Immediately versus early placed bone-level-tapered implants supporting all-ceramic crowns on titanium base abutments: 1-year radiographic and pink esthetic outcomes of a multicenter pilot RCT.

OBJECTIVES: Aim of this study was to assess survival rates, radiographic, and pink esthetic outcomes of a bone-level-tapered (BLT) implant following immediate or early implant placement. MATERIALS AND METHODS: Patients in need of tooth extraction and one implant in the anterior or premolar area were recruited in five centers. Patients were randomly assigned to the immediate or early placement protocol. Implants were restored with all-ceramic crowns cemented to titanium-base-abutments. Radiographic bone levels, implant stability quotient (ISQ), and pink esthetic outcomes were assessed. Data were analyzed descriptively. Level of significance was set at 0.05. Differences between groups were tested using Wilcoxon-signed-rank and Mann-Whitney-U test as nonparametric tests. RESULTS: A total of 60 patients received 60 BLT implants (Institut Straumann). At 12-months, 59 implants (98.3%) were osseointegrated. The mean distance from implant shoulder to first bone-to-implant contact was 0.15 ± 0.59 mm without significant differences between the groups. Median ISQ values increased from 75.5 to 78.5. A mean buccal recession of 0.1 ± 0.70 mm occurred with no difference between groups. The mean papilla height gain in both groups was 0.5 ± 1.47 mm mesially and 0.4 ± 1.36 mm distally. CONCLUSIONS: After 1 year, immediately and early placed BLT implants exhibit similar bone level changes, ISQ values, and pink esthetic outcomes. CLINICAL SIGNIFICANCE: The present research contributes to the knowledge on clinical outcomes of immediately and early placed BLT implants restored with buccally microveneered ceramic single crowns out of two different ceramic materials. The research shows that similar esthetic and radiographic outcomes can be reached by means of immediate implant placement compared to the conventional early placement protocol. The improvement of esthetic soft-tissue parameters over time was shown for both implant placement protocols.

Laser induced temperature changes on the outer surface of titanium dental implants-an in vitro study.

PURPOSE: to measure the surface temperature distribution after CO2-laser heating of titanium dental implants using different power settings, application intervals and irradiation times. MATERIALS AND METHODS: 10 tissue-level-type titanium implants (Camlog Screw-line Promote Plus 4.3mm x 11mm) were embedded (Epofix, Struers ApS, Copenhagen, Denmark) and irradiated with a carbon-dioxide-laser (Denta II, Lutronic Corporation, Fremont, USA) with a wavelength of 10.6µm and at power levels of 4watts (group 1), 6watts (group 2), 8watts (group 3) and 10watts (group 4). A continuous beam mode (setting I) and non-continuous beam modes with 5second (setting II) and 10second (setting III) pause intervals were used. For each setting, a total irradiation time of 50seconds was used and repeated 10 times. The temperature was measured using external thermocouples (Testo SE & Co. KGaA, Lenzkirch, Germany) in contact with the implant surface at implant shoulder, middle and apex. A linear regression model was used to analyse the data (p = 0.05). RESULTS: Setting I demonstrated the most rapid increase in implant surface temperature in all three test sites as well as the greatest total temperature at 50 seconds of irradiation time. The greater the pause interval (settings II and III) during the 50 seconds of irradiation, the lower the rate of temperature increase as well as the total temperature in all three test sites and with all power levels. The average temperature difference between the apex and shoulder site was significant for test setting III for all groups, but not for any groups in settings I and II. CONCLUSION: Heating the internal aspect of a dental implant with a CO2-laser produces different temperature distribution profiles depending on the laser power level and the application interval. Laser-beam irradiation leads to a temperature gradient which is greatest at the implant apex and smallest at the implant shoulder.

O-Ring Attachments on One-Piece Mini Dental Implants: In Vitro Analysis of Retention Force Reproducibility Using Different Pristine Matrix-O-Ring Combinations

PURPOSE: To analyze the influence of pristine matrix and O-ring dimensions on retention force and reproducibility in single one-piece mini dental implants (MDIs) with ball patrices under in vitro conditions. MATERIALS AND METHODS: Three different matrix and O-ring combinations (MH1-MH3) were evaluated (n = 50 per group) on 1.8-mm-diameter implants. The matrices were manually mounted on the implants and were subsequently removed in a vertical linear manner using a metal pin with two strain gauges, recording the maximum force during disconnection. After five disconnections, the O-rings were exchanged, and the mean retention force was calculated, resulting in 50 values for each matrix and O-ring combination. Mean retention forces, SDs, and 95% CI were calculated. Analysis of variance was used to test the global differences, and post hoc pairwise comparisons were subsequently applied. The level of significance was set to P < .05. RESULTS: ANOVA (global P < .0001) and pairwise comparisons (all P < .0001) demonstrated statistically significant differences among the three different matrix and O-ring combinations, with mean values of 5.18 N (MH 1), 6.73 (MH 2), and 9.08 (MH 3). Within each combination, retention force variations of > 1 N could not be demonstrated; ie, by exchanging O-rings, a similar retention force can be reestablished. CONCLUSION: Matrix and O-ring dimensions have a significant influence on retention forces in one-piece MDIs. Pristine O-rings demonstrated highly reproducible initial retention forces in all matrices.

Immediate loading of ø 2,4 mm narrow-diameter implants in the edentulous maxilla and mandible / Implantatsofortbelastung eines zahnlosen Patienten

A 61-year-old healthy patient was referred for prosthetic rehabilitation in the maxilla and mandible. The primary wish of the very anxious patient was to improve the masticatory function and his aesthetic appearance with the least invasiveness and as efficiently as possible. Furthermore, he desired to receive a reliable long-term solution. The patient had no general medical restrictions and was a non-smoker. At the time of the first clinical examination, the patient presented nearly edentulous, with a few root remnants in the mandible and remaining wisdom teeth in the maxilla. The main objective of the treatment, hence, was to improve both his chewing function and the stability of the prostheses without invasive surgeries. After the removal of the root remnants and one of the two wisdom teeth (18), two new complete dentures were fabricated. Thereafter, 6 diameter reduced mini implants (SLA® one-piece self-tapping Straumann® Mini Implants made of Roxolid®, with a diameter of 2.4 mm and a length of 10 mm) were inserted in the maxilla, and 4 mini implants (SLA® one-piece self-tapping Straumann® Mini Implants made of Roxolid®, with a diameter of 2.4 mm and a length of 10 mm) were inserted in the mandible. After the implant insertion with good primary stability, the two new complete dentures were transferred into two implant-supported removable dental prostheses and retained by means of the transmucosal integrated attachment system of the mini implants (Optiloc®). At the 3-month follow-up visit, the patient was very satisfied with the outcomes, both from a functional and aesthetic point of view.

Evolution of in vivo assessed retention forces in one-piece mini dental implant-retained mandibular overdentures: 5-Year follow-up of a prospective clinical trial.

BACKGROUND: The evolution of retention forces in one-piece mini dental implants (MDIs) retaining implant overdentures (IODs) is of major importance, as the male parts cannot be exchanged, due to the implant design. PURPOSE: To report the evolution of retention forces of one-piece MDIs, retaining mandibular IODs with ball/ O-ring attachments during 5 years assessed in vivo. MATERIALS AND METHODS: Four MDIs were installed in the interforaminal region and immediately loaded using the existing mandibular complete denture. Directly post-op, at the 1-year and the 5-year follow-up, the retention forces were assessed with a validated strain gauge at each implant site separately. RESULTS: At the male part, changes could only be observed at implant site 34: During the first year, there was a statistically significant increase, whereas the retention forces were decreased at the 5-year follow-up. At the female part, retention forces decreased significantly over time. Baseline values could be reestablished by exchanging the O-rings. The changes of the retention forces were more obvious in the posterior, compared to the anterior implants. CONCLUSIONS: Retention forces at the female part decrease significantly over time, when retaining mandibular IODs by MDIs with ball/ O-ring attachments. Baseline values can be reestablished by exchanging the O-rings. At the male part, changes of retention forces depend on the implant location.

A prospective cohort study on survival and success of one-piece mini-implants with associated changes in oral function: Five-year outcomes.

OBJECTIVE: To investigate in a prospective cohort study the 5-year post-loading survival and success of one-piece mini dental implants (MDIs) in edentulous subjects with mandibular implant overdentures (IODs) and to report the associated changes of oral function with respect to patient age. MATERIALS AND METHODS: Independently living edentulous patients were recruited and provided with new complete dentures. After an adaptation period, four one-piece MDIs (diameter 1.8 mm) were installed in the interforaminal region and immediately loaded. At baseline pre-operative (BL), as well as at 1-year and 5-year follow-up examinations, chewing efficiency was assessed with a validated color-mixing ability test and maximum voluntary bite force (MBF) was recorded with a digital force gauge. Implant survival and success were evaluated at 5-year follow-up. Non-parametric tests served to analyze the differences between time points. RESULTS: Twenty patients participated in the study (5 men and 15 women; age at BL: n = 10 ≤ 65 years and n = 10 > 65 years). All patients were available for a 5-year follow-up (n = 2 in their long-term care facility; n = 1 only by telephone). The survival and success rates were both 100% after 61 ± 5.7 months. Chewing efficiency did not change over the first year (p = 0.167), but was improved at 5 year fup (n = 19) compared to baseline (p = 0.033) and to 1 year (p < 0.001). The MBF (n = 19 at 5-year follow-up) increased continuously over time (p < 0.001), but was less pronounced in the older cohort (p = 0.009). CONCLUSIONS: Mini dental implants seem to be a successful treatment option for edentulous elderly patients with very high survival and success rates, and serve to improve long-term oral function.

Explantation of an Osseointegrated Titanium Implant Using Laser-Induced Thermo-necrosis: A Case Report.

Explantation of fully or partially osseointegrated titanium implants is a complex procedure for myriad reasons and often results in major bone loss and pronounced defects of the hard and soft tissues. This may require more elaborate surgical interventions in cases of re-implantation. In this patient case, an osseointegrated titanium implant with some visible bone loss, missing attached mucosa at the buccal aspect, and a nonideal three-dimensional (3D) position had to be explanted. For this, the implant's inner connection was heated using a CO2 laser, which resulted in localized laser-induced thermo-necrosis at the bone-to-implant contact. One week following laser application, explantation could be performed easily with a torque slightly more than 35 Ncm. No complications occurred during the healing period. The result was a very easily performed explantation while preserving a maximum of the surrounding bony structure. Healing was uneventful, and no further visible bone loss could be observed during the healing time.

Long-term changes in oral health-related quality of life over a period of 5 years in patients treated with narrow diameter implants: A prospective clinical study.

OBJECTIVES: The aim of this study was to assess long-term changes in oral health-related quality of life (OHRQoL) over a period of 5 years in patients treated with narrow diameter implants (NDI) in the mandible for support of an overdenture. METHODS: In this prospective clinical study, a consecutive sample of 20 edentulous patients who had worn sufficient complete dentures for at least 12 weeks was provided with four immediately loaded one-piece titanium NDIs in the mandible. The German 49-item version of the Oral Health Impact Profile (OHIP) was applied to assess OHRQoL at baseline and all follow-ups (4 and 8 weeks, 3, 6, and 12 months, and 3 and 5 years after treatment was finished). RESULTS: Before treatment, OHRQoL was substantially impaired indicated by high OHIP summary score (39.9 points). Four weeks after treatment, a substantial treatment-induced drop of OHRQoL impairment was observed (21.8 OHIP points), and at all follow-ups, OHIP scores were lower than at baseline (15.9-26.5 OHIP points; ANOVA: p<.001). Based on mixed-effect linear regression analyses, the treatment-induced effect on OHRQoL improvement over the entire study period was statistically significant for the OHIP summary scores as well as for all four OHIP domains: Oral Function, Orofacial Pain, Orofacial Appearance, and Psychosocial Impact (all: p<.001). CONCLUSIONS: This study suggests that four immediately loaded NDIs for the support of conventional complete dentures in edentulous patients with substantially impaired OHRQoL may lead to a long-lasting treatment-induced improvement in OHRQoL. CLINICAL SIGNIFICANCE: The provision of four NDI in the edentulous mandible is a promising treatment option for patients with substantial OHRQoL impairment and a positive attitude towards implant treatment. Furthermore, patients can be informed that improvements in OHRQoL are expected to last for at least 5 years.

Performance and marginal bone level alteration around immediately loaded narrow-diameter implants. A prospective clinical study: Results after 1 year.

OBJECTIVE: The aim of the present prospective clinical study was to assess the survival rate and the radiologic crestal bone level alteration around four interforaminal immediately loaded narrow-diameter implants (NDIs) in the edentulous mandible. METHOD AND MATERIALS: A total of 20 participants received each 4 NDIs (MDI, 3M Espe; diameter 1.8 mm, length 13 or 15 mm) in the edentulous mandible. Immediate loading was performed if insertion torque was 35 Ncm or higher. The implants were loaded the same day by converting the existing full denture into an implant overdenture. Follow-up visits were performed five times (baseline to 52 weeks). Standardized radiographs were taken at baseline and 12, 26, and 52 weeks post-loading. Clinical parameters (Plaque Index, probing depth, bleeding on probing) were assessed. The nonparametric ANOVA test was used to assess crestal bone level changes. RESULTS: In all 20 patients the healing of the total 80 implants was uneventful and no implant was lost. Sixty-eight (85%) implants were loaded immediately. All clinical parameters showed healthy, stable, and well-maintained peri-implant soft tissue conditions. The mean (± standard deviation) radiographic bone loss after 1 year was 0.78 (± 0.64) mm. CONCLUSION: According to the 1-year results of this prospective clinical study, NDIs seem to be a reliable alternative to support prostheses in edentulous patients with a reduced horizontal mandibular bone volume.

Monolithic zirconia reconstructions supported by teeth and implants: 1- to 3-year results of a case series.

OBJECTIVE: Today, only scarce information is available on monolithic zirconia reconstructions. The objective of this study was to evaluate the performance of monolithic zirconia for tooth- and implant-borne reconstructions. METHOD AND MATERIALS: Monolithic zirconia single crowns (SCs) and fixed dental prostheses (FDPs) supported by implants or teeth were included in this study. Implant placement and prosthetic treatment were done in the same clinical setting. One technician performed all laboratory work using the same CAD/CAM workflow (DentalDesigner, Ceramill Motion 2, Amann Girrbach). The endpoints were technical outcome, color match, marginal adaptation, anatomical form, and biologic aspects. The modified United States Public Health Service (USPHS) criteria and periodontal parameters were applied for the clinical evaluation by two independent examiners. Descriptive statistics and nonparametric tests were used for statistical comparisons. RESULTS: Forty patients (17 men, 23 women, mean age 59.1 ±â€¯14.7 years) with 109 reconstructions (74 SCs, 35 FDPs) supported by 38 implants and 71 teeth were assessed, resulting in a total of 238 monolithic zirconia units (including 62 pontics and 18 cantilevers). Median follow-up time was 23.8 months (12 to 36 months). No technical failures were observed. The total prosthesis survival rate was 99.6% (teeth, 100%; implants, 98.4%) due to the loss of one implant. The periodontal/peri-implant parameters stand for healthy tissue, and caries was not detected. The records obtained by the USPHS revealed good clinical outcomes. CONCLUSION: These short-term results indicate that monolithic zirconia reconstructions for teeth and implants may be a satisfactory treatment option, particularly in the posterior region.

Chewing efficiency, bite force and oral health-related quality of life with narrow diameter implants - a prospective clinical study: results after one year.

OBJECTIVE: This prospective study aimed to investigate the evolution of chewing efficiency, maximum voluntary bite force (MBF) and oral health-related quality of life (OHRQoL) in edentulous patients treated with narrow diameter implants (NDIs) over the course of 1 year. MATERIALS AND METHODS: Four NDIs (MDI® , 3M ESPE, diameter 1.8 mm) were placed interforaminally in 20 edentulous patients. They were immediately loaded by converting the existing prosthesis into an implant overdenture. Participants were examined six times pre- and postoperatively [baseline (BL) to week 52 (w52)]. Chewing efficiency was evaluated with a colour-mixing ability test by evaluation of the standard deviation of hue (VOH, ViewGum©). MBF was measured using a digital force gauge. OHRQoL was determined with the Oral Health Impact Profile (OHIPG49). Nonparametric Brunner-Langer models were applied for statistical testing. RESULTS: The study failed to demonstrate an effect on chewing efficiency. MBF increased continuously during the observation period (medians: MBF[N]@BL = 46.6 [iqr 50.1]; MBF[N]@w52 = 103.9 [iqr 76.0]; P = 0.002). OHRQoL increased steeply after implant loading and continued improving (medians: BL ∑OHIPG49 = 31 [iqr 40.0]; w4 ∑OHIPG49 = 11.5 [iqr 19.5]; w52 ∑OHIPG49 = 6 [iqr 13.0], P < 0.001). CONCLUSIONS: The stabilisation of a lower complete prosthesis with four NDIs is a feasible minimally invasive and economical approach to improve oral function and OHRQoL, especially in elderly patients with limited bone support. Functional benefits might be more evident if patients receive chewing instructions. Larger studies need to confirm a positive effect on chewing efficiency and develop long-term maintenance solutions if patients become frail because no easy downgrading approaches of one-piece titanium implants exist.

Bone resorption in different parts of the mandible in patients restored with an implant overdenture. A retrospective radiographic analysis.

AIM: This study investigated the pattern of resorption of the mandibular ridge under implant-supported overdentures. MATERIAL AND METHODS: Files of 60 patients were available for analysis (45 women and 15 men, mean age at the time of the follow-up 76.5 ± 8.5 years, 54 patients restored with bars, 6 with ball anchors). A baseline was defined by different stable landmarks and quartered. Linear measurements from this baseline at different clinical relevant sites approximately at: (i) the area close to the mental foramen/close to the implant, (ii) the chewing center, and (iii) the distal edge of the denture flange were carried out on rotational tomograms (OPTs). The OPTs were taken after prosthetic restoration and at an individual follow-up time (mean 11 ± 4.75 years). The known implant length served to scale each measurement to avoid any distortion errors. RESULTS: The resorption rate showed a high individual variation, but among the three sites, the difference was highly significant. Median values of site (i) left = -0.07 mm/right = +0.05 mm, site (ii) left = -0.60 mm/right = -0.55 mm, and site (iii) left = -1.58 mm/right = -2.01 mm. CONCLUSIONS: The load of the distal flange of a mandibular implant overdenture increases bone resorption as a local factor, whereas implants may help to prevent resorption in the neighboring bone. An individual-adapted follow-up protocol should be established for each patient restored with an implant overdenture.

Retrievability of implant-supported crowns when using three different cements: a controlled clinical trial.

PURPOSE: The purpose of this study was to analyze the removal of implant-supported crowns retained by three different cements using an air-accelerated crown remover and to evaluate the patients' response to the procedure. MATERIALS AND METHODS: This controlled clinical trial was conducted with 21 patients (10 women, 11 men; mean age: 51 ± 10.2 years) who had received a total of 74 implants (all placed in the posterior zone of the mandible). Four months after implant surgery, the crowns were cemented on standard titanium abutments of different heights. Three different cements (two temporary: Harvard TEMP and Improv; and one definitive: Durelon) were used and randomly assigned to the patients. Eight months later, one blinded investigator removed all crowns. The number of activations of the instrument (CORONAflex, KaVo) required for crown removal was recorded. The patients completed a questionnaire retrospectively to determine the impact of the procedure and to gauge their subjective perception. A linear regression model and descriptive statistics were used for data analysis. RESULTS: All crowns could be retrieved without any technical complications or damage. Both abutment height (P = .019) and cement type (P = .004) had a significant effect on the number of activations, but the type of cement was more important. An increased total number of activations had no or only a weak correlation to the patients' perception of concussion, noise, pain, and unwillingness to use the device. CONCLUSIONS: Cemented implant crowns can be removed, and the application of an air-accelerated device is a practicable method. A type of cement with appropriate retention force has to be selected. The impact on the patients' subjective perception should be taken into account.

Zirconia-Based Screw-Retained Prostheses Supported by Implants: A Retrospective Study on Technical Complications and Failures.

BACKGROUND: Little information is yet available on zirconia-based prostheses supported by implants. PURPOSE: To evaluate technical problems and failures of implant-supported zirconia-based prostheses with exclusive screw-retention. MATERIAL AND METHODS: Consecutive patients received screw-retained zirconia-based prostheses supported by implants and were followed over a time period of 5 years. The implant placement and prosthetic rehabilitation were performed in one clinical setting, and all patients participated in the maintenance program. The treatment comprised single crowns (SCs) and fixed dental prostheses (FDPs) of three to 12 units. Screw-retention of the CAD/CAM-fabricated SCs and FDPs was performed with direct connection at the implant level. The primary outcome was the complete failure of zirconia-based prostheses; outcome measures were fracture of the framework or extensive chipping resulting in the need for refabrication. A life table analysis was performed, the cumulative survival rate (CSR) calculated, and a Kaplan-Meier curve drawn. RESULTS: Two hundred and ninety-four implants supported 156 zirconia-based prostheses in 95 patients (52 men, 43 women, average age 59.1 ± 11.7 years). Sixty-five SCs and 91 FDPs were identified, comprising a total of 441 units. Fractures of the zirconia framework and extensive chipping resulted in refabrication of nine prostheses. Nearly all the prostheses (94.2%) remained in situ during the observation period. The 5-year CSR was 90.5%, and 41 prostheses (14 SCs, 27 FDPs) comprising 113 units survived for an observation time of more than 5 years. Six SCs exhibited screw loosening, and polishing of minor chipping was required for five prostheses. CONCLUSIONS: This study shows that zirconia-based implant-supported fixed prostheses exhibit satisfactory treatment outcomes and that screw-retention directly at the implant level is feasible.

Technical complications and failures of zirconia-based prostheses supported by implants followed up to 7 years: a case series.

PURPOSE: To evaluate technical complications and failures of zirconia-based fixed prostheses supported by implants. MATERIALS AND METHODS: Consecutive patients received zirconia-based single crowns (SCs) and fixed dental prostheses (FDPs) on implants in a private clinical setting between 2005 and 2010. One dentist performed all surgical and prosthetic procedures, and one master technician performed and coordinated all laboratory procedures. One-piece computer-aided design/ computer-assisted manufacture technology was used to fabricate abutments and frameworks, which were directly connected at the implant level, where possible. All patients were involved in a recall maintenance program and were finally reviewed in 2012. Data on framework fractures, chipping of veneering ceramics, and other technical complications were recorded. The primary endpoint was failure of the prostheses, ie, the need for a complete remake. A life table analysis was calculated. RESULTS: A total of 289 implants supported 193 zirconia-based prostheses (120 SCs and 73 FDPs) in 127 patients (51 men, 76 women; average age: 62.5 ± 13.4 years) who were reviewed in 2012. Twenty-five (13%) prostheses were cemented on 44 zirconia abutments and 168 (87%) prostheses were screw-retained directly at the implant level. Fracture of 3 frameworks (1 SC, 2 FDPs) was recorded, and significant chipping resulted in the remake of 3 prostheses (1 SC, 2 FDPs). The 7-year cumulative survival rate was 96.4% ± 1.99%. Minor complications comprised 5 loose screws (these were retightened), small chips associated with 3 prostheses (these were polished), and dislodgement of 3 prostheses (these were recemented). Overall, 176 prostheses remained free of technical problems. CONCLUSIONS: Zirconia-based prostheses screwed directly to implants are clinically successful in the short and medium term.

[Limited mouth opening - what now?]. / Eingeschränkte Mundöffnung – was nun?

This case report illustrates a rare complex of symptoms leading to limited mouth opening in a young woman. The 28-year old suffered from a progressively limited mouth opening over several years that finally resulted in restricted alimentation and made dental treatment impossible. Clinical findings suggest a structural alteration, including a hyperplastic mandibular angle and marked hypertrophy of the masseter muscle. Further radiologic investigations reveal a thickened aponeurosis of the masticatory muscles and hyperplastic coronoid processes that are not interfering with the zygomatic bone. Primary therapeutic options for such conditions are mainly surgical, including reduction of the masseter muscles volume and aponeurorectomy as well as bony reductions, such as coronoidectomy and mandibular angle reduction. With this treatment, the outcome and prognosis are good. Long-term results depend on concomitant physical therapy. A uniform nomenclature for this condition is yet lacking and propositions such as “masticatory muscle tendon-aponeurosis hyperplasia” have been made. However, knowledge of this condition and its typical clinical signs can make the diagnosis and treatment straightforward, thus leading to an improved quality of life of affected patients.

Optimal number of oral implants for fixed reconstructions: a review of the literature.

BACKGROUND AND AIM: So far there is little evidence from randomised clinical trials (RCT) or systematic reviews on the preferred or best number of implants to be used for the support of a fixed prosthesis in the edentulous maxilla or mandible, and no consensus has been reached. Therefore, we reviewed articles published in the past 30 years that reported on treatment outcomes for implant-supported fixed prostheses, including survival of implants and survival of prostheses after a minimum observation period of 1 year. MATERIAL AND METHODS: MEDLINE and EMBASE were searched to identify eligible studies. Short and long-term clinical studies were included with prospective and retrospective study designs to see if relevant information could be obtained on the number of implants related to the prosthetic technique. Articles reporting on implant placement combined with advanced surgical techniques such as sinus floor elevation (SFE) or extensive grafting were excluded. Two reviewers extracted the data independently. RESULTS: A primary search was broken down to 222 articles. Out of these, 29 studies comprising 26 datasets fulfilled the inclusion criteria. From all studies, the number of planned and placed implants was available. With two exceptions, no RCTs were found, and these two studies did not compare different numbers of implants per prosthesis. Eight studies were retrospective; all the others were prospective. Fourteen studies calculated cumulative survival rates for 5 and more years. From these data, the average survival rate was between 90% and 100%. The analysis of the selected articles revealed a clear tendency to plan 4 to 6 implants per prosthesis. For supporting a cross-arch fixed prosthesis in the maxilla, the variation is slightly greater. CONCLUSIONS: In spite of a dispersion of results, similar outcomes are reported with regard to survival and number of implants per jaw. Since the 1990s, it was proven that there is no need to install as many implants as possible in the available jawbone. The overwhelming majority of articles dealing with standard surgical procedures to rehabilitate edentulous jaws uses 4 to 6 implants.