Tooth extraction is the most common oral surgical procedure performed by dentists. It may require temporary discontinuation of anticoagulants to reduce the risk of bleeding. However, discontinuing anticoagulants can increase the potential risk of life-threatening thromboembolism. There is conflicting advice regarding whether direct oral anticoagulants (DOACs) should be discontinued during and after tooth extractions. Nevertheless, it is standard practice to perform tooth extractions while patients are still taking warfarin.

This thesis evaluates whether it is necessary to discontinue DOACs during and after tooth extractions. It includes a prospective clinical cohort study and a systematic review with meta-analysis, both of which assess the risk of bleeding in patients who continue to use DOACs during and after simple and surgical tooth extractions. Additionally, the thesis incorporates a laboratory study that evaluates a method for measuring blood loss during oral surgery, as well as a population-based cohort study assessing the general risk of bleeding and thrombosis for patients using various antithrombotic medications.

The main finding of the thesis is that the risk of bleeding after both simple and surgical tooth extractions seems to be lower for patients receiving uninterrupted DOACs, compared to those receiving vitamin K antagonists such as warfarin. Therefore, patients may safely continue DOAC use during and after simple and surgical extractions. This eliminates the potentially higher risk of serious thromboembolic events that are associated with a pause in anticoagulant therapy. To minimise the risk of bleeding that requires treatment, it is essential to apply effective local haemostatic measures and provide patients with clear post-operative instructions.

Tandborttagning är den vanligaste kirurgiska behandlingen som tandläkare gör. I samband med tandborttagning kan blodförtunnande mediciner behöva pausas för att minska risken för blödning. Problemet är att ett uppehåll i medicineringen kan öka risken för blodproppar – något som kan leda till livshotande tillstånd som stroke. Därför är det viktigt att undvika onödiga pauser.

Den här avhandlingen fokuserar på en grupp av blodförtunnande mediciner som kallas direkta orala antikoagulantia (DOAK). Den mest använda av dessa är Eliquis®. När patienter som tar DOAK behöver ta bort en tand finns det olika riktlinjer för om medicinen ska pausas eller inte – och råden skiljer sig åt. Detta är intressant eftersom man sedan länge har tagit bort tänder på patienter som använder den äldre medicinen Waran® utan att göra uppehåll i behandlingen.

Risken för blödning vid tandborttagning hos personer som tar DOAK utan uppehåll undersöktes på två sätt: genom att sammanställa tidigare forskning och genom att ta bort tänder hos patienter som tog DOAK eller Waran® utan paus. En annan del av arbetet gjordes i ett laboratorium. Där testades viktiga delar av en metod som går ut på att mäta blodförlust i samband med att tänder tas bort. Dessutom användes information från flera olika register för att undersöka risken för blödning och blodproppar i allmänhet hos de som tar olika blodförtunnande mediciner.

Det viktigaste fyndet är att det verkar vara lägre risk för blödning efter tandborttagning hos de som tar DOAK utan uppehåll jämfört med de som tar Waran®. Detta gäller oavsett om en eller flera tänder tas bort och oavsett om det sker genom utdragning eller operation. De blödningar som kan uppstå hos de som tar DOAK är oftast små och kan hanteras hemma – om patienten fått tydliga instruktioner. Det är också viktigt att tandläkaren syr och använder blodstillande medel för att ytterligare minska risken för blödning.

Sammanfattningsvis kan patienter fortsätta ta DOAK utan uppehåll vid tandborttagning. På så sätt undviker man ökad risk för blodproppar, och blödningarna som kan uppstå är oftast små och lätta att hantera.

BACKGROUND: No consistent approach to the management of direct oral anticoagulants (DOACs) during and after oral surgery has been established. Thus, DOACs may be unnecessarily discontinued, raising the potential risk of life-threatening thromboembolism. To address the inconsistency in this approach, our study assessed the risk of bleeding and other complications in patients who continue to use DOACs during and after simple and surgical tooth extractions.

METHODS: Between May 2016 and December 2023, this prospective study recruited patients aged 18 years or older who were receiving a DOAC or warfarin and were in need of simple or surgical extractions of one or more teeth. Local haemostatic agents were being used to control bleeding. Patients were instructed to manage minor postoperative bleeding at home by biting down on gauze soaked in tranexamic acid for at least 30 min. After surgery, all patients were followed for 7 days. The chi-squared test compared dichotomous variables; the two-sample t-test, continuous variables; logistic regressions, dichotomous outcomes; and linear regressions, continuous outcomes.

RESULTS: In all, 354 teeth were extracted from 160 patients receiving DOACs and 56 patients receiving warfarin. The incidence of any type of postoperative bleeding was 27% in patients receiving DOACs and 37% in those receiving warfarin (OR 0.66, 95% CI: 0.28-1.57; p = 0.35). Most patients were able to manage any bleeding at home themselves. Clinically relevant bleeding necessitating prompt evaluation or a secondary surgical intervention by a dentist or healthcare professional occurred in 3% of patients receiving DOACs and 11% of patients receiving warfarin (OR 0.30, 95% CI: 0.08-1.06; p = 0.06). No reports of major bleeding requiring hospitalization or blood transfusion were found. Perioperative bleeding volume was comparable between the two groups.

CONCLUSIONS: Patients receiving DOACs without interruption during surgery may have a lower risk of bleeding than those on warfarin. Patients may safely continue to use DOACs during and after simple and surgical extractions. This eliminates the potentially higher risk of serious thromboembolic events that are associated with a pause in anticoagulant therapy.

CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov (ID: NCT04662515). Retrospectively registered 4 December 2020.

OBJECTIVE: The recommendations for the management of direct oral anticoagulants (DOACs) in oral surgery are inconsistent. The present review evaluated whether DOACs increase the risk of bleeding during oral surgery and postoperative complications.

STUDY DESIGN: The patients undergoing oral surgery and receiving a DOAC were compared with the patients receiving a DOAC different from the exposure, a vitamin K antagonist (VKA), or no anticoagulant. Three electronic databases were searched for eligible clinical trials and systematic reviews. The risk of bias was assessed, data were extracted, a meta-analysis was done, and the Grading of Recommendations, Assessment, Development and Evaluations certainty-of-evidence ratings were determined.

RESULTS: Three clinical trials comparing patients receiving DOAC medication with patients on a VKA were eligible. A meta-analysis of bleeding 7 days postoperatively detected no significant differences between patients continuing DOAC or VKA medication during and after surgery. All of the point estimates favored uninterrupted DOAC over VKA therapy. Tranexamic acid was topically administered to some patients.

CONCLUSIONS: Based on an interpreted trend among 3 studies with mixed patient populations, the risk of bleeding during the first 7 postoperative days may be lower for patients on uninterrupted DOAC than VKA therapy (⨁⨁⭘⭘), but the effect size of the risk is unclear. 80 of 274 included patients experienced postoperative bleeding.

Objectives: Estimating blood loss is an important factor in several surgical procedures. The accuracy of blood loss measurements in situations where blood is mixed with saliva and saline is however uncertain. The purpose of this laboratory study was to ascertain if blood loss measurements in mixtures of blood, saline, and saliva are reliable and could be applicable in a clinical setting.

Material and Methods: Venous blood and resting saliva were collected from six volunteers. Saliva, saline, and combinations thereof were mixed with blood to obtain different concentrations. A portable spectrophotometer was first used to measure the haemoglobin concentration in undiluted venous blood followed by measurements of the haemoglobin concentration after each dilution. To examine the strength of linear relationships, linear regression and Pearson correlations were used.

Results: The measurements of haemoglobin concentrations in mixtures of blood, saline, and saliva were proven to be accurate for haemoglobin measurements > 0.3 g/dl (correlation = 0.986 to 1). For haemoglobin measurements < 0.3 g/dl, a small increase in haemoglobin values were reported, which was directly associated to the saliva concentration in the solution (correlation = 0.983 to 1). This interference of saliva was significantly eliminated by diluting the samples with saline, mimicking the clinical situation.

Conclusions: The results suggest that a portable spectrophotometer can be used clinically to preoperatively measure the haemoglobin value of a venous blood sample and postoperatively measure the haemoglobin value of the collected liquids, including shed blood, thereby achieving a highly accurate method of measuring blood loss during oral and maxillofacial surgery.

Our aim was to investigate the possible impact of contamination with saliva on osseointegration during placement of implants with simultaneous bone augmentation. Six hemispheric shape bone defects (8mm in diameter×4mm deep) were prepared in each iliac bone of six sheep. A dental implant (2.9mm in diameter×10mm long) was placed in the centre of each defect, and then pairs of defects were filled with one of the following bone augmentation materials: autogenous bone, autogenous bone plus bovine bone, or resorbable biphasic ceramic bone substitute. One site in each augmentation group was impregnated with saliva (contaminated group), while the other was not (non-contaminated group). Bone-to-implant contact (BIC) and bone area fraction occupancy (BAFO) within implant threads were measured after a healing period of five weeks, both in respect of the implant inserted in the augmented bone and in that inserted in the residual bone. Overall results showed that there was a significant difference between the contaminated and non-contaminated group for BIC in the augmented implant (p=0.028), while there were no significant differences in the implant in residual bone (p=0.722). For BAFO, there were no significant differences between the contaminated and non-contaminated groups among the different augmentation materials. The results showed that contamination with saliva during placement of an implant with simultaneous bone augmentation had a serious deleterious effect on osseointegration of the aspect of the implant within the augmented defect. Contamination with saliva during placement of an implant with simultaneous bone augmentation should therefore be avoided.

Our aim was to try and find out whether contamination with saliva during insertion of dental implants affects osseointegration in bone that has been augmented with different grafts. Six bony defects were created in each of the calvaria of six sheep, and then augmented with three different materials (autogenous bone, bovine bone, and resorbable biphasic ceramic bone substitute) After five weeks of healing, three implants contaminated with saliva (contaminated group) and three not contaminated (uncontaminated group) were placed in the centre of the augmented areas. For histomorphometric analysis, bone implant contact, bone area fraction occupancy, bone and material area, and bony area were measured after a healing period of five weeks. There was a significant difference between the contaminated and uncontaminated groups (p=0.036) for bone implant contact only in the augmented areas, but there were no significant differences in bone area fraction occupancy, bone and material area, and bony area. We conclude that contamination with saliva during placement of dental implants can significantly compromise bone implant contact in augmented areas, but had no significant effect on the formation of bone in areas more distant from the surface of the implant. We suggest that salivary contamination should be avoided during placement of dental implants in augmented areas.

INTRODUCTION: Contamination during surgery negatively influences the prognosis of orthopaedic implants; however, it has not been proven whether contamination influences the success of dental implant treatment. The aim of the systematic review was to investigate if there exists evidence in the literature whether contamination of dental implants during surgery affects osseointegration and clinical success. MATERIALS AND METHODS: Four data bases were used for the literature search. Primary studies and reviews regarding both clinical and preclinical research were eligible. Rating of the summarized quality of the evidence was performed. RESULTS: Five preclinical studies were included. Because of the estimated high risk of bias in all included studies and extensive differences in study design between the included studies, meta-analysis was not performed and no reliable aggregated data could be extracted. CONCLUSIONS: It is suggested that the scientific evidence with regard to the current topic is insufficient. Further controlled studies are warranted.