possible influence of the vitamin D level on bone healing still remains unacknowledged.

At present there is no clinical indication of examining the vitamin D level as a matter of routine prior to an implantation.

Osteoporosis or osteopenia as an imbalance between bone regeneration and bone deterioration typically affects women in the post-menopausal age. The bone mineral density (BMD) is typically examined in a radiographic investigation. As the bone density declines with an increasing age and is in the case of women lower than men, as a gender-related issue, the diagnosis of a deficit is recorded depending on the age and sex in relation to the standard distribution. Depending on the level, osteopenia or osteoprosis is diagnosed.

From an implantological viewpoint, in particular with implants in the lateral maxilla, the specialists face the problematic situation of an extremely „soft“ bone which with regard to the feeling in drilling is often compared with polystyrene. In many cases this requires under-dimensioned treatment and possibly prolongs the time required for healing. If these special aspects are taken into account, it seems that an implant treatment is also possible even if osteoporosis has been diagnosed. A current cohort study on implant treatment in the case of elderly women thus accordingly does not show any influence of osteoporosis on the implant prognosis [25]. Neither is any different with regard to the development of the long-term bone level shown [29]. Systematic reviews in this context also document the reliability of an implantological treatment in the case of patients with osteoporosis [6, 12].

Osteoporosis typically affects women after the menopause; however, the long-term administration of certain medication, such as antidepressants are linked to a reduced bone density [21]. However, there is no link between a premature implant loss and the administration of antidepressants, so that with regard to day-to-day practice no consequences result therefrom.

The fact that the majority of patients with osteoporosis take antiresorptive medication, e.g. bisphosphonates or Denosumab. These substances reduce the remodelling activity of the bone and can also be responsible for necroses in the case of patients with osteoporosis. In particular in implantology the interrelation between implant survival and the administration of bisphosphonates has been exclusively examined. The first case reports of implant-associated bisphosphonate necrosis are now found. In a case collection from Korea covering 6 patients there were also 2 patients who had taken an oral bisphosphonate after osteoporosis had been diagnosed. These patients in actual fact ranked amount the low-risk group [24]. Within the scope of establishing the patient’s past medical history and for the purpose of a direct risk evaluation it is urgently necessary to raise this question directly. In this context reference should be drawn to the DGI checklist. An extensive paper on this issue can be found at another position [9, 30].

In the case of suspected osteoporosis the patient should be asked if antiresorptives have been/are currently administered and the protocol with regard to the risk of necrosis should then be adapted.

In the case of osteoporosis a reduced „bone quality“ and thus a reduced primary stability should be taken into account. If applicable the drilling protocol should be adapted, as necessary.

The reduced primary stability in general requires longer healing periods and therefore speaks rather against concepts of immediate loading.

Antidepressants most probably do not represent any constraint in connection with implant healing.

Rheumatic und ?auto-immune diseases

Rheumatic diseases paint such a heterogeneous picture that it is indeed impossible to give a simplifying summary. Patients frequently suffer from chronic polyarthritis, but often more seldom diseases, such as scleroderma or sarcoidosis and thus do call for the surgeon’s attention. In the long term such diseases are often treated with cortisol, chemotherapy and in the more recent past complex immune therapies are the treatment of choice. In particular in the case of the latter consequences for bone and soft-tissue healing cannot be foreseen at this point in time. At least in the long-term increased bone resorption should be taken into account [13]. In the established medical documentation a long-term treatment with cortisol is described as critical with regard to bone healing. In a clinical and preclinical respect, however, no evidence is found in that respect.

„Harmless“ non-steroidal anti-rheumatic medication (e.g. Diclofenac) is frequently administered. A much-discussed study had revealed a considerably higher number of implant losses among patients who were not on non-steroidal antiphlogistic medication; in this case in particular more so-called Cluster Failures were identified, in other words, frequent implant losses in only few patients [32]. Another study group found analog data for these drugs [33]; in addition thereto proton pump blockers are identified as critical.

In the case of rheumatic diseases and auto-immune diseases the treating specialist should be consulted in most cases due to their complexity, disease history and therapy.

The question of the negative influence of non-steroidal anti-rheumatic drugs (e.g. Ibuprofen, Voltaren) on implant healing essentially requires further attention. An absolute clinical warning cannot (as yet) be expressed on the basis of two retrospective studies.

Organ transplantation and other immune suppression

Patients after organ transplantations, depending on the organ in concern, have a life-long high-grade suppressed immune system. Nevertheless some successful case reports have described a successfully performed implantological rehabilitation [10, 11, 17]. This assessment goes hand in hand with the data of a case control study which reflects that the biological parameters as well as microflora and bone deterioration of implants in organ-transplanted patients do not differ from those of healthy patients [15, 16].

Also in the case of other immune-suppressive treated diseases (e.g. Epidermolysis bullosa) cases of successful implantological restoration have been described [3]. The long-term disease history, however, reflects that in the case of a reactivation of the disease increased peri-implant problems should be taken into account.

In the case of organ-transplanted patients the degree of immune suppression has to be taken into consideration; it is recommended to consult the treating specialist.

The patient under immune suppression should be informed of the possibly more critical long-term forecast. In this case a particularly strict diagnosis is required.

Cardiovascular ?diseases

In the case of patients suffering from cardiovascular diseases the question primarily arises as to what extent patients can tolerate surgery under local anaesthetics. In particular after a fresh heart attack (< 6 months) not only an elective intervention is prohibited, but also in the case of loss of resilience in the recent past, special care should be applied. The large majority of patients with cardiovascular diseases, and in particular patients after a stent implantation, regularly receive oral anticoagulation or thrombocyte aggregation inhibitors. This means that the possible scope of operative intervention in the case of patients suffering from cardiovascular diseases may be frequently limited, and these patients may in particular benefit from dimension-reduced implants.

Limitations with regard to osseointegration are not described if cardiovascular diseases exist [12]. However, a study group also presented critical data or peri-implant bone stability in patients with cardiovscular or rheumatological diseases [13].

Osseointegration and long-term disease history are in most cases not disturbed in the case of cardiovascular diseases.

The patient’s individual resilience should be discussed preoperatively.

Oral anticoagulants and thrombocyte aggregation inhibitors are frequently applied and require appropriate precautionary measures in the case of surgery.

Coagulation disorder

Severe intraoperative bleeding fortunately occurs seldom in implantology. The main reason in the case of non-anticoagulated patients are a perforation of implants in the mandible front in lingual direction or the wrong implant angulation [4, 26]. In case reports life-threatening situations are described by supra-hyoidal bleeding [22].

Important is above all the correct assessment of the risk of bleeding in the case of patients with oral anticoagulation. Fortunately the first large case series are available which reflect that under appropriate measures it is possible to offer the patients out-patient care [5]. The authors indicate that the measure with the lowest risk of bleeding should be selected. S3-Clinical Practice Guidelines of AWMF in connection with this issue are currently being adopted

In particular bleeding in the floor of the mouth can represent a life-threatening situation for the patient.

Patients with oral anticoagulation therapy or thrombocyte aggregation inhibitors require a special investigation of the surgical measures required.

Under this prerequisite treatment as an outpatient is often possible.

Infections (Hepatitis, HIV)

Viral infectious diseases, such as Hepatitis B and C, or also HIV, can be treated with a modern approach and persons who have already contracted such a disease require an adequate rehabilitation with full chewing function. In the case of infectious diseases it is recommended to closely monitor the current viral load which the patient is in the majority of cases well able to assess in order to keep the risk of infection for the treating team under control. With an adequate therapy this is often no longer measurable and has thus reached a non-critical situation.

A disturbed osseointegration is neither described for hepatitis nor for HIV. Hepatitis, however, seems to be principally associated with a higher loss of teeth and peri-implant problems [19, 34]. To what extent the underlying disease itself or effects as a result of a reduced awareness of oral hygiene are responsible for such a development, remains unclear.

In several current reviews the same literature on HIV-infected patients is repeatedly published. The total number of case series lead to the conclusion that HIV-infected patients who are treated with anti-retroviral therapy (HAART) might by candidates for an implant rehabilitation as long as the HIV-viral load and CD4+-T-lymphocytes are suggestive of an immune stability [2, 28]. It is necessary, however, to observe that the substances used frequently cause a secondary osteoporosis.

With a low viral load and good infectiological medication doses patients with HIV or Hepatitis infection can be well rehabilitated in an implantological respect.


Whereas a few years ago contraindications were stated if general diseases existed, this term has yielded to a risk assessment. The aim is to compare the possible additional benefit in terms of quality of life with possible complications. A higher significance is surely attributed to the complications of the underlying disease than the loss of implants examined in the typical studies. In particular if a moderate underlying disease is given, the use of dimension-reduced implants and other minimal invasive treatment forms can be advantageous as against extensive augmentative measures. Adequate planning and information of the patient with regard to specific risks and therapy alternatives are essential.?

Conflicting interests: The author Prof. Dr. Dr. Bilal Al-Nawas states that there are no conflicting interests in connection with this contribution.


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Fig. 1–14: B. Al-Nawas

Photo: B. Al-Nawas


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Issue: 03/2017 - Max Seidemann - Rainer Haak - Constanze Olms
A pilot study for evaluating interfaces by OCT: loading of a Resin Nano Ceramic on one-piece ZrO2 implants

Introduction: The prosthetic treatment of one-piece ZrO2 implants is a challenge because of the scarce long-term data available. In order to achieve a physiological rehabilitation on rigid, one-piece implant systems, a certain resilience is desired according to the natural tooth. The best way to achieve this, is with the restoration and asuitable bonding procedure to secure a stable and durable bond. The aim of this study was to visualize changes at interfaces before and after dynamic loading of adhesively bonded Resin Nano Ceramic (RNC) crowns on one-piece ZrO2 implants by optical coherence tomography (OCT).

Material and Method: A total of 20 one-piece ZrO2 trialimplants were produced and 20crowns from LAVA Ultimate (LU, 3M ESPE, Seefeld, Germany) were made using CAD/CAM procedures. After tribochemical pretreatment (SB) of all crowns, as well as half of the implant abutments (CoJet, 30?m, 2bar), the crowns were bonded to the implants with Scotchbond Universal (SU) and RelyX Ultimate (RU) according to the manufacturer’s instructions. Subsequently, OCT images (Telesto II, Thorlabs GmbH) ofthe attached crowns were recorded before and after chewing simulation (CS, 1.2million cycles with 50N at 5–55 °C for 60sec each, SD Mechatronik GmbH). The changes in the signal lines visible in the OCT-B scans wereassessed visually as “indistinct”, “equal” or “more pronounced”.

Results: An evaluation of the visible changes to the signal lines in the OCT-B scan was performed according to a visual classification into “indistinct”, “equal” or “more pronounced”. For all samples in the OCT-B scan a signal was visible along the SU+RU/ZrO2 interface not only before, but also after the CS. This signal was “more pronounced” for non-SB before CS than for samples that received pretreatment (SB). The signal intensity on the SU+RU/ZrO2 interface did not increase after CS for non-SB, whereas in SB samples it was “more pronounced”. In the occlusal B-scans, a second signal line was visible only in non-SB test samples after dynamic loading.

Conclusion: The pilot study shows that non-invasive imaging of changes in RNC interfaces by OCT is possible and thereby additional visual information on the bond can be attained.

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