Dielectric Characterization of Healthy Human Teeth from 0.5 to 18 GHz with an Open-Ended Coaxial Probe

Dental caries is a major oral health issue which compromises oral health, as it is the main cause of oral pain and tooth loss. Early caries detection is essential for effective clinical intervention. However, methods commonly employed for its diagnosis often fail to detect early caries lesions, which motivates the research for more effective diagnostic solutions. In this work, the relative permittivity of healthy permanent teeth, in caries-prone areas, was studied between 0.5 and 18 GHz. The reliability of such measurements is an important first step to, ultimately, evaluate the feasibility of a microwave device for caries detection. The open-ended coaxial probe technique was employed. Its performance showed to be compromised by the poor probe-tooth contact. We proposed a method based on applying coupling media to reduce this limitation. A decrease in the measured relative permittivity variability was observed when the space between the probe tip and tooth surface was filled by coupling media instead of air. The influence of the experimental conditions in the measurement result was found to be less than 5%. Measurements conducted in ex vivo teeth showed that the relative permittivity of the dental crown and root ranges between 10.0-11.0 and 8.0-9.5, respectively.

A Prognostic Model for the Outcome of Nobel Biocare Dental Implants with Peri-Implant Disease after One Year

Background: This investigation, based on a 1-year retrospective cohort study, aimed to estimate and validate a prognostic model for ailing and failing implants due to peri-implant disease. Methods: A total of 240 patients (male: 97; female: 143; average age of 57.3 years) with at least one ailing or failing implant were included: 120 patients for model derivation and 120 patients for model validation. The primary outcome measure was the implant status: success, defined as the arrest of the disease, or failure defined as implant extraction, prevalence or re-incidence of peri-implant disease). Potential prognostic risk indicators were collected at the baseline evaluation. The relative risk (RR) was estimated for the predictors through logistic regression and the c-statistic (95% confidence interval) was calculated for both derivation and validation sets. The significance level was set at 5%. Results: The risk model retrieved the prognostic factors age (RR = 1.04), history of Periodontitis (RR = 3.13), severe peri-implant disease status (RR = 3.26), implant length (RR = 3.52), early disease development (RR = 3.99), with good discrimination in both the derivation set (0.763 [0.679; 0.847]) and validation set (0.709 [0.616; 0.803]). Conclusions: A prognostic risk model for estimating the outcome of implants with peri-implant disease is available, with a good performance considering the c-statistic evaluation.

The All-on-4 treatment concept for the rehabilitation of the completely edentulous mandible: A longitudinal study with 10 to 18 years of follow-up

BACKGROUND

There is a need for studies evaluating the long term outcomes of the All-on-4 treatment concept.

PURPOSE

To evaluate the long term clinical and radiographic outcomes of the All-on-4 treatment concept in the mandible.

MATERIALS AND METHODS

This retrospective longitudinal case series study included 471 patients (women: 286, men: 185, average age = 57.7 years) rehabilitated with 1884 implants in immediate function supporting 471 fixed full-arch mandibular prostheses and followed for 10 to 18 years. Primary outcome measures were prosthetic survival and implant success and survival (estimated using life tables). Secondary outcome measures were marginal bone loss (MBL) at 10 and 15 years, biological and mechanical complications. Multivariable analysis was used to estimate potential risk indicators for implant failure (Cox regression to estimate hazard ratios and 95% confidence intervals (95%CI)), MBL > 3 mm at 10 and 15 years, biological and mechanical complications (binary logistic regression to estimate odds ratios [ORs] with 95%CI).

RESULTS

Twenty-seven patients deceased (5.7%) and 149 patients (31.6%) were lost to follow-up. The cumulative prosthetic survival rate was 98.8%; the implant cumulative survival and success rate was 93% and 91.7%, respectively up to 18 years of follow-up. Previous biological complications (HR = 4.43) were significantly associated with implant failure. Average (95% CI) MBL at 10- and 15-years were 1.72 mm (95%CI: 1.59, 1.85) and 2.32 mm (95% CI: 1.98, 2.66). Smoking (OR = 2.72), previous failure of a contiguous implant (OR = 3.89) and biological complication (OR = 8.11) were associated with MBL > 3 mm. The incidence of biological complications was 11.8% at implant level, with previous failure of a contiguous implant (OR = 5.56), smoking (OR = 1.75), and systemic condition (OR = 1.65) were significantly associated. The incidence of mechanical complications was 36.7% with male gender (OR = 1.67) and type of prosthetic material used in the restoration significantly associated (metal-acrylic OR = 0.30; metal-ceramic OR = 0.22)).

CONCLUSIONS

Considering the implant, prosthetic and MBL outcomes it is concluded that the All-on-4 is a viable treatment option validated in the long term. Nevertheless, biological and mechanical complications can occur.

Risk Score to Predict Dental Caries in Adult Patients for Use in the Clinical Setting

BACKGROUND

There is a need for risk prediction tools in caries research. This investigation aimed to estimate and evaluate a risk score for prediction of dental caries.

MATERIALS AND METHODS

This case-cohort study included a random sample of 177 cases (with dental caries) and 220 controls (randomly sampled from the study population at baseline), followed for 3 years. The risk ratio (RR) for each potential predictor was estimated using a logistic regression model. The level of significance was 5%.

RESULTS

The risk model for dental caries included the predictors: "presence of bacterial plaque/calculus" (RR = 4.1), "restorations with more than 5 years" (RR = 2.3), ">8 teeth restored" (RR = 2.0), "history/active periodontitis" (RR = 1.7) and "presence of systemic condition" (RR = 1.4). The risk model discrimination (95% confidence interval) was 0.78 (0.73; 0.82) (p < 0.001, C-statistic). Patients were distributed into three risk groups based on the pre-analysis risk (54%): low risk (

CONCLUSIONS

The present study estimated a simple risk score for prediction of dental caries retrieved from a risk algorithm with good discrimination.

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Key Words

• caries
• epidemiology
• risk
• tooth

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MESH Headings Collapse

Grants Collapse

Immediate function dental implants inserted with less than 30N·cm of torque in full-arch maxillary rehabilitations using the All-on-4 concept: retrospective study

The aim of this retrospective clinical study was to evaluate the short-term implant success rate and marginal bone loss in full-arch fixed prosthetic maxillary rehabilitations supported by implants in immediate function with the All-on-4 treatment concept placed with insertion torque of <30N·cm or ≥30N·cm. This study included 83 patients (69 female, 14 male) with 332 implants placed (120 inserted with <30N·cm and 212 inserted with ≥30N·cm) who were treated between January 2010 and March 2013. Outcome measures were implant success and marginal bone loss at 1year of follow-up. Ten patients (12.0%; 13 implants inserted with <30N·cm and 27 implants with ≥30N·cm) were lost to follow-up. The cumulative implant success rate was 97.5% at the patient level, and 98.3% for implants inserted with <30N·cm and 97.5% for implants inserted with ≥30N·cm. The mean±standard deviation marginal bone loss at 1year was 1.14±0.38mm for implants inserted with <30N·cm and 1.39±0.49mm for implants inserted with ≥30N·cm (significant difference; P<0.001, Wilcoxon signed rank test). These results indicate that implants with insertion torques of <30N·cm may render comparable success rates and marginal bone loss at 1year compared to implants inserted with insertion torques of ≥30N·cm.

Prevalence of periodontitis, dental caries, and peri-implant pathology and their relation with systemic status and smoking habits: Results of an open-cohort study with 22009 patients in a private rehabilitation center

OBJECTIVES

This investigation, based on a 3-year epidemiological surveillance open cohort study, aimed to provide an insight of the prevalence of periodontitis, dental caries and peri-implant pathology and to compare inferentially between healthy and systemic compromised patients.

METHODS

A total of 22009 patients were observed consisting in 9035 men (41.1%) and 12974 women (58.9%) with an average age of 48.5 years (standard deviation of 15.6years). The prevalence of the 3 chronical oral diseases was calculated. The comparison between healthy and systemic compromised patients for each oral disease was performed through multivariate logistic regression: Odds ratios (OR) with 95% confidence intervals (95%CI) were estimated in one general model and one systemic condition specific model adjusted for age and gender. Attributable fractions were estimated for systemic conditions (both models). The level of significance was set at 5%.

RESULTS

The prevalence rate of periodontitis, dental caries and peri-implant pathology was 17.6%, 36.6% and 13.9%, respectively. The systemic compromised status was associated with the prevalence of the three chronical oral diseases on the general models. The systemic condition specific models yielded Diabetes [OR=1.49, 95%CI (1.24;1.79)] and HIV+ [OR=4.37, 95%CI (1.05;18.24)] as risk indicators for Periodontitis; cardiovascular conditions [OR=1.10, 95%CI (1.01;1.20)], Diabetes [OR=1.24, 95%CI (1.05;1.46)] and neurologic conditions [OR=1.84, 95%CI (1.32;2.57)] as risk indicators for dental caries; and smoking habits as a risk indicator for all three oral diseases [OR=1.90, 95%CI (1.74;2.07) for Periodontitis; OR=1.18, 95%CI (1.09;1.27) for dental caries; OR=1.84, 95%CI (1.64;2.07) for peri-implant pathology]. Attributable fractions estimated a potential reduction of 12.2% of Periodontitis, and 4.3% of dental caries cases if the exposure to systemic conditions was prevented; while the prevention of exposure to smoking alone would result in a potential reduction of 37%, 7%, and 39% of Periodontitis, dental caries, and peri-implant pathology cases, respectively.

CLINICAL SIGNIFICANCE

The present study describes an epidemiological approach to the distribution and determinants of the three principal chronical oral diseases. The association of systemic conditions and smoking habits with oral disease prevalence highlight the importance of a narrow monitoring system.

CONCLUSIONS

The present study reported a high prevalence for oral disease and a potential association of a systemic compromised status and smoking habits with the three chronical oral diseases.

Immediate full-arch rehabilitation of the severely atrophic maxilla supported by zygomatic implants: a prospective clinical study with minimum follow-up of 6 years

The aim of this study was to evaluate the outcomes of immediate full-arch prostheses supported by zygomatic implants alone or in combination with standard fixtures after a minimum of 6 years of loading. From October 2008 to April 2010, 15 patients with severely atrophic maxillae were treated using four zygomatic implants or two zygomatic implants in conjunction with two conventional fixtures. All subjects received a fixed screw-retained prosthesis within 3hours of surgery, while the final restoration was delivered after 6 months. Follow-up examinations were scheduled to evaluate zygomatic implant survival, conventional dental implant success, prosthetic success, plaque and bleeding scores, marginal bone loss for conventional dental implants, and patient satisfaction. Forty-two zygomatic fixtures and 18 standard implants were placed. Patients were followed up for a minimum of 79 months (range 79-97 months, average 90.61 months). No implant was lost, leading to implant and prosthetic survival rates of 100%. Bone loss for conventional implants averaged 1.39±0.10mm after 6 years of function, leading to a 100% implant success rate. High levels of patient satisfaction were recorded. These medium-term results indicate that immediate full-arch rehabilitation supported by zygomatic implants could be considered a viable treatment modality for the severely atrophic maxilla.

Partial Rehabilitation with Distally Tilted and Straight Implants in the Posterior Maxilla with Immediate Loading Protocol: A Retrospective Cohort Study with 5-Year Follow-up

PURPOSE

The purpose of this study was to compare the outcome of fixed partial prostheses in the posterior maxilla with two axially placed implants or one implant placed distally tilted and one axially placed implant following an immediate loading protocol.

MATERIALS AND METHODS

A sample of 60 patients was divided into two groups-group 1: 30 patients rehabilitated with one axially placed implant and one implant placed distally tilted in the posterior maxilla; group 2: 30 patients rehabilitated with two axially placed implants in the posterior maxilla. Outcome measures were implant survival based on function, marginal bone resorption, and the incidence of mechanical and biologic complications at 5 years; inferential statistics were used to analyze the intergroup and intragroup differences. The level of significance was set at 5%.

RESULTS

No significant differences were found between both groups in survival, complications, or marginal bone resorption. One axially placed implant was lost at 58 months in group 1, rendering a cumulative survival estimate at 5 years of 96.7% and 98.3% in group 1 and the total sample, respectively (P = .317). Mechanical complications occurred in 16 patients (26.7%; n = 8 patients in each group; [P > .999]), consisting of fractures in the provisional prosthesis (n = 8 patients), chipped ceramics of the definitive prosthesis (n = 2 patients), loosening of prosthetic components (n = 5 patients), and fracture of an attachment screw (n = 1 patient). Biologic complications occurred in 5 patients (8.3%; group 1 = 4 patients; group 2 = 1 patient; [P = .161]), consisting of peri-implant pathology. The mean ± SD marginal bone loss was 2.02 ± 0.36 mm and 1.90 ± 0.69 mm for groups 1 and 2, respectively (P = .235). In group 1, the mean ± SD marginal bone loss was 1.92 ± 0.48 mm and 2.11 ± 0.44 mm for the implant placed distally tilted and axially placed implant, respectively; the difference was significant (P < .001).

CONCLUSION

Within the limitations of this study, the use of implants placed distally tilted together with axially placed implants or two axially placed implants in the fixed partial rehabilitation of the posterior maxilla are viable treatment alternatives.

Outcomes of Immediate Function Implant Prosthetic Restorations with Mechanical Complications: A Retrospective Clinical Study with 5 Years of Follow-Up

Mechanical complications may have a significant impact on the outcome of implant-supported restorations; however, few studies address the topic. This study investigated the outcomes of implant supported restorations with mechanical complications. A total of 378 patients with 378 restorations supported by 1283 implants were included. Results demonstrated a prosthetic and implant cumulative survival rate at 5 years of 99.7% and 95.7%, respectively. Maxillary implants were a determinant for implant failure (hazard ratio= 6.7), while a reduced risk was registered for single tooth restorations (hazard ratio= 0.1) after adjusting for other variables of interest.

Seven mm long dental implants in posterior jaws: 3-year report of an ongoing prospective single cohort study

PURPOSE

To report on the outcome of 7 mm long implants in the rehabilitation of posterior areas of atrophic jaws 3 years after loading.

MATERIALS AND METHODS

This prospective study included 127 patients treated with 217 implants supporting 165 fixed prostheses. Final abutments were delivered at surgery stage and in the large majority of patients (n = 116) the implants (n = 199) were loaded after 4 months. Primary outcome measures were implant success and prosthetic success calculated at patient level; secondary outcome measures were complications, and marginal bone level changes calculated at patient level.

RESULTS

Thirteen patients with 21 implants dropped out of the study after 3 years. Implant losses occurred in 10 of the 127 patients and 14 of the 217 implants placed failed, giving a cumulative success rate of 93.7% at 3 years, using the patient as unit of analysis. Eight prosthetic failures occurred in six patients, rendering a prosthetic success rate 95.3% at patient level. The average (standard deviation) marginal bone resorption after 3 years of follow-up was 1.46 mm (0.78 mm). Complications occurred in 13 patients (10.2%) and 15 implants (6.9%).

CONCLUSIONS

Within the limitations of this study, 7 mm long implants in posterior atrophic jaws can be a viable treatment option given the good prosthetic and implant success rates, low marginal bone loss and low incidence of complications. Nevertheless, longer follow-ups are needed to validate the long-term outcome. Conflict-of-interest statement: This study was funded by grant no. 2015-1378 from Nobel Biocare Services. Paulo Maló is currently a consultant for Nobel Biocare. The remaining authors declare no conflicts of interest.

Attributable fractions, modifiable risk factors and risk stratification using a risk score for peri-implant pathology

PURPOSE

This study aimed to estimate the impact of risk factors for peri-implant pathology, to identify potentially modifiable factors, and to evaluate the accuracy of the risk algorithm, risk scores and risk stratification.

METHODS

This retrospective case-control study with 1275 patients (255 cases; 1020 controls) retrieved a model according to the predictors: history of Periodontitis, bacterial plaque, bleeding, bone level, lack of passive fit or non-optimal screw joint, metal-ceramic restoration, proximity to other implants/teeth, and smoking habits. Outcome measures were the attributable fraction; the positive and negative likelihood ratios at different disease cut-off points illustrated by the area under the curve statistic.

RESULTS

Six predictors may be modified or controlled directly by either the patient or the clinician, accounting for a reduction in up to 95% of the peri-implant pathology cases. The positive and negative likelihood ratios were 9.69 and 0.13, respectively; the area under the curve was 0.96; a risk score was developed, making the complex statistical model useful to clinicians.

CONCLUSIONS

Based on the results, six predictors for the incidence of peri-implant pathology can be modified to significantly improve the outcome. It was possible to stratify patients per risk category according to the risk score, providing a tool for clinicians to support their decision-making process.

Complete Edentulous Rehabilitation Using an Immediate Function Protocol and an Implant Design Featuring a Straight Body, Anodically Oxidized Surface, and Narrow Tip with Engaging Threads Extending to the Apex of the Implant: A 5-year Retrospective Clinical Study

PURPOSE

To report the 5-year outcome of NobelSpeedy design implants in immediate function fixed prosthetic rehabilitations.

MATERIALS AND METHODS

This retrospective clinical study included 46 consecutive patients (29 women and 17 men) with an average age of 55 years (range, 32 to 78 years) who were rehabilitated between 2003 and 2004 with full-arch restorations supported by dental implants in immediate function. The primary outcome measures were implant survival calculated based on implant function and using life tables. The secondary outcome measures were marginal bone levels measured at 3 and 5 years, and the incidence of mechanical and biologic complications.

RESULTS

Five patients with 21 study implants dropped out (11%). One-hundred eighty-nine implants were inserted in the maxilla (n = 166) and mandible (n = 23). Five patients lost five implants, giving a cumulative survival rate of 97.3% at 5 years of follow-up. The average (SD) marginal bone levels were 1.45 mm (0.83 mm) and 1.72 mm (1.04 mm) at 5 years of follow-up. The incidence of mechanical complications in the provisional and definitive prostheses was registered in 14 and 6 patients, respectively: prosthetic screw loosening (n = 4 provisional prostheses, n = 3 definitive prostheses), abutment screw loosening (n = 5 provisional prostheses), fracture of the acrylic resin prostheses (n = 5 provisional prostheses, n = 1 definitive prosthesis), chipping of a ceramic crown (n = 1 definitive prosthesis), and fracture of a ceramic crown (n = 1 definitive prosthesis). The incidence of biologic complications (peri-implant pathology) was registered in 6 patients and 12 implants (7.1%).

CONCLUSION

Within the limitations of this study, it is possible to conclude that implants of the NobelSpeedy type used in immediate function for support of fixed prosthetic full-arch rehabilitations are a valid option, with a high survival rate.

Outcome of dental implants in diabetic patients with and without cardiovascular disease: A 5-year post-loading retrospective study

PURPOSE

To investigate the outcome of immediate function of dental implant rehabilitations in diabetic patients with and without coexisting cardiovascular diseases (CVD).

MATERIALS AND METHODS

This retrospective study included 70 diabetic patients (33 females and 37 males, average age: 59 years old), rehabilitated with 352 implants and divided into two groups (CVD: 38 patients; non-CVD: 32 patients). Diabetes mellitus was defined as fasting plasma glucose ≥ 7.0 mmol/l (126 mg/dl) or 2 h plasma glucose ≥ 11.1mmol/l (200 mg/dl). The data was retrieved from patient records. Primary outcome measures were prosthesis and implant survival; secondary outcome measures were marginal bone loss and complications (biological or mechanical). The follow-up was 5 years after loading for all patients.

RESULTS

Seven patients (10%) were lost to follow-up (one patient in the CVD group; and six patients in the non-CVD group). One prosthesis failed in the non-CVD group, rendering a 97.4% survival rate, compared to 100% in the CVD group (non-significant difference between groups; P = 0.359). Ten implants failed in 7 patients: CVD group with eight implant failures in 5 patients (86.7% cumulative survival rate) versus two implants in 2 patients in the non-CVD group (93.8% cumulative survival rate) with a non-significant difference between both groups (P = 0.365). The average (95% confidence interval) marginal bone loss at 1- and 5-years was 0.95 mm (0.66 mm; 1.23 mm) and 1.52 mm (1.20 mm; 1.88 mm), respectively in the CVD group; and 0.78 mm (0.40 mm; 1.16 mm) and 1.54 mm (0.86 mm; 2.31 mm), respectively for the non-CVD group; with no significant differences between groups at 1 year (P = 0.979) and 5 years (P = 0.300). Complications occurred in 38 patients (CVD group: 21 patients; non-CVD group: 16 patients); with a non-significant difference between both groups (P = 0.660).

CONCLUSIONS

Implant rehabilitations represent a valid treatment for diabetic patients with or without coexisting CVD, with a good risk/benefit ratio.

Three-Year Outcome of Fixed Partial Rehabilitations Supported by Implants Inserted with Flap or Flapless Surgical Techniques

PURPOSE

The aim of this prospective clinical study was to evaluate the 3-year outcome of fixed partial prostheses supported by implants with immediate provisionalization without occlusal contacts inserted in predominantly soft bone with flap and flapless protocols.

MATERIALS AND METHODS

Forty-one patients partially rehabilitated with 72 NobelSpeedy implants (51 maxillary; 21 mandibular) were consecutively included and treated with a flapless surgical protocol (n = 20 patients; 32 implants) and flapped surgical protocol (n = 21 patients; 40 implants). Primary outcome measure was implant survival; secondary outcome measures were marginal bone resorption (comparing the bone levels at 1 and 3 years with baseline) and the incidence of biological, mechanical, and esthetic complications. Survival was computed through life tables; descriptive statistics were applied to the remaining variables of interest.

RESULTS

Eight patients with eight implants dropped out of the study. One implant failed in one patient (flapless group) giving an overall cumulative survival rate (CSR) of 98.6%. No failures were noted with the flapped protocol (CSR 100%), while for the implants placed with the flapless surgical technique, a 96.9% CSR was registered. The overall average marginal bone resorption at 3 years was 1.37 mm (SD = 0.94 mm), with 1.14 mm (SD = 0.49 mm) and 1.60 mm (SD = 1.22 mm) for the flap and flapless groups, respectively. Mechanical complications occurred in nine patients (n = 5 patients in the flapless group; n = 4 patients in the flap group). Implant infection was registered in three implants and three patients (flapless group), who exhibited inadequate oral hygiene levels.

CONCLUSIONS

Partial edentulism rehabilitation through immediate provisionalization fixed prosthesis supported by dental implants inserted through flap or flapless surgical techniques in areas of predominantly soft bone was viable at 3 years of follow-up. The limitations and risks of the "free-hand" method in flapless surgery should be considered when planning implant-supported fixed prosthetic reconstructions.

Immediate loading short implants inserted on low bone quantity for the rehabilitation of the edentulous maxilla using an All-on-4 design

More studies evaluating the outcome of short-length dental implants in immediate loading are needed. To evaluate the use of short-length tapered implants in immediate loading for complete edentulous maxillae rehabilitations using an All-on-4 design. This retrospective clinical study included a cohort of 43 patients with 172 implants (74 short-length implants) inserted in low bone quantity. The patients were followed between 4 months and 6 years (average = 3 years). Outcome measures were implant survival, marginal bone remodelling, biological and mechanical complications. Two patients with four short-length implants were lost to follow-up during the first year. Three short and three long implants failed in four patients, rendering an overall cumulative survival rate implant and patient level, respectively, of 95.7% and 95.1% for short implants, 100% for regular implants and 96.6% and 95.2% for long implants. The average marginal bone remodelling at 1 and 3 years was 0.97 and 1.25 mm for the short implants, 0.82 and 0.87 mm for regular implants and 0.87 and 0.98 mm for long implants. Three patients presented 4 short-length implants with peri-implant pockets (3 implants in 2 patients were pseudo-pockets). Mechanical complications were registered in 13 patients (7 provisional prostheses fractures and 6 abutment screw loosening). All complications were treated successfully. Within the limitations of this clinical study, the short-term outcome of fixed prosthetic complete edentulous maxillae rehabilitations supported by short-length implants inserted in low bone quantity areas is viable. Long-term clinical studies are necessary for evaluating the outcome of these implants.

Posterior maxillary implants inserted with bicortical anchorage and placed in immediate function for partial or complete edentulous rehabilitations. A retrospective clinical study with a median follow-up of 7 years

PURPOSE

The aim of this study was to report the outcome of posterior maxillary implants inserted with "bicortical anchorage" in medium or low-density bone and placed in immediate function for the rehabilitation of patients with partial or complete edentulism.

METHODS

Eighty-eight patients (32 males and 56 females, mean age = 54 years; range 28-78 years) were included from October 1999 to November 2008, and followed between 6 months and 13 years (median of 7 years). A total of 124 posterior maxillary implants were inserted with bicortical anchorage (engaging the cortical plates of the maxillary crest along with that of either the sinus or nasal cavities) as follows: MkII (n = 1), MkIII (n = 6), MkIV (n = 18), and NobelSpeedy Groovy (n = 99); (Nobel Biocare AB). Implants were evaluated on the basis of survival, marginal bone levels, and complications (mechanical and biological).

RESULTS

Eleven patients dropped out of the study (12.5 %). Four implants were lost in four patients who underwent complete edentulous rehabilitations, yielding a cumulative survival rate of 94.2 % after a median follow-up of 7 years. The survival rate for the prostheses was 100 %. The marginal bone levels were on average 1.56 mm (standard deviation of 0.87 mm), after 5-years of follow-up. Biological complications occurred with 17 implants in 17 patients. Mechanical complications occurred in 49/88 patients. Thirty of these 49 patients were heavy bruxers.

CONCLUSIONS

Within the limitations of this study, fixed prosthetic rehabilitations for partial and complete edentulism supported by implants in the posterior maxilla which are inserted with bicortical anchorage and placed in immediate function is a viable concept on long-term follow-up. Nevertheless, controlling the occlusion is mandatory in order to decrease the likelihood of mechanical complications.

All-on-4® Treatment Concept for the Rehabilitation of the Completely Edentulous Mandible: A 7-Year Clinical and 5-Year Radiographic Retrospective Case Series with Risk Assessment for Implant Failure and Marginal Bone Level

BACKGROUND

Studies are needed to evaluate long-term outcomes of the All-on-4® treatment concept (Nobel Biocare AB) for rehabilitation of edentulous mandibles by assessing marginal bone levels and risk indicators for implant failure.

PURPOSE

To evaluate 7-year clinical outcomes and 5-year radiographic outcomes of the All-on-4 treatment concept.

MATERIALS AND METHODS

This retrospective case series included patients admitted for implant rehabilitations in the mandible, who were followed for 7 years clinically and 5 years radiographically. Primary outcome measures were cumulative prosthetic and implant survival using patient as the unit of analysis (Kaplan-Meier product limit estimator). Secondary outcome measure was marginal bone level (MBL) at 5 years. Variables associated with implant failure were analyzed using the Cox proportional hazards regression model to calculate hazard ratios (HRs) with 95% confidence intervals (CIs). Binary logistic regression was used to compute odds ratio (OR) with 95% CIs for variables associated with MBL ≥2.8 mm at 5 years.

RESULTS

A total of 324 patients (194 women, 130 men, average age = 58.9 years) were rehabilitated with 1,296 implants supporting 324 full-arch fixed immediately loaded mandibular prostheses. Sixty-four patients (19.8%) were lost to follow-up. Prosthetic survival was 323/324 (99.7%), and 14 patients lost 18 implants, with an estimated cumulative survival rate of 95.4% at 7 years. Variables associated with implant failure were smoking (HR = 5.28; 95% CI: 1.33, 20.91]) and the learning curve effect (0.69 < HR < 0.33 for more experienced levels). Mean MBL at 5 years was 1.81 mm (95% CI: 1.70, 1.92), and smoking was associated with MBL ≥2.8 mm (OR = 2.4; 95% CI: 1.02, 5.62).

CONCLUSIONS

The high implant and prosthetic survival rates and excellent MBL outcome confirm the predictability and safety of the All-on-4 treatment concept over a longer term than previously reported.