Comparison of immediately loaded flapless-placed one-piece implants and flapped-placed conventionally loaded two-piece implants, both fitted with all-ceramic single crowns, in the posterior mandible: 3-year results from a randomised controlled pilot trial.

PURPOSE: To compare outcomes for immediately loaded one-piece implants (OPI), placed flapless, and conventionally loaded two-piece implants (TPI), placed after two-stage flapped surgery. MATERIALS AND METHODS: Thirty-eight participants were randomised to receive either one OPI (19 participants, OPI group) or one TPI (19 participants, TPI group) inserted in the posterior mandible with a torque of at least 35 Ncm according to a parallel group design. OPI were immediately loaded with non-occluding temporary crowns. After 3 months, TPI were exposed and implants in both groups were occlusally loaded with zirconia crowns. Outcome measures were implant failure, prosthesis failure, any complication and changes of probing pocket depth (PPD), plaque index (PI), gingiva index (GI), and peri-implant marginal bone level, recorded by unblinded assessors. RESULTS: Three years after occlusal loading, three participants dropped out from the TPI group. There were no statistically significant differences between the groups with regard to participants with implant failure (OPI group 1/19; TPI group 0/16; difference in proportions (DIP), -5.3%; 95% confidence interval (CI) -15.3 to 4.8; P = 1.000), prosthesis failure (OPI group 3/19, TPI group 5/16; DIP, 15.5%; 95% CI -12.6 to 43.5; P = 0.424), any complication (OPI group 6/19, TPI group 5/16; DIP, -0.3%; 95% CI -31.2 to 30.5; P = 1.000), or changes of PPD (P =0.174), PI (P = 0.222), or GI (P = 0.415). Veneer chipping accounted for most prosthesis failures and complications. On average OPI and TPI lost 1.34 mm and 0.67 mm of marginal bone, respectively, the difference between groups being statistically significant (mean difference, 0.66 mm; 95% CI -0.02 to 1.34; P = 0.024) in favour of TPI implants. CONCLUSIONS: Both implant procedures might be viable in the short term, but statistically significantly more bone loss might be indicative of future problems with OPI. Because of the high incidence of chipping, veneered zirconia crowns cannot be recommended on posterior implants. Conflict-of-interest statement: The authors are grateful to Nobel Biocare for providing the study materials free of charge. Money received from the manufacturer was used to reimburse participants for regular attendance at follow-up appointments and to finance data management. The authors declare no conflict of interest.

Radiographic monitoring of changes in bone height after implant placement in combination with an internal sinus lift without graft material.

PURPOSE: The objective was to investigate changes in bone height after implant placement in combination with simultaneous internal sinus lift (ISL) without graft material. MATERIALS AND METHODS: For a retrospective clinical study, 101 implants placed in combination with ISL without graft were selected. The study included 66 patients (mean age 59.6 years) with radiographs from baseline (T0) and two follow-ups after mean times of 7 months (T1) and 17 months (T2). Apical changes in bone height were measured at the mesial and distal aspects of the implant. Correlation analysis was performed to identify factors affecting changes in bone height. RESULTS: Mean apical bone gains of 1.0 mm (mesial) and 1.7 mm (distal) were observed at T1. At T2, mean apical bone gains were 1.5 mm and 2.1 mm (distal). The change in apical bone height was significant between T0 and T1, between T0 and T2, and between T1 and T2. Rank correlation analysis revealed a significant correlation (Spearman rho: -0.2 to -0.4) between small initial bone height and a greater amount of apical bone gain. CONCLUSIONS: A gain in apical bone height can be expected if implants are placed in combination with ISL without graft material. Variability is high, however.

Short-term complications of implant-supported and combined tooth-implant-supported fixed dental prostheses.

OBJECTIVE: The objective of this clinical study was to evaluate survival and incidence of complications for metal-ceramic and all-ceramic implant-supported fixed dental prostheses (FDPs) and tooth-implant-supported FDPs. MATERIAL AND METHODS: One-hundred and sixty-six FDPs placed in 132 patients from a prospective study were selected for this retrospective analysis. Included were 91 conventional implant-supported FDPs with implant support on both extremities, 27 implant-supported cantilever FDPs, and 48 tooth-implant-supported FDPs. All restorations were veneered with ceramic. Twenty-six FDPs had a zirconia framework and 140 had a metal framework. Kaplan-Meier analysis was performed to estimate FDP success defined as complication-free survival and the Cox regression model was used to isolate risk factors for the most frequent complications. RESULTS: Within a median follow-up of 1 year and 2 months, three failures were caused by a failed implant (n = 2) and by extended chipping of the veneer (n = 1). In contrast with this low incidence of failure was a high incidence of complications including chipping (n = 29), loss of retention (n = 35), and abutment fractures (n = 2). Multivariate survival analysis revealed a significantly greater incidence of chipping for males and a tendency to increased incidence of chipping for zirconia-based FDPs. The incidence of loss of retention tended to be less for tooth-implant-supported FDPs, for which semi-permanent cement was the only significant risk factor, with a hazard ratio of almost 5. CONCLUSIONS: As chipping of the ceramic veneer was the most frequent complication leading to substantial aftercare, improvements of ceramic veneers are desirable for zirconia-based and metal-based FDPs.

Influence of bone augmentation procedures on the short-term prognosis of simultaneously placed implants.

OBJECTIVES: The purpose of this study was to investigate the effect of simultaneous bone-augmentation procedures, and their combination, on the survival of dental implants and on the incidence of complications. MATERIAL AND METHODS: Within a retrospective analysis, 958 implants placed in 404 patients (mean age 58.18) were selected from a prospective clinical study. In 304 cases of reduced bone width, bone spreading (n = 217) with hand osteotomes, or bone splitting (n = 15), or guided bone regeneration (n = 72) combined with autogenous bone grafts were also performed. Eighty-eight implants were placed in combination with simultaneous internal sinus floor elevation without using graft material. For 194 additional implants, several augmentation procedures were combined because of extensive bone deficits. Three-hundred and seventy-two conventionally placed implants served as controls. Implant failures and complications were recorded after a mean observation period of 2.1 years (maximum 6.9 years). RESULTS: Seventeen failures and nine additional implant-related complications were observed. After 4 years, Kaplan-Meier curves revealed a probability of survival without complication of 97.5% for conventionally placed implants, and 95.8% for implants placed in combination with a single augmentation technique. If several augmentation techniques were combined, success decreased to 94.1%. Complication-free survival differences between combined augmentation techniques and conventionally placed implants were significant (P = 0.004). Age, gender, and location showed no effect on implant survival. CONCLUSIONS: It can be concluded that simultaneous bone-augmentation techniques slightly reduce short-term prognosis for dental implants. This effect was more pronounced when advanced defects required the combination of several augmentation procedures.

Clinical success of implant-supported and tooth-implant-supported double crown-retained dentures.

The objective of this retrospective study was to compare biological and technical complications of implant-supported and tooth-implant-supported double crown-retained dentures (DCRDs) with those of tooth-supported DCRDs. Sixty-three DCRDs were monitored. One study group included 16 prostheses with a combination of implants and natural teeth as double crowns (ti group), whereas in the second study group, 19 dentures were retained exclusively on implants (ii group); a third study group with 28 exclusively tooth-supported dentures served as controls (tt group). Tooth loss, implant failure, and technical complications (loss of retention of primary crown, abutment screw loosening, loss of facing, fracture of resin denture teeth and fracture of saddle resin) were analysed. During the observation period of 24 months, no implants or teeth were lost in the ti group and three technical complications were recorded. In the ii group, two implants were lost, two cases of peri-implantitis occurred and four technical complications were observed. In the tt group, two cases of tooth loss and seven technical complications were observed. At the time of the last examination, all prostheses of the ti group and the ii group were functional. Patients of these two study groups reported high satisfaction with both function and aesthetics with no significant difference between the two groups. Treatment with DCRDs showed comparable results in the three study groups. The 2-year results indicate that double crowns can be recommended for implant and combined tooth-implant-retained dentures.

Fracture load of tooth-implant-retained zirconia ceramic fixed dental prostheses: effect of span length and preparation design.

OBJECTIVES: Evaluation of the effect of different span length and preparation designs on the fracture load of tooth-implant-supported fixed dental prostheses (TIFDPs) manufactured from yttrium-stabilized zirconia frameworks. MATERIAL AND METHODS: Forty-eight TIFDPs were manufactured using a CAD/CAM system and veneered with a press ceramic. Rigidly mounted implants (SLA, diameter 4.1 mm, length 10 mm) in the molar region with a titanium abutment were embedded in PMMA bases pairwise with premolars. All premolars were covered with heat-shrink tubing to simulate physiological tooth mobility. Six different test groups were prepared (a) differing in the preparation design of the premolar (inlay [i]; crown [c]), (b) the material of the premolar (metal [m]; natural human [h]) and (c) the length of the TIFDPs (3-unit [3]; 4-unit [4]). All TIFDPs underwent thermomechanical loading (TCML) (10,000 × 6.5°/60°; 6 × 10(5) × 50 N). The load to fracture (N) was measured and fracture sites were evaluated macroscopically. RESULTS: None of the restorations failed during TCML. The mean fracture loads (standard deviations) were 1,522 N (249) for the 3-unit, inlay-retained TIFDPs on a metal abutment tooth (3-im), 1,910 N (165) for the 3-cm group, 1,049 N (183) for group 4-im, 1,274 N (282) for group 4-cm, 1,229 N (174) for group 4-ih and 911 N (205) for group 4-ch. Initial damages within the veneering ceramic occurred before the final failure of the restoration. The corresponding loads were 24-52% lower than the fracture load values. CONCLUSIONS: All restorations tested could withstand the mastication forces expected. Fracture-load values for 3- and 4-unit inlay-crown and crown-crown-retained TIFDPs should spur further clinical investigation.

Effect of the osteotome technique in cases of deficient edentulous ridge.

PURPOSE: The use of dental implants may be limited by lack of sufficient bone. The effectiveness of the alveolar ridge bone-spreading technique in the maxilla was compared with the standard technique. Bone spreading is a technique in which hand osteotomes are used to progressively enlarge the remaining deficient edentulous ridge to enable placement of dental implants. MATERIALS AND METHODS: In the test group (bone spreading), 72 patients received 126 implants. Thirty-six patients with 63 implants placed with conventional implant preparation served as a control group. Measurements of outcome were implant failure and complications after therapy. Kaplan-Meier curves were used to depict time from implant placement to implant failure or complication. RESULTS: Six complications were observed after placement of the implants (3 implant failures, peri-implant inflammation in 2 implants, and 1 exposure of rough implant surface). There was a trend toward more implant failures in the control group. CONCLUSIONS: Results of the ridge-spreading technique seem to be similar to those of the standard technique. However, these results should be regarded with caution because of the small number of complications.

Effect of gingival ceramic veneer thickness on the fracture strength of zirconia-based fixed dental prostheses.

PURPOSE: To assess the effect of different thicknesses of porcelain at the gingival of pontics, on the fracture load of zirconia-based, all-ceramic fixed dental prostheses (FDPs), anchored by inlays. METHODS: Box inlay cavities were prepared on mandibular molars and premolars. 40 FDPs with yttrium-stabilized zirconia frameworks of identical dimensions were manufactured using a CAD/CAM system and veneered with a press ceramic. The FDPs, replacing a premolar and a molar, were divided into four groups. In Group FR, the framework was all around unveneered. The next three groups received a 1 mm ceramic veneer on the buccal, occlusal and lingual side, but differed in the thickness of the ceramic veneer in the gingival, tensile zone of the pontics. In Group B-0, the gingival veneering was 0 mm, in Group B 1 mm and in Group B-2, 2 mm of gingival porcelain. A group of inlay-retained metal-ceramic FDPs (mc) served as control. All FDPs were subjected to thermal cycling and 600,000 cycles of mechanical load of 50 N. The load to fracture (N) was measured and fracture sites were evaluated macroscopically. A single-factor Analysis of Variance was used to analyze the data. RESULTS: None of the FDPs debonded after thermal cycling or mechanical loading and no signs of fractures or other defects were observed. The mean fracture loads and standard deviations in parentheses were: 647 N (123) for Group B-0, 716 N (102) for Group FR, 812 N (48) for Group B-1, 934 N (129) for Group B-2 and 1005 N (SD 81) for Group MC. Means for Groups B-0 and FR were not shown to differ, and the same for mean fracture strength of Groups B-2 and MC.

Early loading of implants with fixed dental prostheses in edentulous mandibles: 4.5-year clinical results from a prospective study.

AIM: The purpose of this study was to evaluate the survival and success of early-loaded implants placed in the intraforaminal area of the edentulous mandible, and the survival of the implant-supported fixed dental prostheses (FDP). MATERIAL AND METHODS: Thirty-seven patients (18.9% male, mean age 64.5 years) with edentulous lower jaws were treated with implant-supported FDPs in the mandible. One hundred and eighty-five screw-type implants were placed in the intraforaminal area of the symphysis (five implants per patient). Immediately after implant placement, a framework was fabricated and the FDP was manufactured on the framework. Within 2 weeks, the implants were rigidly connected and loaded with the implant-retained FDP. RESULTS: During the 1-8-year observation period (mean 4.5 years), a total of 32 implant-retained complications occurred. Nineteen implants were lost in 10 patients, resulting in a cumulative survival of 89.7%. Nine implants in five patients did not osseointegrate. Although these implants were not removed, because stability within the connective tissue was acceptable and inflammation was absent, they were recorded as unsuccessful. Consequently, the cumulative success declined to 84.9%. Four implants in three patients had clinical signs of periimplantitis (2.2% of all implants). Denture-related complications included one complete failure, when one FDP had to be removed after the last of five implants had been replaced. Furthermore, 10 fractures of the framework occurred in six patients, three FDPs had to be adapted or modified, and the facing of the FDP had to be repaired 16 times in 11 patients. CONCLUSION: Although one-stage early-loaded implants functioned well for most patients with edentulous mandibles, immediate loading is associated with a larger number of implant-related complications than in other studies investigating delayed loading. Because of the substantial prosthetic complications and aftercare, this procedure cannot be generally recommended.

Fracture-load values of all-ceramic cantilevered FPDs with different framework designs.

The purpose of this study was to evaluate the fracture-load values of cantilevered all-ceramic fixed partial dentures (FPDs). Fifty FPDs were manufactured using a zirconia frame to replace a missing molar. The FPDs were divided into five groups, each with a different framework design. After thermocycling and mechanical loading, the load to fracture was measured. The Mann-Whitney Utest was used for statistical analysis. The mean fracture-load values for the test groups ranged from 346 to 548 N. Reinforcement of the shoulder on the oral side of the occlusal wall resulted in higher fracture load values, while increasing the wall thickness of the distal abutment did not improve fracture resistance. The results indicate that all-ceramic cantilever FPDs cannot yet be recommended for clinical replacement of a missing molar.

Implants placed in combination with an internal sinus lift without graft material: an analysis of short-term failure.

AIM: Investigation of the short-term survival of implants placed in combination with an internal sinus lift (ISL) without graft material. MATERIAL AND METHODS: Thirty-six patients received 92 screw-shaped dental implants in combination with an ISL. No bone grafts or bone substitutes were used. Forty-four patients with 77 implants in the native posterior maxilla served as controls. X-rays taken after implant placement and 6 months later were evaluated for the presence of bone gain at the apical aspect of the implants. Kaplan-Meier survival curves and Cox regression analysis were used to estimate survival curves and to isolate risk factors for implant failures. RESULTS: Within a mean observation period of 1.2 years (minimum 9 months; maximum 3.7 years), four failures were recorded in the experimental group and two in the controls. The probability of survival was above 94% for both groups. Six-nine months after surgery, bone gain was observed in 29 out of 92 implants. Comparison of the experimental group and controls revealed no effect of ISL and membrane perforation on the probability of survival. CONCLUSIONS: Promising short-term outcomes were observed for implants with ISL without graft material; for a substantial proportion of implants, apical bone gain was observed in the first 6-9 months.

Fracture behaviour of zirconia ceramic cantilever fixed dental prostheses in vitro.

OBJECTIVE: Evaluation of the fracture resistance of all-ceramic cantilever fixed dental prostheses (FDPs) manufactured from zirconia frameworks and veneered with a press ceramic. MATERIAL AND METHODS: Two mandibular premolars were prepared either with a box inlay cavity or with a full crown chamfer preparation and then duplicated. 40-three-unit cantilever FDPs replacing one premolar, with a group size of eight for each design, were manufactured. In group i-i the cantilever FDPs were retained by two inlays, in group i-c by an inlay-crown combination, and in group c-c by two crowns. The frameworks in groups i-c-R and c-c-R were reinforced by an additional shoulder on the oral side of the zirconia frameworks. All FDPs were subjected to thermal cycling (TC) and 600,000 cycles of mechanical loading (ML) with 50 N. The load to fracture was measured and fracture sites were evaluated. RESULTS: The mean fracture values ranged from 172 N to 792 N. Fracture-strength values were significantly lower for the i-i retained FDPs than for the i-c and c-c combinations. There was no significant effect of the reinforcing shoulder in groups i-c-R and c-c-R. For FDPs with a crown on the terminal tooth, fractures were usually within the distal wall of the distal crown. CONCLUSIONS: Inlay-inlay retained cantilever FDPs cannot withstand the mastication forces expected. Fracture load values for inlay-crown and crown-crown-retained FDPs encourage further clinical investigation. The mode of fracture indicates that reinforcement of the distal crown wall might enhance fracture resistance.

All-ceramic inlay-retained fixed partial dentures: preliminary results from a clinical study.

OBJECTIVES: The objective of this study was to evaluate the clinical performance of zirconia-based all-ceramic fixed partial dentures anchored by inlays. METHODS: A total of thirty FPDs, manufactured using a zirconia frame and veneered with press ceramic, were anchored by use of inlay retainers. All FPDs were designed to replace one missing molar and were adhesively luted by use of one of two different resin cements. Documentation included failures and other complications, plaque accumulation, and aesthetic and functional performance. Statistical analysis was performed using a cox-regression model. RESULTS: During the 12 months observation period a total of thirteen clinically relevant complications occurred-four delaminations of the veneer and six decementations. Three FPDs had to be replaced because of a fracture of the framework. The cement chosen, the location, and the design of the retainer had no statistically significant effect on the occurrence of complications. During the observation period, accumulation of plaque on the abutment teeth was not significantly greater than on reference teeth. Postoperative sensitivity did not differ significantly between the different luting cement groups. The aesthetic and functional performance of the FPDs was acceptable. CONCLUSIONS: Improved adhesion between resin cement and inlay retainer is desirable before general recommendation of all-ceramic inlay-retained FPDs. Use of different luting cements seems to have no effect on the occurrence of complications.

The effect of two luting agents, pretreatment of the post, and pretreatment of the canal dentin on the retention of fiber-reinforced composite posts.

OBJECTIVES: The purposes of this study were to evaluate the push-out strength of core-build-up resin used for fiber-post cementation and to test the effects of different post and dentin pretreatment for different regions of the root. METHODS: After endodontic treatment 216 human teeth received a glass-fiber post. The teeth were divided into test groups to simulate the effects of: (I) cementation material (specifically core-build-up resin or conventional luting cement), (II) pretreatment of the root dentin (none, dual-curing bonding, light-curing bonding), (III) pretreatment of the post (none, hydrofluoric acid, tribochemical pretreatment), and (IV) different regions of the root. After thermal cycling all post-cemented roots were sectioned and each specimen was loaded in a universal testing machine until failure occurred. Statistical analysis was performed by use of a mixed-effects regression model. RESULTS: The cementation material (p

Influence of clinical baseline findings on the survival of 2 post systems: a randomized clinical trial.

PURPOSE: The aim of this prospective randomized controlled trial was to evaluate the influence of clinical baseline characteristics on the survival of 2 post systems. MATERIALS AND METHODS: One hundred patients needing a post were included. Half the patients received a glass fiber-reinforced post (FRP), and the other half received metal screw posts (MSP). The posts were assigned randomly. In addition to demographic data, the following parameters were recorded: type of tooth (incisor/canine versus molar/premolar), length of the post in relation to root length (percentage), extent of coronal tooth destruction (percentage), ferrule height (in millimeters), type of restoration (fixed or removable partial denture), and presence of antagonistic contacts (yes/no). After at least 1 year (mean: 13.84 months), the patients were recalled. Statistical analysis was performed using the log-rank test and Cox regression analysis. RESULTS: The survival rate of FRPs was 93.5%. In the MSP group, the survival rate was significantly lower (75.6%; log-rank test, P = .049). Additionally, the metal posts were associated with more unfavorable complications, for example, root fracture. The type of the tooth and the degree of coronal tooth destruction influenced the survival of MSPs, whereas no influence of these variables could be seen for FRPs. CONCLUSION: FRPs are superior to MSPs with respect to short-term clinical performance. Especially for MSPs, clinical survival depends on several variables.

Fracture load of fixed partial dentures anchored by composite inlays.

PURPOSE: To evaluate in vitro the fracture load of fixed partial dentures (FPDs) anchored by use of composite inlays. The effects of span length, silica-coating, mechanical loading and framework material were also tested. METHODS: Defined box inlay cavities were made on a mandibular molar and a premolar. Fifty-six FPDs were manufactured using a polymer composite material and received an industrial prefabricated polymethylmethacrylate (PMMA) frame for stabilization. All FPDs underwent thermal cycling. The FPDs were divided into test groups simulating the effect of different span length (7 or 12 mm), tribochemically silicoating (yes or no) and mechanical loading (yes or no). The load to fracture was measured and fracture sites were evaluated. As a control group for the PMMA frame, a metal alloy frame was used, and evaluated under the most unfavorable conditions. The Mann-Whitney U-test followed by the Bonferroni correction was used for statistical analysis. RESULTS: The span length significantly affected the fracture load. Values ranged from 413 N for the 12 mm span length to 706 N for the 7 mm span length. Thermal cycling and mechanical loading significantly reduced fracture load values for FPDs with the 12 mm span length, but there were no significant effects for FPDs with 7 mm span length. Silicoating pretreatment of the metal abutments significantly reduced fracture load values. Replacement of the PMMA frame with a metal frame increased fracture load values up to 1,075 N.

Assessment of the reliability and validity of panoramic imaging for assessment of mandibular condyle morphology using both MRI and clinical examination as the gold standard.

OBJECTIVES: The purpose of this study was to evaluate both reliability and validity of the assessment of the shape of the mandibular condyle in panoramic images of the TMJ. STUDY DESIGN: Forty subjects were included and were examined according to the Research Diagnostic Criteria for Temporomandibular Disorders. Panoramic radiographs (PRs) and magnetic resonance images (MRIs) were completed for all subjects. Both MRIs and PRs were rated by raters blinded to the clinical diagnosis. Kappa statistics were used to compare the results of the raters of the PRs. Additionally, the specificity and the sensitivity of the PRs were calculated for 2 scenarios: one with MRI and the other with clinical findings as the gold standard. RESULTS: The sensitivity was 0.94 (specificity = 0.45) for the assumption that MRI is the gold standard and 0.86 (specificity = 0.49) for the assumption that the clinical examination is the gold standard. For reliability, the results for kappa ranged from 0.06 to 0.327. CONCLUSION: It can be concluded that PRs are not a reliable method of accurately judging the shape of the mandibular condyle.

Prediction of TMJ arthralgia according to clinical diagnosis and MRI findings.

PURPOSE: The aim of this study was to investigate the ability of clinical and magnetic resonance imaging (MRI) diagnoses to predict pain in the temporomandibular joint (TMJ). MATERIALS AND METHODS: One hundred forty-nine patients were examined by 2 calibrated examiners in strict accordance with the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD). All patients who presented with a defined clinical RDC/TMD diagnosis were included and underwent bilateral coronal and sagittal MRI of the TMJ. Two raters blinded to the clinical diagnosis interpreted the MRI scans for TMJ pathology. The results were tested against the clinical diagnosis according to the RDC/TMD, including pain-related disability and psychosocial status, for associations to TMJ arthralgia using logistic regression analysis (GENMOD procedure, P < .05). RESULTS: MRI-depicted anatomic changes, such as joint effusions, disc displacement, and osteoarthrosis, were not significantly correlated with the presence of pain in the TMJ. However, a significant relationship between pain on palpation of the masseter muscle origin (P = .0050) and psychosocial factors (P = .0452) and pain in the TMJ was demonstrated. CONCLUSIONS: Pain in the TMJ caused by the anatomic proximity of the muscle masseter origin and the lateral TMJ pole and the possible existence of trigger points in the musculature may lead to a false-positive or a false-negative diagnosis of arthralgia. Additionally, clinicians must consider the psychosocial aspects of pain in ideal treatment planning.

Elevated levels of gene expression for collagen and decorin in human gingival overgrowth.

OBJECTIVES: It has been demonstrated that extracellular matrix molecules are involved in cyclosporine-induced gingival overgrowth (GO). However, for many of these molecules, it remains unclear whether their abundance is modulated on the protein and gene expression level. MATERIAL AND METHODS: To contribute to this clarification, we have analysed the protein and mRNA expression of type-I collagen (COL1) and decorin (DC) in native specimens obtained from five patients with GO, and matched normal tissue using indirect immunofluorescence (IIM), in situ hybridization (ISH) and quantitative polymerase chain reaction (PCR). RESULTS: IIF revealed a largely co-localized although remarkably increased abundance for COL1 and DC in GO. This increase coincided with an up-regulated gene expression observed for both molecules, as detected by ISH and quantitative PCR. CONCLUSIONS: Analysis of our data clearly demonstrates elevated levels for COL1 and DC and shows for the first time in native human tissue that involvement of these genes in GO is not confined to the protein level but also includes the transcriptional level.

Elevated gene expression of MMP-1, MMP-10, and TIMP-1 reveal changes of molecules involved in turn-over of extracellular matrix in cyclosporine-induced gingival overgrowth.

In humans, pathogenesis in cyclosporine A (CsA)-induced gingival overgrowth (GO) includes the accumulation of extracellular matrix (ECM) constituents, viz., collagen type-1 and type-3 and proteoglycans, in subgingival connective tissue. However, whether this increase is associated with alterations of molecules pivotal for the turn-over of collagens and proteoglycans remains unclear. The present study explores the status of matrix metalloproteinase MMP-1 and MMP-10, which are important for fibrillar collagen and proteoglycan turn-over, and their tissue inhibitor TIMP-1, on their gene expression and protein levels in frozen sections derived from GO and matched normal tissue. In situ hybridization (ISH) revealed elevated levels of MMP-1 gene expression in the connective tissue of GO compared with normal tissue. This elevation also applied to MMP-10 and TIMP-1, the latter exhibiting the strongest gene transcription in the deep connective tissue. These differences detected by ISH were corroborated by quantitative reverse transcription/polymerase chain reaction; relative gene expression analysis indicated a 1.9-fold increase for MMP-1, a 2.3-fold increase for MMP-10, and a 4.8-fold increase for TIMP-1. Detection of the protein by indirect immunofluorescence showed that normal gingival tissue was devoid of all three proteins, although they were detectable in GO tissue, with emphasis on TIMP-1. Analysis of our data indicates elevated levels of MMP-1 and-10, and particularly TIMP-1. With respect to TIMP-1, this elevation may in turn lead to alterations in ECM turn-over by abrogating MMP-1 and MMP-10, thereby contributing to ECM accumulation associated with GO.