Platform switching in two-implant bar-retained mandibular overdentures: 1-year results from a split-mouth randomized controlled clinical trial.

OBJECTIVES: The concept of platform switching is widely applied in current implant dentistry; however, the influence on peri-implant bone-level alterations (ΔIBL), especially in the field of implant overdentures (IODs), remains inconclusive. Therefore, the present study aimed to test the alternative hypothesis that there is an equivalent ΔIBLs at platform-switching and platform-matching implant abutments in 2-implant bar-retained IODs. MATERIALS AND METHODS: Two interforaminal implants were placed in 32 subjects, who were randomly assigned to either an immediate- or a 3-month post-placement loading group. Furthermore, one implant in each subject was randomly assigned to receive a platform-switched abutment (test), and one a platform-matching abutment (control). The implants were splinted with prefabricated, chairside customized bars. ΔIBL was recorded by using customized radiograph holders at implant placement, implant loading, 3 months, 6 months, and 12 months after loading. RESULTS: After 1 year, equivalent ΔIBL could be identified (test: -0.51 mm ± 0.49 versus control: -0.56 mm ± 0.52; p < .001). ΔIBL increased over time and was more pronounced in the delayed-loaded implants (-0.87 mm ± 0.61) relative to the immediately loaded implants (-0.35 mm ± 0.43; p = .022). CONCLUSIONS: The prosthetic concept of platform switching does not necessarily lead to reduced bone loss. Immediate-loading of implants, primarily splinted with a bar, might be beneficial regarding peri-implant bone-level alterations over a short-term period.

On Implant Prosthodontics: One Narrative, Twelve Voices - 6.

No abstract available.

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.

Are there differences in the changes in oral-health-related quality of life (OHRQoL) depending on the type (rigidity) of prosthetic treatment?

OBJECTIVE: This prospective pilot study investigated differences in changes in oral-health-related quality of life (OHRQoL) depending on the prosthetic treatment type (rigidity). METHOD AND MATERIALS: Sixty participants seeking prosthetic treatment were included. The following data were collected before (T1) and 4 weeks after completion of prosthetic treatment (T2): OHRQoL (OHIP-G14) and dental status, categorized in terms of rigidity of the denture as fixed dental prosthesis (FDP, maximal rigidity), removable partial denture prosthesis (RPD, medium rigidity), or complete dentures (CDs, minimal rigidity). After prosthetic treatment, there were three groups of 20 participants: group 1, change in dental status to less rigid; group 2, equally rigid; group 3, more rigid restorations. Data were evaluated using nonparametric statistical test methods and power analysis. The minimally important difference (MID) of two OHIP-G14 units was determined to be clinically relevant. RESULTS: At T1, 20 participants had FDP, 18 RPD, and 22 CD; at T2, 10 had FDP, 37 RPD, and 13 CD. Overall, average OHIP-G14 values improved clinically relevantly and statistically significantly (P < .001) with treatment. OHRQoL improved more in group 3, with a median of 8 (IQR 14.75; P = .002), than in group 2, with 2.5 (IQR 9.5; P = .033), or group 1, with 4.5 (IQR 16.5; P = .116). Applying MID, all groups improved clinically significantly. Compared to groups 1 and 2, group 3 improved clinically more significantly. CONCLUSION: OHRQoL improved with prosthetic treatment. A patient-customized treatment regime seems as important as prosthesis type (rigidity).

Mucosal Manifestations in the Edentulous Maxilla with Implant Supported Prostheses: Clinical Results from a Well-Maintained Patient Cohort.

BACKGROUND: Prostheses in the edentulous maxilla affect the mucosa. PURPOSE: To evaluate mucosal alterations with implant supported fixed prostheses (FDP) and overdentures (IOD). MATERIAL AND METHODS: Patients receiving prostheses during a time period of 10 years were recruited. Maxillary mucosal conditions in relation to FDPs, IODs were analyzed. Peri-implant parameters were measured and the Oral Health Impact Profile (OHIP) was administered. RESULTS: One hundred seven patients wearing 74 IODs and 33 FDPs were identified with a total of 519 implants, the mean observation time was 6.5 ± 2.7. Cumulative implant survival was 93%. Erythema and hyperplastic tissue were identified in 71% of the IOD wearers, but were mostly absent with FDPs. The peri-implant parameters demonstrated healthy peri-implant mucosa. Medication and smoking had no effect on mucosal alteration (OR = 1.065 and 1.568). The average OHIP value was 3.73 ± 4.12. A lower value (p < 0.0048) was found for FDPs and one type of IOD. CONCLUSIONS: A rigorous maintenance program did not prevent IOD mucosal alterations in IOD wearers, but the health of the peri-implant mucosa was maintained and was comparable for all types of prostheses.

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.

Die chirurgische Kronenverlängerung zur Verbesserung der biologischen Breite und Ästhetik.

The aims of surgical crown lengthening procedures are to improve prosthetic reconstructions at teeth with limited hard tissue, to prevent periodontal problems and/or to improve esthetics. When planning and performing surgical crown lengthening, it is important to consider not only periodontal and technical aspects but also the gingival profile of the neighbouring teeth. This paper presents the systematic approach starting with the diagnosis and indication to the performed treatments and the obtained results and gives clinical recommendations.

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.

Space requirement of a prefabricated bar on two interforaminal implants: a prospective clinical study.

OBJECTIVES: This clinical study measured the dimensional changes of existing lower complete dentures due to the integration of a prefabricated implant bar. Additionally, the impact of this dimensional change on patient satisfaction and oral function was analyzed. METHODS: Twenty edentulous patients (10 men/10 women; aged 65.9 ± 11.8 years) received two interforaminal implants. Subsequent to surgery, a chair side adapted, prefabricated bar (SFI Bar(®), C+M, Biel, Switzerland) was inserted, and the matrix was polymerized into the existing lower denture. The change of the denture's lingual dimension was recorded by means of a bicolored, silicone denture duplicate that was sectioned in the oro-vestibular direction in the regions of the symphysis (S) and the implants (I-left, I-right). On the sections, the dimensional increase was measured using a light microscope. Six months after bar insertion, patients answered a standardized questionnaire. RESULTS: All dentures exhibited increased lingual volume, more extensively at S than at I (P = 0.001). At S, the median diagonal size of the denture was doubled (+4.33 mm), and at I, the median increase was 50% (I-left/-right = +2.66/+2.62 mm). The original denture size influenced the volume increase (P = 0.024): smaller dentures led to a larger increase. The amount of denture increase did not have negative impact on either self-perceived oral function or patient satisfaction. Approximately, 95% of the patients were satisfied with the treatment results. CONCLUSIONS: The lingual size of a lower denture was enlarged by the integration of a prefabricated bar without any negative side effects. Thus, this attachment system is suitable to convert an existing full denture into an implant-supported overdenture.

The patent nasopalatine duct: a potential cause of unclear pain in the anterior maxilla.

OBJECTIVE: The aim of this report is to describe symptoms that can suggest the presence of a patent nasopalatine duct and to illustrate three cases. SUMMARY: Patent nasopalatine ducts connecting the oral cavity with the nasal cavity are extremely rare. This malformation can be considered a developmental abnormality. Clinically, patent nasopalatine ducts appear as single or double spherical or oval apertures lateral or posterior to the incisive papilla. This type of anatomical malformation can be associated with an unclear pain sensation in the anterior maxillary region, which may be misinterpreted for example as toothache of endodontic origin. However, persisting nasopalatine ducts can also exist as an asymptomatic abnormality with no clinical sign of discomfort. Accordingly, understanding the differential diagnosis of a possible patent nasopalatine duct can prevent a general practitioner from performing unnecessary interventions, such as endodontic treatments, apical surgeries, or tooth extractions.

CAD/CAM fabrication accuracy of long- vs. short-span implant-supported FDPs.

OBJECTIVE: To compare the precision of fit of long-span vs. short-span implant-supported screw-retained fixed dental prostheses (FDPs) made from computer-aided-design/computer-aided-manufactured (CAD/CAM) titanium and veneered with ceramic. The null hypothesis was that there is no difference in the vertical microgap between long-span and short-span FDPs. MATERIALS AND METHODS: CAD/CAM titanium frameworks for an implant-supported maxillary FDP on implants with a flat platform were fabricated on one single master cast. Group A consisted of six 10-unit FDPs connected to six implants (FDI positions 15, 13, 11, 21, 23, 25) and group B of six 5-unit FDPs (three implants, FDI positions 21, 23, 25). The CAD/CAM system from Biodenta Swiss AG (Berneck, Switzerland) was used for digitizing (laser scanner) the master cast and anatomical CAD of each framework separately. The frameworks were milled (CAM) from a titanium grade V monobloc and veneered with porcelain. Median vertical distance between implant and FDP platforms from the non-tightened implants (one-screw test on implant 25) was calculated from mesial, buccal, and distal scanning electron microscope measurements. RESULTS: All measurements showed values <40 µm. Total median vertical microgaps were 23 µm (range 2-38 µm) for group A and 7 µm (4-24 µm) for group B. The difference between the groups was statistically significant at implant 21 (P = 0.002; 97.5% CI -27.3 to -4.9) and insignificant at implant 23 (P = 0.093; -3.9 to 1.0). CONCLUSIONS: CAD/CAM fabrication including laboratory scanning and porcelain firing was highly precise and reproducible for all long- and short-span FDPs. While all FDPs showed clinically acceptable values, the short-span FDPs were statistically more precise at the 5-unit span distance.

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.

Complications with computer-aided designed/computer-assisted manufactured titanium and soldered gold bars for mandibular implant-overdentures: short-term observations.

BACKGROUND: Implant-overdentures supported by rigid bars provide stability in the edentulous atrophic mandible. However, fractures of solder joints and matrices, and loosening of screws and matrices were observed with soldered gold bars (G-bars). Computer-aided designed/computer-assisted manufactured (CAD/CAM) titanium bars (Ti-bars) may reduce technical complications due to enhanced material quality. PURPOSE: To compare prosthetic-technical maintenance service of mandibular implant-overdentures supported by CAD/CAM Ti-bar and soldered G-bar. MATERIALS AND METHODS: Edentulous patients were consecutively admitted for implant-prosthodontic treatment with a maxillary complete denture and a mandibular implant-overdenture connected to a rigid G-bar or Ti-bar. Maintenance service and problems with the implant-retention device complex and the prosthesis were recorded during minimally 3-4 years. Annual peri-implant crestal bone level changes (ΔBIC) were radiographically assessed. RESULTS: Data of 213 edentulous patients (mean age 68 ± 10 years), who had received a total of 477 tapered implants, were available. Ti-bar and G-bar comprised 101 and 112 patients with 231 and 246 implants, respectively. Ti-bar mostly exhibited distal bar extensions (96%) compared to 34% of G-bar (p < .001). Fracture rate of bars extensions (4.7% vs 14.8%, p < .001) and matrices (1% vs 13%, p < .001) was lower for Ti-bar. Matrices activation was required 2.4× less often in Ti-bar. ΔBIC remained stable for both groups. CONCLUSIONS: Implant overdentures supported by soldered gold bars or milled CAD/CAM Ti-bars are a successful treatment modality but require regular maintenance service. These short-term observations support the hypothesis that CAD/CAM Ti-bars reduce technical complications. Fracture location indicated that the titanium thickness around the screw-access hole should be increased.

In vitro precision of fit of computer-aided designed and computer-aided manufactured titanium screw-retained fixed dental prostheses before and after ceramic veneering.

OBJECTIVE: To compare the precision of fit of full-arch implant-supported screw-retained computer-aided designed and computer-aided manufactured (CAD/CAM) titanium-fixed dental prostheses (FDP) before and after veneering. The null-hypothesis was that there is no difference in vertical microgap values between pure titanium frameworks and FDPs after porcelain firing. MATERIALS AND METHODS: Five CAD/CAM titanium grade IV frameworks for a screw-retained 10-unit implant-supported reconstruction on six implants (FDI tooth positions 15, 13, 11, 21, 23, 25) were fabricated after digitizing the implant platforms and the cuspid-supporting framework resin pattern with a laser scanner (CARES(®) Scan CS2; Institut Straumann AG, Basel, Switzerland). A bonder, an opaquer, three layers of porcelain, and one layer of glaze were applied (Vita Titankeramik) and fired according to the manufacturer's preheating and fire cycle instructions at 400-800 °C. The one-screw test (implant 25 screw-retained) was applied before and after veneering of the FDPs to assess the vertical microgap between implant and framework platform with a scanning electron microscope. The mean microgap was calculated from interproximal and buccal values. Statistical comparison was performed with non-parametric tests. RESULTS: All vertical microgaps were clinically acceptable with values <90 µm. No statistically significant pairwise difference (P = 0.98) was observed between the relative effects of vertical microgap of unveneered (median 19 µm; 95% CI 13-35 µm) and veneered FDPs (20 µm; 13-31 µm), providing support for the null-hypothesis. Analysis within the groups showed significantly different values between the five implants of the FDPs before (P = 0.044) and after veneering (P = 0.020), while a monotonous trend of increasing values from implant 23 (closest position to screw-retained implant 25) to 15 (most distant implant) could not be observed (P = 0.169, P = 0.270). CONCLUSIONS: Full-arch CAD/CAM titanium screw-retained frameworks have a high accuracy. Porcelain firing procedure had no impact on the precision of fit of the final FDPs. All implant microgap measurements of each FDP showed clinically acceptable vertical misfit values before and after veneering. Thus, the results do not only show accurate performance of the milling and firing but show also a reproducible scanning and designing process.

Internal bacterial colonization of implants: association with peri-implant bone loss.

OBJECTIVES: The aim of the present longitudinal study was to investigate bacterial colonization of the internal implant cavity and to evaluate a possible association with peri-implant bone loss. METHODS: A total of 264 paper point samples were harvested from the intra-implant cavity of 66 implants in 26 patients immediately following implant insertion and after 3, 4, and 12 months. Samples were evaluated for Aggregatibacter actinomycetemcomitans, Fusobacterium nucleatum, Porphyromonas gingivalis, Prevotella intermedia, Treponema denticola, and Tannerella forsythia as well as total bacterial counts by real-time PCR. Bone loss was evaluated on standardized radiographs up to 25 months after implant insertion. For the statistical analysis of the data, mixed effects models were fitted. RESULTS: There was an increase in the frequency of detection as well as in the mean counts of the selected bacteria over time. The evaluation of the target bacteria revealed a significant association of Pr. intermedia at 4 and 12 months with peri-implant bone loss at 25 months (4 months: P = 0.009; 12 months: P = 0.021). CONCLUSIONS: The present study could demonstrate a progressive colonization by periodontopathogenic bacteria in the internal cavities of two-piece implants. The results suggest that internal colonization with Pr. intermedia was associated with peri-implant bone loss.

[Enlargement of keratinized peri-implant mucosa at the time of second stage surgery (re-entry)]. / Verbreiterung der keratinisierten periimplantären Mukosa zum Zeitpunkt der Implantatwiedereröffnung.

A tightly attached keratinized mucosa around endosseous dental implants is believed to be protective against peri-implant bone loss. Tension caused by buccal frena and mobile non keratinized mucosa is to avoid. This case report documents the optimization of peri-implant mucosal conditions in the upper and lower jaw. At the time of second stage surgery (re-entry) at submucosally osseointegrated dental implants an enlargement of keratinized mucosa and a thickening of soft tissue was obtained administrating a vestibuloplasty combined by a free gingival graft or a vestibuloplasty combined by an apically moved flap.

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.