Essay IV: Ongoing alveolar growth, continuous tooth eruption, and implants.

It is common knowledge that dental implants should not be inserted in adolescents, before completion of skeletal growth, because they behave as ankylosed teeth and remain in a fixed position while the surrounding bone and teeth are still developing, with consequential worsening esthetic damage. However, there is growing evidence that this phenomenon may continue throughout life in a large number of adult patients, although with a great variability in onset, progression, and extent. Infraocclusion and interproximal contact loss are the more common complications, and the majority of clinically significant cases are located in the anterior maxilla. The esthetic impact is mostly minimal, but in some cases the patient's smile may be severely compromised. Therefore, adult patients need to be informed when dental implants are considered to replace anterior missing teeth.

Continuous craniofacial growth in adult patients treated with dental implants in the anterior maxilla.

BACKGROUND: In the Literature, there are several studies demonstrating that infraposition happens also in adult patients. PURPOSE: To conduct a retrospective evaluation of infraocclusion of implant-retained crowns in the anterior maxilla of adult patients and of the patient awareness and perception of the problem. MATERIAL AND METHODS: From January to June 2017, all adult patients who in the last 5 to 20 years had received in the same clinic implant restorations in the upper anterior maxilla were recalled to assess the presence of crown infraocclusion. Ninety-four patients were recalled. Twenty-six males, 34 females, with 76 implants were included in the study. According to the age, patients were divided into group I (<30 years: 12 males, 14 female) and group II (>30 years: 14 males, 20 females). Digital photographs, taken at the time of final prosthesis delivery (T0) and at time of the study examination (T1) were compared by three blinded previously calibrated examiners. Cast models of the dental arches were taken at T1 and served as a reference for infraocclusion measurements. According to the Literature, cases were included in three categories: infraocclusion <0.5 mm, infraocclusion 0.5-1.0 mm, and infraocclusion >1 mm. An awareness and perception score (APS) was prepared to classify patients in: "unaware patients" (0), "aware but disinterested patients" (1), "aware patients requiring explications" (2), and "aware patients requiring treatment" (3). RESULTS: Infraocclusion was present in 73.3% of all cases, 65.4% among males, 79.4% among females. Infraocclusion was less than 1 mm in 88.2% of males and in 85.1% of females. No significant differences were found for sex (P = .223). No significant differences were found for age: group I: 47.7%, group II: 52.2%, (P = .481). The overall APS was: "unaware patients" = 38.6%, "aware but disinterested patients" = 27.3%, "aware patients requiring explications" = 15.9%, "aware patients requiring treatment" = 18.2%. CONCLUSION: Within the limit of the study, infraocclusion might present a quite high prevalence. Data analysis failed to identify specific predisposing risk factors.

Infraposition of Implant-Retained Maxillary Incisor Crown Placed in an Adult Patient: Case Report.

Several studies have clearly shown that osseointegrated implants, when inserted in growing bone, such as in adolescents, do not follow the eruptive path of adjacent teeth; instead, they act like ankylosed teeth, remaining in a stationary position for the lifetime, thus developing a progressive infraposition of the implant-supported crown. However, further studies have demonstrated that similar changes also occur in adult patients, although mostly in a small amount and over long time spans. Here the case of a female patient aged 35 years is presented, in which infraposition of the maxillary central incisor developed in a very short time (15 months). The treatment provided was a combined orthodontic/prosthetic approach with a 4-year follow-up.

Soft and hard tissue response to an implant with a convergent collar in the esthetic area: preliminary report at 18 months.

AIM: The purpose of this prospective cohort study was to investigate, over an 18-month period, soft and hard tissue response to a transmucosal implant with a convergent collar inserted in the anterior maxillary esthetic area. MATERIALS AND METHODS: From June 2013 to January 2014, 14 consecutive patients were enrolled (7 men and 7 women; mean age 63.7 ±â€¯14 years) with 20 implants, needing at least one implant-supported restoration between the canines in the maxillary anterior esthetic area. Six months after hopeless tooth extraction and an alveolar socket graft, a transmucosal-type implant with convergent collar walls was inserted in a midcrestal position with mini-flap surgery. An impression was taken 2 months later, and a definitive abutment with a provisional restoration was positioned. The final restoration was seated 2 weeks later. Clinical parameters, photographs, radiographs, and impressions were taken at this timepoint, and after 6 and 18 months. Using dedicated software, radiographic analysis (to detect marginal bone-level changes) and cast analysis (to detect soft tissue vertical and horizontal changes) were performed. RESULTS: At the 18-month follow-up, all implants were clinically osseointegrated, stable, and showed no sign of infection. At baseline, interproximal radiographs revealed no bone defect around the implant. After an initial minimal bone loss (0.09 ±â€¯0.144 mm), radiographic analysis showed a stable condition of bone remodeling (mean value 0.09 ±â€¯0.08; range 0.0 to 0.5 mm) at the 18-month follow-up. No statistically significant horizontal dimensional changes of the alveolar ridge were observed between each timepoint. Mean soft tissue levels significantly improved between baseline and 18 months. The mean heights of the mesial papilla (MP) and distal papilla (DP) changes were 0.38 ±â€¯0.22 and 0.47 ±â€¯0.31, respectively. The level of the labial gingival margin (LGM) was 1.01 ±â€¯0.63. Periodontal parameters never exceeded the physiological levels. CONCLUSIONS: Within the limitations of this preliminary study, the analyzed implants produced positive results in these esthetically demanding cases. This outcome should encourage long-term studies in order to assess, through controlled clinical trials, whether this convergent collar design offers advantages over other designs. Furthermore, due to the peculiar crestal module, together with the use of delayed implant insertion and a postextraction ridge preservation technique with biomimetic hydroxyapatite, the analyzed implants seem to help prevent the negative bone remodeling typically associated with two-piece implant systems, but without the well-known drawbacks of traditionally designed transmucosal implants. Therefore, wherever crestal bone preservation is a critical issue for clinical success in the anterior maxillary area can be considered of particular interest.

Clinical evaluation of an improved cementation technique for implant-supported restorations: a randomized controlled trial.

BACKGROUND: Cement remnants were frequently associated with peri-implantitis. Recently, a shoulderless abutment was proposed, raising some concern about cement excess removal. AIM: To compare different cementation techniques for implant-supported restorations assessing the amount of cement remnants in the peri-implant sulcus. Additional aim was to compare the effect of these cementation techniques using two different abutment designs. MATERIAL & METHODS: Forty-six patients requiring double implant-supported restoration in the posterior maxilla were randomly divided in two groups according to the cementation modality: intraoral and extraoral. According to the abutment finishing line, implants in each patient were randomly assigned to shoulderless or chamfer subgroup. In the intraoral group, crowns were directly seated onto the titanium abutment. In the extraoral group, crowns were firstly seated onto a resin abutment replica and immediately removed, then cleansed of the cement excess and finally seated on the titanium abutment. After cement setting, in both groups, cement excess was carefully tried to remove. Three months later, framework/abutment complexes were disconnected and prepared for microscopic analysis: surface occupied by exposed cement remnants and marginal gaps were measured. Additionally, crown/abutment complexes were grinded, and voids of cement were measured at abutment/crown interface. Related-samples Friedman's two-way analysis of variance by ranks was used to detect differences between groups and subgroups (P ≤ 0.5). RESULTS: At the end of the study, a mean value of 0.45 mm2 (±0.80), 0.38 mm2 (±0.84), and 0.065 mm2 (±0.13) and 0.07 mm2 (±0.15) described surface occupied by cement remnants in shoulderless and chamfer abutment with intraoral cementation and shoulderless and chamfer abutment with extraoral cementation, respectively. A mean value of 0.40 mm2 (±0.377), 0.41 mm2 (±0.39) and 0.485 mm2 (±0.47) and 0.477 mm2 (±0.43) described cement voids at the abutment/crown interface; a mean value of 0.062 mm (±0.03), 0.064 mm (±0.35), 0.055 mm (±0.016) and 0.054 mm (±0.024) described marginal gaps. Statistics showed tendency of intraoral cementation to have significantly higher cement remnants compared with abutments with extraoral cementation groups. At the same time, the presence of voids was significantly higher in case of extraoral cementation. No significant differences between groups for the variable "gap". CONCLUSIONS: Despite the presence of more voids, extraoral cementation reduces cement excess. However, using low adhesivity cement and careful cement removal, a very limited quantity of cement remnants was observed also in the intraoral cementation.

The "hybrid abutment": a new design for implant cemented restorations in the esthetic zones.

Cemented implant restorations are widely used by many dentists. The traditional abutment design resembles a natural tooth prepared for a crown with a similar taper and a chamfer finish line. A frequent complication associated with implant restorations in the esthetic zones is the recession of buccal gingiva over time. Abutment morphology, among several other prosthetic factors, may play an important role in the stability of the gingival margin in esthetically sensitive areas, but this has never been thoroughly analyzed. Recently, a prosthetic technique called biologically oriented preparation technique (BOPT) has been proposed, which utilizes a feather-edge preparation on natural abutments, and it has been claimed that applying the concepts of this technique to implant abutments could improve long-term gingival margin stability. At present, there is no available evidence to confirm this claim. Moreover, some concerns may arise if this particular design is implemented in every clinical situation. With these considerations in mind, this article proposes the "hybrid abutment" design (HAD), a new design that includes a combination of the two types of features--a feather edge on the buccal side, and a chamfer finish line on the lingual side. The article also presents a rationale for the use of different abutment designs for different situations.

Immediate positioning of a definitive abutment versus repeated abutment replacements in post-extractive implants: 3-year follow-up of a randomised multicentre clinical trial.

PURPOSE: The aim of this randomised clinical trial was to evaluate the influence of restoration on marginal bone loss (MBL) using immediately definitive abutments (one abutment­one time concept) versus provisional abutments later replaced by definitive abutments. MATERIALS AND METHODS: In three private clinics, 32 patients with 32 hopeless maxillary premolars were selected for post-extractive implant-supported immediate restoration and randomised to provisional abutment (PA) and definitive abutment (DA) groups, 16 sites in each group. After tooth extraction, 7 patients had to be excluded for buccal wall fracture at tooth extraction or lack of sufficient primary implant stability (< 35 Ncm). The remaining 25 patients (10 PA, 15 DA) received a post-extractive wide-diameter implant. Immediately after insertion, the PA group were immediately restored using a platform-switched provisional titanium abutment. In the DA group, definitive platform-switched titanium abutments were tightened. In both groups, provisional crowns were adapted, avoiding occlusal contacts. All implants were definitively restored after 3 months. In the PA group, a traditional impression technique with coping transfer was adopted, dis/reconnecting abutments several times; in the DA group, metal prefabricated copings were used and final restorations were seated, avoiding abutment disconnection. Digital standardised periapical radiographs using a customised film holder were recorded at baseline (T0 = implant insertion), final restoration (T1 = 3 months later), and at 18-month (T2) and 3-year (T3) follow-ups. The MBL was evaluated with a computerised measuring technique and digital subtraction radiography (DSR) software was used to evaluate radiographic density. RESULTS: At the 3-year follow-up a success rate of 100% in both groups was reported. In the PA group, peri-implant bone resorption was 0.36 mm at T1, 0.43 mm at T2, and 0.55 mm at T3. In the DA group, peri-implant bone resorption was 0.35 mm at T1, 0.33 mm at T2, and 0.34 mm at T3. Statistically significant lower bone losses were found at T2 (0.1 mm) and T3 (0.2 mm) for the DA group. At T3, significantly higher DSR values around implant necks were recorded in the DA group (72 ± 5.0) when compared with the PA group (52 ± 9.5). CONCLUSIONS: The current trial suggests that the 'one abutment­one time' concept might be a possible additional strategy in post-extraction immediately restored platform-switched single implants to further minimise peri-implant crestal bone resorption, although a 0.2 mm difference may not have any clinical effect. Additional clinical trials with larger groups of patients should be performed to better investigate this hypothesis.

The abutment duplication technique: a novel protocol for cementable implant-supported restorations.

The purpose of this study was to present a new laboratory technique for cementable implant-supported restorations and to evaluate its efficacy in reducing chair time for both patients and clinicians, while maintaining the precision of an indirect procedure for crown fabrication. The technique consisted of the duplication of the implant portion of a working cast prepared using double-pour or plastic base die systems for single or multiple crowns. For this purpose, a flask previously intended for the production of ceramic inlays and onlays was used. Duplication was obtained using a high-precision addition silicon material and a low-shrinkage polyurethane resin. The duplicated implant abutment was used to finalize the fixed partial denture restorations after the originals were delivered to the patients. Fifty abutments were tested consecutively. The castings (19 single crowns, 31 fixed partial dentures) produced on the original abutments were seated on the duplicate abutments and evaluated by two prosthodontists and two dental technicians using a visual inspection method (laboratory microscope at 163 magnification). Forty-eight restorations were "good" (completely seated, no marginal opening) and 2 were "acceptable" (incomplete seating but amendable), with a 98% success rate. The technique presented demonstrates efficacy and predictability in reducing the number of clinical sessions for delivering precisely fitting cementable implant-supported restorations.

Evaluation of hard tissue response around wider platform-switched implants.

The use of a narrower-diameter abutment over a larger-diameter implant platform has been shown to decrease peri-implant bone resorption. This technique, known as platform switching, shifts the implant-abutment microgap inward. The aim of this study was to examine whether shifting the microgap further inward by increasing the discrepancy between the implant platform and abutment diameter would result in a decrease in crestal bone loss. Ten patients requiring mandibular or maxillary implant restorations were included in this study. The inclusion criteria called for an alveolar crest thickness of at least 8.0 mm at the implant placement site. Fifteen Certain PREVAIL implants with a body diameter of 5.0 mm, an expanded platform feature with a maximum diameter of 5.8 mm at the collar, and a prosthetic seating surface of 5.0 mm were used in lengths of 8.5, 10.0, 11.5, or 13.0 mm. The implants were connected to 4.1-mm healing abutments in a single-stage protocol. Periapical radiographs taken before and immediately after surgery, 8 weeks after implant placement, immediately after definitive prosthesis insertion, and at 12 and 18 months after loading revealed an average peri-implant bone loss of 0.30 mm. Increasing the discrepancy between the diameter of the implant platform and the restorative abutment may lead to a decrease in the amount of subsequent coronal bone loss.

Immediate provisionalization of NanoTite implants in support of single-tooth and unilateral restorations: one-year interim report of a prospective, multicenter study.

BACKGROUND: Clinical studies reporting immediate loading of endosseous implants for edentulous cases and for fixed partial restorations have been well documented with satisfactory survival rates. Implants with a recently developed, nanometer-scale surface topography (NanoTite, BIOMET 3i, Palm Beach Gardens, FL, USA), created by discrete crystalline depositions (DCD) of calcium phosphate nano-crystals onto a dual acid-etched (DAE) surface, show enhanced early fixation in preclinical studies when compared with DAE-surfaced implants. These outcomes suggest DCD-surfaced implants may be advantageous for immediate loading approaches. OBJECTIVE: The aim of this prospective, multicenter, observational study is to report clinical outcomes for DCD-surfaced implants placed in immediate functional support of single- and multi-unit restorations according to an immediate loading protocol. MATERIALS AND METHODS: One hundred eighty-five patients enrolled at 15 international study centers received a total of 335 implants supporting 216 immediate provisionalizations consisting of 128 single-tooth restorations and 88 fixed restorations. Of the 335 implants, 77% are located in posterior and 23% in anterior regions with 55.5% of the total in mandibles and 44.5% in maxillae. Patients were evaluated for implant mobility, gingival health, symptomatology, and radiographic outcomes. RESULTS: At the time of this 1-year interim report, a total of 17 failures have been observed in 11 patients, yielding a cumulative survival rate of 94.9%. CONCLUSION: Relative to other prospective, multicenter studies of immediately loaded implants with various surface enhancements, NanoTite implants perform comparatively well when immediately provisionalized with single-tooth and fixed restorations.

Evaluation of peri-implant bone loss around platform-switched implants.

This clinical and radiographic prospective study evaluated bone loss around two-piece implants that were restored according to the platform-switching protocol. One hundred thirty-one implants were consecutively placed in 45 patients following a nonsubmerged surgical protocol. On 75 implants, a healing abutment 1 mm narrower than the implant platform was placed at the time of surgery. On the remaining implants, a healing abutment of the same diameter as the implant was inserted. All implants were positioned at the crestal level. Clinical and radiographic examinations were performed prior to surgery, at the end of surgery, 8 weeks after implant placement, at the time of provisional prosthesis insertion, at the time of definitive prosthesis insertion, and 12 months after loading. The data collected showed that vertical bone loss for the test cases varied between 0.6 mm and 1.2 mm (mean: 0.95 +/- 0.32 mm), while for the control cases, bone loss was between 1.3 mm and 2.1 mm (mean: 1.67 +/- 0.37 mm). These data confirm the important role of the microgap between the implant and abutment in the remodeling of the peri-implant crestal bone. Platform switching seems to reduce peri-implant crestal bone resorption and increase the long-term predictability of implant therapy.

Bone contact around osseointegrated implants: histologic analysis of a dual-acid-etched surface implant in a diabetic patient.

The clinical applicability and predictability of osseointegrated implants in healthy patients have been studied extensively. Although successful treatment of patients with medical conditions including diabetes, arthritis, and cardiovascular disease has been described, insufficient information is available to determine the effects of diabetes on the process of osseointegration. An implant placed and intended to support an overdenture in a 65-year-old diabetic woman was prosthetically unfavorable and was retrieved after 2 months. It was then analyzed histologically. No symptoms of implant failure were detected, and histomorphometric evaluation showed the bone-to-implant contact percentage to be 80%. Osseointegration can be obtained when implants with a dual-acid-etched surface are placed in properly selected diabetic patients.

Hard and soft tissue responses to the platform-switching technique.

Platform switching is a concept recently introduced in implant dentistry. It is intended to reduce the crestal bone loss that is commonly found around implants exposed to the oral environment. The aim of this study was to examine biopsy specimens to help explain the biologic processes occurring around a platform-switched implant. A mandibular implant was removed 2 months after placement because of prosthetic rehabilitation difficulties. The implant was then sectioned and subjected to histologic and histomorphometric analysis. An inflammatory connective tissue infiltrate was localized over the entire surface of the implant platform and approximately 0.35 mm coronal to the implant-abutment junction, along the healing abutment. A possible reason for bone preservation around a platform-switched implant may lie in the inward shift of the inflammatory connective tissue zone at the implant-abutment junction, which reduces its injurious effect on the alveolar bone.

A new implant design for crestal bone preservation: initial observations and case report.

Following the exposure and restoration of two-piece dental implants, some change in the vertical level of the peri-implant crestal bone height has been reported. This change in crestal bone height has not, however, negatively impacted long-term implant success. This article describes how the concept of platform switching is incorporated into a new implant design as a means of reducing or eliminating the occurrence of crestal bone loss. Preliminary observations from clinicians utilizing this new implant design are herein presented.

Guided Tissue Regeneration in Mucogingival Surgery.

The use of expanded polytetrafluoroethylene (ePTFE) membranes in the treatment of mucogingival problems such as gingival recession, has been recently described. The major issues raised dealt with creating and maintaining space under the membrane and designing a flap that could be coronally positioned and at the same time capable of maintaining a good blood supply. The authors proposed the use of a trapezoidal flap and some technical space-making solutions, such as the use of a suturing technique and different metal structures to support the membranes. J Periodontol 1993; 64:1184-1191.