The number of patients receiving dental implants has rapidly increased since the mid‐1960’s until present. In 1970, the success of dental implants was around 50%. One of the reasons was the risk of infection [1]. Number of factors have changed since then, allowing for their 10‐year survival rate to be around 94.6%, ranging from 73.4 to 100% [2]. Approximately 70% of the implant failures occurred after placement of the abutment and the final restoration. The absence of a periodic preventive maintenance program may affect implant survival rates [2]. It is of paramount importance that patients with periodontal disease should have a stable/healthy periodontium, without flare‐ups, and very low plaque score <10%, before they begin implant treatment [3, 4]. In addition, all the restorations should have cleansable and clear margins [3, 4]. Presence of residual pocket depths ≥5 mm and BOP>30% indicates a significant factor for peri‐implantitis and subsequent implant loss [4]. The bacteria that colonize the peri‐implant tissues are similar to those found in the periodontal tissues [5–8]. Porphymonas gingivalis, prevotella intermedia, and fusobacterium nucleatum have been associated with the onset of peri‐mucositis and peri‐implantitis [5–8]. After the placement of the final restorations, the patients must take part in a strict maintenance program [5].

According to the Glossary of Periodontal terms of the American Academy of Periodontology, maintenance procedures are all the procedures performed at selected intervals to assist the patient in maintaining oral health [9]. Maintenance procedures include an update of the medical and dental histories, radiographic review, extraoral and intraoral soft tissue examination, dental examination, periodontal evaluation, removal of the bacterial flora from crevicular and pocket areas, scaling and root planing where indicated, polishing of the teeth, and a review of the patient’s plaque control efficacy [9].

Schallhorn and Snider described the four types of maintenance around teeth and implants: (i) preventive, (ii) trial, (iii) compromise, and (iv) post‐treatment [10].

• Preventive periodontal maintenance (PM): to prevent inception of peri‐implant disease in patients without pathology,
• Trial PM: to maintain borderline peri‐implant conditions, to assess over time any progression of disease, and the need for further treatment,
• Compromise PM: to slow disease progression in patients who would benefit from corrective treatment but are not surgical candidates because of health, economics, inadequate oral hygiene, or other considerations, and
• Post‐treatment PM: Designed to prevent recurrence of disease after successful corrective therapy. The post‐treatment PM is the most applied among patients [11].

The aim of maintenance around dental implants is to minimize the bacterial plaque, to limit the risk of further disease activity that causes continued peri‐implant attachment and bone loss, and to ensure the long‐term success of dental implant care. It also allows for close monitoring of the patient, so if a recurrence of peri‐implant disease takes place, an intervention can be provided [11]. Several different maintenance protocols have been suggested regarding dental implants; (i) initial placement: 6 months, 12 months and then every 2 years, (ii) initial placement: 1, 3, and 5 years if no pathology present, and (iii) initial placement: 6 and 12 months, annually if no pathology present – if pathology present, every 6 months until resolution [12, 14]. Regardless of the suggested protocols, maintenance should be tailored to the specific patient needs [11]. Due to the high volume of implants being placed worldwide, the maintenance is mainly performed by general dentists and dental hygienists [3].

Patient home care plays a very important role, and it needs to be kept simple. Multiple oral hygiene devices confuse and discourage the patients. When patients applying several toothbrushing techniques, either with manual or electric toothbrushes, miss the most lingual aspects of the implant surface, so this finding should be reinforced at the time of the oral hygiene instructions (OHI) [15]. The use of sonic toothbrush was suggested to be very effective in reduction of bacterial plaque, gingival inflammation, and BOP [16].

An interdental brush has been recommended to massage the gingival tissue around an implant to increase blood flow and enhance the tone of the surrounding gingiva (Figure 9.1). The patient should be instructed to insert the tip interdentally, parallel to the occlusion, allowing the tip to insert the marginal gingiva in a passive way and then apply a rotary motion [17]. Patients to ensure the optimal peri‐implant health should maintain daily biofilm removal (up to at least 85%) and be compliant to professional care through periodontal maintenance [18].

The establishment of baseline data before the enrollment of a patient in a maintenance program is another important factor [3]. For implant restorations, a periapical radiograph at the time of the placement of the final crown is a prerequisite, along with initial probing depth as it shows the baseline‐reference information to compare with the findings, in future maintenance appointments [3]. Especially, when the implants are placed more than 4 mm apically from the adjacent CEJ, they tend to have deeper baseline probing depths (Figure 9.2) [11].

Any bone loss ≥2 mm from the baseline bone level with associated probing depth (PD) ≥6 mm and bleeding on probing (BOP) is considered peri‐implantitis. In the absence of baseline‐reference bone level, ≥3 mm bone loss with the associated BOP and PD, are indicative of peri‐implantitis [19].

The need for keratinized tissue or attached mucosa for the maintenance of dental implants has been controversial. Chung et al. reported that, regardless of the implant surface configuration, the absence of adequate keratinized tissue or attached mucosa was associated with higher plaque scores and gingival inflammation but not with more alveolar bone loss [20]. Romanos et al. are in accordance with the previous findings, showing that absence of keratinized tissue around dental implants, was associated with significant higher plaque scores, bleeding, and recession, compared to a wide band of ≥2 mm of keratinized tissue [21].

Patients exhibiting poor plaque control, peri‐mucositis and not attending regular maintenance therapy are at higher risk of developing peri‐implantitis [22]. The incidence of peri‐implantitis was lower in subjects enrolled in a regular maintenance program (18%) compared to patients without regular maintenance care (43%) [23]. Another important factor that does not facilitate the proper oral hygiene and maintenance is the post‐restorative presence of submucosal cement, therefore screw‐retained restorations are recommended [24]. In addition, the use of angled screw channel abutments allows the design of screw‐retained restorations even in areas in the anterior zone, which require more angular correction of the final restoration, such as the lateral incisors [25].

Several etiological factors, such as developmental defects, congenital missing teeth, tooth extractions without ridge preservation, periodontal disease, odontogenic cysts, tumors, and trauma may lead to Seibert class I, II, or III defects [26, 27]. These defects require rehabilitation with the use of horizontal (HRA) and/or vertical ridge augmentation (VRA) procedures [28–30]. HRA and VRA can be achieved with the use of guided bone regeneration (GBR), the use of bone blocks, or distraction osteogenesis. GBR has become more predictable with less morbidity for the patients over the years, due to advancement of the surgical techniques and the barrier membranes, and the use of autogenous, allografts, and xenografts [31–38]. A better aesthetic outcome can be achieved with VRA due to more favorable anatomy, along with better access for oral hygiene and maintenance [30, 39]. However, it is a technique‐sensitive approach performed by trained and experienced clinicians due to the potential for severe complications [38, 39, 40].

It is of paramount importance to follow the prescribed surgical principles for buccal and lingual flap management, to predictably attain, and maintain primary closure and avoid any complications (Figures 9.3a–c and 9.4) [34, 40–46].During the lingual flap management, severe complications may occur including the risk of damaging the lingual nerve, the sublingual artery, the Wharton’s duct, the sublingual and submandibular glands, and perforation/over‐thinning of the lingual flap [42, 44, 45]. These events may result in hematoma which can be a life‐threatening complication due to possible respiratory obstruction [42, 44–49].

The rate of complications, especially for the VRA procedures, range between 2.78 and 17%, and include, but are not limited to, membrane exposure and post‐operative site infection. Sites exhibiting primary exposure gained only 65% of the anticipated bone height compared with sites without membrane exposure. Cases with late exposures, compared to early exposures (<four weeks post‐operatively), showed sufficient bone consolidation, which allowed for measurable bone regeneration [50, 51]. Defect morphology plays an additional significant role in the regenerative potential; wider and flat ridges are better candidates for VRA due to better blood supply, stability of the grafting materials and the numerous growth factors acting as chemoattractant and powerful modifiers of the healing process [30, 52–55]. Finally, proper case selection and execution of the treatment plan, strict post‐operative protocol, and appropriate implant loading can ensure the success of ridge augmentation procedures [50, 56].

However, due to the aforementioned parameters, in several cases, it is preferred the option of short implants, placement of implants where the alveolar bone allows, placement of implants in adjacent sites, or the use of pink ceramic to mimic the normal soft tissue anatomy [56]. Restorative therapies employing short implants (<7 mm) are well documented in the literature. Reduced costs and treatment times, fewer surgical complications with similar treatment outcomes as longer implants, provide justification as alternative treatments to ridge augmentation procedures [57–59]. Although short implants do not demonstrate more crestal bone loss per se, compared to standard length implants, by default there is a lower percentage of bone‐to‐implant contact. Therefore, crestal bone loss or bone remodeling around the implant platform of a short implant, might be detrimental for the long‐term survival rate [60]. The use of ultra‐short implants (<5 mm) needs further investigation, before the clinical application on a regular basis [61, 62].

There is no statistically significant difference between implants placed in pristine native bone compared to augmented sites both at patient and implant levels [39]. Minimum buccal bone thickness of 2 mm is required for the placement of implants in the anterior region, and 1.5–2 mm for the posterior region [63]. The interproximal distances between teeth and implants, adjacent implants and crestal bone, to the contact point should be followed in order to have harmonious restorations that allow for proper cleansibility and maintenance [64]. Ideally, between adjacent implants, the distance in a vertical dimension, from the contact point to the crestal bone is 3 and 3–5 mm between a tooth and an implant. In a horizontal dimension, 3–4 mm distance is critical between either teeth and implants or between implants [63, 64]. Generally, implants are placed around 3–4 mm apical to the neighboring/restorative CEJ (Figures 9.5a, b, 9.6a–d, 9.7, 9.8a, b, 9.9a–c, 9.10, 9.11a–c, 9.12–9.14, 9.15a, b, 9.16a, b, and 9.17a–c) [35].

Unfortunately, most of the locations used for placement of dental implants, are not in the ideal prosthetic position, when the distance from the neighboring CEJ is more than 4 mm, creating several problems such as lack of proper cleansability of the final restoration, alveolar/crestal bone loss in the proximal areas, high crown to implant ratio, and lack of proper distribution of the occlusal forces. Specifically, when implants are placed apically more than 4 mm from the restorative CEJ, significantly greater bone loss on the mesial and distal surfaces was noted, compared to implants placed within 3 mm from the neighboring CEJ (Figures 9.18a–d).

Bone loss around implants is the most important etiological factor that may lead to implant failure. In restorations with high crown‐to‐implant ratio, the occlusal stress is distributed around the implant platform, which may cause implant failure. Ideally, all the occlusal discrepancies and parafunctional habits should be addressed before the beginning of the implant treatment [65–71].