Study on prosthodontic procedure in patients with unilateral cleft lip and palate--effects of various extensions of splint on tooth-borne ability of teeth adjacent to the cleft

It is mandatory that the prosthodontic devices for the cleft palate patients not only prevent the relapse of the corrected arch and teeth by orthodontic and/or surgical intervention but also equilibrate the tooth-borne ability between the upper and the lower jaw. The purpose of this paper is to set up a criterion for the extension of the splint from the point of the tooth-borne ability. Four patients with unilateral cleft lip and palate were examined for the maximal biting force at the tooth adjacent to the cleft in each alveolar segment in the case of various extensions of the splints. The findings were as follows: 1. The maximal biting force increased significantly in every splint, compared with the non-splint. 2. The maximal biting force increased significantly in the splints where the neighbouring tooth in the same segment was involved, compared with that in the splints where only the tooth adjacent to the cleft was involved, even if the tooth in another segment increased in number for splinting. 3. The maximal biting force did not increase significantly in most splints where three teeth in the same segment were involved, compared with that in the splints where two teeth in that segment were involved.     

Oral function in patients wearing fixed prosthesis on osseointegrated implants in the maxilla

Abstract – Bite force, chewing efficiency and tactile sensibility were investigated in 21 subjects with OIB (Osseointegrated Implant bridges) in the maxilla or in both jaws. Recordings were performed before treatment, approximately I wk and finally 3–6 months after treatment. The bite force was recorded in the incisor, canine, and premolar areas and was tested at gentle biting, biting as when chewing, and maximal biting. In the chewing tests the chewing time, the chewing velocity, the time to swallowing, and the C_i (Chewing Efficiency Index) were calculated. The occlusal thickness perception was tested in the front with a 12.8 × 10⁻³ mm thick plastic foil. The maximal bite force was more than doubled, the C_i improved about one index unit, and the occlusal thickness perception improved from on average 57.5 × 10⁻³ mm to 18.7 × 10⁻³ mm during the observation time. It is concluded that treatment with upper OIB has a very positive impact on oral function as reflected by improved bite force, chewing efficiency, and occlusal thickness perception.     

Pathologic attrition and maximal bite force

The maximal bite force was recorded between antagonizing anterior teeth in a group (n = 10) of patients with pathologic attrition and in a control group. No statistically significant difference between the maximal bite forces was recorded. Also, the effect on the maximal bite force of the continuous wearing of a partial bite raising splint for 4 months was recorded. The great individuality in reaction patterns prohibited simple generalizations. However, in some individuals the maximal bite force was larger when biting on the splint than without, both at base line and after 4 months. Also, the maximal bite force showed a tendency to increase with time. The findings indicate that pathologic attrition is not necessarily associated with a high maximal bite force. Also, the maximal bite force recorded under various conditions is seemingly not an absolute value but rather the result of a number of factors of varying importance for different individuals.     

Biomechanical effects of splint types on traumatized tooth: a photoelastic stress analysis

Abstract –  This study was undertaken to assess the effect of splint type on stresses occurring around traumatized tooth by photoelastic stress analysis. Three semi-rigid splint types – a wire-composite splint, fiberglass splint and titanium trauma splint – were utilized for comparisons. Extracted left upper central and lateral incisors and the canine tooth of an otherwise healthy patient were embedded equidistantly in photoelastic resin. For all cases studied, a static axial and 20° oblique force of 100 N was applied on the lateral incisor in separate sessions. The experiments were undertaken without any splint application (unsplinted, control) after which the splints, adhesively bonded to the labial aspects of teeth, were consecutively tested. During each loading sequence, generation of isochromatic fringes was observed in the field of a polariscope, and photographed by a digital camera. Quantification of fringes was performed on magnified images, transferred to a PC. Under vertical loading, the highest stresses in the apical regions were observed for the unsplinted and ribbond-splint groups, whereas the lowest fringes occurred with the use of orthodontic wire as a splinting medium. Titanium trauma splint had absolutely no effect on reduction of stresses, as the fringe orders were slightly higher than the unsplinted lateral tooth. The use of orthodontic wire resulted in lowest fringe orders around the traumatized tooth.     

Comparison of a new dental trauma splint device (TTS) with three commonly used splinting techniques

Abstract – Splinting is the standard of care for stabilization of replanted or repositioned permanent teeth following trauma. The present experimental study compared four dental trauma splints in 10 volunteers. The evaluated splints included a wire-composite splint (WCS), a button-bracket splint (BS), a resin splint (RS), and a new device (TTS=Titanium Trauma Splint) specifically developed for splinting traumatized teeth. All splints were bonded to the labial surfaces of the maxillary lateral and central incisors. Splints were left in place for 1 week. After splint removal, the next splint was placed after a 1-week rest period. The sequence of splint application was randomized for each individual. The following parameters were assessed: tooth mobility with horizontal and vertical Periotest values (PTV) before and after splint application and splint removal, respectively; probing depths, plaque and bleeding on probing indices before splint application and removal, and chair time needed for splint application and removal. After splint application, horizontal PTV were significantly lower in central incisors for BS compared to TTS ( P =0.04), and for RS compared to TTS ( P =0.005) and to WCS ( P =0.006). Reduction of lateral tooth mobility (=splint effect) expressed by the difference between horizontal pre- and postoperative PTV was significantly greater in RS compared to TTS and WCS ( P <0.05) for central as well as for lateral incisors. However, changes of vertical tooth mobility were not significant across the splinting techniques. Periodontal parameters remained unchanged, reflecting the excellent oral hygiene by the study subjects. The chair time needed for splint application was significantly shorter for TTS ( P <0.01). In conclusion, all tested splints appeared to maintain physiologic vertical and horizontal tooth mobility. However, the latter was critically reduced in RS splints.     

Effects of jaw clenching while wearing an occlusal splint on awareness of tiredness,bite force,and EEG power spectrum

PurposeTreatment with an occlusal splint is used for temporomandibular disorders, bruxism, and occlusal disturbance to relieve orofacial symptoms such as myofascial pain and jaw movement restriction. However, the effects of various types of occlusal splints have not been elucidated. We investigated the effects of jaw clenching with soft and hard occlusal splints on the awareness of tiredness, bite force, and EEG activity.MethodsSix healthy adults were used as subjects, with a visual analogue scale utilized to evaluate the awareness of each patient's tiredness both preceding the session and following the clenching trials. In addition, a Dental Prescale was used to measure bite force and an EEG recording was conducted while performing jaw clenching. The jaw clenching task comprised 1 min of maximal voluntary clenching under 3 kinds of clenching conditions: with natural dentition, and with soft and hard occlusal splints, which were each repeated 5 times.ResultsJaw clenching with natural dentition and a hard occlusal splint did not cause a significant awareness of tiredness following repetitive jaw clenching, and there was not a significant alteration of EEG spectrum values with those conditions. In contrast, jaw clenching with a soft occlusal splint caused a significant increase in awareness of tiredness, as well as significant decreases in bite force and EEG alpha 2 power spectrum values.ConclusionsJaw clenching with a soft resilient occlusal splint causes an awareness of tiredness, which might be accompanied by declines in bite force and EEG spectrum values.     

正常(牙合)牙尖交错位咬合平衡的定量研究

目的　对正常（牙合）牙尖交错位（ICP）最大（牙合）力咬合进行定量研究，初步探讨ICP咬合平衡的生理范围。方法　应用T－Scan　Ⅱ系统记录123名正常骀者ICP最大（牙合）力的咬合情况，测量并计算力的中心点（COF）、（牙合）力百分比值、胎接触点数目。结果　正常胎者ICP最大（牙合）力时力的中心点相对位置、（牙合）力百分比差值以及不对称系数均服从正态分布，95％参考值范围分别为：－6．60～6．68mm，－15．50％～12．10％，0．65～1．39；98．4％的正常（牙合）者ICP最大（牙合）力咬合时力的中心点分布于后牙区。结论　正常（牙合）者最大（牙合）力时ICP咬合是稳定、平衡的咬合。     

Maximal bite force in patients with reduced periodontal tissue support with and without splinting

BACKGROUND: Chewing and biting forces are supposed to be limited by sensory input from periodontal mechanoreceptors. This is why the threshold level of those receptors should be lower in teeth with reduced periodontal tissue support. The purposes of the present study were to evaluate the influence of reduced periodontal tissue support on maximal bite force in natural dentitions and to study the effect of splinting on maximal bite force. METHODS: In 10 patients with reduced periodontal tissue support (test), as well as in 10 periodontally healthy subjects (control), maximal bite force was measured. The remaining periodontal ligament area in the test group was calculated from x-rays. Bite force was assessed at 4 mm mouth opening in the premolar region without and following splinting of the posterior teeth and transduced using a strain-gauge (full-bridge circuit). Maximal bite force measured with and without splinting was compared between test and control subjects, and within each group. RESULTS: In test subjects, the mean periodontal ligament area was 48.5% (SD = 10.1) across first premolars and 50.0% (SD = 12.2) across posterior teeth (control: 100%). In test subjects, the mean maximal bite force without splinting was 357 N (SD = 70), and in control subjects, 378 N (SD = 66; P > 0.05). After splinting, the bite force in test subjects was 509 N (SD = 75), and in control subjects, 534 N (SD = 49; P > 0.05). Bite force before and after splinting was P < 0.05 within each group. CONCLUSIONS: Reduced periodontal tissue support does not seem to limit bite force with maximal strength in natural dentitions as measured by a device that opens the bite by 4 mm. Furthermore, maximal biting forces at 4 mm mouth opening are increased when molar teeth are included in a posterior splint.     

Maximal bite force with centric and eccentric load

Premolar bite force was measured conventionally with a pressure transducer. During biting the tips of the buccal cusps made contact with the transducer. It was shown that the maximal bite force increased significantly if the eccentric load on the upper premolar was made centric and axial with respect to the transducer by covering the whole occlusal surface of the tooth with a plastic filling. Possible neurophysiological explanations of the difference in bite force are discussed. It is concluded that biting on a pressure transducer with an eccentric load cannot give a fair estimation of the true value of the maximal bite force during clenching in the position of intercuspidation.     

Impact of posterior occlusal support on the condylar position

The purpose of this study was to investigate condylar displacement related to the loss of posterior occlusal support. Each of 23 subjects received one occlusal adjusted splint that covered all teeth from the right to the left second mandibular molar. None of the subjects had a third molar and none of them had a missing tooth or showed tooth mobility. The splint was inserted and vertical and horizontal condylar position was measured by an ultrasonic motion analyser. The splint was then unilateraly shortened tooth-by-tooth up to the canine tooth and the measurement was repeated after each shortening. Cutting off the splint's second molar on one side lead to a slight ipsilateral cranial motion of the condyle if subjects clenched with maximum voluntary force. If the second and first molar were cut off, a noticeable cranial condylar movement of about 0.3 mm was observed even when teeth occluded with low force. These results suggest that loss of posterior occlusal support as it happens in routine oral rehabilitation leads to a noticeable cranial condyle movement during registration, even if the clenching force is low.     

Rigidity of commonly used dental trauma splints

Abstract – Background/Aims: The stability of immobilization devices varies from flexible to rigid, depending on the trauma. We evaluated the rigidity of various commonly used splints in vitro Material and Methods: An acrylic resin model was used. The central incisors simulated injured teeth, with increased vertical and horizontal mobility. The lateral incisors and canines stimulated uninjured teeth. Tooth mobility was measured with the Periotest^® device. Vertical and horizontal measurements were made before and after splinting, and the difference between values was defined as the splint effect. We evaluated 4 composite splints, 3 wire‐composite splints, a titanium trauma splint, a titanium ring splint, a bracket splint, and 2 Schuchardt splints Results: For all injured teeth and all splints, there was a significant splint effect for the vertical and horizontal dimensions (P < 0.05). For injured teeth, the composite splints produced the largest changes in vertical tooth mobility; wire‐composite splints 1 and 2, using orthodontic wires, produced the smallest vertical splint effects. For uninjured teeth, the Schuchardt 1 splint and the bracket splint produced the largest splint effects; wire‐composite splints 1 and 2 produced only a slight change in tooth mobility. Composite splints 2 and 3 produced the largest horizontal splint effects for injured teeth, and the 4 composite splints produced the largest horizontal splint effects for uninjured teeth. The most horizontally flexible splints were the titanium trauma splint and wire‐composite splints 1 and 2. Conclusions: According to the current guidelines and within the limits of an in vitro study, it can be stated that flexible or semirigid splints such as the titanium trauma splint and wire‐composite splints 1 and 2 are appropriate for splinting teeth with dislocation injuries and root fractures, whereas rigid splints such as wire‐composite splint 3 and the titanium ring splint can be used to treat alveolar process fractures.     

Comparison of the flexibility of various splinting methods for tooth fixation

An experimental model was constructed to test the flexibility of the arch bar splint and the Schuchardt splint as compared with a newly introduced wire-composite splint. Vertical movement in 4 flexible incisors was tested by producing compressive forces between 15-95 Newtons on the incisal edges. The thinnest wire-composite splint was also tested for lateral flexibility by producing palatal forces from 2 angles. Movement without the splint served as the control. The tests showed that a 0.3 mm thick wire-composite splint had the flexibility closest to the control, followed by the arch bar splint, and 0.4 mm and 0.5 mm wire-composite splints, while the Schuchardt splint virtually prevented vertical movement. Lateral movement was markedly reduced by the 0.3 mm wire-composite splint as compared with the control with both a 10 degree and a 45 degree force. The experiments showed that a 0.3 mm wire-composite splint can be regarded as acting as a functional fixation allowing slight vertical movement of the teeth during immobilisation; it should be recommended for tooth fixation whenever possible.     

Oral function in subjects with overdentures supported by osseointegrated implants

Abstract – Nine subjects treated with overdentures on osseointegrated implants in the mandible were functionally evaluated before and after treatment. The last recordings were performed 1 yr after treatment. The evaluation comprised a subjective and a clinical examination. Measurements of bite force and of chewing efficiency were also performed. The bite force was measured during gentle biting, biting as when chewing and biting with maximal effort. Almonds, were used as test food. All subjects improved subjectively as well as clinically after treatment. The bite force during gentle biting increased on average from 17.3 N before treatment to 24.0 N 1 yr after treatment. A corresponding improvement of biting as when chewing was also found, from on average 24.0 N before to 38.7 N after treatment. The maximal bite force increased from on average 74.6 N at the baseline examination to 131.5 N at the 1-yr follow-up. The chewing efficiency improved from C_i=4 (Median value) before treatment to C_i=2.8 (Median value) after treatment. It is concluded that treatment with an overdenture supported by osseointegrated implants in the mandible improves oral function compared to the situation before treatment.     

Effects of difference of occlusal splint contacts on masticatory system]

The short-term effects of the difference of occlusal splint contacts on the jaw function were investigated on five healthy subjects. The maxillary stabilization splint (S-type) was fabricated and sectioned into three parts: an anterior section (A-type) and two posterior sections (P-type). These 3 types of splints were used for 10 days for each subject. The EMG activity of the masseter and the anterior and the posterior temporal muscles were measured during the maximum clenching in the intercuspal position and on the wearing splint. Subsequently on the bite force-measuring device with two transducers the bite and the EMG activity were measured during the maximum clenching, and the intercuspal occlusal contacts were recorded. The results were as follows: 1. After wearing the P-type, the total EMG activity during clenching in the intercuspal position was decreased, then increased after removal. 2. After wearing the S-type and the A-type the anteroposterior distribution of the bite force during clenching was changed, then returned after removal. 3. After wearing the A-type, the occlusal contact area of the anterior teeth in the intercuspal position was decreased, then increased after removal, while after wearing the S-type and the P-type that of the posterior teeth was decreased, then increased after removal.     

[牙合]垫对牙齿重度磨耗患者口颌功能影响的临床研究

目的：研究殆垫对牙齿重度磨耗患者口颌功能的影响。方法：用殆垫恢复10例牙齿重度磨耗患者的垂直距离,分别检测治疗前、治疗后1个月、3个月、6个月的咬合平衡性、咬肌及颞肌前束的肌电幅值、颌位及殆的稳定性以及边缘运动的平滑度及对称性的变化。结果：①咬合平衡性、颌位及胎的稳定性以及边缘运动轨迹的平滑度及对称性在治疗后呈逐渐改善趋势,治疗6个月后80％的患者恢复正常;②治疗后各组的息止位肌电幅值均较治疗前显著降低（P〈0．05）,正中颌位紧咬时肌电幅值在治疗后3个月组和6个月组较治疗前显著增加（P〈O．05）。结论：通过6个月的治疗和观察,聆垫对重度磨耗患者的口颌功能的影响呈现持续改善趋势。     

A 10-year follow-up study of the masticatory system after treatment with osseointegrated implant bridges

Abstract – Twenty-one patients with osseointegrated implant bridges (OIB), with an average age of 65 yr, were functionally examined at a 10-yr follow-up. Altogether 27 OIBs, supported by 138 fixtures, were examined. The examination comprised an anamnestic and clinical examination and registration of bite force. 90% of the patients were very satisfied with the outcome of the treatment. According to the anamnestic dysfunction index (Ai), 80% of the patients were symptom free in their masticatory system. The occlusal state was found to be good. Seventy-five percent of the patients were found to have only mild dysfunction of their masticatory system or to be symptomless according to the clinical dysfunction index (Di). The bite force ranged from 3 to 118 N at gentle biting, from 25 to 250 N at "biting as when chewing" and from 77.5 to 495.5 N at maximal bite force. On average the bite force had improved significantly at all biteforce levels tested compared to an examination 10 yr earlier. It is concluded that oral function in patients with OIBs is very favorable.     

Effect of muscle relaxation splint therapy on the electromyographic activities of masseter and anterior temporalis muscles

The purpose of this study was to compare the effectiveness of splint therapy on the electromyographic activity of masticatory muscles (anterior temporalis and masseter) before and after the application of a muscle relaxation splint. Electromyography recordings from the masseter and anterior temporalis muscles were analyzed quantitatively during maximal biting in the intercuspal position both before and after treatment without a splint. Fourteen patients whose chief complaint was masticatory muscle pain were selected for the study. After the initial evaluations muscle relaxation splints were applied, and the patients were instructed to use the splints for 6 weeks. Surface electromyographic recordings were taken from each patient before the beginning of clinical therapy and after 6 weeks of wearing the splints. The data obtained were analyzed through paired sample t tests and Wilcoxon's signed rank tests. The results of the study were as follows: (1) the electromyographic activity of the two muscles during maximal biting was not markedly changed after the muscle relaxation splint was used; and (2) the changes observed in electromyographic activity of the involved and noninvolved sides were insignificant as well.     

Rigidity of various fixation methods used as dental splints

Abstract Horizontal and vertical rigidity of teeth fixed with seven types of denial splints were evaluated by two tooth mobility measuring devices. Altogether 21 dissected sheep mandibles including soft tissues were used for the experiments in which Fermit, flexible wire-composite, Kevlar, Fiber, Protemp, rigid wire-composite and Triad Gel splints were applied to four incisors. The mean rigidity of the central incisors within the splint was measured by means of Mühlemann periodontometer (horizontal mobility) and Periotest (horizontal and vertical mobilities). Mobility values of teeth before splinting were used as covariants and the values with the splints were illustrated as adjusted mobility. Statistical significance between the rigidity of various splints was analyzed by an unpaired t-test. It was shown that the most rigid splints both in horizontal and vertical directions were Triad Gel, rigid wire-composite and Fermit splints. Kevlar and Fiber splint allowed more horizontal movement than other splints. Protemp and flexible wire-composite splints proved to produce adequate lateral support for the fixed teeth and allowed vertical flexibility which is experimentally known to improve periodontal healing of luxated teeth.     

The effect of splint material and thickness on tooth mobility after extraction and replantation using a human cadaveric model

Although current guidelines for the treatment of traumatic injuries recommend the use of 'flexible' splints, the precise definition of what is considered flexible versus rigid has not been rigorously defined, leaving the clinician with a wide range of options for this critical factor. The purpose of this study was to quantify and compare the effect of eight different splints on tooth mobility after extraction and replantation using a human cadaveric model. Following strict selection criteria including complete root maturation, lack of periodontal disease, normal bone levels, and crown integrity, a maxillary central incisor was atraumatically extracted and splinted with eight different splints. The experimental splints included a 30-pound test monofilament nylon-composite splint and six wire-composite splints made of wires of 0.012' (0.3 mm), 0.016' (0.4 mm), or 0.020' (0.5 mm) diameter stainless steel (SS) or nickel titanium (NT). A direct composite splint represented the most rigid type of splint. These eight splints were applied five times each, and tooth mobility was measured before and after each splint was applied. The average splint effect, defined as the difference between the presplint and the postsplint measurements quantified using the Periotest, was calculated for each splint and compared. No significant differences were found between the nylon-composite and the wire-composite splints. There was significantly less tooth mobility with the direct composite splint compared to all other splints. In conclusion, the results of this study suggest that nylon and SS or NT wires up to 0.016' diameter are significantly more flexible than direct composite splints and thus may be better suited for the splinting and management of traumatized teeth.     

Rigidity of various fixation methods used as dental splints.

Horizontal and vertical rigidity of teeth fixed with seven types of dental splints were evaluated by two tooth mobility measuring devices. Altogether 21 dissected sheep mandibles including soft tissues were used for the experiments in which Fermit, flexible wire-composite, Kevlar, Fiber, Protemp, rigid wire-composite and Triad Gel splints were applied to four incisors. The mean rigidity of the central incisors within the splint was measured by means of Mühlemann periodontometer (horizontal mobility) and Periotest (horizontal and vertical mobilities). Mobility values of teeth before splinting were used as covariants and the values with the splints were illustrated as adjusted mobility. Statistical significance between the rigidity of various splints was analyzed by an unpaired t-test. It was shown that the most rigid splints both in horizontal and vertical directions were Triad Gel, rigid wire-composite and Fermit splints. Kevlar and Fiber splint allowed more horizontal movement than other splints. Protemp and flexible wire-composite splints proved to produce adequate lateral support for the fixed teeth and allowed vertical flexibility which is experimentally known to improve periodontal healing of luxated teeth.