HOW TO IDENTIFY SUBGROUPS IN LONGITUDINAL CLINICAL DATA: TREATMENT RESPONSE PATTERNS IN PATIENTS WITH A SHORTENED DENTAL ARCH.

BACKGROUND: When dental patients seek care, treatments are not always successful,that is patients' oral health problems are not always eliminated or substantially reduced. Identifying these patients (treatment non-responders) is essential for clinical decision-making. Group-based trajectory modeling (GBTM) is rarely used in dentistry, but a promising statistical technique to identify non-responders in particular and clinical distinct patient groups in general in longitudinal data sets. AIM: Using group-based trajectory modeling, this study aimed to demonstrate how to identify oral health-related quality of life (OHRQoL) treatment response patterns by the example of patients with a shortened dental arch (SDA). METHODS: This paper is a secondary data analysis of a randomized controlled clinical trial. In this trial SDA patients received partial removable dental prostheses replacing missing teeth up to the first molars (N = 79) either or the dental arch ended with the second premolar that was present or replaced by a cantilever fixed dental prosthesis (N = 71). Up to ten follow-up examinations (1-2, 6, 12, 24, 36, 48, 60, 96, 120, and 180 months post-treatment) continued for 15 years. The outcome OHRQoL was assessed with the 49-item Oral Health Impact Profile (OHIP). Exploratory GBTM was performed to identify treatment response patterns. RESULTS: Two response patterns could be identified - "responders" and "non-responders." Responders' OHRQoL improved substantially and stayed primarily stable over the 15 years. Non-responders' OHRQoL did not improve considerably over time or worsened. While the SDA treatments were not related to the 2 response patterns, higher levels of functional, pain-related, psychological impairment in particular, and severely impaired OHRQoL in general predicted a non-responding OHRQoL pattern after treatment. Supplementary, a 3 pattern approach has been evaluated. CONCLUSIONS: Clustering patients according to certain longitudinal characteristics after treatment is generally important, but specifically identifying treatment in non-responders is central. With the increasing availability of OHRQoL data in clinical research and regular patient care, GBTM has become a powerful tool to investigate which dental treatment works for which patients.

Rehabilitation of shortened dental arches: A fifteen-year randomised trial.

BACKGROUND: Few long-term studies on treatments in the shortened dental arch (SDA) are available. OBJECTIVE: The objective of this trial was to analyse the long-term success of two different treatment concepts. METHODS: Patients over 35 years of age with missing molars in one jaw and at least the canine and one premolar present on both sides were eligible. In the partial removable dental prosthesis (PRDP) group (N = 81), molars and missing second premolars were replaced by a precision attachment retained prosthesis. In the SDA group (N = 71), the dental arch ended with the second premolar that had to be present or replaced by a cantilever fixed dental prosthesis. Follow-up examinations were carried out over 15 years. RESULTS: A comprehensive outcome variable comprised four failure categories for which Kaplan-Meier survival (success) analyses were conducted. Half of the patients exhibited a continuous preservation of the per protocol prosthetic status that remained totally unaffected by complications for more than 10 years. The event-free success rates for moderate or worse failure implied a loss of the per protocol prosthetic status. The respective survival rates fell below 50% at 14.2 years in the PRDP group and 14.3 years in the SDA group. In none of the analyses, a significant group difference was found. CONCLUSIONS: In patients with an SDA condition, changes in the prosthetic status have to be expected. The affected proportion increases almost linearly from shortly after treatment and comprises the majority after 15 years. The influence of the examined treatments on success appears to be low.

IMPACT OF SHORTENED DENTAL ARCH ON ORAL HEALTH-RELATED QUALITY OF LIFE.

BACKGROUND: A shortened dental arch (SDA) is an established treatment concept for patients with missing molars. However, little is known regarding long-term course of oral health-related quality of life (OHRQoL) in patients with SDA and the benefits from replacement of missing molars. OBJECTIVE: Purpose of this multi-center randomized clinical trial was to assess OHRQoL over a period of 15 years in patients with molar replacement by a removable partial denture (RPD) compared to patients with a restored SDA without molar replacement. METHODS: Patients at least 35 years of age with all molars missing in 1 jaw and at least the canine and one premolar present on each side were included. Patients received either a precision attachment-retained, RPD for replacement of missing molars (n = 79), or the dental arch ended with the second premolar (SDA) that had to be present or replaced by a cantilever fixed dental prosthesis (n = 71). Follow-up examinations continued for 15 years. OHRQoL was assessed with the 49-item Oral Health Impact Profile (OHIP). OHIP summary and dimension scores were longitudinally modeled in the statistical analyses to assess course of OHRQoL over time applying an intention-to-treat approach. In addition, scores for the OHRQoL dimensions Oral Function, Orofacial Pain, Orofacial Appearance, and Psychosocial Impact were analyzed. RESULTS: After an initial improvement in OHRQoL indicated by a mean decrease of 20.0 OHIP points with an effect size of 0.61 in the entire study population, OHRQoL stayed relatively constant over the entire follow-up period. Assuming a constant time and treatment effects over the study period, OHRQoL did not differ statistically significant between the 2 treatments (0.4 OHIP points; 95%-CI: 7.1 - 6.2). OHRQoL after treatment did not change notably over 15 years and was statistically nonsignificant as well (P = .872). Similar findings were observed in all 4 OHRQoL dimensions. CONCLUSIONS: In patients, missing all molars in one jaw OHRQoL improved providing RPD or restoring SDA to a clinically relevant degree. Treatment-related improvement remained mostly stable over a period of at least 15 years. Therefore, patients can be informed that both treatment concepts are equivalent concerning long-term OHRQoL. Accordingly, patients' preferences regarding treatment options should be granted priority in treatment decision making with the SDA treatment option being the default.

The randomized shortened dental arch study: temporomandibular disorder pain.

OBJECTIVES: The aim of this multi-center, randomized controlled trial was to assess the impact of missing posterior support on the risk for temporomandibular disorder (TMD) pain by comparing patients with either shortened dental arches (SDA) or molar replacement by removable dental prostheses (RDP). METHODS: A sample of 215 patients with bilateral molar loss in at least one jaw was consecutively recruited in 14 prosthodontic departments of dental schools in Germany. Of the initial sample, 152 patients (mean age: 59.7 years; 53.9 % female) received randomly allocated interventions (SDA: n = 71; RDP: n = 81). Presence of TMD pain was assessed using patients' self-reports and was verified by physical examination and by pain intensity, as the mean of current pain, worst pain, and average pain in the last 6 months, with 10-point ordinal rating scales. Assessments were performed before treatment and at follow-ups until 60 months after treatment. Impact of interventions on TMD risk and pain intensity was computed by applying logistic and linear random-intercept models. RESULTS: Tooth replacement (RDP) did not significantly change the risk for self-reported (odds ratio [OR]: 1.1; confidence interval [CI]: 0.4 to 3.4) or clinically verified (OR: 0.7; CI: 0.1 to 4.3) TMD pain compared to no tooth replacement (SDA). Mean characteristic pain intensity was virtually identical in both groups (Coeff: 0.01; CI: -0.30 to 0.32). CONCLUSION: Retaining or preservation of an SDA is not a major risk factor for TMD pain over the course of 5 years when compared to molar replacement with RPDs. CLINICAL RELEVANCE: Seemingly, missing molars do not have to be replaced in order to prevent TMD pain.

Periodontal health in shortened dental arches: A 10-year RCT.

PURPOSE: This analysis focused on periodontal health in shortened dental arches (SDAs). METHODS: In a randomized controlled clinical trial, patients with missing molars in one jaw and at least one premolar and canine on both sides were eligible for participation. In the partial removable dental prosthesis (PRDP) group (n = 79), molars were replaced with a precision attachment retained PRDP. In the SDA group (n == 71), the SDA up to the second premolars was either left as is or restored with fixed dental prostheses. Outcome variables were vertical clinical attachment loss (CAL-V), pocket probing depth (PPD), bleeding on probing (BOP) and plaque index (PLI). For CAL-V and PPD, the changes at six measuring points per tooth were analyzed. For BOP and PLI, patient related rates were calculated for each point in time. Statistical methods included linear regression analyses. RESULTS: In the intention-to-treat (ITT) analysis for CAL-V in the study jaw, the 10 year patient related mean changes were 0.66 mm in the PRDP group and -0.13 mm in the SDA group. The resulting mean patient related group difference of 0.79 mm (95% CI: 0.20 mm-1.38 mm) was significant (p = 0.01). There were no significant differences in the ITT analyses for PPD. For BOP and PLI, significant group differences with more favorable results for the SDA group were found. CONCLUSIONS: In view of lacking substantial differences for CAL-V and PPD, the overall differences were considered of minor clinical relevance. The results add confirmatory evidence to the shortened dental arch concept and its clinical viability (controlled-trials.com ISRCTN97265367).

Impact of shortened dental arch on oral health-related quality of life over a period of 10 years - A randomized controlled trial.

OBJECTIVES: To compare oral health-related quality of life (OHRQoL) in patients with either molar replacement by partial removable dental prostheses (PRDP) or with restored shortened dental arches (SDA) over a period of 10 years. METHODS: In this multi-center RCT, a consecutive sample of 215 patients with bilateral molar loss in at least one jaw was initially recruited in 14 prosthodontic departments. Of those patients, 150 could be randomly allocated to the treatment groups (SDA: n = 71; PRDP: n = 79), received the allocated treatment, and were available for follow-up assessments. OHRQoL was assessed using the 49-item version of the Oral Health Impact Profile (OHIP) before treatment (baseline) and at follow-ups after treatment (4-8 weeks and 6, 12, 24, 36, 48, 60, 96, and 120 months). To investigate the course of OHRQoL over time, we longitudinally modelled treatment and time effects using mixed-effects models. RESULTS: OHRQoL substantially improved from baseline to first follow-up in both groups indicated by a mean decrease in OHIP scores of 20.0 points (95%-CI: 12.5-27.5). When compared to the SDA group, OHRQoL in the PRDP group was not significantly different (-0.6 OHIP points; 95%-CI: -7.1 to 5.9) during the study period when assuming a constant time effect. OHRQoL remained stable over the 10 years with a statistically insignificant time effect (p = 0.848). CONCLUSIONS: For patients requesting prosthodontic treatment for their lost molars, treatments with SDA or PRDP improve clinically relevantly OHRQoL and maintain it over a period of 10 years with no option being superior to the other. CLINICAL SIGNIFICANCE: Since there was no significant difference between the two treatment options over the observation period of 10 years, and since results have stayed stable over time, patients can be informed that both treatment concepts are equivalent concerning OHRQoL.

Oral Health-Related Quality of Life in Edentulous Patients with Two- vs Four-Locator-Retained Mandibular Overdentures: A Prospective, Randomized, Crossover Study.

PURPOSE: To compare the oral health-related quality of life (OHRQoL) in a prospective, randomized crossover trial in patients with mandibular overdentures retained with two or four locators. MATERIALS AND METHODS: In 30 patients with edentulous mandibles, four implants (ICX-plus implants [Medentis Medical]) were placed in the intraforaminal area. Eight weeks after transgingival healing, patients were randomly assigned to have two or four implants incorporated in the prosthesis. After 3 months, the retention concepts were switched. The patients with a two-implant-supported overdenture had four implants incorporated, whereas patients with a four-implant-supported overdenture had two retention locators taken out. After 3 more months, all four implants were retained in the implant-supported overdenture in every patient. To measure OHRQoL of the patients, the Oral Health Impact Profile 14, German version (OHIP-14 G), was used. RESULTS: A considerable increase in OHRQoL could be seen in all patients after the prosthesis was placed on the implants. Also, a statistically significant difference of OHRQoL could be seen in the OHIP-14 G scores between two-implant and four-implant overdentures. Patients had a higher OHRQoL after incorporation of four implants in the overdenture compared with only two implants. CONCLUSION: Patients with implant-retained overdentures had better OHRQoL compared with those with conventional dentures. The number of incorporated implants in the locator-retained overdenture also influenced the increase in OHRQoL, with four implants having a statistically significant advantage over two implants.

Sensitivity and Specificity of Stability Criteria for Immediately Loaded Splinted Maxillary Implants.

BACKGROUND: To assess the suitability of dental implants for immediate loading, primary stability is usually evaluated intraoperatively. PURPOSE: This retrospective study aimed to assess the suitability of three stability parameters - namely, insertion torque (IT), implant stability quotient (ISQ; measured by resonance frequency analysis), and Periotest (PT) values - as potential predictors for the risk of nonosseointegration of immediately loaded splinted implants. The stability parameters were routinely collected under immediate loading. MATERIALS AND METHODS: Nineteen patients with 11 edentulous and 8 partially edentulous maxillae were treated with 105 dental implants, which were immediately loaded using temporary fixed dentures. The IT results, PT values, and ISQ results were recorded. Receiver operating characteristic analysis was performed to assess the quality of each parameter as a diagnostic test. RESULTS: After a 3-month observation period, 11 implants in four patients were not osseointegrated. The IT and ISQ (IT 25.0 ± 12.5 Ncm and 8.4 ± 2.3 Ncm; PT -1.5 ± 3.0 and +2.7 ± 3.0; and ISQ 62.6 ± 6.7 and 54.7 ± 6.2) differed significantly between the osseointegrated and failed implants (p < .005). The IT showed the greatest specificity at a sensitivity of 1 and the greatest area under the curve (AUC; 0.929), followed by the PT value (AUC = 0.836) and ISQ (AUC = 0.811). CONCLUSIONS: Among the intraoperative parameters analyzed, IT showed the highest specificity at a high sensitivity of 1. Therefore, the IT can be considered the most valid prognostic factor for osseointegration of immediately loaded splinted dental implants.

A comparison of three different attachment systems for mandibular two-implant overdentures: one-year report.

BACKGROUND: There is a lack of clinical studies on the self-aligning attachment system (Locator(R); Zest Anchors, Inc. homepage, Escondido, CA, USA) for two-implant-retained overdentures in the edentulous mandible. Therefore, a comparison of the Locator with two traditional designs (a rotational gold matrix and a rubber O-ring type) in clinical 1-year use was conducted. MATERIALS AND METHODS: From 2003 to 2007, 60 patients received two Osseotite(R) TG Standard implants (BIOMET 3i Implant Innovations, Palm Beach Gardens, FL, USA) in the intraforaminal area of the edentulous mandible. The implants were left unloaded for 3.5 months, randomized to three different attachment systems, and loaded through a mandibular overdenture. Twenty-three patients received a self-aligning attachment system (Locator) and 33 patients a ball attachment (Dal-Ro(R)[BIOMET 3i Implant Innovations]n = 25; TG-O-Ring(R)[Cendres & Metaux SA, Biel-Bienne, Switzerland]n = 8). After 12 months of delivery of the overdentures, the oral situation was evaluated: prosthodontic maintenance and biologic complications, subjective patients' experience, and oral health-related life quality (Oral Health Impact Profile [OHIP-G 49]). RESULTS: After 1-year of clinical service, 8 of 120 implants were lost (9.6%). The Locator system brought up 34 prosthetic complications, especially the need for change of the male parts or activation because of loss of retention. The TG-O-Ring patients showed 14 complications, most of them the change of the O-Rings. The patients with the Dal-Ro abutment had seven minor complications in 12 months of clinical use. Biologic complications and patients' oral health-related life quality showed no significant difference among the three experimental groups. CONCLUSIONS: Prosthodontic maintenance was restricted to loss of retention for all systems. Within the observation period of this study, the self-aligning attachment system showed a higher rate of maintenance than the ball attachments. The patients' oral health-related life qualities as well as the biologic parameters do not differ when using the three abutment systems.

The Randomized Shortened Dental Arch study (RaSDA): design and protocol.

BACKGROUND: Various treatment options for the prosthetic treatment of jaws where all molars are lost are under discussion. Besides the placement of implants, two main treatment types can be distinguished: replacement of the missing molars with removable dental prostheses and non-replacement of the molars, i.e. preservation of the shortened dental arch. Evidence is lacking regarding the long-term outcome and the clinical performance of these approaches. High treatment costs and the long time required for the treatment impede respective clinical trials. METHODS/DESIGN: This 14-center randomized controlled investigator-initiated trial is ongoing. Last patient out will be in 2010. Patients over 35 years of age with all molars missing in one jaw and with at least both canines and one premolar left on each side were eligible. One group received a treatment with removable dental prostheses for molar replacement (treatment A). The other group received a treatment limited to the replacement of all missing anterior and premolar teeth using fixed bridges (treatment B). A pilot trial with 32 patients was carried out. Two hundred and fifteen patients were enrolled in the main trial where 109 patients were randomized for treatment A and 106 for treatment B. The primary outcome measure is further tooth loss during the 5-year follow-up. The secondary outcome measures encompassed clinical, technical and subjective variables. The study is funded by the Deutsche Forschungsgemeinschaft (German Research Foundation, DFG WA 831/2-1, 2-2, 2-3, 2-4, 2-5). DISCUSSION: The particular value of this trial is the adaptation of common design components to the very specific features of complex dental prosthetic treatments. The pilot trial proved to be indispensable because it led to a number of adjustments in the study protocol that considerably improved the practicability. The expected results are of high clinical relevance and will show the efficacy of two common treatment approaches in terms of oral health. An array of secondary outcome measures will deliver valuable supplementary information. If the results can be implemented in the clinical practice, the daily dental care should strongly profit thereof. TRIAL REGISTRATION: The trial is registered at ClinicalTrials.gov under ISRCTN68590603 (pilot trial) and ISRCTN97265367 (main trial).