Abstract

The objective of the study is to examine used but sterilized healing abutments for contamination and to evaluate the effectiveness of treatment with sodium hypochlorite for used healing abutments. The study was conducted at three institutions, of which two were private hospitals. The third site was the King Abdulaziz University School of Dentistry. The researcher predicted that used healing abutments stayed contaminated despite sterilization with sodium hypochlorite. Indeed, the researcher established that five percent of the studied sample grew bacteria positive cultures. The microorganisms grown from the culture of sterilized used abutments include Aspergillus species (candidal growth), Streptococcus sanginis, Dermobacter hominis (small colonies) and Staphylococcus haemolyticus (Large colonies). These findings are consistent with other research carried out on the topic. For instance, Umul Cakan and Cagri Delilbasi 2015 observed that although reuse of healing abutments is cost-effective, it portends the risk of cross-infection (Cakan 2015). Umul Cakan 2015 proposed resterilization of the used healing abutments to decrease the incidence of cross-contamination further. Indeed, resterilized healing abutments elicited culture negative results. This study, therefore, generates important insights with important health care implications. Dentists should, therefore, endeavor to resterilize used healing abutments to reduce the risk of cross infection.

Introduction

The healthcare service, like other sectors in the economy, grapples with insufficient resources competing to satisfy unlimited wants. As such, the health system must adopt cost-effective strategies that increase efficiency in the value addition process. Efficiency involves apt use of resources while Effectiveness is the shaping of a product or service to satisfy the client’s specific needs (Michael P. Chernew 2012), the reuse of used healing abutments is a strategy at ensuring both efficiency and effectiveness in service delivery.

The penultimate goal of reuse is to minimize expenses while providing inexpensive quality care. This depicts the paradigm shift that has taken place in recent years – a shift from primary health to primary health care in the Alma Ata Declaration (WHO 1978). Despite this shift, inequity is still predominant; and in some cases, there has been deterioration (Tham 166). The principles of equity- justice, beneficence, and non-maleficence, are established frameworks of service provision in the health system. The reuse of HA, though benign and not ill-intentioned, portends great cross-infection risk to the client. This is a breach of the principle of justice. Moreover, continued use without adequate and proper sterilization would be breach beneficence and no maleficence as it would inevitably lead to cross-infection with grave consequences to the patient and the health system.

For this research, abutment refers to support, propping or adjoining. Healing abutments are the connecting elements made of titanium, stainless steel and gold among other materials that support dentures. Implant healing abutments (HAs) serve many purposes depending on their physical characteristics. For instance, titanium and titanium alloys allow for healing of the soft tissue. When healing is satisfactory, as confirmed by integration of the HA into the bone- osteointegration.it is removed after which a definitive abutment or the prostheses can be implanted. The implant HA can then be sterilized via many methods and reused.

Although the producers of the implant HA recommend single use of the HAs, it is common practice among dentists to either sterilize and reuse or send used HAs to the producers who then sterilize and repackage them for resale. Interestingly, sterilized titanium HAs have been associated with better adhesion of soft tissue with the attendant expedition in healing provided that a clean surface is achieved. Even so, the achievement of clean used HA surface is difficult often requiring rigorous sterilization and resterilization.

The sources of infection/contamination of HAs include the saliva, blood, food and the mucosal/epithelial surfaces. The mouth has a rich and diverse microbiome. The microorganisms that are commensals in the mouth include bacteria, fungi, protozoa, and even viruses. This microbiome contributes significantly to human disease. For instance, the cause of periodontitis and dental caries (Wade 2013). This indicates the rationale previously used for providing prophylactic antibiotic cover for clients undergoing long dental procedures who are at risk of endocarditis or prosthetic joints infection (Tong 2000). However, experts have failed to conclude the need for antibiotic prophylaxis. The researcher recommends further research on the topic to establish clear guidelines.

Prosthetics in the mouth risk colonization by the microflora in the mouth. The principal predisposing conditions to the colonization of implant HAs are contaminated surfaces enabling colonization and host susceptibility for instance due to poor oral hygiene. This paper purposes to outline the prevalence of contamination in used prosthetics at the three chosen sites and the disparities in contamination risk of HAs as determined by material and parts.

MATERIALS AND METHODS

Study Design

The Participants

This research complied with the World Medical Association Declaration of Helsinki that provides for ethical practices in experiments. Therefore, the identity of the health professionals was treated with the utmost confidentiality. Additionally, the autonomy and right to informed consent for the people involved in the study were invoked (World Medical Association 2018). Three health facilities were selected for the study randomly within the target location. The researcher sought informed consent from the hospitals by explaining the purpose of the study and the idea underlying the conception of the research. After this, the hospitals consented to the research proposal and provided the materials needed. The main inclusion criterion for the selected sample was prior use within the past four weeks. Each facility confirmed the status of the eighty-five healing abutments as having been used in the recent past. Additionally, the facilities confirmed sterilization of the used HAs using there customized routine protocols which they failed to disclose. Any unused material provided by the institutions was immediately rejected. Generally, the sterilization process applied by the facilities includes mechanical brushing/scraping with sterile clothes or brushes, soaking in ultrasonic baths containing various antiseptic solutions like alcohol for about forty minutes and steam autoclaves sterilization. The researcher accepted various HA materials from different companies like Biomet 3I, Astra,  Nobel Biocare, and Straumann; which are leading producers of HAs.

The Procedure

This research involved three experiments. To begin with, forty-five of the assigned used HAs together with unused new were stained with Phloxine B and photographs were taken. Staining was performed by isolating each HA into its plastic bag containing two milliliters of Phloxine B and placing the sealed plastic bag with its contents into an ultrasonic bath for six hundred seconds. After these ten minutes, the HAs were removed from the bags and washed in deionized water and subsequently air dried. The dry HAs were then observed in oblique light and pictures taken. The photographs zoomed in the main body and screw holes of the abutments. The researcher then scrutinized the abutments using a t31 rebel camera which took photographs. The photographs were then projected to a computer screen at times fifteen zoom. Here, the unused abutments served as controls- a representative of the baseline or normal appearance.

Secondly, twenty other abutments which remained in the sterilization bags were inspected procedurally. First, the sterilization bags were assessed for perforation. The purpose of this examination was to rule out extraneous contamination. The perforated bags and their contents were then immediately excluded. Next, the abutments were aseptically inserted into sterile test tubes holding ten milliliters of brain heart infusion broth (BHI) – a growth medium for bacteria. An additional test tube containing ten milliliters of BHI was set up to act as a control. All the tubes were then cultured for ten days at thirty-seven degrees Celsius in five percent CO_2. After this duration had elapsed, the test tubes were assessed for cultures or colonies of microorganisms by checking for turbidity. In those test tube that was found positive for turbidity, an inoculum was obtained and added to Petri dishes containing BHI and Potato Dextrose Agar (PDA). BHI Petri dishes were cultured at 37^oC in 5% carbon (IV) oxide for up to 48 hours. On the other hand, the PDA Petri dishes with the inoculum were cultured at 30⁰C for five days. This process was repeated severally to obtain a pure culture of bacterial colonies which were then stored in 20% glycerol at -80⁰C. The microorganisms that had grown were then scrutinized as follows. Bacterial colonies were subjected to Gram staining and biochemical tests, chiefly the catalase test and growth in alkaline medium (pH of 9.2) to establish the characteristics and possibly the identity of the colonies. To confirm findings, bacteria were identified using an automated identification system known as the VITEK 2 which allows for rapid identification. Moreover, the fungi were grown in PDA were subjected to multiple cultures for seven days at 30⁰C, pure cultures obtained and stored. The identification of fungus was based on morphology, reverse appearance as well as surface/front appearance/coloration. The colorations of the fungal colonies were assessed in three media- PDA, Malt extract agar and Capek’s solution.

Lastly, the researcher took twenty used abutments and resterilized them using sodium hypochlorite. This involved initial sterilization with sodium hypochlorite followed by resterilization in plastic bags containing ten milliliters sodium hypochlorite incubated in an ultrasonic bath for ten minutes. After the incubation in sodium hypochlorite and the subsequent steam autoclaving, the abutments were extracted and incubated for ten days in the Petri dishes as outlined above. When the ten days had elapsed, the cultures were assessed for turbidity, bacterial colonies, and molds. In this procedure, new and unused abutments were subjected to the same procedure to act as controls. Photographs of the main body and the screw holes of both groups of abutments were taken and scrutinized by the researcher.

RESULTS

All the eighty-five abutments were cultured to assess contamination. From the used abutments that were handed presented to the researcher by the three facilities, four gave positive results for various microorganisms including Aspergillus species (candidal growth), Streptococcus sanginis, Dermobacter hominis (small colonies) and Staphylococcus haemolyticus (Large colonies). This corresponds to a contamination rate of 4.71%. Moreover, all used healing abutments showed contaminations/debris on their main bodies and screwed holes even after sterilization from the photographs assessed.

For the resterilized abutments, all of them showed contamination debris on their main bodies and screw holes before resterilization on sodium hypochlorite. However, upon resterilization, no turbidity, bacterial or fungal colonies were obtained after incubation for ten days. Even though debri largely disappeared from the screw hole, significant debris remained in the main bodies of the abutments even after resterilization. Moreover,

DISCUSSION

This research shows that primary sterilization fails to clear microorganisms from used HAs in five percent of the cases. This is consistent with earlier research done on the topic by preceding researcher (Cakan 2015).

Additionally, it is clear from the research that resterilization. With sodium hypochlorite leads to the achievement of sterility/decontamination. Even so, sodium hypochlorite does not clear the debris of the main bodies and screw holes of the abutments. Typically, these debris consists of tightly adherent proteins and amino acids. Therefore, used HAs portend the risk of transmission of prion diseases even after resterilization with sodium hypochlorite. The recommendation by Cakan and Delilbasi for the use of HAs after resterilization is therefore not advocated in this paper (Cakan 2015).

Dermobacter hominis is a rod-shaped commensal of the human skin. It is rarely associated with human disease. The bacterium is a Gram-positive, facultative anaerobe preferring temperatures between 20⁰C to 40⁰C. It ferments glucose, is catalase positive and decarboxylates ornithine and lysine. Its isolation from used abutments is rather unusual since it is not a commensal of the mouth.

Even so, this study suffers from grave limitations like the limited sample size, non-disclosure of the initial sterilization methods and failure to identify the debris on the used healing abutments. These factors could contribute to the contamination. For example, the positive culture results could be attributable to specific sterilization methods that fail to clear decontaminate HAs. Resterilization leads to the destruction of the abutment surfaces which decreases fibroblast adhesion and thus, the efficacy of HA. Likewise, this study failed to analyze the effect of multiple/repeated sterilization on the HAS. More study into the relationship of these factors to the results above is therefore imperative if clear and concise guidelines are to be established on the safety of reusing healing abutments.

CONCLUSION

The reuse of healing abutment is not recommended since some samples were contaminated. Sodium hypochlorite resulted in decontamination of used healing abutments but no complete removal of debris as possible. As such, resterilization healing abutments do not offer foolproof protection from cross contamination via reused HAs in implant dentistry.

Bibliography

Cakan, Umut, Cagri Delilbasi, Sevda Er, Merih Kivanc. “Is it safe to reuse dental implant healing abutments sterilized and serviced by dealers of dental implant manufacturers? An in vitro sterility analysis.” Implant dentistry 24, no. 2 (2015), 2015: 174-179.

Michael P. Chernew, Joseph p. Newhouse. Handbook of Health Economics Volume 2. Edited by Thomas Maguire Mark V. Pauly. Amsterdam: Elsevier, 2012.

Tong, Darryl C., and Bruce R. Rothwell. “Antibiotic prophylaxis in dentistry: a review and practice recommendations.” The Journal of the American Dental Association 131, no. 3, 2000: 366-374.

Wade, William G. “The oral microbiome in health and disease.” Pharmacological research 69, no. 1, 2013: 137-143.

WHO. The Declaration of Alma Ata. 1978. https://www.who.int/publications/almaata_declaration_en.pdf (accessed February 21, 2019).

World Medical Association, WMA. WMA Declaration of Helsinki. July 9th, 2018. www.wma.net/policies-post/wma-declaration-of-helsinki-ethical-principles-for-medical-research-involving-human-subjects/ (accessed March 8th, 2019).