Dental implants are constantly exposed to the microbe-laden environment of the oral cavity which leads to a rapid formation and growth of biofilms on the prosthetic and connecting elements of the restoration [13]. Supported by appropriate oral hygiene measures these biofilms are held in a stable balance (homeostasis) by the patient’s immune system with the result of clinical peri-implant health.

Peri-implant mucositis and peri-implantitis represent undesired biological complications that may ultimately lead to implant loss and treatment failures¹⁴. Restorative designs, treatment regimens and maintenance protocols have to ensure that conditions can be achieved and maintained that successfully prevent such complications. Here we present 5 simple, but fundamental aspects that should be considered in your clinical practice to ensure the long-term success of full arch restorations.

1. Start at the beginning - Presurgical hygiene

Patients considered for full-arch restorations often present with a failing dentition affected by severely progressed caries and periodontitis. These clinical findings are often associated to a history of poor oral hygiene skills and habits. Implant-placement in such patients seems to be counter-intuitive as any reoccurrence of such pathogen associated conditions may represent a risk-factor to the future implant restoration. Therefore, the reestablishment of an adequate oral health status is as important as the instillation of the fundamentals and habits of good oral hygiene into patients prior to commencing any advanced implant treatment.

Along and following causative treatment of any pathogenic conditions patients may be prepared for implant therapy by thorough instructions for oral hygiene. Reevaluation visit may e.g. not only be used to assess the patient’s response to treatments but also to ensure that adequate levels of plaque control are achieved and maintained by compliance with oral hygiene routines¹⁴.

Further treatment planning should comprise a thoughtful analysis of risk factors related to e.g. the recurrence of periodontal disease or the onset of any future peri-implant disease. As a general guideline, any precondition that may interfere or alter the innate or adaptive immune responses to a bacterial challenge, like. e.g. smoking may put the oral health status and any future implant restoration at risk^{15, 16}.

The implementation of an early preoperative hygiene therapy regimen represents an integral part to our treatment approach at Campbell clinic when providing full arch restorations. We routinely provide patient individualized oral hygiene instruction and constantly evaluate patient compliance with oral hygiene principles to improve post-operative outcomes and the results of our maintenance regimes^17–19.

2. Plan carefully- consider hygiene and maintenance aspects of implant and prosthetic restorative designs

The prosthetic design is critical to any full arch reconstruction. Besides mechanical and esthetics aspects the ability to successfully allow for adequate plaque control should be considered already at the planning stage of the implant and prosthetic restorations. Full arch restorations should be planned with the aim to limit the accumulation and allow a facile removal of pathogenic bacteria. Furthermore, patient specific risk factors for peri-implantitis as well as individual skills and abilities to clean may vary from patient to patient^{20, 21}. Such patient-specific factors should be taken into consideration when planning the hygienic aspects and requirements of the individual full arch restorative design.

Depending on the available restorative space and esthetic requirements the prosthetic cervical and specifically pontic and connecting designs of the prosthetic framework can be individually and even locally adapted to meet the requirements for cleaning and maintenance²². Access for cleaning needs also to be considered when planning the spacing between implants. Inter-implant pontic sections should remain accessible for cleaning. Implant emergence and pontic profiles should be designed with hygenic, i.e. preferably ovate contours (Fig. 4). Ridge lap pontic designs should whenever possible be avoided for the design of fixed full arch restorations as they are associated with an elevated risk for food entrapment and plaque accumulation while impeding the ability to clean (Fig.3)²³. Lastly whenever possible screw retained restorations should be used, which facilitates the management of any mechanical and biological complications after prosthetic delivery.

3. Advice properly - Post-Surgical Instructions

Post-surgical instructions for adequate homecare are essential to support the healing of implant sites in full arch restorations, specifically when applying immediate loading regimens. These instructions should be related to both oral care, food intake and inform the patients on the specific conditions that may require immediate assistance.

Specifically, in the case of immediately loaded full arch restorations more careful instructions may be need. Such instructions should restrict or prevent mechanical cleaning routines that may be adequate for routine cleaning, like e.g. the use of air or water jet devices. Patients may be instructed to apply specific brushing techniques, e.g. in a vertical, apical direction to support the soft tissue adaptation to the prosthetic framework, however without compromising the provisional soft tissue fixation around the implants (Fig. 5). Chlorhexidine mouthwashes may be used to support plaque control during this period. Also depending on the specific individual indication patients may be advised to refer to soft diet only for the first weeks after surgery.

In the case of zygomatic implants, all pressured cleaning devices would be avoided due to the tenuous nature of the soft tissue connection around the implants. These patients should be advised to carry out manual and very careful cleaning only.

Patients further may need to be sensitized that a series of conditions like e.g. excessive bleeding, severe pain etc. may occur that require immediate assistance by the treating clinician.

4. Remain flexible and adapt your approach to cleaning

Adequate self-administered and professional oral hygiene routines are crucial to ensure proper plaque control and to limit the accumulation of pathogenic bacteria causing peri-implant inflammation. Such routines may comprise brushing at least twice daily, use of floss, interdental cleaners, and water irrigators and/or a combination of these measures.

It is essential that clinicians, both dentists and hygienists, are flexible in their approach to full arch maintenance, which may require to establish a patient-specific program of home and professional care. Besides considering patient-specific conditions, like e.g. age, frailty and comorbidities when designing the restoration clinicians and patients may need to individualize cleaning routines to the requirements and capabilities of the corresponding patient. Some patients will e.g. be able to use bridge floss, while elderly or frail patients may only be able to use interdental brushes or powered cleaning devices. Following strict dogmatic and rigid approaches to cleaning may unsettle, discourage and ultimately disenfranchise patients with less dexterity. Hence, clinicians need to individualize instructions and assist patients in applying appropriate routines to ensure successful maintenance of their full arch restorations.

Lastly the setup and implementation of patient-specific and individualized approaches to oral care may be facilitated by a seamless communication between clinicians, i.e. dentists and hygienists that should include both technical details related to the specific type of restoration as well as to the details of in office and home care protocols.

Courtesy Dr Alessandro Perucci, Switzerland

5. Make it a routine- Set out a strict hygiene schedule

The maintenance of peri-implant soft tissue health is of utmost importance to ensure long-term success of full arch rehabilitations. Well-designed supportive implant therapy programs with periodic in-office recall visits represent an integral part of full arch implant therapy¹⁸. The primary aim of these recalls is to prevent the onset of biological complications, i.e. peri-implant mucositis and peri-implantitis. This is achieved by thorough examination of implant health related parameters and mechanical fit, by applying professional cleaning and by reconfirming and reinforcing home care routines²⁴. Professional cleaning routines represent important elements to ensure the complete removal of any residual supra- and subgingival microbial deposits. The use of instruments, tools or agents that may scratch and roughen the implant or abutments surfaces should be prevented as this may increase the tendency for plaque accumulation as potential source of inflammation²⁵. A recently introduced chitosan brush (Labrida BioCleanTM) represents an attractive candidate that enables the soft and gentle cleaning of the implant surface without showing the typical risks for pro-inflammatory plastic remnants associate to e.g. plastic curettes^{26, 27.}

A regular assessment of the diagnostic parameters can help to identify any biological complications early. Diagnostic parameters may comprise visual analysis for any signs of redness, swelling as well as changes in probing depth, bleeding on probing and suppuration. Depending on the individual design of the prosthetic restoration probing under fixed full arch restorations might be difficult. Nevertheless, the aim should be to identify at least one surface per implant where probing can be performed²⁸.

We routinely start with an in-office implant maintenance interval of 3 months which may be individually adapted and can be shortened or even prolonged based on the patient’s oral hygiene status, compliance with regular home care routines and which can be tailored to the patient’s risk profile. The latter can be usually assessed by evaluating e.g. any history of smoking, periodontitis, systemic conditions as well as the patient’s capabilities and dexterity to clean. Such profiles may change in time and it is advised to regularly update corresponding evaluations and to confirm or readapt intervals and regimens over the course of time. It is important to generate awareness for and to openly communicate the importance of supportive implant therapy programs and the associated time and financial efforts associated to it at the very beginning of implant therapy. Patients may need to be prepared for and willing to commit to supportive therapy for the lifetime of the restoration. Additionally, the standard of care comprises to take radiographs every 1 to 2 years and to compare them to baseline radiographs in order to exclude any changes of the peri-implant bone and to reconfirm firm and adequate passive fit of the prosthetic superstructure to the implant base and connecting parts.

Finally, in our practice, we use to remove the prosthesis every 2 years or otherwise in case of any mechanical or biological complication that may not be solved without removal. This allows for a thorough assessment and direct cleaning of the abutments and implants. Abutment and implant screws are checked and may be exchanged or retightened only if necessary. The prosthesis can be cleaned in antiseptic solution in an ultrasonic bath to remove the biofilm, the screws should be exchanged. It is important to note that this is the protocol in our clinic and other opinions (such as the AAP) suggest leaving the bridge in place unless there is a complication. It is up to the individual clinician to make their own judgement and it is clear that further research is required to form a solid consensus.

Conclusions

Full arch restorations represent a successful treatment modality for the rehabilitation of edentulous patients. Maintenance and implant supportive therapy represents an integral part of implant therapy that is indispensable to ensure the long-term success of such restorations. Aspects for maintenance need to be individually assessed and patient-specifically adapted and considered during the design of the restoration, in the instructions for home care routines and in in-office recall regimens.