A 25-Year Retro-prospective Study on Prosthetic Rehabilitation with Bonded Ceramics of Patients with Amelogenesis Imperfecta.

PURPOSE: The purpose of the study was to examine the long-term performance of bonded all-ceramic restorations, veneers in particular, in patients with Amelogenesis Imperfecta (AI). There are few studies of long-term outcome using a minimally invasive procedure in these patients. This aspect is essential when treating young patients. All-ceramic restorations, especially veneers, offer a more tissue-preserving treatment but rely on a successful bonding. Due to the defect enamel in AI patients, the bond strength is however lower. MATERIAL AND METHODS: A retro-prospective evaluation of 40 subjects with AI (26 women, 14 men) was provided with a total of 360 bonded restorations (282 veneers, 78 crowns). The restorations were evaluated according to complications, survival- and success rate. RESULTS: The patients were observed up to 25,3 years (mean 15,4 ± 4,3 years). The mean age when receiving the restorations was 18,5 (± 4,2) years. There had been 59 (16,4%) restorations with prosthetic complications of which 29 (8.1%) had been remade (6 due to esthetic reasons, all in one patient) and 30 (8.3%) recemented (60% caused by trauma). We found 11 teeth with caries and 3 with endodontic complications. The over-all survival rate was 91,9% and the over-all success rate was 83,6%. CONCLUSION: Bonded all-ceramic restorations with no active retention in AI patients perform excellent. The most common complications were debonding and fractures. The treatment should be on individual indications and been preceded by a multidisciplinary approach.

White matter abnormalities mediate the association between masticatory dysfunction and cognition among older adults.

BACKGROUND: Masticatory parameters, such as reduced number of teeth and posterior contacts, have been shown to be associated with reduced cognitive status. The underlying mechanisms that affect these associations, are however, not well understood. OBJECTIVES: The study aims to investigate the association between masticatory dysfunction and cognition and explore the mediating effect of brain structure. METHODS: In this cross-sectional study, 45 older adults with subjective masticatory dysfunction (mean age 72.3 ± 4.0 years) were included. Mini-Mental State Examination score <25, brain trauma, neurological disease, neurodegenerative disorders, depression or poor Swedish language skills were criteria for exclusion. Cognitive functions (executive function and episodic memory) and masticatory dysfunction defined by functional occluding status (FOS; the number of occluding units and number of remaining teeth) were analysed with partial correlation models. Structural magnetic resonance imaging was performed on 28 feasible participants. Multiple regression analyses were performed to evaluate the predictive value of brain structure and white matter hypointensities (WM-hypo) on cognitive functions. A mediation analysis was applied to assess significant predictor/s of the association between FOS and cognition. RESULTS: Both episodic memory and executive functions were positively correlated with FOS. WM-hypo predicted cognitive status (executive function, p ≤ .01). WM-hypo mediated 66.6% (p = 0.06) of the association between FOS and executive functions. CONCLUSION: Associations between FOS and cognitive functions are reported, where FOS, a potential modifiable risk factor, was related to both episodic memory and executive functions. The mediating effect of WM-hypo on the association between FOS and executive functions highlights the impact of the vascularisation of the brain on the link between mastication and cognition. The present study provides increased knowledge that bridges the gap between masticatory dysfunction and cognition.

Long-term results of a randomized clinical trial of 2 types of ceramic crowns in participants with extensive tooth wear.

STATEMENT OF PROBLEM: Evidence is sparse regarding the long-term outcomes of restorative treatment of patients with extensive tooth wear. PURPOSE: The purpose of this long-term prospective randomized clinical trial was to evaluate the performance and success rate of pressed lithium disilicate (LD) and translucent zirconia (TZ) crowns in participants with extensive tooth wear. MATERIAL AND METHODS: A total of 62 participants with extensive tooth wear (17 women, 45 men; mean age 44.8 years; range 25-63 years) received a total of 713 crowns, LD=362 and TZ=351. Both types of crowns had chamfer preparations and were adhesively luted with dual-polymerizing composite resin cement (PANAVIA F 2.0; Kuraray Noritake Dental Inc). The restorations were clinically reevaluated on average 14, 31, 39, 54, and 65 months after insertion of the crowns according to the modified United States Public Health Service (USPHS) criteria. RESULTS: After an observation period of up to 6 years, the survival rate for both types of crowns was 99.7%, with 1 lost LD crown after 1 year as a result of loss of retention and 1 lost TZ crown after 3 years because of tooth fracture at the cemento-enamel junction. The success rates were similar for both types of crowns: 98.6% for LD and 99.1% for TZ. Reasons for failures were that 3 participants in each group developed apical lesions, minimal ceramic fractures, or their crowns were rebonded after loss of adhesion. Assessment of color at baseline was significantly different with a better match for LD (84.8% Alfa, 15.2% Bravo) than for TZ crowns (36.5% Alfa, 63.5% Bravo), including TZ crowns with veneered porcelain (P<.001). Secondary caries and cracks did not occur. A post hoc analysis of clinical performance did not indicate any significant differences between extensive tooth wear with primarily mechanical or chemical factors. CONCLUSIONS: No differences were found between the 2 types of ceramic materials concerning the long-term success and clinical performance, except that TZ crowns were rated by a blinded clinician as less esthetic than LD crowns. The use of high-strength ceramic materials, as well as reliable adhesive bonding, are probably the key factors in the long-term success of ceramic crowns in participants with extensive tooth wear independent of the specific etiology.

3-D tooth movement adjacent to single anterior implants and esthetic outcome. A 14- to 20-year follow-up study.

OBJECTIVES: To report three-dimensional (3-D) movement of teeth adjacent to single-implant crowns (SICs) in the anterior maxilla and to relate the findings to patient characteristics and esthetic outcome. MATERIALS AND METHODS: 3-D movements of teeth adjacent to anterior maxillary SICs were measured in 30 patients with original SICs in function after 14-20 years. The movements were related to facial type, lower anterior facial height (LAFH), age at crown delivery, sex, the position of the implant, implant occlusion, cause of tooth loss, follow-up period, orthodontic treatment prior to implant placement, and marginal bone-level changes. The esthetic outcome and quality were assessed using Visual Analog scale (VAS) and California Dental Association (CDA) index. RESULTS: 3-D movement of adjacent teeth between 0 and 2.5 mm was observed at follow-up with incisal and palatal movement being most pronounced. Incisal tooth movement of >1 mm was observed in 30% of the patients and was significantly associated with LAFH ≥70 mm. VAS rating associated poorly between patients and clinicians with scores of >80% in 63% and 20%, respectively. The CDA rating was assessed as satisfactory in 87% of the patients. CONCLUSIONS: Significantly more extensive infraposition was observed in patients with SICs without occlusion, other causes of tooth loss than trauma, implant in lateral incisor and canine position, and a LAFH of ≥70 mm. Although infraposition occurs, patients are highly satisfied with the esthetics of their implants and the esthetic results are valued as higher by patients than dentists.

Cognitive changes and neural correlates after oral rehabilitation procedures in older adults: a protocol for an interventional study.

BACKGROUND: Epidemiological studies show an association between masticatory function and cognitive impairment. This has further strengthened the notion that tooth loss and impaired masticatory function may be risk factors for dementia and cognitive decline. Animal experiments have indicated a causal relationship and several possible mechanisms have been discussed. This evidence is, however, lacking in humans. Therefore, in the current interventional study, we aim to investigate the effect of rehabilitation of masticatory function on cognition in older adults. METHODS: Eighty patients indicated for prosthodontic rehabilitation will be randomly assigned to an experimental or a control group. Participants will conduct neuropsychological assessments, masticatory performance tests, saliva tests, optional magnetic resonance imaging, and answer questionnaires on oral health impact profiles and hospital anxiety and depression scale before, 3 months, and 1 year after oral rehabilitation. The difference between the two groups is that the control group will be tested an additional time, (at an interval of about 3 months) before the onset of the oral rehabilitation procedure. The primary outcome is a change in measures of episodic memory performance. DISCUSSION: Although tooth loss and masticatory function are widespread in older people, it is still an underexplored modifiable risk factor potentially contributing to the development of cognitive impairment. If rehabilitation of masticatory function shows positive effects on the neurocognitive function, this will have great implications on future health care for patients with impaired masticatory status. The present project may provide a new avenue for the prevention of cognitive decline in older individuals. TRIAL REGISTRATION: The protocol for the study was retrospectively registered in ClinicalTrials.gov Identifier: NCT04458207, dated 02-07-2020.

A retrospective clinical evaluation of extensive tooth-supported fixed dental prostheses after 10 years.

STATEMENT OF PROBLEM: The survival and success of tooth-supported fixed dental prostheses (FDPs) in long-term studies vary greatly, depending on the patient and the size of the FDP. Influencing factors for FDP survival or success may include advanced patient age at the time of FDP treatment, treatment severity, and use of new and cheaper FDP materials. As the patient population ages, prosthodontists will treat tooth wear in a greater number of older adults; however, recent long-term studies on such treatments are lacking. PURPOSE: The purpose of this retrospective clinical study was to examine extensive, tooth-supported FDPs made at 2 specialist clinics in Sweden after 10 years and to compare the outcomes with those of previous studies. MATERIAL AND METHODS: Patients rehabilitated by using FDPs of at least 5 units at 2 specialist clinics in Sweden between 2002 and 2006 were recalled after 10 years. Clinical examinations were supplemented by reviewing clinical records and existing radiographs. Statistical analysis was performed by using the Student t test, chi-squared test, Fisher exact test, and Kruskal-Wallis test (α=.05). RESULTS: A total of 152 patients were recalled for clinical examination. Of these, 78 patients attended and were examined. The mean age of the examined group was 70 years (range 36-94), lower than that of those not attending (80 years; range 46-100; P<.05). The mean number of units of the 78 examined FDPs was 7.3 (range 5-12) and 8.0 (range 5-14) for those not examined. FDP configurations in terms of number of units, abutments, pontics, and post-and-cores did not differ significantly between the 2 groups (P>.05). The survival proportion of the examined 78 FDPs (all units of the original FPD) was 74.4%. The success proportion (FDPs without complications) was 52.6%. The most frequent complications were caries (14.1%), endodontic complications (11.5%), loose retainers (7.7%), root fractures (5.1%), and framework fractures (3.8%). FDPs with post-and-cores (P<.05) and cantilevers (P=.054), especially when in combination (P<.05), showed more complications than FDPs without. Chipping fractures in porcelain were found in 38% of the FDPs (7.7% of the units), with more porcelain fractures on Co-Cr frameworks than on gold and titanium alloy frameworks (P<.05). CONCLUSIONS: This long-term retrospective study indicated that the prognosis for complicated and extensive FDPs in aging patients does not worsen with increased clinical complexity. New materials, treatment complexity, and older patients did not seem to markedly influence prognosis.

Clinical presentation of two phenotypes of tooth wear patients.

OBJECTIVE: To assess the clinical presentation of wear lesions in two phenotypes of tooth wear (TW) patients based on distribution and morphological features of wear. MATERIALS AND METHODS: 103 patients (mean age = 43.1 years) were divided into two groups based on cluster analysis; cluster A (61 patients) and cluster B (42 patients). The distribution of wear lesions, scores of presence or absence of 10 defined morphological TW criteria and number of teeth fulfilling each criteria were compared between groups. Intra- and inter-examiner reliability of the 10 TW criteria was determined by Cohen's kappa and intraclass correlation coefficient. RESULTS: While cluster A had more wear in maxillary anterior teeth and mandibular molars compared with the same opposing tooth groups (p < 0.001, p < 0.007 respectively), there were no differences for cluster B. Cluster A was characterized by higher prevalence of 4 chemical morphological criteria and the highest number of teeth affected by one chemical criteria, whereas cluster B had a higher prevalence of one mechanical criteria and higher number of teeth affected by an additional mechanical criteria. Both intra- and inter-examiner values for the defined TW criteria were fair to excellent. CONCLUSION: The results may indicate a more chemical background for TW in cluster A and mechanical background in cluster B. Furthermore, clinicians may use certain clinical features of TW to distinguish between individuals who belong to a specific TW cluster with a presumed chemical or mechanical etiology. These preliminary findings need to be confirmed in future studies.

Phenotypes of patients with extensive tooth wear-A novel approach using cluster analysis.

OBJECTIVES: Explore a new approach to identify phenotypes of tooth wear (TW) patients using an unsupervised cluster analysis model, based on demographic, self-report, clinical, salivary and electromyographic (EMG) findings. METHODS: Data was collected for 34 variables from 125 patients, aged 17-65 years, with a TW index > grade 2. Demographic information and presumed risk factors for chemical and mechanical TW were collected. A 14-item stress scale was completed and salivary flow rates, pH and buffer capacity were measured. Sleep bruxism was assessed with a portable single channel EMG device. RESULTS: The final cluster model comprised 16 variables and 103 patients and indicated two groups of TW patients; 61 participants in cluster A and 42 in cluster B. Cluster assignment was determined by several presumed mechanical risk factors and diseases affecting saliva. Cluster B had the highest percentage of sleep bruxism self-reports (A 1.6%, B 92.9%, p ≤ 0.001), awake bruxism self-reports (A 45.9%, B 85.7%, p ≤ 0.001), heavy sport exercises (A 1.6%, B 21.4%, p = 0.001); and highest percentage of diseases affecting saliva (A 13.1%, B 47.6%, p ≤ 0.001). A notable finding was the lack of significant differences between clusters in many other presumed risk factors for mechanical and chemical TW. CONCLUSION: TW patients can be clustered in at least two groups with different phenotypic characteristics but also with a large degree of overlap. Based on this type of algorithm, tools for clinical application may be developed and underpin TW classification and treatment planning in the future.

A retro-prospective long-term follow-up of Brånemark single implants in the anterior maxilla in young adults. Part 1: Clinical and radiographic parameters.

BACKGROUND: Single implant restorations have become the primary treatment option for young adults with missing anterior teeth. Yet, long-term studies of single-implants are limited in the literature. PURPOSE: To report long-term survival, success, and complications in young adults with single-implants in the anterior maxilla. MATERIALS AND METHODS: A group of 42 patients (mean age 20.7 years) received 53 anterior maxillary single-implants during 1996 and 1997. Data were collected at delivery of the crown, at 1-year examination, and at 14-20-year examination. Descriptive statistics, estimated cumulative survival rates, Pearson correlation test, and t-test were performed. RESULTS: After 14-20 years, 40 out of 42 patients were examined. Two patients were lost to follow-up, two implants failed and ten original single-crown restorations were replaced. Estimated cumulative survival rates were 96.1% for implants and 80.4% for implant-supported crowns. Complications were seen in 21 patients. Mean probing depth was 4.0 ± 1.8 mm and mean marginal bone loss was 0.1 ± 1.1 mm. No correlation was found between marginal bone loss and probing depth, occlusal contact in maximal intercuspal position or usage of nicotine. CONCLUSIONS: Long-term prognosis of single implant treatments in the anterior maxilla in young adults must be regarded as good, with high survival and success rates.

Clinical evaluation of fixed partial dentures made in Sweden and China.

The aim of this study was to compare the quality of fixed partial dentures (FPDs) made in a Chinese dental laboratory with corresponding FPDs made in Swedish dental laboratories. Twenty-one patients were fitted with FPDs between March 2007 and December 2008. Single crowns and prostheses of up to seven units were made. All dentures, gold and CoCr alloys covered with ceramic, were produced in duplicate: one by a dental technician in China and the other by a dental technician in Sweden. The dentures were blind-tested with regard to marginal integrity, anatomic form and color, approximal and occlusal contacts, and time taken for adjustments. The composition of dentures was analyzed, and the material used, framework weight, compliance of the laboratories, and costs (material and labour) were recorded. There was no difference in the quality of marginal integrity, anatomic form, color, approximal and occlusal contacts, or in the time taken for adjustments. The bridge frameworks made in China were thinner and lighter (p<0.01) than those made in Sweden. Three FPDs from China showed elastic deformation when tested clinically and were considered too thin for clinical use. In 11 out of 14 orders from the Chinese laboratory, the gold alloy specified was not delivered and the cobalt-chromium alloy contained small amounts (0.19%) of nickel.The prostheses with gold-alloy frameworks from China cost 47% of those from Sweden (p<0.01) and those with cobalt/chromium frameworks 44% (p<0.01). In conclusion, the quality of the FPDs made in Sweden and China was comparable, with the exception of the dimension of the Chinese bridges, which in some cases was considered too weak. The gold alloy ordered from the Chinese laboratory was often not the alloy delivered and the CoCr alloy contained small amounts of nickel. FPDs from China cost less than half the price of those from Sweden.

Implant-level prostheses in the edentulous maxilla: a comparison with conventional abutment-level prostheses after 5 years of use.

PURPOSE: Long-term comparisons of frameworks at the implant or abutment level are not available, and knowledge of the clinical function of cobalt-chromium (Co-Cr) alloy frameworks is limited. Primarily, the aim of this study was to compare the 5-year clinical performance of frameworks with or without abutment connections to implants. Secondly, the outcomes of prostheses made from Co-Cr alloy with porcelain veneers to those made of commercially pure titanium (CP Ti) with acrylic veneers were compared. MATERIALS AND METHODS: The test groups comprised patients treated with screw-retained fixed prostheses made at the implant level according to the Cresco method in either dental porcelain-veneered Co-Cr alloy (n = 15) or acrylic-veneered CP Ti (n = 25). A control group of 40 randomly selected patients were provided with prostheses made at the standard abutment level in CP Ti with acrylic veneers. For all patients, clinical and radiologic 5-year data were retrospectively collected and evaluated. RESULTS: Five-year implant cumulative survival rates (CSRs) were 98.6% and 97.6% for test and control groups, respectively (P > .05). No major differences in bone level were demonstrated between the groups after 5 years (P > .05). Significantly more complications occurred in the test groups compared to the control group (P < .01), with the most common complications being mucositis and fracture of veneers. CONCLUSIONS: After 5 years, the clinical outcomes of implant-level prostheses made of porcelain-veneered Co-Cr or acrylic-veneered CP Ti seem comparable to acrylic-veneered titanium prostheses made at the standard abutment level regarding implant CSR and bone levels. However, more complications were registered in implant-level prostheses compared to the standard abutment-level prostheses.

Cellular responses to cobalt-chrome and CP titanium--an in vitro comparison of frameworks for implant-retained oral prostheses.

The responses of cell types in peri-implant tissues to cobalt-chrome and titanium were studied in vitro. Cylinders were made from both a cobalt-chrome alloy and commercially pure titanium (length 6 mm, diameter 7.9 mm). Plastic tubes were placed over the cylinders to create cell culture wells, in which human epithelial cells or mouse fibroblasts were cultivated. Cell viability was studied using the Alamar Blue method. The surface structure of two samples of each material was analyzed with optical interferometry. The morphology of cells grown on cylinders of each material was studied with scanning electronic microscopy. Epithelial cells and fibroblasts in the titanium group were more viable than those in the cobalt-chrome group (p = 0.001 and p = 0.000, respectively). The titanium surfaces had a greater height deviation (S(a), p = 0.027) but were less dense (S(ds), p = 0.044) than the cobalt-chrome group. The scanning electronic microscopy revealed no major deviations from normal cell morphology. Within the limitations of the present study, the findings indicate that epithelial cells as well as fibroblasts have a stronger negative response to cobalt-chrome alloy than to titanium. We suggest that these differences can be explained only bythe material per se and not by the minor differences in surface structure. Further and clinical studies are needed to confirm the significance of these findings.

Precision of fit to implants: a comparison of Cresco™ and Procera® implant bridge frameworks.

BACKGROUND: The Cresco™ (Astra Tech AB, Mölndal, Sweden) method aims to reduce the inevitable distortions when cast metal frameworks for implant-supported prostheses are fabricated. However, limited data are available for the precision of fit for this method. PURPOSE: To measure and compare the precision of fit of Cresco- and computer numeric controlled (CNC)-milled metal frameworks for implant-supported fixed complete prostheses. MATERIALS AND METHODS: Two groups of frameworks were fabricated according to the Cresco method, either in titanium (Cresco-Ti, n = 10) or in a cobalt-chrome alloy (Cresco-CoCr, n = 10). A third group comprised CNC-milled titanium frameworks (Procera® Implant Bridge [PIB], Nobel Biocare AB, Göteborg, Sweden), made from individual model/pattern measurements (PIB, n = 5). Measurements of fit were performed by means of a coordinate measuring machine linked to a computer. The collected data on distortions were analyzed. RESULTS: Overall, a maximal three-dimensional range of center point distortion of 279 µm was observed for measured frameworks. The framework width (x-axis) decreased for Cresco-CoCr, but increased in Cresco-Ti and PIB; Cresco-CoCr compared to Cresco-Ti (p = .0002) and Cresco-CoCr compared to PIB (p < .0001). In vertical dimension (z-axis), less distortions were present in PIB compared to Cresco-CoCr (p = .0007) and in PIB compared to Cresco-Ti (p < .0001). CONCLUSIONS: None of the frameworks presented a perfect, completely "passive fit" to the master. Although the direction of distortions varied, the horizontal distortions were of similar magnitudes. However, the PIB frameworks had statistical significant less vertical distortions as compared to the Cresco groups.

Early loading of mandibular full-arch bridges screw retained after 1 week to four to five Monotype implants: 3-year results from a prospective multicentre study.

OBJECTIVES: This prospective multicentre study provides clinical experience up to 3 years to support a simplified treatment for mandibular edentulism within 1 week by using one-stage implant surgery and a screw-retained full-arch bridge. METHODS: Two hundred and fifty ITI Monotype implants were installed in 62 patients out of 66 patients; 60 patients got four implants each and two got five implants. After 1 week, a final bridge was in function. Radiographs were taken as baseline for vertical bone loss up to 3 years post-loading for the whole cluster and specific effects of gender, centre, age, bone class, implant length over time were compiled. Clinical (mPI, SBI) and subjective parameters such as general oral hygiene and patient satisfaction were recorded and repeated at specified intervals up to 3 years. RESULTS: Four patients were excluded at surgery and are not involved in the follow-ups. At 1 year, 61 patients (244 implants) were evaluable and all bridges were in function. After 3 years, 49 patients (194 implants) came to control. Eight patients died during the follow-up period. Three patients lost one implant each. The cumulative implant survival rate was 98.55% and the success rate for the prosthesis was 100%. As calculated from measurable radiographs, the mean bone level at baseline was 1.63+/-0.78 and at 1 and 3 years 2.50+/-0.60 and 2.56+/-0.74, respectively. Using the mixed model analysis and Friedman test, the time in situ, centre and bone class had significant effect on the bone resorption and to some small extent even, the implant length. Gender and age were unaffected. Oral hygiene and patient satisfaction of the treatment were improved. CONCLUSIONS: The results indicate that one-part self-tapping sandblasted, large-grit, acid-etched (SLA) implants are suitable for loading within 1 week. In the whole period, the mean bone crestal resorption was <1 mm, which is in agreement with other similar studies.

Early loading of mandibular full-arch bridges screw retained after 1 week to four to five Monotype® implants: 3-year results from a prospective multicentre study.

OBJECTIVES: This prospective multicentre study provides clinical experience up to 3 years to support a simplified treatment for mandibular edentulism within 1 week by using one-stage implant surgery and a screw-retained full-arch bridge. METHODS: Two hundred and fifty ITI Monotype® implants were installed in 62 patients out of 66 patients; 60 patients got four implants each and two got five implants. After 1 week, a final bridge was in function. Radiographs were taken as baseline for vertical bone loss up to 3 years post-loading for the whole cluster and specific effects of gender, centre, age, bone class, implant length over time were compiled. Clinical (mPI, SBI) and subjective parameters such as general oral hygiene and patient satisfaction were recorded and repeated at specified intervals up to 3 years. RESULTS: Four patients were excluded at surgery and are not involved in the follow-ups. At 1 year, 61 patients (244 implants) were evaluable and all bridges were in function. After 3 years, 49 patients (194 implants) came to control. Eight patients died during the follow-up period. Three patients lost one implant each. The cumulative implant survival rate was 98.55% and the success rate for the prosthesis was 100%. As calculated from measurable radiographs, the mean bone level at baseline was 1.63±0.78 and at 1 and 3 years 2.50±0.60 and 2.56±0.74, respectively. Using the mixed model analysis and Friedman test, the time in situ, centre and bone class had significant effect on the bone resorption and to some small extent even, the implant length. Gender and age were unaffected. Oral hygiene and patient satisfaction of the treatment were improved. CONCLUSIONS: The results indicate that one-part self-tapping sandblasted, large-grit, acid-etched (SLA) implants are suitable for loading within 1 week. In the whole period, the mean bone crestal resorption was <1 mm, which is in agreement with other similar studies.

A 3-year retrospective study of Cresco frameworks: preload and complications.

PURPOSE: The aim of this retrospective clinical study was to evaluate the clinical outcome of fixed implant-supported complete prostheses on Astra or Brånemark implants when using either conventional cast frameworks or frameworks produced according to the Cresco Ti Precision method (Cresco Ti Systems Sàrl., Lausanne, Switzerland). MATERIALS AND METHODS: Forty-six patients treated 3 years previously were divided into four groups according to implant system and framework design. Clinical examinations were performed and case records were scrutinized. The stability for each prosthesis retention screw was recorded as the torque profile and was monitored using the Osseocare torque controller (Nobel Biocare AB, Göteborg, Sweden). Complications in association with implants and superstructures were registered. Patient opinions were recorded. The significance level was set to 5%. RESULTS: The Astra-Cresco group demonstrated a lower degree of prosthesis retention screw stability compared with the Astra group. No differences among the four groups were seen regarding plaque, bleeding on probing, or marginal bone resorption. The Brånemark group (Brånemark System, Nobel Biocare AB) demonstrated more mechanical complications than the Brånemark-Cresco group. Mobile prostheses were found in the Brånemark and the Astra-Cresco groups. Fracture of veneer was seen in 20% of the prostheses and was more frequently found in the groups with mobile prostheses. Sixty percent of the prostheses showed reactions in the surrounding soft tissues. The most common reaction was mucosal proliferation. No differences were detected in the patients' opinions. CONCLUSION: Within the limitations of this retrospective study, the following can be concluded: (1) compared with conventional frameworks, the Cresco distortion correction method does not provide a better clinical outcome after prosthesis connection in patients with fixed implant-supported complete prostheses; and (2) the two framework-producing methods behave differently on Astra implants compared with Brånemark implants concerning prosthesis retention screw stability, mechanical and biologic complications, and reactions in patients with fixed implant-supported complete prostheses.

A retrospective study of the prosthodontic management of patients with amelogenesis imperfecta.

PURPOSE: This article reports on a retrospective study on patients with a diagnosis of amelogenesis imperfecta and on their prosthodontic management, oral health status, and attitudes toward their condition. MATERIALS AND METHODS: The study comprised 15 patients and consisted of a clinical evaluation and questionnaire. Clinical examination included records of types of restorations and cements used, rating of restoration quality, as well as complications and periodontal variables. RESULTS: The 15 patients had a total of 213 prosthetic restorations. The median age of the restorations was 60 months. Following the California Dental Association's system, all restorations were rated as acceptable to excellent, with one exception. During the follow-up period, four (2%) restorations had been recemented and 16 (8%) restorations had been redone, five (2%) because of porcelain fractures and 11 (5%) because of caries; two (1%) endodontic treatments were performed after prosthetic restoration. Plaque and Bleeding Indices were 28% and 21%, respectively, while pocket depths of more than 3 mm were found at 7% of all tooth surfaces. All patients judged their condition as having affected them negatively. However, after prosthodontic rehabilitation, patients experienced an improvement in self-esteem. CONCLUSION: Patients with severe clinical manifestations of amelogenesis imperfecta obtained extensive prosthodontic treatment at an early age. The restorations had in general performed well, and all patients were affected positively as a result.

Analysis of a device for assessment of abutment and prosthesis screw loosening in oral implants.

Screw loosening is an irritating problem in implant dentistry. Loosened abutment screws and prosthesis screws are often found at yearly examinations. Loosened screws may cause costly complications, such as screw fractures and fracture of the framework, and methods to prevent them would be welcome. The purpose of this study is firstly to describe a mechanical protractor device designed to fit the electrical Torque Controller (Nobel Biocare, DEA 020, Gothenburg, Sweden) and measure the number of degrees necessary to retighten the abutment screw or the prosthesis screw to reach the target torque value. A second purpose is to analyse the precision and validity of the device. The results of the study indicate that the degree of preset loosening of abutment and prosthesis screws can be well reflected in the number of degrees necessary for retightening. It was also shown that it is possible to retighten the abutment and prosthesis screws with a precision of 1.7 degrees and 1.3 degrees, respectively. The study shows that the device has good precision and validity. By using this device, we hope to be able to evaluate various parameters for screw stability, such as the type of implant system, the number of fixtures, the type of abutments, the type of bridge material and the need for retightening of the abutment and prosthesis screws.