Tightness of dental contact points in spaced and non-spaced permanent dentitions

Separation effect, pain perception during functional activity and gingival inflammation of elastomeric and Kansal separators-a split mouth study

INTRODUCTION

An effective space opening for band placement with minimal pain and gingival inflammation is a prime requisite during fixed orthodontic procedures. The study aimed to compare the effectiveness of two types of separators, elastomeric and Kansal, in the amount of space opening, pain perception elicited, and gingival inflammation.

METHODS

A random split-mouth study was designed with 30 subjects undergoing fixed orthodontic treatment. Two different separators (Elastomer and Kansal) were placed alternatively on the left and right sides around the mesial and distal sides of the first molars in the mandibular arch of each subject. After 3 days, the amount of separation after 3 days was assessed with a leaf gauge on both mesial and distal sides. The subjective pain perception by visual analog Scale (VAS) at different points and during different functions for each of the 3 days was evaluated. A self-filled chart was utilized to be performed by the patients. Gingival index was used to assess the inflammatory changes.

RESULTS

The most significant amount of separation (0.28 mm) was found with elastomers on the mesial side and is statistically significant (p < 0.001) compared to the mesial side (0.18 mm). The Kansal separators produced equivalent separation on mesial (0.19 mm) and distal sites (0.17 mm). The highest pain score was found after 24 h with elastomeric separators (median-40) for chewing and biting and the least for sleep (median-30). There is a statistical difference of pain perception between elastomers and Kansal separators at different points for the given function (p < 0.001). Both the separators resulted in mild gingival index of score less than 1 (0.70 ± 0.65, 0.97 ± 0.720, and there was no statistically significant difference between the two types of separators.

CONCLUSION

Both the separators produced adequate separation after a minimum 3 days. Kansal produces minimum discomfort and pain compared to elastomeric separators. Mild gingival inflammation was observed with both the separators.

Effect of orthodontic extraction of mandibular premolars on third molar angulation after treatment with fixed appliances : A cross-sectional study

PURPOSE

Orthodontic treatment involving premolar extractions might improve the angulation of lower third molars, which are the teeth most often impacted. This study analyzes the impact of first/second lower premolar extraction during orthodontic therapy on the angulation of mandibular third molars.

METHODS

A total of 120 patients treated non-extraction (n = 40), with extraction of first (n = 40), or second lower premolars (n = 40) were included. The mesiodistal angulation of lower third molars relative to the adjacent tooth and their developmental stage were evaluated from posttreatment orthopantomograms. Between-group differences were statistically evaluated at a significance level of 0.05.

RESULTS

The orthopantomograms of 120 patients (51% female) with a median age of 15.2 years at the time of debonding were evaluated after a mean treatment duration time of 2.9 years. No difference (P > 0.05) was seen between the average angulation of the lower third molars of the right (mean = 24.4°, standard deviation [SD] 13.6°) and the left side (mean = 23.6°, SD 14.1°). No differences in the angulation of the lower third molar were found between the non-extraction and extraction groups for the right (P = 0.44) or the left side (P = 0.22). Likewise, no differences were found when comparing the first and second premolars for the right (P = 0.26) or the left side (P = 0.10). Premolar extraction was associated with an advanced root development stage of the right third molar (odds ratio 7.1; 95% confidence interval 1.1-48.1; P = 0.04), with no differences between extraction of the first or second premolar (P = 0.10).

CONCLUSION

Orthodontic treatment involving premolars extractions might be associated with a small acceleration in root development, but not with the angulation, of lower third molars.

Evaluation of biological changes at the proximal contacts between single-tooth implant-supported prosthesis and the adjacent natural teeth - An in vivo study

Aim

The aim of the study is to evaluate the proximal contact tightness (PCT) between single-tooth implant-supported prosthesis (ISP) and the adjacent natural teeth with and without the intervention of the Essix retainer at the end of 1 year.

Settings and Design

In vivo -experimental study.

Materials and Methods

Forty patients with a single ISP in the first molar region of the mandibular arch are included in the study who were randomly divided into two groups - Group I (20): those without an intervention of Essix retainer and Group II (20): those with the intervention of Essix retainer (2 mm thickness) (Thermo Vac, Inc. USA) delivered immediately after the restoration of implant with the definitive prosthesis. The groups are further subdivided into Subgroups A (control) and B within Group I and Subgroups C (control) and D within Group II. Mesial and distal PCT values were recorded in each quadrant using the digital force gauge, and values obtained at the end of 1 year were subjected for statistical analysis.

Statistical Analysis Used

Independent sample t-test was performed. P < 0.05 was taken as statistically significant.

Results

On nonusage of Essix retainer, in comparison to the control group, there were a 57.9% decrease in PCT values for the ISP on mesial contact (P < 0.05) and a 38.9% decrease for the distal contact (P > 0.05), whereas on the usage of Essix retainer, the PCT values for ISP on mesial contact decreased to 25.3% (not significant) and 33.7% on the distal contact (P > 0.05). The incidence of contact loss was found to be 30%, whereas it decreased to 15% on the usage of Essix retainer.

Conclusion

The usage of Essix retainer showed a significant difference in increasing the PCT values, especially on the mesial contact. The incidence of contact loss, which was found to be 30%, decreased to 15% on its usage.

Evaluation of presence of proximal contacts on recently inserted posterior crowns in different health sectors in Riyadh City, Saudi Arabia

Background

For the successful outcome of the rehabilitation of the teeth with crown, the proximal contact points play a significant role hence the aim of the present study was to evaluate the presence of proximal contacts on recently inserted crowns in posterior teeth.

Methods and Materials

The cross-sectional study was conducted on recently inserted posterior crowns. Clinical assessment of proximal contact points on crowns was made with dental floss, the floss was wrapped around the index fingers of both hands and was passed through the crowns mesial and distal contact points and was categorized as acceptable, open contact points, and tight contact points.

Results

In the present study 401 crowns were examined to assess proximal contacts on 788 proximal surfaces. It was found that 522 (66.2%) crowns were in normal proximal contact, 144 (18.3%) showed open proximal contacts, 122 (15.5%) showed tight proximal contacts.

Conclusion

Regarding the assessment of proximal contacts, the study showed that a significant number of crowns had open or tight proximal contacts. Specialists and residents were able to perform better in providing the optimum proximal contacts.

Separation and pain perception of Elastomeric, Kesling and Kansal separators

Introduction:

Various types of separators have been advocated, but the ideal separator should produce optimum separation with minimal pain and discomfort.

Objective:

The objective of this study was to evaluate and compare the amount of separation achieved by three different types of separators (Elastomeric, Kesling and Kansal), and to assess the associated pain and discomfort.

Methods:

A random single-blind split-mouth study was conducted on 108 patients seeking fixed orthodontic treatment, in which two different separators were used on each side in both the arches for a single patient. After five days, the amount of separation was measured with a feeler gauge. Visual Analogue Scale (VAS) scoring was performed by the patient on each day, to evaluate pain perception. Discomfort was evaluated by questionnaire filled by the patient at the time of separator removal.

Results:

The greatest amount of separation was seen with the elastomeric separators, while the smallest separation was seen with Kansal separators. VAS scoring showed maximum pain at day 1 with all the three separator types. Highest pain was perceived in the Elastomeric separators group, followed by Kesling and Kansal separators, respectively. Statistically significant difference was found in VAS score of Elastomeric separators, when compared to both Kesling and Kansal, on day 1 and 2 (p= 0.001). Analysis of the questionnaires revealed that a greater number of patients experienced discomfort with elastomeric separators placement (69.4%), which was statistically significant (p< 0.01) when compared to the other two types of separators. Answers to the other questions were comparable, except for the need for medications, which was reportedly highest with elastomeric separators.

Conclusion:

Kesling separators produce adequate separation with minimal discomfort and pain, compared to Elastomeric and Kansal separators.

The anterior component of occlusal force revisited: direct measurement and theoretical considerations

BACKGROUND

The anterior component of occlusal force (ACF), considered to result from the mesial inclination of teeth relative to the occlusal plane, has been estimated by indirectly measuring contact point tightness (CPT) through interproximal insertion of metal strips. ACF has been observed concurrently with a posterior component, whose theoretical origin is difficult to explain.

OBJECTIVES

Evaluate ACF by measuring CPT directly, and integrate current data to propose a theoretical basis for ACF.

MATERIALS AND METHODS

The sample comprised 14 females (age: 22.3±2.8) and 16 males (age: 20.8±2.5). Our device consisted of two force sensors: one for measuring maximum bite force (MBF) (overall thickness: 4mm), and one for measuring CPT directly (0.2mm thick), inserted between the lower first molar and second premolar. ACF was computed as the difference in CPT between the biting (at 75 per cent of MBF) and non-biting conditions.

RESULTS

Averages of MBF, CPT, and ACF were 666.67 [standard deviation (SD): 36.06], 6.74 (SD: 1.17), and 20.59 (SD: 4.60) N, respectively. ACF, CPT, and MBF were higher in males by approximately 28, 18 and 7 per cent, respectively. A positive correlation was observed between ACF and MBF (R (2): 0.64). CPT was also significantly correlated to MBF (R (2): 0.40). Biomechanical analysis indicates that previously offered explanations do not unriddle the concurrent increase of CPT at anterior and posterior contact points.

CONCLUSIONS

ACF was related to bite force by a logarithmic model. We speculate that CPT increases during biting through a combination of mesial tipping of teeth and mandibular bending.

Appropriateness of viscoelastic soft materials as in vitro simulators of the periodontal ligament

The periodontal ligament is a viscoelastic soft tissue that connects the tooth to the alveolar bone. This tissue should be simulated in numerical as well as in laboratory models. The mechanical properties of this tissue were previously determined ex vivo and in vivo. The aim of the study was to analyse the appropriateness of impression and reline materials used in dentistry to simulate viscoelastic behaviour of the periodontal ligament. Two reline [Durabase (Reliance Dental MFG, Co.) and Soft Liner (GC Corporation)] and two impression [President Plus (Coltene) and Prestige L (Vanini Dental Industry)] materials were examined in recovery and tensile relaxation tests. Recovery: This experiment simulated in vivo test. Roots of a pair of plastic maxillary premolar teeth were covered with each test material and embedded in acryl while maintaining the contact point. A 0·1-mm stainless steel strip, inserted at the contact point and maintained for 10 s, was used to tip the teeth. After removal, the tightness of dental contact point was measured over 30 min by determining the force needed to insert a 0·05-mm metal strip. Tensile relaxation: strips were elongated to 120%, 140% and 160% of their initial length and maintained at that length for 30 min. Two-phase decay function was applied. The results showed that elastic modulus and relaxation behaviour were significantly different between materials. Elastic modulus values were in the same range of those reported in the literature. However, the recovery values and behaviour showed that impression materials, especially President, are the materials of choice for this purpose because they simulated better the in vivo test.

Evaluation of proximal contact strength by postural changes

STATEMENT OF PROBLEM

Proper proximal contact is important for maintaining and stabilizing the dental arch. However, the proximal contact strength (PCS) is not a constant value and can be affected by a variety of factors.

PURPOSE

This study examined the influences of postural changes on the posterior PCS.

MATERIAL AND METHODS

Twelve adults with a normal occlusion and had not undergone prosthetic treatment or proximal restoration were participated in this study. A metal strip was inserted into the proximal surface and removed at a constant velocity. The contact strength was measured in every contact point between canine to second molar in both arches. The PCSs were obtained initially in the upright position, secondly in the supine position and finally in the upright position again. All measurements were repeated after a 2 hour period. Statistical analysis was carried out using the Friedman test (P < .05).

RESULTS

Generally, a decrease in PCS occurred when the posture was changed from the initial upright to supine position, while it increased when the posture was changed from the supine to upright position. A significant change was observed in all areas except for between the canine-first premolar in the maxilla and between the first molarsecond molar in the mandible areas.

CONCLUSION

The posterior PCS, which dentists generally believe to be a static feature of occlusion, is affected significantly by posture.

Posterior and anterior components of force during bite loading

Late anterior crowding of teeth has been associated with the anterior component of force (ACF) developed during biting. Possible physiologic mechanisms countering ACF, including the presence of a posterior component of force (PCF), are hypothesized. In this self-controlled study, 60 subjects aged 27.05+/-3.9 years were examined for ACF and PCF that were calculated as the change in tightness of a mandibular dental contact points from non-biting to biting state. Both ACF and PCF were found to develop simultaneously. However, the PCF was 4-7 folds smaller than the ACF (p<0.001). The ACF progressively declined by 10-20 folds (p<0.001) from the posterior to anterior dentition. The lateral incisor-canine contact point had the greatest ACF decline (63-74%). ACF effect on the anterior dentition is counteracted by a protective mechanism consisted of PCF, progressive dissipation of ACF, and canine blockage.

Deformation/recovery cycle of the periodontal ligament in human teeth with single or dual contact points

The recovery of the human periodontal ligament after transitory tooth deflection is largely obscured. The objective here was to determine the periodontal deformation/recovery cycle of a tooth with a single or dual contact point. 'Single contact point', refers to a tooth with a contact point on one side but not on the other; 'dual contact point' refers to a tooth with two contact points. The hypothesis that a single contact point will recover more slowly due to periodontal changes, as reported in hypofunctional conditions, was tested. The tightness of the contact point between contiguous mandibular premolars (P(1)-P(2)) during a deformation/recovery cycle was measured in three groups: group 1, single contact point of P(2) (14 individuals with a missing mandibular first molar); group 2, dual contact point of the contralateral P(2) (same 14 individuals with no missing mandibular first molar); group 3, dual contact point of both P(2) (32 individuals with no missing mandibular first molars). The deformation/recovery cycle was initiated by placing a spacer for 1 min between P(1) and P(2). The recovery of the contact point P(1)-P(2) to the initial tightness was recorded in five consecutive measurements: four of these were taken at 1-min intervals and an additional measurement was made 30 min later. The contact-point tightnesses of group 1 were significantly (P<0.001) lower ( approximately 50%) than those of the control groups (groups 2 and 3). All groups showed a similar viscoelastic recovery pattern consisting of a short-term elastic response (after 1 min, 82% of the pre-deformation level was regained) and a long-term viscous response (after 30 min, an additional 6% was regained). Thus, contact-point tightness adjacent to an extraction site is strongly affected by the absence of the tooth and presumably due to reorganisation of the transseptal fibres, but this has no effect on the periodontal ligament deformation/recovery cycle, which showed a uniform viscoelastic response independent of contact-point tightness (rejecting the null hypothesis).